Xray system calibration for TID irradiations Dima Maneuski

X-ray system calibration for TID irradiations Dima Maneuski

X-ray tube calibration procedures • Initial calibration (end 2016, beginning 2017) • Used PIN diode supplied by RAL (thanks to John Mathieson). This PIN diode was calibrated against calibrated PIN diode provided by Federico Faccio. • Since the PIN diode changed location (RAL -> Glasgow) and was “second order“ calibrated, decided to go further and cross calibrate it against “gold standard”, namely radio chromic film. • Calibration film was provided in two batches, first batch by Federico Faccio and subsequently by Federico Ravotti. • First batch gave cross calibration accuracy of ~20% and the measurements could’ve been improved ( 1 - the film I was given should’ve been exposed for longer to yield optimal performance, 2 – my mounting and handling of the film was not ideal and left sticky tape residue on most of the films exposed, which could’ve been avoided) • Second batch yielded accuracy of ~10%. I adjusted the calibration coefficient accordingly and used those numbers ever since. • Subsequent calibrations (mid 2017 onwards) • All subsequent calibrations were done with RAL Pin diode only, before each irradiation campaign (and for the first two RD 53 A irradiations – before and after). How stable RAL diode calibration over years remains an open question. 21 October 2020 Dima Maneuski 1

X-ray tube calibration procedures (continued) • Circa 2018 Federico Faccio purchased a batch of AXUVHS 5 diodes, calibrated them inhouse and distributed to interested parties. I’ve got two. • I haven’t used them yet because X-ray tube broke at the time and since we got a new tube, there was no irradiations performed, but I did calibrate the new tube with RAL diode. • I shipped both diodes to Oxford, they will make proper housing for them and will send one diode back. • I would like to cross calibrated RAL vs AXUVHS 5 diodes with our new X-ray tube to see if the doses on both are consistent. Key system parameters: N. B. All doses are always Si. O 2 equivalent! 21 October 2020 Dima Maneuski • 50 k. Vp • Current can vary but usually set to 50 m. A • 150 um Al foil in front of the tube! • Old tube: Thales THX 160, 2. 5 k. W, W • New tube: Varex NDI-161, 3 k. W, W 2

RD 53 B irradiation status • X-ray system is ready • Mounting for up to 3 chips at a time is ready • Would like to do RAL vs AXUVHS 5 calibration before the start • Need to bare in mind that haven’t done this in over a year Slow dose irradiation setup is on its way • Kr-85 source, 3. 7 GBq, VZ-2866, D=20 mm confirmed to be delivered next week (already in the UK at the supplier’s premises) • Need to order the freezer • Need to build the lead castle • Need to calibrate the dose and build XY dose map (can we actually use the same pin diode/method as with the Xray tube? ? ? ) • Progress will depend on my commitment to other activities 21 October 2020 Dima Maneuski 3