A large number of the project results are related to the technical development of the i-TED system, initially proposed in C. Domingo-Pardo, “i-TED: A novel concept for high-sensitivity (n,γ) cross-section measurements”, Nuclear Inst. and Methods A, Volume 825, p. 78-86 (2016).
In order to develop this innovative and complex apparatus, within the HYMNS project we had to perform first a series of technical developments. One such development consisted of large-area position-sensitive radiation detectors with silicon-photomultiplier readout, a work that we published in P. Olleros et al., “On the performance of large monolithic LaCl3(Ce) crystals coupled to pixelated silicon photosensors”, Journal of Instrumentation, Vol 13, Issue 03, pp. P03014 (2018). This type of detector was necessary in order to attain the high detection efficiency required for this type of experiments, while preserving a high energy- and position-resolution for applying the proposed Compton imaging methodology. A second technical achievement was the development of advanced position-reconstruction techniques, which enabled a high spatial resolution, of few mm, for the gamma-ray hit 3D-location in the large scintillation crystal. The results of this work were reported in V. Babiano, et al., “γ-Ray position reconstruction in large monolithic LaCl3(Ce) crystals with SiPM readout”, Nuclear Inst. and Methods A, Vol 931, p. 1-22 (2019) and in J. Balibrea-Correa et al., “Machine Learning aided 3D-position reconstruction in large LaCl3 crystals” Nuclear Inst. and Methods A, Vol 1001, id. 165249 (2021).
After these technical achievements, we were able to develop the first i-TED demonstrator, a work which was published in V. Babiano et al., “First i-TED demonstrator: A Compton imager with Dynamic Electronic Collimation” Nuclear Inst. and Methods A, Vol 953, article id. 163228 (2020). Subsequently, we applied this i-TED demonstrator for the first time in time-of-flight neutron-capture experiments, at the CERN n_TOF facility, in order to demonstrate the capability to reject background events by means of the imaging approach proposed in this project. The successful results of this study were reported in V. Babiano-Suarez et al., “Imaging neutron capture cross sections: i-TED proof-of-concept and future prospects based on Machine-Learning techniques”, The European Physical Journal A, Vol 57, Issue 6, id.197 (2021). These results were also disseminated by the HYMNS research team at international conferences, such as IEEE Nuclear Science and Medical Imaging Symposium, UK, 2019; International Conference on Nuclear Astrophysics IX, Germany, 2019; Nuclei in the Cosmos XVI, China 2021; IEEE Nuclear Science and Medical Imaging Symposium, Japan, 2021.
In an effort to exploit and transfer to society the developments of this project, a study was carried out to evaluate the applicability of the developed i-TED detection system to medical physics. In particular, the treatment of cancer tumors via the modern hadron-therapy technique requires an accurate monitoring of the ion range in the patient tissue. As we describe in J. Lerendegui-Marco et al., “Towards Machine Learning aided real-time range imaging in proton therapy”, Nature Scientific Reports, 12, 2735 (2022), both the hardware and software algorithms developed in the framework of HYMNS can help to improve these treatments by means of real-time range monitoring.
Once the i-TED detection system was fully developed, the 79Se neutron-capture experiment was carried out by the HYMNS research team in 2022 at the CERN n_TOF facility. Online monitoring allowed us to assess the quality of the data taken with i-TED, and preliminary results were presented recently at the Astrophysics with Radioactive Isotopes Conference, Budapest, June 2022. The final data analysis and astrophysical interpretation will be published in the near future.
