Studies of Cosmic-Ray Proton from DAMPE Chuan Yue *, Jing-Jing Zang, - - PowerPoint PPT Presentation
Studies of Cosmic-Ray Proton from DAMPE Chuan Yue *, Jing-Jing Zang, Tie-Kuang Dong, Antonio Surdo, Stefania Vitillo on behalf of the DAMPE Collaboration *speaker: yuechuan@pmo.ac.cn 2017.07.17 BUSAN, KOREA Introduction The Structure of DAMPE
Chuan Yue*, Jing-Jing Zang, Tie-Kuang Dong, Antonio Surdo, Stefania Vitillo
*speaker: yuechuan@pmo.ac.cn 2017.07.17 BUSAN, KOREA
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(Y. S. Yoon et al., CREAM, 2017) (C. Patrignani et al., PDG, 2016)
Interesting Scientific Issues: Proton Flux Hardening at ~200-400 GeV? Other Structures beyond TeV Range? Nearby Sources? Unknown Acceleration Mechanisms? Modification of Propagation Models?
AMS02,ATIC-2,PAMELA,CREAM Proton Flux Measurements
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Plastic Scintillator strip Detector (PSD): charge (Z) measurement Silicon-Tungsten tracKer-converter (STK): track reconstruction; gamma-converter; Z measurement BGO imaging Energy CALorimeter (BGO-ECAL): energy measurement; lepton/hadron identification NeUtron Detector (NUD): high energy lepton/hadron identification
Orbit Information: Sub-Detectors:
Sun-synchronous Orbit Altitude: ~ 500 km Launch Date: Dec.17th, 2015
Main Scientific Goals:
Origins and Propagations of Cosmic-Rays Dark Matter Indirected Detection Gamma-ray Astronomy
DAMPE Collaboration:
Purple Mountain Observatory, National Space Science Center, Inst. High Energy Physics, Inst. Modern Physics, University
Geneva University Bari, Lecce, Perugia (Universities and INFN)
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Day Number (from Jan. 1st 2016) 100 200 300 400 500 Number of Events / Day 1000 2000 3000 4000 5000 6000
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10 ×
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Cut 0: BgoEnergy > 20 GeV Cut 1: High Energy Trigger (G3) Cut 2: STK Track Selection Cut 3: Cross PSD (track-PSD match) Cut 4: Cross BGO (track-BGO match) Particle Identification Cut 5: charge identification Cut 6: e/p separation
Total Proton Candidates (BGO_E >20 GeV):
BGO Energy (GeV)
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10 Number of Events 10
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Cut-0 Cut-1 Cut-2 Cut-3 Cut-4 Cut-5 Cut-6
Event Selection
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BGO Energy (GeV) 10
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10 HighEnergy Trigger Efficiency 0.2 0.4 0.6 0.8 1 1.2
MonteCarlo Proton On-Orbit Proton
Trigger Logics of DAMPE, see CRD117
HE Trigger Efficiency of Proton
Systematic Error: ~ 8% Uncertainty due to the threshold calibration and the limited statistics of unbias trigger events. (unbias trigger pre-scaled by 1/512 at low latitudes <20deg and 1/2048 at high latitudes) By applying proton selections to unbias sample,
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BGO Energy (GeV) 10
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10 Track Reconstruction Efficiency 0.2 0.4 0.6 0.8 1 1.2
MonteCarlo Proton On-Orbit Proton
Track Efficiency of Proton
Systematic Error: ~ 2.5%
Using shower-axis based proton selections to check STK track reconstruction efficiency,
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PSD Energy (MeV) 2 4 6 8 10 12 14 16 18 20 Number of Events 500 1000 1500 2000 2500 3000
On-Orbit Data MC Proton+Helium MC Proton MC Helium
BGO_E ~ 445 - 560 GeV
Sideview of PSD, see Zhang’s poster CRD98
Combined PSD spectrum for protons and helium nuclei Layer-1 Layer-2
X Z
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BGO Energy (GeV) 10
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10 PSD (layer-2) Charge Efficiency 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2
MonteCarlo Proton On-Orbit Proton
BGO Energy (GeV) 10
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10 PSD (layer-1) Charge Efficiency 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2
MonteCarlo Proton On-Orbit Proton
Charge Selection Efficiencies of Proton for PSD layer-1 and layer2
Systematic Error: ~ 2% Systematic Error: ~ 4%
With the help of STK, a “pure” proton sample can be selected for estimating the charge selection efficiencies of proton for PSD layer-1 and layer-2. (see Stefania Vitillo’s poster CRD097)
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/ ndf
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χ 29.43 / 25 p0 0.128 ± 3.597 p1 0.3 ±
p2 0.43 ± 30.08 p3 0.367 ±
p4 0.05 ± 11.25 p5 0.02 ±
p6 0.0034 ± 0.6342 BGO Energy (GeV)
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10 Helium Background (%) 1 2 3 4 5 / ndf
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χ 29.43 / 25 p0 0.128 ± 3.597 p1 0.3 ±
p2 0.43 ± 30.08 p3 0.367 ±
p4 0.05 ± 11.25 p5 0.02 ±
p6 0.0034 ± 0.6342
Helium Background
Helium contamination is estimated using Template-Fit based on MC simulation data < 2% for BGO_E from 20 GeV to 10 TeV Electrons can be easily eliminated given the thick calorimeter (32 radiation lengths) < 1% for BGO_E from 20 GeV to 10 TeV
10-6 10-4 10-2 100 102 104 10-2 100 102 104 106 108 1010 1012 E2dN/dE (GeV m-2s-1sr-1) E (GeV/particle) all-particle p He/2 e-(or e+/-) e+ EGB ν p
1 particle/m2s knee 1 particle/m2yr ankle 1 particle/km2yr GZK cutoff HESS IceCube Akeno Tibet AGASA HiRes Auger 10-6 10-4 10-2 100 102 104 10-2 100 102 104 106 108 1010 1012 E2dN/dE (GeV m-2s-1sr-1) E (GeV/particle) all-particle p He/2 e-(or e+/-) e+ EGB ν p
1 particle/m2s knee 1 particle/m2yr ankle 1 particle/km2yr GZK cutoff CREAM ATIC AMS-02 PAMELA Fermi-LAT
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/ ndf
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χ 63.99 / 59 p0 0.0054 ± 0.4687 p1 0.008 ±
p2 0.007 ± 1.119 p3 0.001 ±
p4 0.0027 ±
p5 0.0011 ± 0.1428 p6 0.00008 ±
Primary Energy (GeV)
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10 Sr)
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Proton Effective Acceptance (m 0.01 0.02 0.03 0.04 0.05
/ ndf
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χ 63.99 / 59 p0 0.0054 ± 0.4687 p1 0.008 ±
p2 0.007 ± 1.119 p3 0.001 ±
p4 0.0027 ±
p5 0.0011 ± 0.1428 p6 0.00008 ±
Cut 0: BgoEnergy > 20 GeV Cut 1: High Energy Trigger (G3) Cut 2: STK Track Selection Cut 3: Cross PSD (track-PSD match) Cut 4: Cross BGO (track-BGO match) Particle Identification Cut 5: charge identification Cut 6: e/p separation Proton Effective Acceptance
Systematic Errors:
HE Tigger: ~ 8% Track Reconstruction: ~ 2.5% Charge Identification: ~ 4.5%
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Preliminary Proton Flux of DAMPE, Compared with Previous Experiments
Kinetic Energy (GeV) 1 10
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10 Flux × E2.7 (m−2sr−1s−1GeV1.7)
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10 AMS-02 (2015) PAMELA (2011) ATIC-2 (2009) CREAM-III (2017) DAMPE Preliminary
Does not include uncertainties from absolute energy measurement
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The DAMPE detector was successfully launched into a sun-synchronous orbit at the altitude of 500 km on Dec. 17th 2015 A proton selection criteria is developed and the cut efficiencies obtained by MC simulations are validated with on-orbit data. The preliminary Proton flux has been reported for the range 50 GeV ‒ 10 TeV (talk CRD096 by Paolo Bernardini for Helium analysis) The hardening of Proton flux at E_k ~ 200 GeV has been observed More studies about systematics including energy uncertainties are in processing In the near future, the Proton flux measurement will be extended up to 100 TeV