Minutes for UCL Proton Calorimetry Meeting, 16th August 2017 (D107, Physics & Astronomy, UCL)
Simon Jolly, Laurent Kelleter, Jordan Silverman
- Ran a few more simulations for build-up paper:
- Bortfeld description fails between 200–300 MeV: at 500 MeV description is very poor (Bortfeld recommends only between 40–200 MeV).
- At 500 MeV "entrance bump" is almost as large as the Bragg peak!
- Electron build-up measured within the simulation by counting energy deposition attributed to electrons at each step.
- Compare dose at depth to dose at 0.07 mm to define build-up (appropriate skin depth): approx. 2% of Bragg peak depth.
- Hadronic build-up defined by secondary protons: several orders of magnitude larger than heavier hadrons.
- Liquid Hydrogen simulations show much smaller entrance bump: secondary proton spectrum still retains Bragg peak (Oxygen no longer disrupting primary proton energy).
- No secondary production of hadrons after Bragg peak in liquid Hydrogen: no neutron production so nothing gets past Bragg peak.
- Testing PRaVDA PRIAPUS CMOS sensor:
- Flashed single scintillator sheets with LED and imaged light with PRIAPUS.
- Checked different scintillator thicknesses (3 and 10 mm) and different LED voltages.
- Checked spacing between sensor and scintillator: need to keep scintillator as close to sensor as possible without touching it! Minimum distance tried was 2 mm.
- Beam test at Birmingham Wednesday 23rd August.