AUTHOR=Toppi Marco , Battistoni Giuseppe , Bochetti Alessandro , De Maria Patrizia , De Simoni Micol , Dong Yunsheng , Fischetti Marta , Franciosini Gaia , Gasparini Leonardo , Magi Marco , Manuzzato Enrico , Mattei Ilaria , Mirabelli Riccardo , Muraro Silvia , Parmesan Luca , Patera Vincenzo , Perenzoni Matteo , Sarti Alessio , Schiavi Angelo , Sciubba Adalberto , Traini Giacomo , Valle Serena Marta , Marafini Michela 

TITLE=The MONDO Tracker: Characterisation and Study of Secondary Ultrafast Neutrons Production in Carbon Ion Radiotherapy

JOURNAL=Frontiers in Physics

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2020.567990

DOI=10.3389/fphy.2020.567990

ISSN=2296-424X

ABSTRACT=<p>Secondary neutrons produced in particle therapy (PT) treatments are responsible for the delivery of a large fraction of the out-of-target dose as they feebly interact with the patient body. To properly account for their contribution to the total dose delivered to the patient, a high precision experimental characterisation of their production energy and angular distributions is eagerly needed. The experimental challenge posed by the detection and tracking of such neutrons will be addressed by the MONDO tracker: a compact scintillating fiber detector exploiting single and double elastic scattering interactions allowing for a complete neutron four-momentum reconstruction. To achieve a high detection efficiency while matching the fiber (squared, <inline-formula id="inf1"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>250</mml:mn><mml:mtext> </mml:mtext><mml:mtext>μm</mml:mtext></mml:mrow></mml:math></inline-formula> side) high granularity, a single photon sensitive readout has been developed using the CMOS-based SPAD technology. The readout sensor, with pixels of <inline-formula id="inf2"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>125</mml:mn><mml:mo>×</mml:mo><mml:mn>250</mml:mn><mml:mtext> </mml:mtext><mml:msup><mml:mrow><mml:mtext>μm</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math></inline-formula> size, will be organised in tiles covering the full detector surface and will implement an autotrigger strategy to identify the events of interest. The expected detector performance in the context of neutron component characterisation in PT treatments delivered using carbon ions has been evaluated using a Monte Carlo simulation accounting for the detector response and the neutrons production spectra.</p>