Proton Calorimetry/Meetings/2017/11/29

Minutes for UCL Proton Calorimetry Meeting, 22nd November 2017 (D17, Physics & Astronomy, UCL)

Present

Simon Jolly, Ruben Saakyan, Laurent Kelleter, Anastasia Basharina-Freshville, Jordan Silverman, Dan Walker, Matthieu Hentz

ABF:

• Fitting finally seems to work for single module spectrum:
  • Landau-Gaussian convolution with second degree polynomial.
  • ROOT requires specific order: fits Landau-Gaussian first.
  • Small features on the left of peak show extra 'wrinkle' which is not quite fitted; not present in July'15 data with UCL negative base.
  • Fit worse for MedAustron data but likely to be a result of pile-up.
  • FWHM from fit overestimates resolution slightly.
• Hamamatsu provided quote for flat panel detectors:
  • Contact person Simon Whitehead.
  • Recommended C9730DK-10 with faster readout rate but larger noise.
  • Will ask for quote for C9728SK-10 and check which has larger dynamic range.
  • Will also check whether we can get demo model to test: full cost £16k + £2k for software.

MH:

• Working on staged simulation to improve speed:
  • Large speed difference between good and bad nodes: trying to script finding fastest nodes...
  • Time limit of 12 hours for medium queue: some jobs overrun due to slow nodes and get ejected.
• Also trying to visualise beam profile every 25mm:
  • Can't define overlapping geometries: need to include parallel world with sensitive detectors.
  • No response from Ben Morgan: will email Geant4 mailing list.
  • Sensitive detectors provide speed up over writing data in the stepping action.
• Will look into getting Oyster cards for ENLIGHT meeting delegates.

RS:

• Visit to Nuvia Monday/Tuesday:
  • Requested 100x100mm sheets, 2mm or 3mm thick depending on reliability of production.
  • Total thickness of 60mm
  • Nuvia produce a thick piece of scintillator, then squeeze under heat to correct thickness, then cut out sheet.
  • Previous issues result from lack of attention to pressing...
  • Samples will arrive before Christmas (perhaps not all...).
  • Hana about to go away on maternity leave...
• Should be possible to cut and polish samples before they arrive:
  • Derek can cut some pieces from existing spares.
  • Georgio Savini and David Brooks should have expertise on polishing.
  • Nuvia may be able to polish themselves.

DW:

• ROOT scripts for reading Lecroy binary files is now working.
  • Defines classes for acquiring and manipulating data.
  • Just got histogram spectrum working.
  • Will reject bad pulses and pulses with high variation in baseline.
  • Can output data to suitable file format.

JS:

• Working on alternate fit for single module spectrum:
  • Fit uses Landau-Gaussian convolution with extra exponential part.
  • Χ² per NDF above 5.
• Not entirely dissimilar from Anastasia's fitting function...
• Will review in a week.

LK:

• All of last few weeks spent writing paper on Build-Up Effects in Proton Therapy:
  • Struggling to define protonic build-up in robust way.
  • Using 30% of Bragg peak good at high energy but poor at low energy.
  • Bortfeld formula works in opposite direction: would rather not use fit (need to check with Adam Gibson).
  • Have contacted Tracey Underwood to review paper.