Accurate bunch-charge measurement is essential for FLASH and ultra-high-dose-rate (UHDR) electron accel erators, where therapeutic doses exceeding 40Gy/s are de livered in nanosecond-to-microsecond macropulses. We present the calibration and characterization of a non intercepting charge-measurement chain, based on a Bergoz integrating current transformer (ICT) coupled to a Libera ADC-500 digitizer, developed for the SAFEST compact C band FLASH linac at Sapienza University of Rome. We show that conventional independent pulse-boundary detec tion introduces spurious pulse-width-dependent charge er rors of up to 40% in the short-pulse regime, arising from ICT-induced pulse broadening rather than true chargeloss. A unified, output-driven integration window, combined with a near-zero-crossing boundary-detection method, removes this artifact entirely, achieving charge-reconstruction repeatabil ity better than 2% and a combined measurement uncertainty of ≤2.2%, over the range 2ns–1000ns and 5pC–75nC, without any pulse-width-dependent correction factor. A seg mented single-shot history buffer is further validated for dead-time-free pulse-by-pulse logging at repetition rates up to 200Hz, relevant for clinical FLASH dosimetry.
High Precision Calibration and Pulse-Invariant Charge Reconstruction in ICT-Based Diagnostics for C-Band FLASH Electron Linacs / Akbar, S., Boldrini, R., Chiadroni, E., Curcio, A., Coppola, M., Farina, S., Franzini, G., Ficcadenti, L., Giuliano, L., Mostacci, A., Migliorati, M., Magi, M., Quartullo, D., Palumbo, L.. - (2026). (15th International Beam Instrumentation Conference Canada ).
High Precision Calibration and Pulse-Invariant Charge Reconstruction in ICT-Based Diagnostics for C-Band FLASH Electron Linacs
Akbar, S.
Primo
Methodology
;Boldrini, R.Secondo
Membro del Collaboration Group
;Chiadroni, E.Supervision
;Curcio, A.Supervision
;Coppola, M.Membro del Collaboration Group
;Farina, S.Membro del Collaboration Group
;Franzini, G.Membro del Collaboration Group
;Ficcadenti, L.Membro del Collaboration Group
;Giuliano, L.Membro del Collaboration Group
;Mostacci, A.Supervision
;Migliorati, M.Membro del Collaboration Group
;Magi, M.Penultimo
Membro del Collaboration Group
;Quartullo, D.Membro del Collaboration Group
;Palumbo, L.Ultimo
Project Administration
2026
Abstract
Accurate bunch-charge measurement is essential for FLASH and ultra-high-dose-rate (UHDR) electron accel erators, where therapeutic doses exceeding 40Gy/s are de livered in nanosecond-to-microsecond macropulses. We present the calibration and characterization of a non intercepting charge-measurement chain, based on a Bergoz integrating current transformer (ICT) coupled to a Libera ADC-500 digitizer, developed for the SAFEST compact C band FLASH linac at Sapienza University of Rome. We show that conventional independent pulse-boundary detec tion introduces spurious pulse-width-dependent charge er rors of up to 40% in the short-pulse regime, arising from ICT-induced pulse broadening rather than true chargeloss. A unified, output-driven integration window, combined with a near-zero-crossing boundary-detection method, removes this artifact entirely, achieving charge-reconstruction repeatabil ity better than 2% and a combined measurement uncertainty of ≤2.2%, over the range 2ns–1000ns and 5pC–75nC, without any pulse-width-dependent correction factor. A seg mented single-shot history buffer is further validated for dead-time-free pulse-by-pulse logging at repetition rates up to 200Hz, relevant for clinical FLASH dosimetry.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
