B.4 Efficiencies
B.4.1 Energy cut in BGO
We tested the efficiency of the discrimination between particles coming from the top or the bottom of DAMPE. The proton sample selected was not completely uncorrelated from the variable that we wanted to test since it requires the activation of the high energy trigger that is related to the deposited energy in the first four layers of BGO.
The result is reported in Fig. B.19. The cut is more effective at low energy (like expected from the distributions in Fig. 4.14) but the difference between data and MC can reach a bit more of 2%. This difference is highly correlated to the systematic error associated to the type of interaction in BGO and the trigger, therefore only once studied it in a purely independent way we will be able to quote a systematic error for this cut.
170
/ ndf
Figure B.11: PSDy distribution for data in the helium region (red Landau fit) and helium MC FTFP (blue Landau fit) for various energy intervals after the smear in MC.
APPENDIX B. ANALYSIS
BGO Energy [GeV]
102 103 104 105
as a function of Energy MPVx
BGO Energy [GeV]
102 103 104 105
as a function of Energy σx
BGO Energy [GeV]
102 103 104 105
BGO Energy [GeV]
102 103 104 105
Figure B.12: Left (right) top and bottom: MPVx(y)and σx,(y) of the Landau fit performed on the reconstructed charge in PSDx(y) as function of energy for helium after the smear in MC..
/ ndf
Figure B.13: Fit with a Landau function of the PSDydistribution for data (red fit) and proton MC (blue fit) for two energy intervals.
172
Energy [GeV]
as a function of Energy MPVx
as a function of Energy σx
Figure B.14: Left (right) top and bottom: MPV and σ of the Landau fit performed on the reconstructed charge in PSDx(y)as function of energy for proton selected with the MIP trigger.
/ ndf
Figure B.15: Fit with a Landau function of the PSDglobal distribution for data (red fit) and proton MC (blue fit) for two energy intervals.
APPENDIX B. ANALYSIS
MPV as a function of Energy
[GeV]
as a function of Energy σ
Figure B.16: Left (right): MPV (σ) of the Landau fit performed on the reconstructed energy in PSDglobal as function of the energy for protons selected with the MIP trigger.
]
Figure B.17: Template fits of proton plus helium MC (blue) to data (red) for two energy intervals.
[GeV]
Energyrec
102 103 104
Helium contamination [%]
0
Figure B.18: Helium background contamination as function of energy, with the MIP sample.
174
Efficiency
0.8 0.85 0.9 0.95 1
1.05 p MC
p Data
BGO Energy [GeV]
102 103 104
Data/MC
0.95 0.96 0.97 0.98 0.99 1 1.01 1.02 1.03 1.04
Figure B.19: Efficiency of the cut (EL0+ EL1)>(EL2+ EL3) in BGO for proton candidates in data and proton MC (top) and their ratio (bottom).
APPENDIX B. ANALYSIS
176
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