Pion Meeting January 6 2023 3:30PM ET

From Moller Wiki
Jump to: navigation, search

Back to Main Page >> Pion Meetings

Zoom link: https://jlab-org.zoomgov.com/j/1608212513?pwd=M25LR1hzN3hLWm0xaFFETjZ0U1lQZz09

Agenda

Agenda:

  1. Comparing the simulations with the beam test at Mainz Microtron (Elham)
  2. Beam Dump backgrounds in Fluka (Neven)

Attendance

David, Elham, Kate, Wouter, Neven, Jim

Minutes

1) (Elham) More results on comparing beam data from Mainz to G4 results

  • Normalized plots of pion detector PEs vs location along detector show reasonably good agreement between data and G4.
  • GEANT 4 pulse-height distributions don't show any high-energy tail in detector response from 855 MeV electrons, unlike the beam data. Tried adding material in front of detector, no change event for 10 cm of Al, but it appears that the GDML code didn't properly put the material in-place. Will change this and try again.
  • (general discussion) Some evidence that the fractional high-energy tail is increased in the data when the thin quartz prototype was placed upstream of lucite (quantitatively: the ratio of standard deviation/(sigma of Gaussian fit) for the longer lucite was 4.00 at a position of -5 cm when the thin quartz was in front, but was 2.96 at -4 cm when it was not; the positions are not exactly equivalent, but the trend with position without the thin quartz was that this ratio decreased as the position increased,i.e. the ratio was 2.54 at -12 cm... so it sure seems like the than quartz added high-energy tail). Perhaps showering and/or delta-rays is the cause of the tail. It may be that the simulation is not generating delta-rays, or has thresholds on some process that are not low enough to see the effect, or that there is more material upstream than in the simulation. Showering/delta rays within the lucite itself may be part of the effect.
  • Could the tail be a pulse pileup issue? Probably not (beam/trigger rate was low, 5 kHz, but if the beam structure was not CW, then there still may be some effect). Could we look at the ADC spectra for the trigger scintillator to look for pileup?

2) (Neven) Fluka to look at background at the back of the Pb Donut coming from beam dump. Initial results say the main source is the diffuser in the beam dump - can we get rid of it?

  • 250 kHz/cm^2 of neutrons
  • 40 kHz/cm^2 of > 0.1 MeV electrons
  • 140 kHz/cm^2 of > 10 MeV gammas
  • should compare to GEANT 4 beam-generator simulations.
Retrieved from "https://moller.jlab.org/wiki/index.php?title=Pion_Meeting_January_6_2023_3:30PM_ET&oldid=4081"