RadioLab: Interdisciplinary Paths of Nuclear Physics

Health effects of radon, most notably lung cancer, have been investigated for several decades. Therefore, indoor radon monitoring is a great way to consider the problem of natural radioactivity but also a way to insert phenomenological elements into physics education useful in understanding the crisis of classical physics and for introducing modern physics. The RadioLab project allowed to explore the possibility of a rapid introduction of elements of modern physics for younger students.


Introduction
In an increasingly interconnected and globalized world with common problems and challenges, skills from a range of disciplinary and professional perspectives have become crucial for the identification and management of new and emerging global concerns.
The world is characterized by new levels of complexity and citizens need a deeper understanding of global societal challenges and their implications for themselves, their families, and their communities as underlined by the United Nations Educational, Scientific and Cultural Organization [1].Scientific literacy for citizenship can be considered the level of knowledge or skills required to act effectively in an active, engaged, and responsible way in a society that is both increasingly complex and science and technology-dependent [2].
Knowledge, skills, attitudes, and values necessary to shape the future need to make changes to science education curricula, pedagogy, and assessment practices and support science educators in embedding such approaches in their classrooms [3].
Examples of global or complex problems that citizens face with collective or individual choices and that require interdisciplinary study include global warming, environmental pollution, and apparently harmless practices that can damage health in a shorter or longer time [4].Rarely, however, students can experience an interdisciplinary approach to a complex real problem [2].
Since 2005 the National Institute of Nuclear Physics (Istituto Nazionale di Fisica Nucleare, INFN) proposed to high schools to carry out a monitoring of the indoor exposure to radon that allows to explore the interdisciplinary aspects of this theme through laboratory activities in nationwide initiative: the RadioLab project.
Citizens participating in contemporary socio-scientific issues (SSI) need to draw on local knowledge and personal experience.The introduction to nuclear phenomena proposed by the RadioLab project is developing in this direction.
Sometimes the subjective perception of a risk doesn't correspond to the objective and real risk of an activity.In particular, the radioactivity theme which is very relevant in scientific literacy (fig. 1) is misled because it is almost unknown; the public links this concept to nuclear arms and their usage in an uncorrected way for producing energy in the nuclear power plants, often totally ignoring the existence of natural radioactivity (see fig. 2).The core objectives of a socio-critical and problem-oriented approach to nuclear phenomena teaching are to increase students' interest in science and technology, to display the relevance of science in societal discussions and decision-making, to promote students' competency in the critical use of information and their reflection upon why, when and how science-related information is used by affected groups or for public purposes, and to promote student-active science learning motivated by relevant, contentious socio-scientific issues.

Figure 2.
Nuclear phenomena: shameless ignorance on this topic usually nourishes both great hopes that great fears often amplified by mass media, internet and social media.

Appalling Ignorance
RadioLab started with the aim of improving scientific communication on environmental radioactivity issues and with the vocation of developing laboratory activities and data analysis in complex experimental situations.
The project aims to increase awareness of the radon risk in the population through measures of concentration.Students start with a survey on radon in the school and surroundings, follow a learning path to introduce nuclear phenomena, are introduced to measures of radon concentration by using active and passive detectors, design a series of measures and implement them.The project activities have many interdisciplinary aspects ranging from health aspects to the risk due to exposure to ionizing radiation, from the history of the discovery of radioactive phenomena to the monitoring of natural radioactivity, from the diffusion of radon in the minerals from the subsoil up to touch technological aspects such as techniques of building construction and the materials used.RadioLab is also an excellent opportunity for professional development for teachers.Physics, biology, geology, mathematics, statistics, and the history of science are the main fields in which students acquire greater and deeper awareness of the basic concepts necessary to act consciously in a complex real context.Above all, they discover that they can acquire knowledge through active practices and cooperation getting to know and quantify even an elusive gas like radon.

Radon: why take care of it
Radon is the second cause of lung cancer in the general population, after smoking.Epidemiological studies have provided convincing evidence of an association between indoor radon exposure and lung cancer, even at relatively low radon levels.
The World Health Organization (WHO) first drew attention to the health effects of residential radon exposures in 1979.Moreover, WHO established the International Radon Project to identify effective strategies for reducing the health impact of radon and to raise public and political awareness about the consequences of long-term exposure to radon [5].
Radon is the only radioactive element produced in natural decay chains in gaseous form at standard temperature and pressure.It is a highly non-reactive noble gas, denser than air, odourless and colourless.Its isotopes decay alpha into solid elements such as polonium, actinium, bismuth, and lead, mainly still alpha emitters.
In closed and poorly ventilated environments, the concentration of radon can increase significantly, increasing the probability of decaying inside the lungs during breathing.This creates an accumulation of radioactive isotopes within the lungs whose epidemiological consequences are correlated to an increase in lung cancer.

Radiolab: active learning promoted in interdisciplinary activities
RADIOactivity-LABoratory is a project promoted in Italy by the National Institute of Nuclear Physics (INFN) to improve awareness of the importance of monitoring radon exposure in the environment.It is a nationwide initiative (fig.3) with a recent sub-project reserved for students living in minor islands (fig.4).The focus is on a hands-on measurement of indoor radon contamination realized in secondary schools.Students start with a survey on radon in the school and surroundings, follow a learning path to introduce nuclear phenomena, and are introduced to measures of radon concentration by using active and passive detectors, they design a series of measures and implement them.The project is characterized by a real experimental approach.It is not an occasional experiment: it usually requires two years, giving the possibility for the students to gain deeper thinking over and acquisition of the theme and it allows the study of the environment outside the school too.The highly multidisciplinary approach to this matter permits to linking of the knowledge of different subjects and the development of communication ability and debate between students and their relatives on these topics.A final spin-off is the training and professional empowerment of the teachers.The adopted strategy in the Radiolab project is focused on a direct engagement of students in laboratory activities, the national level of the initiative, which allows a comparison between different contexts, and the interdisciplinary approach developed through the following activities:  a preliminary survey (at school, at home, elsewhere),  introduction to nuclear phenomena and the radon risk,  monitoring the radon exposure by designing and implementing a campaign of measures in the school area,  data acquisition and statistical analysis,  other actions to promote awareness: the Radon Day (on November 7th, the birthday of Marie Curie) organized by almost all INFN divisions, where students from different schools present the most relevant results of their learning path (fig.5) and a RadioLab stand, with students as researchers, locally presented in some European Researchers' Night.Finally, a RadioLab summer school is organized every year1 in September to allow a direct exchange of experience between students and teachers (fig.6).

Interdisciplinary Paths of Nuclear Physics in Southern Tuscany
Interdisciplinary topics are usually more effective in teaching because they can arouse greater interest and motivate students [6][7][8].This is even more true in the case that the topics treated are perceived as relevant to health and concern phenomena that are not perceivable.A further feature that makes this journey fascinating and effective is to insert the key moments of understanding the complexity of nuclear phenomenology from a historical perspective both in the scientific field and in choices that have changed the history of contemporary society.
Furthermore, these learning paths enhance interest and motivation by clarifying methods and basic concepts.The focus on interdisciplinarity can promote standard lab activities that become more interesting and useful and new labs can be designed and realized.Teachers can be involved in professional empowerment and active applied physics educational research.
In southern Tuscany in the schools of the provinces of Siena, Grosseto and Florence, the project started in 2017 with the following methods:  learning paths can be realized in a School-Work Interchange program in which students gain school credits,  all activities are designed and customized together with teachers,  students work in small groups or all together (active and cooperative learning, problem posing and solving),  activities can be distributed in curriculum timetable or optional and realized at school, university and sometimes outdoors,  final products created by the participants are mandatory (e.g.report, multimedia presentation, essay, events, etc.)The project usually lasts at least two years to perform a full measurement of radon concentration with dosimeters (mean over at least one year of exposition).The duration of the course depends on the class attended by the students and on the concrete availability of time.The most usual designing are the following:  a shorter path: 1 year (usually for students attending the high school final year, age 17-18 y)  a standard path: 2 years (students' age 16-18 y),  a longer path: 3 years (students' age 15-18 y).In the former, the introduction to nuclear phenomena can be shorter because students' mathematical and physical skills are higher.Students are unlikely to be able to completely implement the planned measure, but they can follow all the phases by actively participating in the campaign of measures designed by other students in previous years.
In the standard one, it is possible in the second year to complete the measurements of radon concentration started in the previous one.
In the last case, more care is needed in introducing to younger students the required concepts of physics and mathematics and there is time to explain connections between history, science and nuclear uses in societies.

A survey on Radon.
A preliminary survey is useful for quantifying public awareness in the local surroundings.In the last years, all INFN Divisions have proposed the same survey every year to evaluate the fallout (a paper with the statistical analysis of the data, about 30000, is in preparation).
The survey is very simple and useful for starting contact with people during an event like an open day at school or on a stand during the European Researchers' Night.The survey core consists of only 3 questions: 1. Do you already know the RADON problem? 2. If YES, from which source? 3. Do you consider a measure urgent in your territory?The participants decided where to conduct the survey, e.g., at school (target students and teachers), at home (target family and friends), elsewhere during events or in public places (target generic public).They were prepared to interact kindly with people and were ready to answer properly to main questions that a person with no awareness about the radon issues can pose, also by using material prepared by other students.
The survey proved to be an excellent training ground for developing soft skills in students and showed a full engagement also in students with a minor interest in science.Another important aspect is the possibility of a direct application of statistical concepts in a real and meaningful context.
Since 2017, the participants in Radiolab have collected 3373 responses to the survey, initially using the paper format and from 2020 by inserting them directly into the online survey.
A comparison between two successive surveys in southern Tuscany is shown in fig. 7.

Interdisciplinary Paths of Nuclear Physics
Physics, history of science, mathematics, history of modern societies, and biology are involved in the following introduction to nuclear phenomena, necessary as a scientific and cultural basis for subsequent activities in the laboratory.Physics, biology, soft skills, physics laboratory, and chemistry are necessary for monitoring radon exposure in the everyday life of students.The introduction to radon and related phenomena starts from elements of physics and biophysics, geology for understanding where the radon isotopes are produced and how they can spread in nature and inside buildings (material sciences).
After a review of the main methods of measuring radon, the focus is on one or two methods, usually passive, which are suitable for the area where the students live.In most cases, CR-39 dosimeters are used.CR-39 (polyallyl diglycol carbonate) is a thermoset resin that is a particularly sensitive passive etched-track detector for radon dosimetry.These types of dosimeters perform an integral standing with an exposition of at least 3 months (usually 6).A diffusion chamber and a CR-39 dosimeter inside it are shown in figure 8. Students decided where to put dosimeters, and simultaneously filled a card describing the building and the location where each dosimeter is placed.In figure 9 students during the preparation of dosimeters are shown.After the exposition, the dosimeters must be developed in a chemical bath to observe the traces left by the alpha particles under an optical microscope (see figure 10).Dosimeters were etched in a thermal bath usually with a solution of NaOH 6 M for an hour (T = 375 K).From sub-microscopic damage tracks, it is possible to obtain micrometric tracks easily countable under a microscope.
An interesting learning path can be achieved by applying statistics to data analysis thus completing the realization of the radon concentration measurement.
Moreover, measures can become more or less complex depending on the experimental conditions that can change from one laboratory to another, giving the opportunity to students to explore a real problem posing and solving.A school was in the mountains and therefore the usual bath temperature, very near to the water boiling temperature cannot be reached.Small groups of students studied the problem by using the function modelling how etching velocity depends on the solution's concentration and temperature of the bath.Then all together decided which was the better strategy in their lab (to extend the etching time rather than increasing the concentration).

Results and discussion
Since the beginning of the project in Tuscany, around 500 students and a dozen teachers have participated in 6 schools.There were many activities, and they required a constant commitment of all the actors involved (students, teachers, and researchers) for a long time.
Overall, there was widespread satisfaction among the students who, although often engaged in extracurricular activities, found many issues engaging and interesting.This is especially true for students not particularly interested in physics.This is one of the positive aspects of proposing clearly interdisciplinary learning paths.Each student can find an issue closest to her/his interests.In the case of nuclear phenomena, this is particularly true because the narration that accompanies the introduction to the subject passes from the most famous female scientist, crossing the entire history of the twentieth century and touching hot topics in our society such as pollution deriving from human activities, the health, the sustainability of energy choices up to nuclear weapons, the cold war and the concrete consequences of the use of nuclear weapons.
On the other hand, students more interested in scientific aspects have found in the learning path nontrivial applications of physical and mathematical conceptual tools necessary in the scientific investigation of nature.
Finally, it is necessary to underline that a fundamental element in the success of this challenging and demanding project is the active involvement of the teachers who must carefully follow the progress of the students in unusual situations where reasoning, modelling and the scientific method must be applied constantly and well to obtain results acceptable.In classes where students did not find active support from their teachers, interest remained superficial, and the quality of the final products was poor.
RadioLab project has many aspects interesting in physics and science education, but also in the education of young citizens by touching socio-scientific issues like health risks, prevention, civil and war use of nuclear knowledge, history of science but also of our society, gender gap in science, and others that are emerging in the schools involved.
From an educational point of view, the project allows students and teachers to deepen physical, mathematical, chemical, and biological topics in an interdisciplinary way.
The project in various forms has continued for a decade involving a hundred teachers and thousands of students, but only in the last few years have the INFN divisions trying to coordinate the most important actions (survey, measurements with dosimeters, calibrations, and dissemination events) to obtain comparable results at national level.RadioLab has great educational and scientific literacy potential for citizens and it could be desirable to spread it more widely across Europe.

Figure 3 .
Figure 3. Territorial distribution of the INFN divisions involved in the project (Cagliari, Cosenza, Lecce, Milano, Napoli, Padova, Siena, Torino, Trieste) and the schools involved in ISORAD (a new subproject since 2020)

Figure 4 .
Figure 4. ISORAD, a special RadioLab for schools in minor islands.

Figure 5 .
Figure 5. Radon day in Siena (on the left) and in Cagliari (on the right).

Figure 6 .
Figure 6.On the left the participants of the first summer school in Macugnaga in an alpine refuge on Monte Rosa in 2018.On the right a measure of radon from the Etna volcano ground during the EtnaRadioLab summer school in 2019.

Figure 7 .
Figure 7. Two successive surveys in South Tuscany are shown, where the numbers indicate 1. Do you already know the RADON problem? 2. If YES, from which source? 3. Do you consider a measure urgent in your territory?There appears a doubling of people who know the radon problem in the same territory.A good increase but they remain about one-third of the total.The results from 2018 (3 schools, 378 answers) vs. 2019 (4 schools, 617 answers) were presented by students from Grosseto in the EtnaRadioLab summer school.

Figure 8 .
Figure 8.A diffusion chamber (a plastic holder) is shown on the left, which protects the CR-39 dosimeter from dust (mounted inside on the right).

Figure 9 .
Figure 9.A moment of the preparation of the dosimeters in class before positioning in the chosen sites.

Figure 10 .
Figure 10.Alpha particles damage the dosimeter by creating sub-microscopic traces.After a chemical etching of the surface (shown on the left a group of students during the development of exposed dosimeters), the traces become micrometric and can be observed under an optical microscope like spherical holes (blue or void, depending on the focus plane, as shown on the right).