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
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Presentation Transcript
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X-ray system calibration for TID irradiations Dima Maneuski<br>
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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 RD53A irradiations – before and after). How stable RAL diode calibration over years remains an open question. 1 21 October 2020 Dima Maneuski<br>
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X-ray tube calibration procedures (continued)
Circa 2018 Federico Faccio purchased a batch of AXUVHS5 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 AXUVHS5 diodes with our new X-ray tube to see if the doses on both are consistent. 2 21 October 2020 Dima Maneuski Key system parameters:
50 kVp
Current can vary but usually set to 50 mA
150 um Al foil in front of the tube!
Old tube: Thales THX160, 2.5kW, W
New tube: Varex NDI-161, 3kW, W N.B. All doses are always SiO2 equivalent!<br>
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RD53B irradiation status
X-ray system is ready
Mounting for up to 3 chips at a time is ready
Would like to do RAL vs AXUVHS5 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 3 21 October 2020 Dima Maneuski<br>
