Proton Radiographs Using Position-Sensitive Silicon Detectors and High-Resolution Scintillators

7 pags., 11 figs., 1 tab.Proton therapy is a cancer treatment technique currently in growth since it offers advantages with respect to conventional X-ray and ¿ -ray radiotherapy. In particular, better control of the dose deposition allowing to reach higher conformity in the treatments causing less secondary effects. However, in order to take full advantage of its potential, improvements in treatment planning and dose verification are required. A new prototype of proton computed tomography scanner is proposed to design more accurate and precise treatment plans for proton therapy. Our prototype is formed by double-sided silicon strip detectors and scintillators of LaBr3(Ce) with high energy resolution and fast response. Here, the results obtained from an experiment performed using a 100-MeV proton beam are presented. Proton radiographs of polymethyl methacrylate (PMMA) samples of 50-mm thickness with spatial patterns in aluminum were taken. Their properties were studied, including reproduction of the dimensions, spatial resolution, and sensitivity to different materials. Structures of up to 2 mm are well resolved and the sensitivity of the system was enough to distinguish the thicknesses of 10 mm of aluminum or PMMA. The spatial resolution of the images was 0.3 line pairs per mm (MTF-10%). This constitutes the first step to validate the device as a proton radiography scanner.This work has been supported by the PRONTO-CM B2017/BMD-3888 project funded by Comunidad de Madrid (Spain). The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 654002 (ENSAR2) and grant agreement No [730983] (INSPIRE). This work has been partly supported by the Spanish Funding Agency for Research (AEI) through the PID2019-104390GBI00 and PID2019-104714GB-C21 projects. A.N. Nerio acknowledges the fundings from the Erasmus Mundus Joint Master Degree on Nuclear Physics co-funded by the Erasmus+Programme of the European Union

Populating α-unbound states in 16O via 19F (p, αy)16O reaction

2 pags., 4 figs.The 12C(α, y)16O reaction is important in the production of universal 16O, but its cross-section at the relevant energies of static helium burning is complex and uncertain. The total cross-section originates from a sum of resonance tails and direct captures, making the contributions of sub-threshold states difficult to estimate. One proposed method to estimate these contributions involves determining relevant reduced α-widths of the sub-threshold states through indirect measurements. Therefore, 19F(p, αy)16O reaction was used to populate α-unbound states in 16O using a 2.6 MeV proton beam on a CaF2 target. A detection system consisting of single and telescope configurations of Si detectors was used to detect 2α-particles and a 12C particle in coincidence. Scintillator detectors were included in the setup to study the de-excitation of the states populated in 16O to the ground state. Under good event conditions a preliminar indentification of the particles detected has been conducted.We acknowledge the funding through the grant MCIN/AEI PID2019-104390GB-I00