AUTHOR=Cayley James , Paino Jason , Guatelli Susanna , Rosenfeld Anatoly , Lerch Michael , Tan Yaw-Ren E. 

TITLE=Simulation and commissioning of a Faraday cup for absolute charge measurements of very high-energy electrons in-air at PEER

JOURNAL=Frontiers in Physics

VOLUME=Volume 12 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2024.1448025

DOI=10.3389/fphy.2024.1448025

ISSN=2296-424X

ABSTRACT=<p>The Pulsed Energetic Electrons for Research (PEER) beamline at the ANSTO Australian Synchrotron comprises a 100 MeV linac injector that is currently being developed for ultra-high dose-rate, very high-energy electron radiotherapy research. Previously, dosimetry studies discovered a lack of reliable charge measurement to the in-air end station, though no change in response was recorded in fast current transformer measurements, the only available diagnostic device for measuring charge. This work describes the process of simulating and then commissioning a purpose-built Faraday cup to ascertain absolute in-air charge measurements at PEER. By combining simulation data with experimental results, the PEER Faraday cup is shown to possess a primary electron capture efficiency of (99.22 <inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:math></inline-formula> 0.10)%, with a net capture efficiency due to secondary electron emission of (97.87 <inline-formula id="inf2"><mml:math id="m2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:math></inline-formula> 0.24)%. These results show the PEER Faraday cup performs as intended and, when scaled against simulations, will be suitable for measuring absolute charge at PEER.</p>