Evolution of X-ray calorimeter spectrometers at the Lawrence Livermore Electron Beam Ion Trap

High-resolution broadband, non-dispersive x-ray calorimeter spectrometers have been under development for spaceflight since 1984. As an offshoot of the significant NASA investment in this technology, we have developed a series of calorimeter instruments for laboratory use and installed them at the Electron Beam Ion Trap (EBIT) facility at the Lawrence Livermore National Laboratory. The calorimeter instruments at EBIT have significantly enhanced the capabilities of our laboratory astrophysics program including broad-band measurements of emission from charge exchange recombination and absolute cross sections for collisional excitation. The first Goddard Space Flight Center (GSFC) calorimeter instrument was installed at the EBIT facility in July of 2000 and has seen two major upgrades. The performance of the instrument has significantly improved from the initial instrument that had a resolving power of ∼500 at 6 keV, and essentially no quantum efficiency at energies above 20 keV, to the current instrument that has a resolving power of 1350 and 95% quantum efficiency at 6 keV, and a resolving power of 1800 and 32% quantum efficiency at 60 keV.