Proton Calorimetry/Meetings/2017/11/29

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


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


  • 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.


  • 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.


  • 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.


  • 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.


  • 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.


  • 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.
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