Detecting dark matter through line emission a suggestion for the Chinese space station Guoming Chen IHEP, CAS Sep. 23, 2008 2019/4/17 Guoming CHEN

What to detect in space? Charged particles: AMS Gamma ray: GLAST 2019/4/17 Guoming CHEN

γray from neutralino annihilation smoke gun evidence Mχ=1.5TeV Line emission: large acceptance excellent energy resolution 2019/4/17 Guoming CHEN

Where to detect? advantage disadvantage Galactic Center large statistics Background foreground Sub-halo background free large No. of subs low statistics per subhalo Satellite low background low statistics Extra galactic good statistics background 2019/4/17 Guoming CHEN Jan Conrad

Strategy To detect dark matter through line emission To scan the full sky, mostly depending on sub-halos Different from normal gamma ray detector, this one emphasizes on acceptance, energy resolution and particle ID. 2019/4/17 Guoming CHEN

Detector concept design (High Energy Gamma Ray detector, HEGARD) 50mm thick plastic rubber Tungsten 1000*1000*3.5mm3 Scintillator fiber 5*5*1000mm3 20 radiation lengths Lithium Glass 20*20*5mm3 Plastic Scintillator 10*10*1200mm3 2019/4/17 Guoming CHEN

One layer of the ECAL One layer = one radiation length, 20 layers in total 2019/4/17 Guoming CHEN

take 1m2 scenario as an example Weight and Acceptance ECAL size naked detector support area geo. factor m2 kg kg m2 m2sr 0.71x0.71 854 85 0.5 1.5 1.00x1.00 1707 154 1 3 1.40x1.40 3414 276 2 6 1.73x1.73 5121 393 3 9 take 1m2 scenario as an example 2019/4/17 Guoming CHEN

MC simulation Hits level 2019/4/17 Guoming CHEN

Energy measurement From 30GeV to 4TeV , energy resolution better than 2% (leakage corrected) scale energy resolution deviation from linearity 2019/4/17 Guoming CHEN

Shower shape difference on γ/p 2019/4/17 Guoming CHEN

2019/4/17 Guoming CHEN

Boost decision tree output 2019/4/17 Guoming CHEN

γeff. vs. p eff. 2019/4/17 Guoming CHEN

γ/e separation Veto efficiency 0.9999, i.e., only 10-4 electron can contaminate gamma The problem is gamma efficiency 2019/4/17 Guoming CHEN

Backlash 2019/4/17 Guoming CHEN

backlash property Back scattering particles include both electrons and gammas, gammas dominate Energy mostly less than 2MeV energy of backlash gamma 2019/4/17 Guoming CHEN

Backlash identification Using plastic rubber to absorb electrons in the backlash For the gammas： 1）ID with position 2）ID with energy y gamma efficiency:92% at 200GeV, Ex>1MeV, Ey>1MeV x x 光子效率：〉95% 2019/4/17 Guoming CHEN

HEGARD concept size 112x112x40 cm3 weight 2000kg power consumption 500W time resolution 1ns area 1m2 geometry factor 3m2sr gamma energy measurement 30GeV—4TeV energy resolution 2% angular resolution 0.5o proton rejection 10-7 electron rejection 10-4 2019/4/17 Guoming CHEN

ISS orbit simulation 2019/4/17 Guoming CHEN

effective time in one year survey 2019/4/17 Guoming CHEN

backgrounds astro-ph/0510714v2 1996A&A..120C.465M 2019/4/17 Guoming CHEN

Theoretical calculation bu X.J. Bi 416GeV 2019/4/17 Guoming CHEN

One year sensitivity HEGARD 2019/4/17 Guoming CHEN

Conclusion It is able to detect dark matte through line emission The proposed detector has large acceptance, excellent energy resolution and excellent particle ID. It is able to detect dark matte through line emission 2019/4/17 Guoming CHEN

Thank you You are welcome to give any criticism, comments, and improvements of the design. And you more than welcome to offer collaboration. 2019/4/17 Guoming CHEN

backup 2019/4/17 Guoming CHEN

电磁量能器事例数 能量 (GeV) 50 100 200 500 1000 2000 4000 总和 电子 10k 5k 50k 光子 质子 300k 298k 227k 170k 163k 1.498M 2019/4/17 Guoming CHEN