PS%20Positron%20Simulations

1
PS Positron Simulations

• Stefan Funk
• June 6, 2006

2
Updated geometry

• Included two cherenkov detectors (5 and 3 m) with
  mylar windows and CO2 filling
• Included two plastic scintillators upstream of
  magnet
• Included annihilator blanket (3cm)
• Removed dump
• Included third plastic scintillator as veto
  between annihilator and CU
• Recording of energy in each detector

Plastic 2
Magnet 0
Cherenkov volumes
Plastic 0 and 1
Annihilator
3
Comparison electrons positrons

• Simulated 500,000 positrons and electrons
• Beam energy 1 GeV
• Require trigger in plastic scintillators 0 and 1
• Veto in plastic scintillator 2 to selected
  annihilated positrons
• To increase efficiency in the Monte Carlo, select
  only events that hit plastic 0 by sampling from
  the area covered by plastic0 and extrapolating
  the start of the event back to the beam position
• Annihilation probability ca 1e-3 (for cm
  blanket)

Plastic 2
Plastic 0 and 1
Annihilator
4
Comparison electrons positrons
All Events - Electrons - Positrons
Energy
Energy sum
No Positrons and two gammas in Event at
Reporting plane
Positrons in Event at Reporting plane
Energy vs Distance from center
Distance of two gammas
5
Comparison electrons positrons
Cut on plastic01 veto in plastic2 -
Electrons - Positrons
Some numbers Nparticles 500,000 Trigger
Plastic0 25600 Veto Plastic2 870 Veto Plastic2
above 900 GeV 86
Still some charged particles miss the veto
detector
6
Summary

• Updated geometry and gave code to Francesco
• Positron runs are technically working
• Next step
• See how we can distinguish annihilation events
• Mass production
• Think about how to best perform the positron runs
  to optimise the background studies