Table of contents

This study aims to develop a facility that can irradiate subjects with a desired low dose, which can be used to assess the biological effects of low-dose radiation. We develop a single-occupancy mouse-cage and shelf system with adjustable geometric parameters, such as the distances and angles of the cages relative to the collimator. We assess the irradiation-level accuracy using two measurement methods. First, we calculate the angle and distance of each mouse cage relative to the irradiator. We employ a Monte Carlo n-particle simulation for all of the cages at a given distance from the radiation source to calculate the air kerma and the relative absorbed dose in the in-house designed shelving system; these are found to be approximately 0.108 and 0.109 Gy, respectively. Second, we measure the relative absorbed dose using glass dosimeters inserted directly into the heads and bodies of the mice. For a conventional irradiation system, the irradiation measurements show a maximum discrepancy of 42% between the absorbed and desired doses, whereas a discrepancy of only 6% from the desired dose is found for the designed mouse apartment system. In addition, multi-mouse cages are shown to yield to significantly greater differences in the mouse head and body relative absorbed doses, compared to the discrepancies found for single-occupancy cages in the conventional irradiation system. Our findings suggest that the in-house shelving system has greater reliability for the biological analysis of the effects of low-dose radiation.

A Geant4 simulation code for the Indian National Gamma Array (INGA) consisting of 24 Compton suppressed clover high purity germanium (HPGe) detectors has been developed. The calculated properties in the energy range that is of interest for nuclear γ-ray spectroscopy are spectral distributions for various standard radioactive sources, intrinsic peak efficiencies and peak-to-total (P/T) ratios in various configurations such as singles, add-back and Compton suppressed mode. The principle of operation of the detectors in add-back and Compton suppression mode have been reproduced in the simulation. The reliability of the calculation is checked by comparison with the experimental data for various γ-ray energies up to 5 MeV. The comparison between simulation results and experimental data demonstrate the need of incorporating the exact geometry of the clover detectors, Anti-Compton Shield and other surrounding materials in the array to explain the detector response to the γ-ray. Several experimental effects are also investigated. These include the geometrical correction to angular distribution, crosstalk probability and the impact of heavy metal collimators between the target and the array on the P/T ratio.

The design, construction and test of a charged particle detector made of scintillation counters read by Silicon Photomultipliers (SiPM) is described. The detector, which operates in vacuum and is used as a veto counter in the NA62 experiment at CERN, has a single channel time resolution of 1.14 ns, a spatial resolution of ∼2.5 mm and an efficiency very close to 1 for penetrating charged particles.

In the recent years new digital photon counter devices (also known as silicon photomultipliers, SiPMs) were designed and manufactured to be used specifically in positron emission tomography (PET) scanners. These finely pixelated devices opened new opportunities in PET detector development, hence their application with monolithic scintillator crystals now are of particular interest. We worked out a simulation tool and a corresponding validation method to assist the optimization and characterization of such PET detector modules. During our work we concentrated on the simulation of SPADnet sensors and the LYSO:Ce scintillator material. Validation of our algorithms combines measurements and simulations performed on UV-excited detector modules. In this paper we describe the operation of the simulation method in detail and present the validation scheme for two demonstrative PET detector-like modules: one built of a scintillator with black-painted faces and another with polished faces. By evaluating the results we show that the shape deviation of the average light distributions is lower than 13%, and the pixel count statistics follow Poisson distribution for both measurement and simulation. The calculated total count values have less than 10% deviation from the measured ones.

A detector based on doped silica and optical fibers was developed to monitor the profile of particle accelerator beams of intensity ranging from 1 pA to tens of μA. Scintillation light produced in a fiber moving across the beam is measured, giving information on its position, shape and intensity. The detector was tested with a continuous proton beam at the 18 MeV Bern medical cyclotron used for radioisotope production and multi-disciplinary research. For currents from 1 pA to 20 μA, Ce³⁺ and Sb³⁺ doped silica fibers were used as sensors. Read-out systems based on photodiodes, photomultipliers and solid state photomultipliers were employed. Profiles down to the pA range were measured with this method for the first time. For currents ranging from 1 pA to 3 μA, the integral of the profile was found to be linear with respect to the beam current, which can be measured by this detector with an accuracy of ∼1%. The profile was determined with a spatial resolution of 0.25 mm. For currents ranging from 5 μA to 20 μA, thermal effects affect light yield and transmission, causing distortions of the profile and limitations in monitoring capabilities. For currents higher than ∼1 μA, non-doped optical fibers for both producing and transporting scintillation light were also successfully employed.

High voltage breakdown in liquid argon is an important concern in the design of liquid argon time projection chambers, which are often used as neutrino and dark matter detectors. We have made systematic measurements of breakdown voltages in liquid argon along insulators surrounding negative rod electrodes where the breakdown is initiated at the anode. The measurements were performed in an open cryostat filled with commercial grade liquid argon exposed to air, and not the ultra-pure argon required for electron drift. While not addressing all high voltage concerns in liquid argon, these measurements have direct relevance to the design of high voltage feedthroughs especially for averting the common problem of flash-over breakdown. The purpose of these tests is to understand the effects of materials, of breakdown path length, and of surface topology for this geometry and setup. We have found that the only material-specific effects are those due to their permittivity. We have found that the breakdown voltage has no dependence on the length of the exposed insulator. A model for the breakdown mechanism is presented that can help inform future designs.

This work presents the experimental measurements obtained for UV-induced photo-electron extraction efficiency from a CsI photocathode into He with CF₄ and CH₄ gas mixtures. A 1000Å CsI photocathode was deposited on a gold plated THGEM for photo-electron conversion. Charge-gain measurements were obtained with a Single-THGEM detector operating in these gas mixtures using a continuous UV lamp for the extraction of photo-electrons. Charge-gains in excess of 10⁵ were obtained for gas mixtures containing percentages of quencher higher than 20% while photo-electron extraction efficiency achieved ∼ 50% for He/CF₄ and ∼ 30% for He/CH₄. Single photon electron measurements were also performed to assess the maximal gains reached in this regime. A discussion for future GPM cryogenic applications is presented.

Introduction: Radiochromic films are two-dimensional dosimeters that do not require developing and give values of absorbed dose with accuracy and precision. Since this dosimeter colours directly after irradiation, it can be digitized with commercial optical flatbed scanners to obtain a calibration curve that links blackening of the film with dose. Although the film has an intrinsic high spatial resolution, the scanner determines the actual resolution of this dosimeter, in particular the "dot per inch" (dpi) parameter. The present study investigates the effective spatial resolution of a scanner used for Gafchromic® XR-QA2 film (designed for radiology Quality Assurance) analysis.

Material and methods: The quantitative evaluation of the resolution was performed with the Modulation Transfer Function (MTF) method, comparing the nominal resolution with the experimental one. The analysis was performed with two procedures. First, the 1951 USAF resolution test chart, a tool that tests the performance of optical devices, was used. Secondly, a combined system of mammography X-ray tube, XR-QA2 film and a bar pattern object was used. In both cases the MTF method has been applied and the results were compared.

Results: The USAF and the film images have been acquired with increasing dpi and a standard protocol for radiochromic analysis, to evaluate horizontal and vertical and resolution. The effective resolution corresponds to the value of the MTF at 50%. In both cases and for both procedures, it was verified that, starting from a dpi value, the effective resolution saturates.

Conclusion: The study found that, for dosimetric applications, the dpi of the scanner have to be adjusted to a reasonable value because, if too high, it requires high scanning and computational time without providing additional information.

The improvement of the coincidence resolving time (CRT) is one of the key factors for the next generation of positron emission tomography (PET) scanners. Silicon photomultipliers (SiPMs) are strong candidates to substitute photo multipliers tubes because of their compactness, ruggedness and insensitivity to magnetic fields. In order to achieve the best CRT, the SiPM should have high PDE which can be obtained increasing the bias voltage. We recently improved the NUV SiPM technology, with the addition of a new substrate type that provides significantly lower afterpulsing probability (Low-AP). This enables to extend the maximum bias voltage and thus obtain higher PDE. Additionally, we implemented a lower electric field version (Low-F) to reduce the field-enhanced thermal generation components of the dark count rate. In this work we present results of energy and timing resolution for PET application, using LYSO scintillator crystals, and coupled with 3 × 3 mm² NUV SiPMs of three types: non-Low-AP, Low-AP and Low-AP + Low-F. All the devices reach very similar energy resolutions, around 9.5 %, and close to the intrinsic limit of the LYSO. Concerning the timing resolution, we found that the Low-AP substrate achieves an improvement of the CRT of ≈ 30 ps, confirmed with the Low-F. Using 4 × 4 mm² Low-AP SiPMs coupled to 3 × 3 × 5 mm³ and 3.8 × 3.8 × 22 mm³ LYSO crystals we obtained CRTs of 130 and 200 ps FWHM, respectively.

The digital breast tomosynthesis (DBT) system is a newly developed 3-D imaging technique that overcomes the tissue superposition problems of conventional mammography. Therefore, it produces fewer false positives. In DBT system, several parameters are involved in image acquisition, including geometric components. A series of projections should be acquired at low exposure. This makes the system strongly dependent on the detector's characteristic performance. This study compares two types of x-ray detectors developed by the Korea Electrotechnology Research Institute (KERI). The first prototype DBT system has a CsI (Tl) scintillator/CMOS based flat panel digital detector (2923 MAM, Dexela Ltd.), with a pixel size of 0.0748 mm. The second uses a-Se based direct conversion full field detector (AXS 2430, analogic) with a pixel size of 0.085 mm. The geometry of both systems is same, with a focal spot 665.8 mm from the detector, and a center of rotation 33 mm above the detector surface. The systems were compared with regard to modulation transfer function (MTF), normalized noise power spectrum (NNPS), detective quantum efficiency (DQE) and a new metric, the relative object detectability (ROD). The ROD quantifies the relative performance of each detector at detecting specified objects. The system response function demonstrated excellent linearity (R²>0.99). The CMOS-based detector had a high sensitivity, while the Anrad detector had a large dynamic range. The higher MTF and noise power spectrum (NPS) values were measured using an Anrad detector. The maximum DQE value of the Dexela detector was higher than that of the Anrad detector with a low exposure level, considering one projection exposure for tomosynthesis. Overall, the Dexela detector performed better than did the Anrad detector with regard to the simulated Al wires, spheres, test objects of ROD with low exposure level. In this study, we compared the newly developed prototype DBT system with two different types of x-ray detectors for commercial DBT systems. Our findings suggest that the Dexela detector can be applied to the DBT system with regard to its high imaging performance.

The performance of Al_0.52In_0.48P avalanche photodiodes was assessed as soft X-ray detectors at room temperature. The effect of the avalanche gain improved the energy resolution and an energy resolution (FWHM) of 682 eV is reported for 5.9 keV X-rays.

This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; it reduces the number of cables in the vapor region of the TPC that can produce impurities; and it cuts down on the number of feed-throughs in the cryostat wall that can cause heat-leaks and potential points of failure. We present experimental results that demonstrate the sensitivity of a LArTPC wire plane to photon detector signals. We also simulate the effect of a 1 μs shaping time and a 2 MHz sampling rate on these signals in the presence of noise, and find that a single photoelectron timing resolution of ∼30 ns can be achieved.

Using simulated data, obtained with the FLUKA code, we derive empirical regularities about the propagation and stopping of low-energy negative muons in hydrogen and selected solid materials. The results are intended to help the preliminary stages of the set-up design for experimental studies of muon capture and muonic atom spectroscopy. Provided are approximate expressions for the parameters of the the momentum, spatial and angular distribution of the propagating muons. In comparison with the available data on the stopping power and range of muons (with which they agree in the considered energy range) these results have the advantage to also describe the statistical spread of the muon characteristics of interest.

The successive approximation register-analog to digital converter (SAR-ADC) is widely used in the CdZnTe-based gamma-ray imager because of its outstanding characteristics of low power consumption, relatively high resolution, and small die size. This study proposes a digital bit-by-bit calibration method using an input ramp signal to further improve the conversion precision and power consumption of an SAR-ADC. The proposed method is based on the sub-radix-2 redundant architecture and the perturbation technique. The proposed calibration algorithm is simpler, more stable, and faster than traditional approaches. The prototype chip of the 12-bit, 1 MS/s radiation-hardened SAR-ADC has been designed and fabricated using the TSMC 0.35 μm 2P4M CMOS process. This SAR-ADC consumes 3 mW power and occupies a core area of 856× 802μm². The digital bit-by-bit calibration algorithm is implemented via MATLAB for testing flexibility. The effective number of bits for this digitally calibrated SAR-ADC reaches 11.77 bits. The converter exhibits high conversion precision, low power consumption, and radiation-hardened design. Therefore, this SAR-ADC is suitable for multi-channel gamma-ray imager applications.

We present a study on the dependence of electric breakdown discharge properties on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

Nuclear recoil events produced by neutron scatters form one of the most important classes of background in WIMP direct detection experiments, as they may produce nuclear recoils that look exactly like WIMP interactions. In DarkSide-50, we both actively suppress and measure the rate of neutron-induced background events using our neutron veto, composed of a boron-loaded liquid scintillator detector within a water Cherenkov detector. This paper is devoted to the description of the neutron veto system of DarkSide-50, including the detector structure, the fundamentals of event reconstruction and data analysis, and basic performance parameters.

A Monte Carlo (MC) model of a mechanically-cooled High Purity Germanium detection system IDM-200-V™ manufactured by ORTEC® was created, optimized and validated within the scope of the Joint Research Project ENV57 ``Metrology for radiological early warning networks in Europe''. The validation was performed for a planar source homogeneously distributed on a filter placed on top of the detector end cap and for point sources positioned farther from the detector by comparing simulated full-energy peak (FEP) detection efficiencies with the ones measured with two or three different pieces of the IDM detector. True coincidence summing correction factors were applied to the measured FEP efficiencies. Relative differences of FEP efficiencies laid within 8% that is fully satisfactory for the intended use of the detectors as instruments for airborne radioactivity measurement in field-stations. The validated MC model of the IDM-200-V™ detector is now available for further MC calculations planned in the ENV57 project.

The measurement of high flux charged particle beams, specifically at medical accelerators and with small fields, poses several challenges. In this work we propose a single particle counting method based on CMOS imagers optimized for visible light collection, exploiting their very high spatial segmentation (> 3 10⁶ pixels/cm²) and almost full efficiency detection capability. An algorithm to measure the charged particle flux with a precision of ∼ 1%  for fluxes up to 40 MHz/cm² has been developed, using a non-linear calibration algorithm, and several CMOS imagers with different characteristics have been compared to find their limits on flux measurement.

A study of the radiation hardness of pure CsI crystals 30 cm long was performed with a uniformly absorbed dose of up to 14.3 krad. This study was initiated by the proposed upgrade of the end cap calorimeter of the Belle-II detector, using pure CsI crystals. A set of 14 crystals of truncated pyramid shape used in this study was produced at the Institute for Scintillation Materials NAS from 14 different ingots grown with variations of the growing technology. Interrelationship of crystal scintillation characteristics, radiation hardness and the growing technology was observed.

Data transmission at the upgraded Large Hadron Collider experiments, foreseen for mid 2020s, will be in the multi Gbit/s range per connection for the innermost detector layers. This paper reports on first tests on the possible use of carbon cables for electrical data transmission close to the interaction point. Carbon cables have the potential advantage of being light, having a low activation and easy integration into the detector components close to the interaction point. In these tests commercially available carbon fibres were used, in which the filaments had a very thin nickel coating. For these cables data rates beyond 1 Gbit/s over more than 1 m with an error rate of less than 10^-12 could be reached. The characteristics of the cables have been measured in terms of S-parameters and could be converted to a SPICE model. Some outlook on potential further improvements is presented.

A 100 μm thick silicon detector with 1 mm² pad readout optimized for sub-nanosecond time resolution has been developed and tested. Coupled to a purposely developed amplifier based on SiGe HBT technology, this detector was characterized at the H8 beam line at the CERN SPS. An excellent time resolution of (106 ± 1) ps for silicon detectors was measured with minimum ionizing particles.

The achievement of ultra high accelerating gradients is mandatory in order to fabricate compact accelerators at 11.424 GHz for scientific and industrial applications. An extensive experimental and theoretical program to determine a reliable ultra high gradient operation of the future linear accelerators is under way in many laboratories. In particular, systematic studies on the 11.424 GHz frequency accelerator structures, R&D on new materials and the associated microwave technology are in progress to achieve accelerating gradients well above 120 MeV/m. Among the many, the electroforming procedure is a promising approach to manufacture high performance RF devices in order to avoid the high temperature brazing and to produce precise RF structures. We report here the characterization of a hard high gradient RF accelerating structure at 11.424 GHz fabricated using the electroforming technique. Low-level RF measurements and high power RF tests carried out at the SLAC National Accelerator Laboratory on this prototype are presented and discussed. In addition, we present also a possible layout where the water-cooling of irises based on the electroforming process has been considered for the first time.

Photosensors have played and will continue to play an important role in high-energy and Astroparticle cutting-edge experiments. As of today, the most common photon detection device in use is the photomultiplier tube (PMT). However, we are witnessing rapid progress in the field and new devices now show very competitive features when compared to PMTs. Among those state-of-the-art photo detectors, silicon photomultipliers (SiPMs) are a relatively new kind of semiconductor whose potential is presently studied by many laboratories. Their characteristics make them a very attractive candidate for future Astroparticle physics experiments recording fluorescence and Cherenkov light, both in the atmosphere and on the ground. Such applications may require the measurement of the light flux on the sensor for the purpose of energy reconstruction. This is a complex task due to the limited dynamic range of SiPMs and the presence of thermal and correlated noise. In this work we study the response of three SiPM types in terms of delivered charge when exposed to light pulses in a broad range of intensities: from single photon to saturation. The influence of the pulse time duration and the SiPM over-voltage on the response are also quantified. Based on the observed behaviour, a method is presented to reconstruct the real number of photons impinging on the SiPM surface directly from the measured SiPM charge. A special emphasis is placed on the description of the methodology and experimental design used to perform the measurements.

The non-invasive imaging of dense objects is of particular interest in the context of nuclear waste management, where it is important to know the contents of waste containers without opening them. Using Muon Scattering Tomography (MST), it is possible to obtain a detailed 3D image of the contents of a waste container on reasonable timescales, showing both the high and low density materials inside. We show the performance of such a method on a Monte Carlo simulation of a dummy waste drum object containing objects of different shapes and materials. The simulation has been tuned with our MST prototype detector performance. In particular, we show that both a tungsten penny of 2 cm radius and 1 cm thickness, and a uranium sheet of 0.5 cm thickness can be clearly identified. We also show the performance of a novel edge finding technique, by which the edges of embedded objects can be identified more precisely than by solely using the imaging method.

In this contribution we present results concerning the very first application of fiber optic sensors (FOSs) for relative humidity (RH) monitoring in high radiations environments. After a few years of investigations at CERN in Geneva, since December 2013 our multidisciplinary research group has successfully installed 72 thermo-hygrometers based on Fiber Bragg Grating (FBG) technology, organized in multi-points arrays, in cold areas of the Tracker Bulkhead of the Compact Muon Solenoid (CMS) experiment, where hundreds of electrical connectors are housed and thousands of services, including many cold pipes, cross the volumes through them. In such a complicated environment, a constant hygrometric monitoring is vital, in order to avoid dangerous phenomena of condensation. The collected results in the last year of operation of the proposed sensors are effective and reliable, with temperature, relative humidity and dew point temperature measurements from the FBG-based devices in full agreement with the readings of conventional sensors, temporarily present in the detector. However, experience in operation has shown some limitations of this technology, which are fully detailed in the last section of the paper.

Several modern applications of radiation processing like medical sterilization, rubber vulcanization, polymerization, cross-linking and pollution control from thermal power stations etc. require D.C. electron accelerators of energy ranging from a few hundred keVs to few MeVs and power from a few kilowatts to hundreds of kilowatts. To match these requirements, a 3 MeV, 30 kW DC electron linac has been developed at BARC, Mumbai and current operational experience of 1 MeV, 10 kW beam power will be described in this paper. The LINAC composed mainly of Electron Gun, Accelerating Tubes, Magnets, High Voltage source and provides 10 kW beam power at the Ti beam window stably after the scanning section. The control of the LINAC is fully automated. Here Beam Optics study is carried out to reach the preferential parameters of Accelerating as well as optical elements. Beam trials have been conducted to find out the suitable operation parameters of the system.

A simulation study of two kinds of scintillation detectors has been done using GEANT4. We compare plastic scintillator and liquid scintillator based designs for detecting electron antineutrinos emitted from the core of reactors. The motivation for this study is to set up an experiment at the research reactor facility at BARC for very short baseline neutrino oscillation study and remote reactor monitoring.

A method of measurement of the energy of electrons extracted from the VEPP-4M accelerator is described. The method was verified experimentally. The results obtained are in good agreement with simulation. The energy resolution is 1.8% for electron energy of 1000 MeV and improves to 0.7% for electron energy of 3500 MeV.

Photographic emulsion is a particle tracking device which features the best spatial resolution among particle detectors. For certain applications, for example muon radiography, large-scale detectors are required. Therefore, a huge surface has to be analyzed by means of automated optical microscopes. An improvement of the readout speed is then a crucial point to make these applications possible and the availability of a new type of photographic emulsions featuring crystals of larger size is a way to pursue this program. This would allow a lower magnification for the microscopes, a consequent larger field of view resulting in a faster data analysis. In this framework, we developed new kinds of emulsion detectors with a crystal size of 600-1000 nm, namely 3-5 times larger than conventional ones, allowing a 25 times faster data readout. The new photographic emulsions have shown a sufficient sensitivity and a good signal to noise ratio. The proposed development opens the way to future large-scale applications of the technology, e.g. 3D imaging of glacier bedrocks or future neutrino experiments.

Proportional scintillation counters (PSCs), both single- and dual-phase, can measure the scintillation (S1) and ionization (S2) channels from particle interactions within the detector volume. The signal obtained from these detectors depends first on the physics of the medium (the initial scintillation and ionization), and second how the physics of the detector manipulates the resulting photons and liberated electrons. In this paper we develop a model of the detector physics that incorporates event topology, detector geometry, electric field configuration, purity, optical properties of components, and wavelength shifters. We present an analytic form of the model, which allows for general study of detector design and operation, and a Monte Carlo model which enables a more detailed exploration of S2 events. This model may be used to study systematic effects in current detectors such as energy and position reconstruction, pulse shape discrimination, event topology, dead time calculations, purity, and electric field uniformity. We present a comparison of this model with experimental data collected with an argon gas proportional scintillation counter (GPSC), operated at 20 C and 1 bar, and irradiated with an internal, collimated ⁵⁵Fe source. Additionally we discuss how the model may be incorporated in Monte Carlo simulations of both GPSCs and dual-phase detectors, increasing the reliability of the simulation results and allowing for tests of the experimental data analysis algorithms.

The international Muon Ionization Cooling Experiment (MICE) will perform a systematic investigation of ionization cooling with muon beams of momentum between 140 and 240 MeV/c at the Rutherford Appleton Laboratory ISIS facility. The measurement of ionization cooling in MICE relies on the selection of a pure sample of muons that traverse the experiment. To make this selection, the MICE Muon Beam is designed to deliver a beam of muons with less than ∼1% contamination. To make the final muon selection, MICE employs a particle-identification (PID) system upstream and downstream of the cooling cell. The PID system includes time-of-flight hodoscopes, threshold-Cherenkov counters and calorimetry. The upper limit for the pion contamination measured in this paper is f_π < 1.4% at 90% C.L., including systematic uncertainties. Therefore, the MICE Muon Beam is able to meet the stringent pion-contamination requirements of the study of ionization cooling.

The internal volume structure of a porous medium of light elements determines unique features of the absorption mechanism of laser radiation; the characteristics of relaxation and transport processes in the produced plasma are affected as well. Porous materials with an average density larger than the critical density have a central role in enhancing the pressure produced during the ablation by the laser pulse; this pressure can exceed the one produced by target direct irradiation. The problem of the absorption of powerful laser radiation in a porous material is examined both analytically and numerically. The behavior of the medium during the process of pore filling in the heated region is described by a model of viscous homogenization. An expression describing the time and space dependence of the absorption coefficient of laser radiation is therefore obtained from the model. A numerical investigation of the absorption of a nanosecond laser pulse is performed within the present model. In the context of numerical calculations, porous media with an average density larger than the critical density of the laser-produced plasma are considered. Preliminary results about the inclusion of the developed absorption model into an hydrodynamic code are presented.

Here we present preliminary results for the gain performance of commercially available 3-μm and 6-μm pore-size single-anode microchannel-plate photomultipliers (MCP PMTs) in magnetic fields up to 5 T and for various orientations of the sensor relative to the field direction. The measurements were performed at Thomas Jefferson National Accelerator Facility in Newport News, VA. Our results show that smaller-pore-size PMTs have better gain performance in magnetic fields. At various angles, the shape of the gain dependence on the strength of the magnetic field strongly depends on the type of the sensor. Also, for each sensor, the azimuthal dependence is strongly correlated with the polar angle. Overall, the sensors exhibit a reasonable performance up to 2 T, although that upper limit depends on the sensor, the applied high voltage, and the orientation of the sensor relative to the field. To optimize the operational and design parameters of MCP PMTs for performance in high magnetic fields, further measurements and simulation studies will be pursued. Our studies are part of an R&D for development of a Detector of Internally Reflected Cherenkov Light for the central detector of a future U.S. Electron Ion Collider.

We present a concept of integrated measurements for isotope identification which takes advantage of the time structure of spallation neutron sources for time resolved γ spectroscopy. Time resolved Prompt Gamma Activation Analysis (T-PGAA) consists in the measurement of gamma energy spectrum induced by the radioactive capture as a function of incident neutron Time Of Flight (TOF), directly related with the energy of incident neutrons. The potential of the proposed concept was explored on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (U.K.). Through this new technique we show an increase in the sensitivity to specific elements of archaeometric relevance, through incident neutron energy selection in prompt γ spectra for multicomponent samples. Results on a standard bronze sample are presented.

A detailed analysis of temperature dependencies of I-V-characteristics of high resistive chromium compensated gallium arsenide (HR GaAs:Cr) sensors is presented. Samples had Cr/Ni contacts made using electron-beam deposition that formed Schottky barrier contact to GaAs. Thus the structure of the samples was Ni/Cr – HR GaAs:Cr – Cr/Ni. The I-V curves were investigated in the temperature range from 23°C to 70°C. Current-voltage characteristics quite well obey the thermionic emission model in all ranges of temperature. The barrier height of the Schottky barrier was calculated from experimental data. The results of the investigation are discussed in this paper.

GEMMA and GEMINI, two integrated-circuit front-ends for the Triple-GEM detector are presented. These two ASICs aim to improve detector readout performance in terms of count rate, adaptability, portability and power consumption. GEMMA target is to embed counting, timing and spectroscopic measurements in a single 8-channel device, managing a detector capacitance up to 15 pF. On the other hand, GEMINI is dedicated to counting measurements, embedding 16 channels with a detector capacitance up to 40 pF. Both prototypes, fabricated in 130 nm and 180 nm CMOS respectively, feature an automatic on-chip calibration circuit, compensating for process/temperature variations.

Lens-coupled X-ray in-direct imaging detectors are very popular for high-resolution X-ray imaging at the third generation synchrotron radiation facilities. This imaging system consists of a scintilator producing a visible-light image of X-ray beam, a microscope objective, a mirror reflecting at 90° and a CCD camera. When the thickness of the scintillator is matched with the numerical aperture (NA) of the microscope objective, the image quality of experimental results will be improved obviously. This paper used an imaging system at BL13W beamline of Shanghai Synchrotron Radiation Facility (SSRF) to study the matching relation between the scintillator thickness and the NA of the microscope objective with a real sample. By use of the matching relation between the scintillator thickness and the NA of the microscope objective, the optimal imaging results have been obtained.

A model of metallic target ablation and metallic plasma production by laser irradiation is reported. The model considers laser energy absorption by the plasma, electron emission from hot targets and ion flux to the target from the plasma as well as an electric sheath produced at the target-plasma interface. The proposed approach takes into account that the plasma, partially shields the laser radiation from the target, and also converts absorbed laser energy to kinetic and potential energies of the charged plasma particles, which they transport not only through the ambient vacuum but also through the electrostatic sheath to the solid surface. Therefore additional plasma heating by the accelerated emitted electrons and target heating caused by bombardment of it by the accelerated ions are considered. A system of equations, including equations for solid heat conduction, plasma generation, and plasma expansion, is solved self-consistently. The results of calculations explain the measured dependencies of ablation yield (μ g/pulse) for Al, Ni, and Ti targets on laser fluence in range of (5–21)J/cm² published previously by Torrisi et al.

X-ray phase-contrast imaging has become an attractive technique because it can deliver additional information on weakly absorbing materials. Grating-based phase contrast imaging with conventional x-ray source is a breakthrough in x-ray phase contrast imaging because it provides attenuation, refraction and scattering information simultaneously. Therefore, it has potential to be applied in medical and industrial applications. However, in actual experiments, we found that the photon intensity drift of the x-ray source would influence the final images, especially the refraction images. After analyzing the phase-stepping curve, we proposed a correction method to fix the problem due to the effect of intensity drift. The proposed correction method is successfully applied to grating-based phase-contrast imaging setup having un-stable x-ray source. The experimental results show that our method could solve this problem.

We report the development of a mid-board, TOSA and ROSA based miniature dual channel optical transmitter (MTx) and a transceiver (MTRx). The design transmission data rate is 5.12 Gbps per channel and receiving data rate 4.8 Gbps. MTx and MTRx are only 6 mm tall and are electrically and optically pluggable. Although the fiber TOSA/ROSA coupling is through a custom latch, the fiber uses the standard LC ferrule, flange and spring. The TOSA and ROSA with the LC coupling mechanism ensure light coupling efficiency. With the dual channel serializer LOCx2 sits under MTx, one achieves high data transmission with a small PCB footprint, and enjoys the reliability of the hermetically packaged TOSA. MTx and MTRx are designed for detector front-end readout of the ATLAS Liquid Argon Calorimeter (LAr) trigger upgrade.

The present time-to-digital converter (TDC) chips for the monitored drift tube (MDT) chambers at the ATLAS experiment will be replaced with new ones for the High-Luminosity LHC, expected to begin operation in 2026. The design and the performance of a 24 channel TDC with a variable time binning of down to 0.28 nsec based on a Xilinx Kintex-7 field programmable gate array are reported. The time measurement is provided by a multisampling scheme with quad phase clocks synchronized with an external reference clock. The differential and integral nonlinearities have been measured to be less than half of the time binning. The temperature dependence on the performance is observed to be small. In conclusion the obtained performance of the time measurement is sufficiently high for the use with MDT chambers.

The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a "node-bond" geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1∼ 9.3% closed micropores.

The ALICE Central Trigger Processor (CTP) at the CERN LHC has been upgraded for LHC Run 2, to improve the Transition Radiation Detector (TRD) data-taking efficiency and to improve the physics performance of ALICE. There is a new additional CTP interaction record sent using a new second Detector Data Link (DDL), a 2 GB DDR3 memory and an extension of functionality for classes. The CTP switch has been incorporated directly onto the new LM0 board. A design proposal for an ALICE CTP upgrade for LHC Run 3 is also presented. Part of the development is a low latency high bandwidth interface whose purpose is to minimize an overall trigger latency.

Recent experiments at the laser facility PALS focused on the laser driven fusion of deuterons are reviewed. They benefit of high reaction cross-sections and of a high number of multi-MeV deuterons from thick CD₂ targets irradiated by intensity of 3× 10¹⁶ W cm⁻². In the reported experiments fast fusion neutrons with energy up to 16 MeV were produced through ⁷Li(d, n)⁸Be and ¹¹B(d, n)¹²C reactions in a pitcher-catcher target configuration. When using a large area CD₂ foil as a secondary catcher target the total maximum neutron yield from the ²H(d, n)³He reaction increased by a factor of about 5, from 4× 10⁸ to 2× 10⁹. This result reveals that most of the deuterons having enough kinetic energy to enter a fusion reaction are emitted from the primary target into vacuum.

The current status of research on generating a powerful shock wave with a pressure of up to several gigabars in a laboratory experiment is reviewed. The focus is on results which give a possibility of shock-wave experiments to study an equation of state of matter (EOS) at the level of gigabar pressure. The proposals are discussed to achieve a plane record-pressure shock wave driven by laser-accelerated fast electrons with respect to EOS-experiment as well as to prospective method of inertial fusion target (ICF) ignition as shock ignition.

One of the goals in developing synchrotron radiation x-ray computed tomography (SRCT) for biomedical specimens, is allowing particular tissues and cell types to be marked in the images. This is equivalent to the staining in histology, which enables researchers to visualise and measure tissue structure and biochemical processes within the specimen. Some progress in this direction for SRCT is being made, using a variety of contrast agents that alter the natural x-ray attenuation of the marked tissue [1]. However there are limits to the usefulness of these attenuation altering techniques. Often high concentrations of potentially disruptive chemicals are required with reduced compatibility for in-vivo studies. Another image highlighting technique which might prove more sensitive is x-ray fluorescence imaging. In this case usually endogenous elemental markers are visualised. We would like to develop a lower resolution, but wider field of view means of three-dimensional (3-D) fluorescence imaging compatible with SRCT. We have previously proposed a technique in which x-ray fluorescence CT (FXCT) and SRCT data can be collected simultaneously [2]. This work resulted in proof of concept modelling, and a simple experiment test system. We show data here which demonstrate a two-dimensional (2-D) reconstruction of an iodine fluorescence map from a phantom. Measurements were performed with a fixed beam modulating mask using the Imaging and Medical beam line (IMBL) at the Australian Synchrotron. Fluorescence data was obtained during a CT scan using a single point detector, while transmission data was simultaneously collected using an area detector. A maximum likelihood expectation maximisation (MLEM) iterative algorithm was used to reconstruct the fluorescence map. We report on technique development and now believe compressive sensing (CS) imaging techniques suit SRCT and may overcome the issues encountered so far in combining SRCT and FXCT.

The Tile Calorimeter PreProcessor demonstrator is a high performance double AMC board based on FPGA resources and QSFP modules. This board has been designed in the framework of the ATLAS Tile Calorimeter Demonstrator project for the Phase II Upgrade as the first stage of the back-end electronics. The TilePPr demonstrator has been conceived to receive and process the data coming from the front-end electronics of the TileCal Demonstrator module, as well as to configure it. Moreover, the TilePPr demonstrator handles the communication with the Detector Control System to monitor and control the front-end electronics. The TilePPr demonstrator represents 1/8 of the final TilePPr that will be designed and installed into the detector for the ATLAS Phase II Upgrade.

The Compressed Baryonic Matter (CBM) Experiment at the future FAIR (Darmstadt/Germany) will study the phase diagram of hadronic matter in the regime of highest net-baryon densities. The fixed target experiment will explore the nuclear fireballs created in violent heavy ion reactions with a rich number of probes. To reconstruct the decay topologies of open-charm particles as well as to track low-momentum particles, an ultra-light and precise Microvertex Detector (MVD) is required. The necessary performance in terms of spatial resolution, material budget and rate capability will be reached by equipping the MVD with highly granular, radiation-hard CMOS Monolithic Active Pixel Sensors (CPS) developped at IPHC Strasbourg, which are operated in the target vacuum of the experiment. This contribution introduces the concept of the MVD and puts a focus on the latest results obtained from the R&D of the electronics and read-out chain of the device. Moreover, we briefly introduce the PRESTO project, which realises a prototype of a full size quadrant of an MVD detector station.

We present the development of a low power Silicon Photomultiplier charge readout ASIC for an imaging calorimeter at a future linear collider. The analog front-end is designed to achieve sufficient signal-to-noise ratio for single pixel signals using low gain SiPMs, while allowing charge measurements over the full dynamic range of the sensors. The front-end consists of an input stage, two charge measurement branches and a fast comparator. A SAR ADC with a resolution of 10 bit digitizes the pulse height information. An additional pipelined SAR stage allows to increase the quantization resolution to 12 bit for calibration measurements.

A major upgrade (Phase II Upgrade) to the Large Hadron Collider (LHC), scheduled for 2022, will be brought to the machine so as to extend its discovery potential. The upgraded LHC, called High-Luminosity LHC (HL-LHC), will run with a nominal leveled instantaneous luminosity of 5×10³⁴ cm⁻²s⁻¹, more than twice the expected luminosity. This unprecedented luminosity will result in higher occupancy and background radiations, which will request the design of a new Inner Tracker (ITk) which should have higher granularity, reduced material budget and improved radiation tolerance. A new pixel sensor concept based on High Voltage and High Resistivity CMOS (HV/HR CMOS) technology targeting the ATLAS inner detector upgrade is under exploration. With respect to the traditional hybrid pixel detector, the HV/HR CMOS sensor can potentially offer lower material budget, reduced pixel pitch and lower cost. Several prototypes have been designed and characterized within the ATLAS upgrade R&D effort, to investigate the detection and radiation hardness performance of various commercial technologies. An overview of the HV/HR CMOS sensor operation principle is described in this paper. The characterizations of three prototypes with X-ray, proton and neutron irradiation are also given.

Generation of strong shock waves for the production of Mbar or Gbar pressures is a topic of high relevance for contemporary research in various domains, including inertial confinement fusion, laboratory astrophysics, planetology and material science. The pressures in the multi-Mbar range can be produced by the shocks generated using chemical explosions, light-gas guns, Z-pinch machines or lasers. Higher pressures, in the sub-Gbar or Gbar range are attainable only with nuclear explosions or laser-based methods. Unfortunately, due to the low efficiency of energy conversion from a laser to the shock (below a few percent), multi-kJ, multi-beam lasers are needed to produce such pressures with these methods. Here, we propose and investigate a novel scheme for generating high-pressure shocks which is much more efficient than the laser-based schemes known so far. In the proposed scheme, the shock is generated in a dense target by the impact of a fast projectile driven by the laser-induced cavity pressure acceleration (LICPA) mechanism. Using two-dimensional hydrodynamic simulations and the measurements performed at the kilojoule PALS laser facility it is shown that in the LICPA-driven collider the laser-to-shock energy conversion efficiency can reach a very high value ∼ 15–20 % and, as a result, the shock pressure ∼ 0.5–1 Gbar can be produced using lasers of energy ⩽ 0.5 kJ. On the other hand, the pressures in the multi-Mbar range could be produced in this collider with low-energy (∼ 10 J) lasers available on the market. It would open up the possibility of conducting research in high energy-density science also in small, university-class laboratories.

We present a readout and digitization ASIC featuring low-noise and low-power for time-of flight (TOF) applications using SiPMs. The circuit is designed in standard CMOS 110 nm technology, has 64 independent channels and is optimized for time-of-flight measurement in Positron Emission Tomography (TOF-PET). The input amplifier is a low impedance current conveyor based on a regulated common-gate topology. Each channel has quad-buffered analogue interpolation TDCs (time binning 20 ps) and charge integration ADCs with linear response at full scale (1500 pC). The signal amplitude can also be derived from the measurement of time-over-threshold (ToT). Simulation results show that for a single photo-electron signal with charge 200 (550) fC generated by a SiPM with 320 pF capacitance the circuit has 24 (30) dB SNR, 75(39) ps r.m.s. resolution, and 4(8) mW power consumption. The event rate is 600 kHz per channel, with up to 2 MHz dark counts rejection.

The gaseous Xenon(Xe) time projection chamber (TPC) is an attractive detector technique for neutrinoless double beta decay and WIMP dark matter searches. While it is less dense compared to Liquid Xe detectors, it has intrinsic advantages in tracking capability and better energy resolution. The performance of gaseous Xe can be further improved by molecular additives such as trimethylamine(TMA), which is expected to (1) cool down the ionization electrons, (2) convert Xe excitation energy to TMA ionizations through Penning transfer, and (3) produce scintillation and electroluminescence light in a more easily detectable wavelength (300 nm). In order to test the feasibility of the performance improvements with TMA, we made the first direct measurement of Penning and fluorescence transfer efficiency with gaseous mixtures of Xe and TMA. While we observed a Penning transfer efficiency up to ∼35%, we found strong suppression of primary scintillation light with TMA. We also found that the primary scintillation light with Xe and TMA mixture can be well characterized by ∼3% fluorescence transfer from Xe to TMA, with further suppression due to TMA self-quenching. No evidence of the scintillation light produced by recombination of TMA ions was found. This strong suppression of scintillation light makes dark matter searches quite challenging, while the possibility of improved neutrinoless double beta decay searches remains open. This work has been carried out within the context of the NEXT collaboration.

The benefits of pixelated planar direct conversion semiconductor radiation detectors comprising a thick fully depleted substrate are that they offer low crosstalk, small output capacitance, and that the planar configuration simplifies manufacturing. In order to provide high quantum efficiency for high energy X-rays and Gamma-rays such a radiation detector should be as thick as possible. The maximum thickness and thus the maximum quantum efficiency has been limited by the substrate doping concentration: the lower the substrate doping the thicker the detector can be before reaching the semiconductor material's electric breakdown field. Thick direct conversion semiconductor detectors comprising vertical three-dimensional electrodes protruding through the substrate have been previously proposed by Sherwood Parker in order to promote rapid detection of radiation. An additional advantage of these detectors is that their thickness is not limited by the substrate doping, i.e., the size of the maximum electric field value in the detector does not depend on detector thickness. However, the thicker the substrate of such three dimensional detectors is the larger the output capacitance is and thus the larger the output noise is. In the novel direct conversion pixelated radiation detector utilizing a novel three dimensional semiconductor architecture, which is proposed in this work, the detector thickness is not limited by the substrate doping and the output capacitance is small and does not depend on the detector thickness. In addition, by incorporating an additional node to the novel three-dimensional semiconductor architecture it can be utilized as a high voltage transistor that can deliver current across high voltages. Furthermore, it is possible to connect a voltage difference of any size to the proposed novel three dimensional semiconductor architecture provided that it is thick enough—this is a novel feature that has not been previously possible for semiconductor components. Yet another feature of the novel three dimensional semiconductor architecture is that despite the thick substrate it can also be efficiently cooled.

The high-energy physics experiments at the CERN's Large Hadron Collider (LHC) are preparing for Run3, which is foreseen to start in the year 2021. Data from the high radiation environment of the detector front-end electronics are transported to the data processing units, located in low radiation zones through GBT (Gigabit transceiver) links. The present work discusses the GBT link performance study carried out on custom FPGA boards, clock calibration logic and its implementation in new Arria 10 FPGA.

The design and performance of the upgraded CMS Level-1 Trigger Barrel Muon Track Finder (BMTF) is presented. Monte Carlo simulation data as well as cosmic ray data from a CMS muon detector slice test have been used to study in detail the performance of the new track finder. The design architecture is based on twelve MP7 cards each of which uses a Xilinx Virtex-7 FPGA and can receive and transmit data at 10 Gbps from 72 input and 72 output fibers. According to the CMS Trigger Upgrade TDR the BMTF receives trigger primitive data which are computed using both RPC and DT data and transmits data from a number of muon candidates to the upgraded Global Muon Trigger. Results from detailed studies of comparisons between the BMTF algorithm results and the results of a C++ emulator are also presented. The new BMTF will be commissioned for data taking in 2016.

In the last few years, integrated multi-modality systems have been developed, aimed at improving the accuracy of medical diagnosis correlating information from different imaging techniques. In this contest, a novel dual modality probe is proposed, based on an ultrasound detector integrated with a small field of view single photon emission gamma camera. The probe, dedicated to visualize small organs or tissues located at short depths, performs dual modality images and permits to correlate morphological and functional information. The small field of view gamma camera consists of a continuous NaI:Tl scintillation crystal coupled with two multi-anode photomultiplier tubes. Both detectors were characterized in terms of position linearity and spatial resolution performances in order to guarantee the spatial correspondence between the ultrasound and the gamma images. Finally, dual-modality images of custom phantoms are obtained highlighting the good co-registration between ultrasound and gamma images, in terms of geometry and image processing, as a consequence of calibration procedures.

With the Thomson scattering (TS) system in KSTAR, temporal evolution of electron temperature (T_e) is estimated using a weighted look-up table method with fast sampling (1.25 or 2.5 GS/s) digitizers during the 2014 KSTAR campaign. Background noise level is used as a weighting parameter without considering the photon noise due to the absence of information on absolute photon counts detected by the TS system. Estimated electron temperature during a relatively quiescent discharge are scattered, i.e., 15% variation on T_e with respect to its mean value. We find that this 15% variation on T_e cannot be explained solely by the background noise level which leads us to include photon noise effects in our analysis. Using synthetic data, we have estimated the required photon noise level consistent with the observation and determined the dominant noise source in KSTAR TS system.

In this work, we present the online implementation of attenuation, scatter and random corrections using the LMEM algorithm for the dedicated breast PET named MAMMI. The attenuation correction is based on image segmentation, the random correction is derived from the rate estimation of single photon events and the scatter correction is determined by the dual energy window method. These three corrections are estimated and implemented in the reconstruction process without almost increasing the reconstruction time. The image quality is evaluated in terms of image uniformity and contrast using the reconstructed images of two custom-designed phantoms. When we apply the three corrections, the measured uniformity in the whole field of view is (10± 1)% compared to (17± 1)% without corrections. The adapted recovery contrast coefficients (normalized to 1) are approximately (0.80± 0.02) in hot areas, improving the value of (0.66± 0.07) obtained without corrections. The reconstruction processing time is also studied, finding an increment of around 7% when the three corrections are simultaneously included. Finally, 25 breast image datasets are also analyzed. The average acquisition time per patient is around 1200 seconds and the reconstruction times with corrections vary from 100 to 400 seconds using (1× 1× 1) mm³ voxel size and from 300 to 1800 seconds using (0.5× 0.5× 0.5) mm³ voxel size. These reconstructions are performed with a virtual pixel size of (1.6× 1.6) mm² and twelve iterations.

The India-based Neutrino Observatory (INO) is an approved multi-institutional collaboration neutrino physics project, aimed at building an underground laboratory in the southern India. INO will utilize a large magnetized Iron Calorimeter (ICAL) detector to study the atmospheric neutrinos, and to explore the unresolved issues related to neutrinos. The Resistive Plate Chambers (RPCs), interleaved in between iron absorber layers, are going to be used as the active signal readouts for the ICAL experiment at INO. The research and development is carried out to find structural quality and electrical response for RPC electrode materials available within local domain. The assembled 2 mm gap RPCs are tested using cosmic muons for their detection performance. The study also incorporates preliminary results on detector timing and signal induced charge measurements.

Due to the well-known problem of ³He shortage, a series of different thermal neutron detectors alternative to helium tubes are being developed, with the goal to find valid candidates for detection systems for the future spallation neutron sources such as the European Spallation Source (ESS). A possible ³He-free detector candidate is a charged particle detector equipped with a three dimensional neutron converter cathode (3D-C). The 3D-C currently under development is composed by a series of alumina (Al₂O₃) lamellas coated by 1 μ m of ¹⁰B enriched boron carbide (B₄C). In order to obtain a good characterization in terms of detector efficiency and uniformity it is crucial to know the thickness, the uniformity and the atomic composition of the B₄C neutron converter coating. In this work a non-destructive technique for the characterization of the lamellas that will compose the 3D-C was performed using neutron radiography. The results of these measurements show that the lamellas that will be used have coating uniformity suitable for detector applications. This technique (compared with SEM, EDX, ERDA, XPS) has the advantage of being global (i.e. non point-like) and non-destructive, thus it is suitable as a check method for mass production of the 3D-C elements.

Cerenkov luminescence imaging (CLI) is a novel molecular imaging technique based on the detection of Cerenkov light produced by beta particles traveling through biological tissues. In this paper we simulated using ¹⁸F and ⁹⁰Y the possibility of detecting Cerenkov luminescence in human breast tissues, in order to evaluate the potential of the CLI technique in a clinical setting. A human breast digital phantom was obtained from an ¹⁸F-FDG CT-PET scan. The spectral features of the breast surface emission were obtained as well as the simulated images obtainable by a cooled CCD detector. The simulated images revealed a signal to noise ratio equal to 6 for a 300 s of acquisition time. We concluded that a dedicated human Cerenkov imaging detector can be designed in order to offer a valid low cost alternative to diagnostic techniques in nuclear medicine, in particular allowing the detection of beta-minus emitters used in radiotherapy.

X-ray imaging method based on 2D grating interferometer was proposed and studied recently, to overcome the limitations in signal extraction and phase retrieval when using 1D grating interferometer. In this paper, the concept of angle-signal response function is proposed, and different surfaces of different 2D setups under the condition of parallel coherent light are calculated and depicted with Matlab. Based on this concept, performance of 2D grating interferometer is systematically analyzed and an analytic 2D signal extraction approach is theoretically proposed. Besides, signal extraction, phase retrieval and feasibility of using conventional source are also briefly discussed and compared between 2D grating interferometer and 1D case.

A GPU-based low level (L0) trigger is currently integrated in the experimental setup of the RICH detector of the NA62 experiment to assess the feasibility of building more refined physics-related trigger primitives and thus improve the trigger discriminating power. To ensure the real-time operation of the system, a dedicated data transport mechanism has been implemented: an FPGA-based Network Interface Card (NaNet-10) receives data from detectors and forwards them with low, predictable latency to the memory of the GPU performing the trigger algorithms. Results of the ring-shaped hit patterns reconstruction will be reported and discussed.

The electronics of the LUX-ZEPLIN (LZ) experiment, the 10-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), consists of low-noise dual-gain amplifiers and a 100-MHz, 14-bit data acquisition system for the TPC PMTs. Pre-prototypes of the analog amplifiers and the 32-channel digitizers were tested extensively with simulated pulses that are similar to the prompt scintillation light and the electroluminescence signals expected in LZ. These studies are used to characterize the noise and to measure the linearity of the system. By increasing the amplitude of the test signals, the effect of saturating the amplifier and the digitizers was studied. The RMS ADC noise of the digitizer channels was measured to be 1.19± 0.01 ADCC. When a high-energy channel of the amplifier is connected to the digitizer, the measured noise remained virtually unchanged, while the noise added by a low-energy channel was estimated to be 0.38 ± 0.02 ADCC (46 ± 2 μV). A test facility is under construction to study saturation, mitigate noise and measure the performance of the LZ electronics and data acquisition chain.

The paper describes a preamplifier, elaborated to process the signals of silicon X-ray drift detectors. The preamplifier has been designed in CMOS 0.35 um technology and optimized for operation with detectors, having capacitances of 100 fF. The feedback capacitance of 10 fF provides a gain of 100 mV/fC, ENC at T = −30°C equals 4 e (simulation result) at using shaper of the 6^th order with a time constant of 8 us. Power consumption is 1.3 mW (preamplifier and shaper).

The ALICE experiment is planning to upgrade the ITS (Inner Tracking System) [1] detector during the LS2 shutdown. The present ITS will be fully replaced with a new one entirely based on CMOS monolithic pixel sensor chips fabricated in TowerJazz CMOS 0.18 μ m imaging technology. The large (3 cm × 1.5 cm  = 4.5 cm²) ALPIDE (ALICE PIxel DEtector) sensor chip contains about 500 Kpixels, and will be used to cover a 10 m² area with 12.5 Gpixels distributed over seven cylindrical layers. The ALPOSE chip was designed as a test chip for the various building blocks foreseen in the ALPIDE [2] pixel chip from CERN. The building blocks include: bandgap and Temperature sensor in four different flavours, and LDOs for powering schemes. One flavour of bandgap and temperature sensor will be included in the ALPIDE chip. Power consumption numbers have dropped very significantly making the use of LDOs less interesting, but in this paper all blocks are presented including measurement results before and after irradiation with neutrons to characterize robustness against displacement damage.

In this study a high-resolution gamma detector based on an array of sub-millimeter Ce:GAGG (Cerium doped Gd₃Al₂Ga₃O₁₂) crystals read out by an array of surface-mount type of TSV-MPPC was developed. MPPC sensor from Hamamatsu which has a 26 by 26 mm² detector area with 64 channels was used. One channel has a 3 by 3 mm² photosensitive area with 50 μ m pitch micro cells. MPPC sensor provides 576 mm² sensing area and was used to decode 48 by 48 array with 0.4 by 0.4 by 20 mm³ Ce:GAGG crystals of 500 μ m pitch. The base of the detector with the crystal module was mounted to a read out board which consists of charge division circuit, thus allowing for a read out of four channels to identify the position of the incident event on the board. The read out signals were amplified using charge sensitive amplifiers. The four amplified signals were digitized and analyzed to produce a position sensitive event. For the performance analysis a ¹³⁷Cs source was used. The produced events were used for flood histogram and energy analysis. The effects of the glass thickness between the Ce:GAGG and MPPC were analyzed using the experimental flood diagrams and Geant4 simulations. The glass between the scintillator and the detector allows the spread of the light over different channels and is necessary if the channel's sensitive area is bigger than the scintillator's area. The initial results demonstrate that this detector module is promising and could be used for applications requiring compact and high-resolution detectors. Experimental results show that the detectors precision increases using glass guide thickness of 1.35 mm and 1.85 mm; however the precision using 2.5 mm are practically the same as if using 0.8 mm or 1.0 mm glass guide thicknesses. In addition, simulations using Geant4 indicate that the light becomes scarcer if thicker glass is used, thus reducing the ability to indicate which crystal was targeted. When 2.5 mm glass thickness is used, the scarce light effect becomes dominant for the precision of the detector.

Tetraphenyl-butadiene (TPB) is a wavelength shifting material that can absorb ultraviolet photons and emit blue photons. It is used in the detection of vacuum ultraviolet (VUV) photons, for which typical photo-sensors, such as most photomultiplier tubes (PMT) and silicon photomultipliers (SiPM), do not have any quantum efficiency. The secondary blue light is emitted isotropically, however, due to scattering within the material, its angular distribution upon exiting the material can not be easily predicted. Here we describe a procedure for estimating the scattering length of blue light in TPB, by measuring and modeling the angular distribution as a function of layer thickness. The experiment consists of shining 254nm light at various thicknesses of TPB deposited on fused silica, and measuring the intensity of blue light using SiPMs on either side of the sample. We simulate light propagation within the sample to estimate the light yield and compare that to the data, which allows us to estimate mean scattering length for photons in TPB to be in the range 2–3 μm, with some preference for a central value of 2.75 μm.

The High Luminosity LHC will present a number of challenges for the upgraded ATLAS detector. In particular, data transmission requirements for the upgrade of the ATLAS Pixel detector will be difficult to meet. The expected trigger rate and occupancy imply multi-gigabit per second transmission rates will be required but radiation levels at the smallest radius preclude completely optical solutions. Electrical transmission up to distances of 7m will be necessary to move optical components to an area with lower radiation levels. Here, we explore the use of small gauge electrical cables as a high-bandwidth, radiation hard solution with a sufficiently small radiation length. In particular, we present a characterization of various twisted wire pair (TWP) configurations of various material structures, including measurements of their bandwidth, crosstalk, and radiation hardness. We find that a custom ``hybrid'' cable consisting of 1m of a multi-stranded TWP with Poly-Ether-Ether-Ketone (PEEK) insulation and a thin Al shield followed by 6m of a thin twin-axial cable presents a low-mass solution that fulfills bandwidth requirements and is expected to be sufficiently radiation hard. Additionally, we discuss preliminary results of using measured S-parameters to produce a SPICE model for a 1m sample of the custom TWP to be used for the development of new pixel readout chips.

Thomson scattering is a widely used diagnostic tool for local measurement of both electron temperature and electron density. It is used for both low and high temperature plasmas and it is a key diagnostic on all fusion devices. The extremely low cross-section of the reaction increases the complexity of the design. Since the early days of fusion, when a simple single point measurement was used, the design moved to a multi-point system with a large number of spatial points, LIDAR system or high repetition Thomson scattering diagnostic which are used nowadays. The initial low electron temperature approximation has been replaced by the full relativistic approach necessary for large devices as well as for ITER with expected higher plasma temperature. Along the way, the different development needs and the issues that exist need to be addressed to ensure that the technique is developed sufficiently to handle challenges of the bigger devices of the future as well as current developments needed for ITER. For large devices, the achievement of the necessary temperature range represents an important task. Both high and low temperatures can be measured, however, a large dynamic range makes the design difficult as size of detector and dynamic range are linked together. Therefore, the requirements of the new devices are extending the boundaries of these parameters. Namely, ITER presents challenges as access is also difficult but big efforts have been made to cope with this. This contribution contains a broad review of Thomson scattering diagnostics used in current devices together with comments on recent progress and speculation regarding future developments needed for future large scale devices.

The following paper presents a new 2-D detector (`GEMpix') in the soft X-ray range, having a wide dynamic range thanks to its intrisic gain, working in charge integration mode to be used for diagnosing laser produced plasma (LPP) or X-ray pulsed sources. It is a gas detector based on the Gas Electron Multiplier (GEM) technology with a quad-medipix chip as read-out electronics. In our prototype, the substitution of semiconductor material with a gas triple-GEM allows several advantages with respect to the detectors commonly used in LPP, as X-ray CCDs and Micro Channel Plates or Image Plates. In these experiments the configuration Time-over-Threshold (ToT) has been used, to measure the total charge released to the gas and collected by each pixel, integrated over the X-ray burst duration. Intensity response and spatial resolution has been measured first in laboratory for calibration, as function of the voltage applied to the GEMs, in single photon regime with energies between 3.7 and 17 keV. Subsequently it has been tested at the ABC laser facility (ENEA, Frascati). In this case, we measured the X-rays produced when the ABC neodymium laser, with pulse of 50 J and 3 ns time width, hits plane targets of aluminum. 2-D images have been acquired by means of a pinhole configuration with magnification 1.5 and 50 μ m of spatial resolution. The results are encouraging regarding the capability of this imaging detector to work in experiments where soft X-ray emissivity varies over many orders of magnitude.

The ALICE experiment at the CERN Large Hadron Collider (LHC) is presently going for a major upgrade in order to fully exploit the scientific potential of the upcoming high luminosity run, scheduled to start in the year 2021. The high interaction rate and the large event size will result in an experimental data flow of about 1 TB/s from the detectors, which need to be processed before sending to the online computing system and data storage. This processing is done in a dedicated Common Readout Unit (CRU), proposed for data aggregation, trigger and timing distribution and control moderation. It act as common interface between sub-detector electronic systems, computing system and trigger processors. The interface links include GBT, TTC-PON and PCIe. GBT (Gigabit transceiver) is used for detector data payload transmission and fixed latency path for trigger distribution between CRU and detector readout electronics. TTC-PON (Timing, Trigger and Control via Passive Optical Network) is employed for time multiplex trigger distribution between CRU and Central Trigger Processor (CTP). PCIe (Peripheral Component Interconnect Express) is the high-speed serial computer expansion bus standard for bulk data transport between CRU boards and processors. In this article, we give an overview of CRU architecture in ALICE, discuss the different interfaces, along with the firmware design and implementation of CRU on the LHCb PCIe40 board.

The CMS experiment at the CERN Large Hadron Collider (LHC) will upgrade the photon detection and readout systems of its barrel and endcap hadron calorimeters (HCAL) through the second long shutdown of the LHC in 2018. The upgrade includes new silicon photomultipliers (SiPMs), SiPM control electronics, signal digitization via the Fermilab QIE11 ASIC, data formatting and serialization via a Microsemi FPGA, and data transmission via CERN Versatile Link technology. The first prototype system for the endcap HCAL has been assembled and characterized on the bench and in a test beam. The design of this new system and prototype performance are described.

Unencapsulated aluminum wedge wire bonds are common in particle physics pixel and strip detectors. Industry-favored bulk encapsulation is eschewed due to the range of operating temperatures and radiation. Wire bond failures are a persistent source of tracking-detector failure. Unencapsulated bonds are vulnerable to condensation-induced corrosion, particularly when halides are present. Oscillations from periodic Lorentz forces are documented as another source of wire bond failure. Spray application of polyurethane coatings, performance of polyurethane-coated wire bonds after climate chamber exposure, and resonant properties of polyurethane-coated wire bonds and their resistance to periodic Lorentz forces are under study for use in a future High Luminosity Large Hadron Collider detector such as the ATLAS Inner Tracker upgrade.

The Cavity Ringdown Technique (CRD) is applied for negative hydrogen ion (H⁻) density measurement in H⁻ source for the neutral beam injector. The CRD is one of the laser absorption techniques. Nd:YAG pulse laser was utilized for negative-hydrogen-ion photodetachment. The H⁻ density related to extracted H⁻ beam was successfully observed by a fixed position CRD. A two-dimensional movable CRD has been developed to measure the H⁻ density profile. Measured profiles were consistent with expected profiles from the H⁻ production area in pure hydrogen and cesium seeded plasmas. By applying absorption saturation in the optical cavity, negative hydrogen ion temperature was evaluated and was confirmed as being a similar value measured with other diagnostics.

The ANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (ANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

We describe a novel fast optical imager, TimepixCam, based on an optimized silicon pixel sensor with a thin entrance window, read out by a Timepix ASIC. TimepixCam is able to record and time-stamp light flashes in excess of 1,000 photons with high quantum efficiency in the 400–1000nm wavelength range with 20ns timing resolution, corresponding to an effective rate of 50 Megaframes per second. The camera was used for imaging ions impinging on a microchannel plate followed by a phosphor screen. Possible applications include spatial and velocity map imaging of ions in time-of-flight mass spectroscopy; coincidence imaging of ions and electrons, and other time-resolved types of imaging spectroscopy.

We analyzed a photon detector for positron emission tomography with high spatial resolution and depth of interaction capability. The detector is composed of a monolithic LYSO scintillator crystal coupled on top and bottom sides to two custom SiPM arrays. We investigated the ability to reconstruct the DOI of the 511 keV photon comparing the number of triggered SiPMs on the two sides of the module. Acquisitions were performed scanning the lateral surface of the crystal with a collimated 511 keV photon beam at different incident positions. A standard deviation of 1.5 mm in depth of interaction was obtained at the center of the module.

A new neutron imaging and diffraction facility, called IMAT, is currently being commissioned at the ISIS pulsed neutron spallation source. IMAT will take advantage of neutron time-of-flight measurement techniques for flexible neutron energy selection and effective energy discrimination. The instrument will be completed and commissioned within the next few months, after neutrons have been recently delivered to the sample area. From 2016 IMAT will enable white-beam neutron radiography and tomography as well as energy-dependent neutron imaging. The facility will offer a spatial resolution down to 50 microns for a field of view of up to 400 cm². IMAT will be operated as a user facility for material science applications and will be open for developments of time-of-flight imaging methods.

The upgrade of the silicon pixel sensors for the HL-LHC experiments requires the development of new readout integrated circuits due to unprecedented radiation levels, very high hit rates and increased pixel granularity. The design of a very compact, low power, low threshold analog very front-end in CMOS 65 nm technology is described. It contains a synchronous comparator which uses an offset compensation technique based on storing the offset in output. The latch can be turned into a local oscillator using an asynchronous logic feedback loop to implement a fast time-over-threshold counting. This design has been submitted and the measurement results are presented.

An elongated line plasma generated by a laser ablation of an aluminum target was investigated, which can be used in the laser wakefield acceleration (LWFA) by employing ultra-intense laser pulse through the longitudinal direction of the plasma. To generate a uniform and long plasma channel along the propagation of ultra-intense laser pulse (main pulse), a cylindrical lens combined with a biprism was used to shape the intensity of a ns Nd:YAG laser (pre-pulse) on the Al target. A uniformity of laser intensity can be manipulated by changing the distance between the biprism and the target. The density profile of the plasma generated by laser ablation was measured using two interferometers, indicating that a 3-mm long uniform line plasma with a density of 6 × 10¹⁷ cm⁻³ could be generated. The density with main pulse was also measured and the results indicated that the density would increase further due to additional ionization of the plasma by the main ultra-intense laser pulse. The resulting plasma density, which is a crucial parameter for the LWFA, can be controlled by the intensity of the pre-pulse, the time delay between the pre- and main pulse, and the distance of the main pulse from the target surface.

The High Luminosity LHC (HL-LHC) will deliver luminosities of up to 5 × 10³⁴ Hz/cm², with an average of about 140 overlapping proton-proton collisions per bunch crossing. These extreme pileup conditions place stringent requirements on the trigger system to be able to cope with the resulting event rates. A key component of the CMS upgrade for HL-LHC is a track trigger system which would identify tracks with transverse momentum above 2 GeV/c already at the first-level trigger. This paper presents the status of proposals for implementing the L1 tracking in conjunction with the planned upgrade for the silicon tracker of the CMS experiment.

Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 μm < λ < 1.5 μm). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

In this work spectral investigations of low temperature F-rich photoionized plasmas were performed. The photoionized plasmas were created by irradiation of SF₆ gas with intense EUV (extreme ultraviolet) radiation pulses. Two laser plasma EUV sources of different parameters used in the experiments were based on 0.8 J /4ns and 10 J/ 10 ns Nd:YAG lasers respectively. Both sources operated at 10 Hz repetition rate. The EUV radiation was focused using a dedicated reflective collector onto the gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of the SF₆ gas resulted in dissociative ionization of the molecules, leading to creation of SF_n⁺ ions and fluorine atoms. Further photo- or electron impact ionization and excitation processes allow for formation of photoionized plasmas emitting radiation in the wide spectral range. Emission spectra were measured in the EUV and optical ranges. The EUV spectra contained multiple spectral lines, originating from F II, F III and S II ions. The UV/VIS spectra were composed of spectral lines corresponding to radiative transitions in F II, F I and S II species. A computer simulation of the F II spectrum was performed using a collisional-radiative PrismSPECT code. Parameters of the photoionized plasmas were estimated by fitting the spectrum obtained from the simulations to the experimental one. Apart from that, the electron temperature was estimated employing Boltzmann plots based on the UV/VIS spectrum.

The CERN Beam Instrumentation group has been working during the last years on the beam wire scanners upgrade to cope up with the increasing requirements of CERN experiments. These devices are used to measure the beam profile by crossing a thin wire through a circulating beam, the resulting secondary particles produced from beam/wire interaction are detected and correlated with the wire position to reconstruct the beam profile. The upgraded secondary particles acquisition electronics will use polycrystalline chemical vapour deposition (pCVD) diamond detectors for particle shower measurements, with low noise acquisitions performed on the tunnel, near the detector. The digital data is transmitted to the surface through an optical link with the GBT protocol. Two integrator ASICs (ICECAL and QIE10) are being characterized and compared for detector readout with the complete acquisition chain prototype. This contribution presents the project status, the QIE10 front-end performance and the first measurements with the complete acquisition system prototype. In addition, diamond detector signals from particle showers generated by an operational beam wire scanner are analysed and compared with an operational system.

Results of the experimental study of electron emission from liquid xenon via electroluminescence of the gas phase are presented. We report on observation of a peculiar kind of delayed electroluminescent signal following initial electroluminescence caused by ionizing particles. We also present the results of a study of spontaneous single electron emission following cosmic muon signals. It was found that the rate of spontaneous single electron signals strongly depends on the time passed since the initial electroluminescence happened. The analysis of experimental data showed that both spontaneous single electron signals and delayed electroluminescent signals are associated with ionization electrons which are trapped by the potential barrier at the interface.

Imaging of increasingly complex cartilage in vertebrate embryos is one of the key tasks of developmental biology. This is especially important to study shape-organizing processes during initial skeletal formation and growth. Advanced imaging techniques that are reflecting biological needs give a powerful impulse to push the boundaries of biological visualization. Recently, techniques for contrasting tissues and organs have improved considerably, extending traditional 2D imaging approaches to 3D . X-ray micro computed tomography (μCT), which allows 3D imaging of biological objects including their internal structures with a resolution in the micrometer range, in combination with contrasting techniques seems to be the most suitable approach for non-destructive imaging of embryonic developing cartilage. Despite there are many software-based ways for visualization of 3D data sets, having a real solid model of the studied object might give novel opportunities to fully understand the shape-organizing processes in the developing body. In this feasibility study we demonstrated the full procedure of creating a real 3D object of mouse embryo nasal capsule, i.e. the staining, the μCT scanning combined by the advanced data processing and the 3D printing.

X-ray microradiography and microtomography are imaging techniques with increasing applicability in the field of biomedical and preclinical research. Application of hybrid pixel detector Timepix enables to obtain very high contrast of low attenuating materials such as soft biological tissue. However X-ray imaging of ex-vivo soft tissue samples is a difficult task due to its structural instability. Ex-vivo biological tissue is prone to fast drying-out which is connected with undesired changes of sample size and shape producing later on artefacts within the tomographic reconstruction. In this work we present the optimization of our Timepix equipped micro-CT system aiming to maintain soft tissue sample in stable condition. Thanks to the suggested approach higher contrast of tomographic reconstructions can be achieved while also large samples that require detector scanning can be easily measured.

The CMS experiment Level-1 trigger system is undergoing an upgrade. In the barrel-endcap transition region, it is necessary to merge data from 3 types of muon detectors—RPC, DT and CSC. The Overlap Muon Track Finder (OMTF) uses the novel approach to concentrate and process those data in a uniform manner to identify muons and their transversal momentum. The paper presents the algorithm and FPGA firmware implementation of the OMTF and its data transmission system in CMS. It is foreseen that the OMTF will be subject to significant changes resulting from optimization which will be done with the aid of physics simulations. Therefore, a special, high-level, parameterized HDL implementation is necessary.

The search for dark matter is one of today's most exciting fields. As bigger detectors are being built to increase their sensitivity, background reduction is an ever more challenging issue. To this end, a new type of dark matter detector is proposed, a xenon bubble chamber, which would combine the strengths of liquid xenon TPCs, namely event by event energy resolution, with those of a bubble chamber, namely insensitivity to electronic recoils. In addition, it would be the first time ever that a dark matter detector is active on all three detection channels, ionization and scintillation characteristic of xenon detectors, and heat through bubble formation in superheated fluids. Preliminary simulations show that, depending on threshold, a discrimination of 99.99% to 99.9999+% can be achieved, which is on par or better than many current experiments. A prototype is being built at the University at Albany, SUNY. The prototype is currently undergoing seals, thermal, and compression testing.

Silicon Photomultipliers (SiPMs) are currently being investigated for use in nEXO, a liquid xenon double-beta decay experiment. These detectors must be able to detect photons at 175 nm with high photon detection efficiency (PDE) and low noise. Several manufacturers are collaborating with nEXO to develop devices with high sensitivity at 175 nm. Devices produced by FBK and Hamamatsu have been tested in gas/vacuum and in liquid xenon. Their PDE at 175-180 nm was characterized in liquid xenon and in gas/vacuum and their dark and correlated noise rates were measured at 173 K. This paper will describe the setups, the measurements and analysis, as well as show the performances of SiPMs coated with an organic wavelength shifting material.

A method to determine the gamma-ray emissivity profile from measurements along a few multiple collimated lines of sight in thermonuclear plasmas is presented. The algorithm is based on a generalisation of the known Abel inversion and takes into account the non circular shape of the plasma flux surfaces and the limited number of data points available. The method is applied to synthetic experimental measurements originating from parabolic and non parabolic JET gamma-ray emissivity profiles, where the aim is to compare the results of the inversion with the original, known input parameters. We find that profile parameters, such as the peak value, width and centre of the emissivity, are determined with an accuracy between 1 and 20% for parabolic and 2 to 25% for non parabolic profiles, respectively, which compare to an error at the 10% level for the input data. The results presented in this paper are primarily of relevance for the reconstruction of emissivity profiles from radiation measurements in tokamaks, but the method can also be applied to measurements along a sparse set of collimated lines of sight in general applications, provided that the surfaces at constant emissivity are known to have rotational simmetry.

A novel technique to estimate the range of radial size and density fluctuation amplitude of edge localized modes (ELMs) in the KSTAR tokamak plasma is presented. A microwave imaging reflectometry (MIR) system is reconfigured as a multi-channel microwave interferometer array (MIA) to measure the density fluctuations associated with ELMs, while electron cyclotron emission imaging (ECEI) system is used as a reference diagnostics to confirm the MIA observation. Two dimensional full-wave (FWR2D) simulations integrated with optics simulation are performed to investigate the Gaussian beam propagation and reflection through the plasma as well as the MIA optical components and obtain the interferometric phase undulations of individual channels at the detector plane due to ELM perturbation. The simulation results show that the amplitude of the phase undulation depends linearly on both radial size and density perturbation amplitude of ELM. For a typical discharge with ELMs, it is estimated that the ELM structure observed by the MIA system has density perturbation amplitude in the range ∼  7 % to 14 % while radial size in the range ∼  1 to 3 cm.

This paper utilizes firstly both a scanning device and an optic fiber hydrophone to establish a measurement system, and then proposes the parameter measurement of the focused transducer based on edge detection of the visualized acoustic data and curve fitting. The measurement system consists of a water tank with wedge absorber, stepper motors driver, system controller, a focused transducer, an optic fiber hydrophone and data processing software. On the basis of the visualized processing for the original scanned data, the −3 dB beam width of the focused transducer is calculated using the edge detection of the acoustic visualized image and circle fitting method by minimizing algebraic distance. Experiments on the visualized ultrasound data are implemented to verify the feasibility of the proposed method. The data obtained from the scanning device are utilized to reconstruct acoustic fields, and it is found that the −3 dB beam width of the focused transducer can be predicted accurately.

The high energy spectrum of alpha particles emitted from a single isotope uniformly contaminating a bulk solid has a flat energy spectrum with a high end cutoff energy equal to the maximal alpha kinetic energy (T_α) of the decay. In this flat region of the spectrum, we show the surface rate r_b (Bq keV⁻¹cm⁻²) arising from a bulk alpha contamination ρ_b (Bq cm⁻³) from a single isotope is given by r_b =ρ_b Δ R/ 4 Δ E , where Δ E = E₁−E_2>0  is the energy interval considered (keV) in the flat region of the spectrum and Δ R = R₂−R₁, where R₂ (R₁) is the amount of the bulk material (cm) necessary to degrade the energy of the alpha from T_α to E₂ (E₁). We compare our calculation to a rate measurement of alphas from ¹⁴⁷Sm, (15.32 ± 0.03% of Sm(nat) and half life of (1.06 ± 0.01)× 10¹¹ yr [1]), and find good agreement, with the ratio between prediction to measurement of 100.2%± 1.6% (stat)± 2.1% (sys). We derive the condition for the flat spectrum, and also calculate the relationship between the decay rate measured at the surface for a [near] surface contamination with an exponential dependence on depth and a second case of an alpha source with a thin overcoat. While there is excellent agreement between our implementation of the sophisticated Monte Carlo program SRIM [2] and our intuitive model in all cases, both fail to describe the measured energy distribution of a ¹⁴⁸Gd alpha source with a thin (∼200μg cm⁻²) Au overcoat. We discuss possible origins of the disagreement and suggest avenues for future study.

This paper describes the methodology for processing Ampere-Volts (I-V) characteristics of the Langmuir probe in magnetized plasma using graphical programming language based on LabVIEW. Computing the plasma parameters from I-V characteristic involves several steps that include signal processing, interpolation, linear and non-linear curve fitting based on physical models, finding the derivatives of the experimental curve and determining the zero-crossing of the probe current as a function of the applied voltage. These operations are practically tedious to perform manually causing systematic errors in output parameters. To overcome this challenge, software is developed to analyze the planar Langmuir probe characteristics in magnetized plasma. The software allows simultaneous display of different plasma parameters that helps to verify the consistency of the analyzed plasma parameters with the standard probe theory. Using this software, plasma parameters are obtained in a linear plasma device and its characteristics are discussed.

A low noise Front End Electronics (FEE) for two-dimensional position sensitive Micro-Channel Plate (MCP) detector has been developed. The MCP detector is based on Wedge and Strip Anode (WSA) with induction readout mode. The WSA has three electrodes, the wedge electrode, the strip electrode, and the zigzag electrode. Then, three readout channels are designed in the Printed Circuit Board (PCB). The FEE is calibrated by a pulse generator from Agilent. We also give an analysis of the charge loss from the CSA. The noise levels of the three channels are less than 1 fC RMS at the shaping time of 200 ns. The experimental result shows that the position resolution of the MCP detector coupled with the designed PCB can reach up to 110 μm.

Recently a new generation of picosecond dissectors were created on the basis of the PIF-01/S1 picosecond streak-image tube designed and manufactured at the GPI Photoelectronics Department. The results of the measurements of instrument characteristics of the new dissector, which were carried out in the static mode, showed that temporal resolution of the dissector can be better than 3-4 ps (FWHM). The results of temporal resolution calibration of the new-generation picosecond dissector carried out at the specialized set-up based on a femtosecond Ti:sapphire laser are given in this work.