Updates June 5, 2015
Xiaqing Li
Done
• Compton scattering on proton and deuteron simulation
• Cosmic BG rejection in simulation (by Xuefei)
• Checked the exact geometry of HINDA in the Gamma Vault and
updated G4 simulation
Configuration of HINDA and target
③
②
④
③
①
④
𝜃
⑤
②
⓪
⑤
⑥
①
⑥
⑦
⑦
⓪
3
HINDA and target in Geant4 simulation
Cosmic background simulation
• Cosmic energy deposition from Xuefei’s old study
• Cosmic Muon rejection
• Remove events with E(shield) > 15 MeV in total shield NaI detector energy
deposition
• BPM cut: 4ns Gamma pulse in 180ns
Cosmic BG rejection (by Xuefei)
Event number
Core energy deposition
Total shield energy deposition
No cut
Cut @ 15MeV
Energy/ MeV
Cosmic BG rejection (by Xuefei)
Event number
Core energy deposition
Total shield energy deposition
No cut
Cut @ 25MeV
Energy/ MeV
Cosmic count rate in core (30 – 60 MeV)
• No cut: 3337 counts/hour
• Total shield energy deposition cut at 15 MeV: 270 counts/hour
• Beam time structure: 4ns/180ns = 1/45
BPM cut: 270/45= 6 counts/hour
Compton scattering simulation
• Compton scattering cross section for structure-less particle
• Built Compton event generator in simulation
• Beam energy: 60MeV (w/ energy resolution)
• Limited loss of Compton events induced by cuts for cosmic rejection
Cross section model and angular distribution
# of events
𝑑𝜎
𝜋𝛼 2 𝜔′
= 2
𝑑 cos 𝜃
𝑚
𝜔
2
𝜔′ 𝜔
+ + cos 2 𝜃 − 1
𝜔 𝜔′
1 1
1
− = (1 − cos 𝜃)
𝜔′ 𝜔 𝑚
𝑑𝜎/𝑑 cos 𝜃
°
°
°
°
°
°
°
°
𝜔 = 60 MeV
𝑚𝑝 = 938.3 MeV
𝑚𝑑 = 1875.6 MeV
𝛼 = 1/137
cos 𝜃
Theoretical plot of the differential cross section
Total Compton event number in each HINDA core (1-80 MeV)
Compton on deuteron events in shield
Event number
Cut : E(shield) <15MeV
Energy/ MeV
Compton on deuteron events in core
Event number
Cut : E(shield) <15MeV, loss<1%
Energy/ MeV
Compton on deuteron events in shield
Event number
Cut : E(shield) <10MeV
Energy/ MeV
Compton on deuteron events in core
Event number
Cut : E(shield) <10MeV, loss<3%
Energy/ MeV
Compton on deuteron events in shield
Event number
Cut : E(shield) <5MeV
Energy/ MeV
Compton on deuteron events in shield
Event number
Cut : E(shield) <5MeV, loss<10%
Energy/ MeV
To do
• Include energy resolution in simulation
• Update Cosmic simulation with the latest geometry
• Simulate Compton scattering on 4He
• Simulate beam/room related background
• Update Compton on proton/deuteron simulation with latest cross
section model including 𝛼, 𝛽 and get Compton events count rate
Compton action plan @ HIGS review meeting
2015
2016
𝛽𝑛
60 – 100 Hours
300 Hours 100 Hours
2016
𝛼𝑝 , 𝛽𝑝
2017
Sep
Oct
Nov
Dec
Jan
Setup
Setup
LHe-65
Setup
LH-80
60 – 100 Hours
300 Hours
Measurements at HIGS (Deuteron)
Energy
(MeV)
Angle
Cross Section
(nb/sr)
Rate (counts/hour)
Time
(hours)
%Err
(stat)
65
45
16.5
47
300
0.84%
65
80
12.4
36
300
0.96%
65
115
13.7
40
300
0.91%
65
150
17.8
52
300
0.80%