Proton Calorimetry/Meetings/2017/08/16

Minutes for UCL Proton Calorimetry Meeting, 16th August 2017 (D107, Physics & Astronomy, UCL)

Present

Simon Jolly, Laurent Kelleter, Jordan Silverman

LK:

• 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.

JS: