Recent PandaX-II Results on Dark Matter Search and Status of PandaX-4T Yong Yang Shanghai Jiao Tong University On behalf of Collaboration 12th IDM conference, Brown University 2018/7/24 Yong Yang, SJTU 1 Outline • Introduction to PandaX experiment and China Jinping Underground Laboratory • Recent results from PandaX-II • PandaX Future 2018/7/24 Yong Yang, SJTU 2 PandaX Collaboration Shanghai Jiao Tong University Formed in 2009, ~50 people Peking University Shandong University Nankai University Shanghai Institute of Applied Physics Yalong Hydropower Company University of Maryland University of Science & Technology of China China Institute of Atomic Energy Sun Yat-Sen University Lawrence Berkeley National Lab Alternative Energies & Atomic Energy Commission University of Zaragoza Suranaree University of Technology 2018/7/24 Yong Yang, SJTU 3 China JingPing Underground Lab • Deepest (6800 m.w.e ), 1µ/week/m2 • Horizontal access! Jinping Mountain 2400m 8000m 2018/7/24 Yong Yang, SJTU 4 PandaX experiments PandaX = Particle and Astrophysical Xenon Experiments PandaX-III: Phase I: Phase II: PandaX-xT: 200 kg to 1 ton 120 kg DM 500 kg DM multi-ton DM 136Xe 0vDBD 2009-2014 2014-2017 future future 2018/7/24 Yong Yang, SJTU 5 PandaX-II dual-phase TPC • 60 cm x 60 cm dual-phase xenon Time Projection Chamber • Measure bothD ascintillationrk matte (S1)r se andarc delayedhes w ichargeth du (S2)al-p signalhase TPC • 3-D vertexing • Excellent background rejection Drift time S1 S2 Drift time S1 S2 S1 S2 Dark matter: nuclear recoil (NR) Gamma background: electron recoil (ER) 2018/7/24 Yong Yang, SJTU 6 (S2/S1)NR<<(S2/S1)ER 5 Assembling the detector 2018/7/24 Yong Yang, SJTU 7 PandaX-II Site 2018/7/24 Yong Yang, SJTU 8 PandaX-II Run History Released Run9 =79.6 days, exposure: 26.2 ton-day DM Data Run10 = 77.1 days, exposure: 27.9 ton-day Mar. 9 – June 30, Nov. 2016 – Mar. Jul. 2017-Now, a few low background 2017, 2nd distillation months 220Rn/AmBe with 10-fold campaign and runs, followed by DM reduction of Kr recommissioning data taking, 3x stat of (Run9, 79.6 days) Run10 (blinded) 2015 2016 2017 2018 Nov. 22 – Dec. 14, Jul – Oct, ER Apr.22 – July15, Physics commission calibration & dark matter data (Run8, 19.1 days, tritium removal taking (Run10, stopped due to high 77.1 days) Krypton background) 2018/7/24 Yong Yang, SJTU 9 PandaX-II Results Physics Topics Exposure Publication (ton-day) WIMP spin-independent 33 PRL 117, 21303 (2016) WIMP spin-dependent 33 PRL 118, 071301 (2017) Inelastic scattering 27 PRD 96, 102007 (2017) Axion and Axion-Like-Particle 27 PRL 119, 181806 (2017) WIMP spin-independent 54 PRL 119, 181302 (2017) Light mediator and Self-Interacting Dark Matter(*) 54 PRL 121, 021304 (2018) General EFT and spin dependent(*) 54 arXiv:1807.01936 Results from 54 ton-day are presented in this talk. (*) Very recent results from collaborating with theorists: Hai-bo Yu (UCI) and Wick C. Haxton (UCB&LBNL) 2018/7/24 Yong Yang, SJTU 10 Run9+Run10 WIMP Search Results ER median NR median ER background in mDRU (10-3 evts/kg/day/keV) 2018/7/24 Yong Yang, SJTU 11 WIMP-nucleon SI cross section limits PandaX-II 54 ton-day PRL 119, 181302 (2017) -47 2 Lowest exclusion at 8.6×10 cm at 40GeV, most stringent for mc > 100 GeV when published Improved from PandaX-II 2016 limit about 2.5 time at high masses 2018/7/24 Yong Yang, SJTU 12 2018/7/24 Yong Yang, SJTU 13 Light-mediator DM • Heavy mediator EFT contact interaction • Foundation of “main” SI/SD results in direct detection • typical q ~ 10-50 MeV for 10GeV-1TeV DM • Light mediator: mediator mf is compared to or smaller than q • Signal spectrum more peaked towards to low-energy • q can not be simply ignored 2018/7/24 Yong Yang, SJTU 14 New constraints on s (DM-nucleon) PandaX-II 54 ton-day PRL 121, 021304 (2018) Our Limits For light-mediator (scalar/vector) DM models 2018/7/24 Yong Yang, SJTU 15 Self-Interacting DM with a light mediator State-of-art hydrodynamical CDM simulations From Hai-Bo Yu (PBSM-2018) Santos-Santos et al. (2017) Points : Observed galaxy rotation curves Solid Lines: SIDM Fits Gray lines : CDM Simulated 2018/7/24 Yong Yang, SJTU 16 Self-Interacting DM with light-mediator “Direct Detection Portals for Self-interacting Dark Matter”, M. Kaplingha et. al, PRD 89,035009(2014) “Direct Detection Signatures of Self-Interacting Dark Matter with a Light Mediator”, E. Del. Nobile, JCAP1510, 055 (2015) • If the mediator mixes with SM particles (through g/Z/H mixing ), SIDM could be detected at direct detection experiments. 2018/7/24 Yong Yang, SJTU 17 SIDM particle-physics model M. Kaplingha et. al, PRD 89,035009(2014) New Parameter Description ac Fine structure in DM sector eg Mixing parameter between mediator and photon ac • For Symmetric SIDM models, where DM and eg anti-DM are equally populated in early Universe, ac can be fixed by the observed DM relic density. , g/Z mixing , H mixing • For Asymmetric SIDM models, ac = 0.01 is assumed • Very recently, H. Ran et. al. PLB783(2018) 76-81, derive best-fit value of mf and ac 2018/7/24 Yong Yang, SJTU 18 Constraining Self-Interacting Dark Matter PandaX-II 54 ton-day PRL 121, 021304 (2018) • Lower limits on mediator mass vs DM mass for Asymmetric (left) and Symmetric SIDM with photon kinetic mixing. • In the favored SIDM parameter space, PandaX-II is sensitive for as small as 10-10 mixing parameter 2018/7/24 Yong Yang, SJTU 19 2018/7/24 Yong Yang, SJTU 20 General EFT DM-SM interaction 7 typical relativistic operators studied, complete list in Phys. Rev. C89, 065501 (2014) Dimension Operator Interactions 4 vector/axial- vector interactions (L5/15: standard SI/SD) 5 coupling the WIMP magnetic moment or electric dipole moment with the nucleon’s vector current 6 coupling WIMP and nucleon magnetic moments A unit dimensionless coupling is assumed here, this will be constrained by PandaX-II data. 2018/7/24 Yong Yang, SJTU 21 Energy spectra for EFT operators ] 19 5 19 V 10 L isoscalar 10 e int isovector k / 7 y Lint isoscalar isovector a 16 16 d 10 13 10 / L isoscalar isovector • 7 typical relativistic g int k 15 / 13 13 1 10 Lint isoscalar isovector 10 [ R operator, leading to E 10 10 d / 10 10 R d dramatically different 107 107 spectra 104 104 10 10 • m =40GeV q and v dependence 10-2 C 10-2 mC =400GeV 1019 10 20 30 40 50 60 70 80 901019 10 20 30 40 50 60 70 80 90 • Isospin scalar (coupling 9 Lint isoscalar isovector 16 1016 10 L10 isoscalar isovector to proton and neutron int 13 L17 isoscalar isovector1013 with same sign) 10 int 1010 1010 • isospin vector (p,n 107 107 opposite sign) 104 104 10 10 m =40GeV m =400GeV 10-2 C 10-2 C 10 20 30 40 50 60 70 80 90 10 20 30 40 50 60 70 80 90 ER [keV] 2018/7/24 Yong Yang, SJTU 22 Upper limits on coupling PandaX-II 54 ton-day arXiv:1807.01936 g 1 5 g 1 n L isoscalar isovector n i int 9 i l 7 l Lint isoscalar isovector p L isoscalar int isovector p u 13 u 10 o L isoscalar isovector L isoscalar o -2 int isovector -2 int C 15 C 10 17 10 s Lint isoscalar isovector s L isoscalar isovector s int s e e l l n n o o i -4 i -4 s 10 s 10 n n e e m m i i D -6 D 10 10-6 -8 10 10-8 Dim-4 Dim-5, Dim-6 -10 10 10-10 10 102 103 104 105 2 3 4 5 2 10 10 10 10 10 WIMP mass (GeV/c ) WIMP mass (GeV/c2) Constraints strongly depending on the operator/isospin L5/15: standard SI/SD 2018/7/24 Yong Yang, SJTU 23 Constraints on Spin-dependent Interaction neutron-only proton-only -35 -30 ) ) 2 10 2 10 PandaX-II full SM PICO60 m m c -36 c + - ( ( PandaX-II chiral EFT IceCube(n n ) -32 10 - n n 10 LUX SuperK(t+t ) o o i -37 i t t XENON100 CMS c 10 c e e -34 s s ATLAS -38 10 s s s 10 s o o r -39 r -36 c c 10 10 n n o o t r -40 t o -38 u 10 r 10 e p - n - -41 PandaX-II full SM P P 10 -40 M PandaX-II chiral EFT I 10 M I -42 10 LUX W W -42 -43 XENON100 D D 10 S S 10 10-44 10-44 10 102 103 104 105 10 102 103 104 105 WIMP mass (GeV/c2) WIMP mass (GeV/c2) • Two “nuclear matrix element” calculations: • Full basis shell-model GCN5082, J. Mendende et al., Nucl. Phys. A818, 139 (2009) • Chiral EFT matrix element, P. Klos, Phys. Rev. D 88, 083516 (2013) • Proton-only interaction more sensitive to the calculation • Most stringent limits on neutron-only SD cross section for mc > 40 GeV 2018/7/24 Yong Yang, SJTU 24 PandaX Future • PandaX-xT for DM search • PandaX-III for 0vbb search PandaX-I: 120 kg PandaX-II: 500 kg PandaX-xT: PandaX-III: 200 kg to DM experiment DM experiment multi-ton (~4-T) 1 ton HP gas 136Xe 2009-2014 2014-2018 DM experiment 0vDBD experiment Future Future CJPL-I CJPL-II 2018/7/24 Yong Yang, SJTU 25 New experiment hall at CJPL-II • B2 Hall • 14m(H)x14m(W)x65m(L) • Water Shielding • 5000Ton pure water • U/Th <10-14 g/g Experiment Hall Water Pool 2018/7/24 Yong Yang, SJTU 26 PandaX-xT facilities 512 TPC Drift region: F ~1.2m, H ~1.2m • Intermediate stage: • PandaX-4T (4-ton in sensitive region) with SI sensitivity ~10-47 cm2 • On-site assembly and commissioning: 2019-2020 2018/7/24 Yong Yang, SJTU 27 Current Status and Schedule • R&D work-in-progress • 2019-2020: assembly and commissioning Cooling bus Inner vessel Krypton measurement TPC prototype PMT test DAQ board 2018/7/24 Yong Yang, SJTU 28 PandaX-4T background estimation • Simulate the ER and NR events arXiv:1806.02229 • Detector materials: inner/outer vessels, flanges, copper plates, electrodes, PTFE materials, PMTs etc • Radioactivity in xenon: 85Kr, 222Rn, 136Xe • Neutrino • Below NR median: • Total ER background: 0.05 mDRU • Total NR background: 1 event / t-y 2018/7/24 FV=2.8ton Yong Yang, SJTU 29 PandaX-4T projected sensitivity • With two-year exposure, x10 SI improvement on sensitivity could be achieved.