Detecting dark matter through line emission a suggestion

Detecting dark matter through line emission a suggestion for the Chinese space station Guoming Chen IHEP, CAS Sep. 23, 2008 2021/12/31 Guoming CHEN 1

What to detect in space? • Charged particles: AMS • Gamma ray: GLAST 2021/12/31 Guoming CHEN 2

γray from neutralino annihilation smoke gun evidence Mχ=1. 5 Te. V Line emission: • large acceptance • excellent energy resolution 2021/12/31 Guoming CHEN 3

Where to detect? advantage disadvantage Galactic Center large statistics Sub-halo Satellite background free large No. of subs low background Background foreground low statistics per subhalo Extra galactic good statistics 2021/12/31 Guoming CHEN low statistics background Jan Conrad 4

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. 2021/12/31 Guoming CHEN 5

Detector concept design (High Energy Gamma Ray detector, HEGARD) Tungsten 1000*3. 5 mm 3 Scintillator fiber 5*5*1000 mm 3 50 mm thick plastic rubber 20 radiation lengths Lithium Glass 20*20*5 mm 3 2021/12/31 Plastic Scintillator 10*10*1200 mm 3 Guoming CHEN 6

One layer of the ECAL One layer = one radiation length, 20 layers in total 2021/12/31 Guoming CHEN 7

Weight and Acceptance ECAL size m 2 naked detector support kg kg area m 2 geo. factor m 2 sr 0. 71 x 0. 71 854 85 0. 5 1. 00 x 1. 00 1707 154 1 3 1. 40 x 1. 40 3414 2 6 1. 73 x 1. 73 5121 276 393 3 9 take 1 m 2 scenario as an example 2021/12/31 Guoming CHEN 8

MC simulation Hits level 2021/12/31 Guoming CHEN 9

Energy measurement From 30 Ge. V to 4 Te. V , energy resolution better than 2% (leakage corrected) scale energy resolution deviation from linearity 2021/12/31 Guoming CHEN 10

Shower shape difference on γ/p 2021/12/31 Guoming CHEN 11

2021/12/31 Guoming CHEN 12

Boost decision tree output 2021/12/31 Guoming CHEN 13

γeff. vs. p eff. 2021/12/31 Guoming CHEN 14

γ/e separation • Veto efficiency 0. 9999, i. e. , only 10 -4 electron can contaminate gamma • The problem is gamma efficiency 2021/12/31 Guoming CHEN 15

Backlash 2021/12/31 Guoming CHEN 16

backlash property • Back scattering particles include both electrons and gammas, gammas dominate • Energy mostly less than 2 Me. V 2021/12/31 energy of backlash gamma Guoming CHEN 17

Backlash identification Using plastic rubber to absorb electrons in the backlash For the gammas： 1）ID with position 2）ID with energy y xx gamma efficiency: 92% at 200 Ge. V, Ex>1 Me. V, Ey>1 Me. V 光子效率：〉95% 2021/12/31 Guoming CHEN 18

HEGARD concept • • • size 112 x 40 cm 3 weight 2000 kg power consumption 500 W time resolution 1 ns area 1 m 2 geometry factor 3 m 2 sr gamma energy measurement 30 Ge. V— 4 Te. V energy resolution 2% angular resolution 0. 5 o proton rejection 10 -7 electron rejection 10 -4 2021/12/31 Guoming CHEN 19

ISS orbit simulation 2021/12/31 Guoming CHEN 20

effective time in one year survey 2021/12/31 Guoming CHEN 21

backgrounds astroph/05107 14 v 2 1996 A&A. . 120 C. 465 M 2021/12/31 Guoming CHEN 22

Theoretical calculation bu X. J. Bi 416 Ge. V 2021/12/31 Guoming CHEN 23

One year sensitivity HEGARD 2021/12/31 Guoming CHEN 24

Conclusion The proposed detector has large acceptance, excellent energy resolution and excellent particle ID. It is able to detect dark matte through line emission 2021/12/31 Guoming CHEN 25

Thank you You are welcome to give any criticism, comments, and improvements of the design. And you more than welcome to offer collaboration. 2021/12/31 Guoming CHEN 26

backup 2021/12/31 Guoming CHEN 27

电磁量能器事例数 能量 (Ge. V) 50 100 200 500 1000 2000 4000 总和 电子 10 k 5 k 50 k 光子 10 k 5 k 5 k 5 k 45 k 质子 300 k 298 k 227 k 170 k 163 k 1. 498 M 2021/12/31 Guoming CHEN 28