Proton Calorimetry/Meetings/2017/05/11 - Revision history

SimonJolly at 16:19, 11 May 2017

2017-05-11T16:19:37Z

← Older revision		Revision as of 16:19, 11 May 2017
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	** 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.		** 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 eV since otherwise Geant4 models might fail.		** There is a '''safety energy threshold''' for the production of secondary particles of 990 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''':

SimonJolly at 16:18, 11 May 2017

2017-05-11T16:18:20Z

← Older revision		Revision as of 16:18, 11 May 2017
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	* '''SJ''' and '''ABF''' visiting Nuvia a.s. on Monday 29th May. '''SJ''' needs to pull his finger out and book his flights...		* '''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.		* '''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.

SimonJolly at 14:34, 11 May 2017

2017-05-11T14:34:36Z

← Older revision		Revision as of 14:34, 11 May 2017
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	** Generally excellent linear response between energy and ADC peak; some odd results, probably due to pile-up.		** Generally excellent linear response between energy and ADC peak; some odd results, probably due to pile-up.
	** Energy is highly reproducible despite PMT current limit: good performance from UCL detector and MedAustron accelerator!		** Energy is highly reproducible despite PMT current limit: good performance from UCL detector and MedAustron accelerator!
	** Energy resolution as a function of energy shows ~~sort~~(E) dependence but data hand-selected...		** Energy resolution as a function of energy shows √(E) dependence but data hand-selected...
	** Clear double peaks seen in 112.4 MeV measurements: probably correlated to PMT current limit; lower current at start of spill, then higher current gives 2 rates.		** Clear double peaks seen in 112.4 MeV measurements: probably correlated to PMT current limit; lower current at start of spill, then higher current gives 2 rates.
	* Need to confirm how Caen ADC is doing pedestal subtraction.		* Need to confirm how Caen ADC is doing pedestal subtraction.

SimonJolly at 14:33, 11 May 2017

2017-05-11T14:33:57Z

← Older revision		Revision as of 14:33, 11 May 2017
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	** For 30 second spill, pile-up seen for longer gates.		** For 30 second spill, pile-up seen for longer gates.
	** Fit to resolution peak needs improvement: sometimes double peaks appearing on fitted peak.		** Fit to resolution peak needs improvement: sometimes double peaks appearing on fitted peak.
	** PMT may be saturating: running HV at -1200 V.		** PMT may be saturating: running HV at -1200 V.
	* Second night:		* Second night:
	** Some reduction in beam current through reducing final quad strengths; much better low current stability from increasing chopper current to scrape on chopper dump.		** Some reduction in beam current through reducing final quad strengths; much better low current stability from increasing chopper current to scrape on chopper dump.
	** 6mm collimator and chopper scraping gave 100–~~150kHz~~ rates.		** 6mm collimator and chopper scraping gave 100–150 kHz rates.
	** Ran energy scan from 252.4–62.4 MeV.		** Ran energy scan from 252.4–62.4 MeV.
	** Generally excellent linear response between energy and ADC peak; some odd results, probably due to pile-up.		** Generally excellent linear response between energy and ADC peak; some odd results, probably due to pile-up.
	** Energy is highly reproducible despite PMT current limit: good performance from UCL detector and MedAustron accelerator!		** Energy is highly reproducible despite PMT current limit: good performance from UCL detector and MedAustron accelerator!

SimonJolly: Created page with "== Minutes for UCL Proton Calorimetry Meeting, 11th May 2017 (D17, Physics & Astronomy, UCL) == === Present === '''Simon Jolly''', '''Laurent Kelleter''', '''Anastasia Basharin..."

2017-05-11T14:31:21Z

Created page with "== Minutes for UCL Proton Calorimetry Meeting, 11th May 2017 (D17, Physics & Astronomy, UCL) == === Present === '''Simon Jolly''', '''Laurent Kelleter''', '''Anastasia Basharin..."

New page

== Minutes for UCL Proton Calorimetry Meeting, 11th May 2017 (D17, Physics & Astronomy, UCL) ==

=== Present ===

'''Simon Jolly''', '''Laurent Kelleter''', '''Anastasia Basharina-Freshville'''

'''ABF''':
* [http://www.hep.ucl.ac.uk/pbt/wikiData/presentations/2017/ABF_medAustron_mar2017_analysis.pdf Summary of data taken at MedAustron].
* First night:
** Rates generally too high for 5 second spill: lots of pile-up.
** For 30 second spill, pile-up seen for longer gates.
** Fit to resolution peak needs improvement: sometimes double peaks appearing on fitted peak.
** PMT may be saturating: running HV at -1200 V.
* Second night:
** Some reduction in beam current through reducing final quad strengths; much better low current stability from increasing chopper current to scrape on chopper dump.
** 6mm collimator and chopper scraping gave 100–150kHz rates.
** Ran energy scan from 252.4–62.4 MeV.
** Generally excellent linear response between energy and ADC peak; some odd results, probably due to pile-up.
** Energy is highly reproducible despite PMT current limit: good performance from UCL detector and MedAustron accelerator!
** Energy resolution as a function of energy shows sort(E) dependence but data hand-selected...
** Clear double peaks seen in 112.4 MeV measurements: probably correlated to PMT current limit; lower current at start of spill, then higher current gives 2 rates.
* Need to confirm how Caen ADC is doing pedestal subtraction.
* Also finished running a whole battery of tests on PMT rate and current saturation: all sent to Hamamatsu.
* Tested signal cables to see effect on resolution: longer cables degrade resolution.

'''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]:
** Electron contribution to dose increases with smaller range cut: more short-range electrons produced.
** Threshold at ~1 micron: for shorter range cuts, no difference in dose. Probably due to 990 eV "safety threshold" for ionisation in Geant4.
* Fun facts about Geant4:
** '''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 eV since otherwise Geant4 models might fail.

'''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.