Proton Calorimetry/Meetings/2017/05/24: Difference between revisions

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* [http://www.hep.ucl.ac.uk/pbt/wikiData/presentations/2017/ABF_LEMO_splitter_tests_24.05.17.pdf Looking at effect of splitting signals for remote testing]:
* [http://www.hep.ucl.ac.uk/pbt/wikiData/presentations/2017/ABF_LEMO_splitter_tests_24.05.17.pdf Looking at effect of splitting signals for remote testing]:
** Need to split signal from PMT to Caen digitiser and scope with 50 Ω splitter.
** Need to split signal from PMT to Caen digitiser and scope with 50 Ω splitter.
** Spectra become less Gaussian and more difficult to fit when using splitter.
** &sigma;<sub>pedestal</sub> and &sigma;<sub>width</sub> very similar...
** Effects get worse with lower ADC counts.
** Current 50&nbsp;&Omega; splitter will '''not''' work for our purposes.
* Need to find a solution in order to monitor signal in 2 places:
** Make an active splitter?
** Get a 50&nbsp;&Omega; BNC splitter to reduce number of cables and connectors.
** '''SJ''' suggest contacting '''Samer Al-Kilani''' and '''Izzat Darwazeh''' (UCL EE) for optimal cables and splitting. 


'''LK''':
'''LK''':
* [http://www.hep.ucl.ac.uk/pbt/wikiData/presentations/2017/LK20170510_BuildUpAndSecondaries.pdf Looking at dose build-up effect in proton therapy and secondary particles]:
* [http://www.hep.ucl.ac.uk/pbt/wikiData/presentations/2017/LK20170524_SegCal_Update.pdf Update on segmented calorimeter simulations]:
** Electron contribution to dose increases with smaller range cut: more short-range electrons produced.
** Corrected Physics List to include nuclear interactions.
** Threshold at ~1 micron: for shorter range cuts, no difference in dose.  Probably due to 990&nbsp;eV "safety threshold" for ionisation in Geant4.
** Simulations more accurate due to inclusion of nuclear build-up: fit now slightly worse as a result.
* Fun facts about Geant4:
**'''SJ''' agrees that these effects should be included in the model, but probably not at this stage.
** '''Deposited energy''' ignores energy of secondary particles.
** '''Energy loss''' records energy of tracked particle and its secondaries BUT in the place where they are produced! (not where the secondaries deposit their energy).
** '''Range cut''': Only secondaries which are expected to travel further then the range cut will be tracked BUT this theoretically only applies to secondary electrons, positron, gammas and protons.
** To be more clear: exotic secondaries as neutrons will always be produced and tracked, independently from the range cut. No influence of the range cut on the number of secondary protons seen.
** There is a '''safety energy threshold''' for the production of secondary particles of 990&nbsp;eV since otherwise Geant4 models might fail.
* LET-weighted results show much higher contribution from hadronic secondaries, particularly at high energy.
* Range cut effects not clearly understood: '''ABF''' suggests contacting '''Ben Morgan''' at Warwick.
 
'''SJ''':
* '''SJ''' and '''ABF''' visiting Nuvia a.s. on Monday 29th May.  '''SJ''' needs to pull his finger out and book his flights...
* '''SJ''' talking at [https://www.ucl.ac.uk/medphys/research/protons UCL Medical Physics PART Group] meeting; '''LK''' may be press-ganged into joining.
* During 3-day trip to PSI, discussed collaboration with '''Ros Perrin''', '''Tony Lomax''' and '''Sairos Safai''' to look at effect of lung motion interplay during PBT dose delivery:
** '''LuCa''' lung phantom is tissue equivalent with air-driven breathing cycle: [http://www.hep.ucl.ac.uk/pbt/wikiData/photos/PSI_LuCa_03-05-17/ photos and movies can be found here].
** Plastic scintillator disc would be inserted into phantom and irradiated during treatment: light emission imaged by camera.
** PSI would look after camera, mounting and optics.
** UCL (ie. '''LK''') would write the code to reconstruct the dose distribution in each slice from camera movie by fitting to quenched light output.
** Approximately 3 months total work for '''LK''': would include time spent at PSI as part of OMA placement.
** '''ABF''' also interested in spending time at PSI.

Latest revision as of 13:58, 24 May 2017

Minutes for UCL Proton Calorimetry Meeting, 24th May 2017 (D17, Physics & Astronomy, UCL)

Present

Simon Jolly, Laurent Kelleter, Anastasia Basharina-Freshville, Jordan Silverman

ABF:

  • Full data acquisition now running completely over the network:
    • Single 50m cat6a cable runs into treatment room.
    • Network hub in treatment room connects to DAQ PC/laptop and scope.
    • DAQ PC connects to Caen digitiser, HV and detector emulator.
    • Connect to scope and DAQ PC via Windows Remote Desktop.
  • Looking at effect of splitting signals for remote testing:
    • Need to split signal from PMT to Caen digitiser and scope with 50 Ω splitter.
    • Spectra become less Gaussian and more difficult to fit when using splitter.
    • σpedestal and σwidth very similar...
    • Effects get worse with lower ADC counts.
    • Current 50 Ω splitter will not work for our purposes.
  • Need to find a solution in order to monitor signal in 2 places:
    • Make an active splitter?
    • Get a 50 Ω BNC splitter to reduce number of cables and connectors.
    • SJ suggest contacting Samer Al-Kilani and Izzat Darwazeh (UCL EE) for optimal cables and splitting.

LK:

  • Update on segmented calorimeter simulations:
    • Corrected Physics List to include nuclear interactions.
    • Simulations more accurate due to inclusion of nuclear build-up: fit now slightly worse as a result.
    • SJ agrees that these effects should be included in the model, but probably not at this stage.
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