Direct Dark Matter Search with Noble Liquids Marc Schumann Physik Institut, Universität Zürich Recontres de Moriond 2012, Cosmology Session, La Thuile, March 2012 [email protected] www.physik.uzh.ch/groups/groupbaudis/xenon/ M. Schumann (U Zürich) – Liquid Noble Gas Detectors 2 Baryonic Matter Dark Matter? Dark Energy???? M. Schumann (U Zürich) – Liquid Noble Gas Detectors 3 Dark Matter Search Direct Detection Indirect Production Detection @Collider M. Schumann (U Zürich) – Liquid Noble Gas Detectors 4 Direct WIMP Search WIMP Elastic Scattering of WIMPs off target nuclei WIMP v ~ 230 km/s nuclear recoil ER ~ O(10 keV) Recoil Energy: WIMP Expectations Event Rate: CMSSM: Trotta et al. CMSSM+LHC: Buchmueller et al. Result: Tiny Rates 1 event/kg/yr R < 0.01 evt/kg/day ER < 100 keV 1 event/ton/yr M. Schumann (U Zürich) – Liquid Noble Gas Detectors 5 M. Schumann (U Zürich) – Liquid Noble Gas Detectors WIMP Searches – Evolution Spin-Independent Cross Section @ ~60 GeV/c² 1e 1e 1e 1e 1e 1e 1e 1e – 47 – 46 – – 45 – 44 – 43 – 42 – – 41 – 40 – 1985 1 evt/ton/day 1 evt/ton/year 1 evt/kg/year 1990 1995 2000 Year 2005 2010 2015 2020 Plot adadped from R. Gaitskell 6 M. Schumann (U Zürich) – Liquid Noble Gas Detectors WIMP Searches – Evolution Spin-Independent Cross Section @ ~60 GeV/c² 1e 1e 1e 1e 1e 1e 1e 1e – 47 – 46 – – 45 – 44 – 43 – 42 – – 41 – 40 – 1985 1 evt/ton/day 1 evt/ton/year 1 evt/kg/year Homestake Oroville 1990 Crystals 1995 HDMS 94 HDMS DAMA 98 DAMA Ge / UKDMC HDMS 98 HDMS NaI 2000 DAMA 00 DAMA IGEX Year 2005 DAMA/Libra 08 DAMA/Libra 2010 2015 2020 Plot adadped from R. Gaitskell 7 M. Schumann (U Zürich) – Liquid Noble Gas Detectors WIMP Searches – Evolution Spin-Independent Cross Section @ ~60 GeV/c² 1e 1e 1e 1e 1e 1e 1e 1e – 47 – 46 – – 45 – 44 – 43 – 42 – – 41 – 40 – 1985 1 evt/ton/day 1 evt/ton/year 1 evt/kg/year Homestake Oroville 1990 Detectors Cryogenic Crystals 1995 HDMS 94 HDMS DAMA 98 DAMA Ge / UKDMC CDMS I 99 I CDMS HDMS 98 HDMS NaI EDELWEISS03 EDELWEISS 98 2000 DAMA 00 DAMA IGEX EDELWEISS01 Year CDMS I 02 I CDMS 2005 CDMS II 04 II CDMS CDMS II 10 II CDMS DAMA/Libra 08 DAMA/Libra 2010 EDELWEISS 09 EDELWEISS 11 CRESST 11 CRESST 2015 2020 Plot adadped from R. Gaitskell 8 M. Schumann (U Zürich) – Liquid Noble Gas Detectors WIMP Searches – Evolution Spin-Independent Cross Section @ ~60 GeV/c² 1e 1e 1e 1e 1e 1e 1e 1e – 47 – 46 – – 45 – 44 – 43 – 42 – – 41 – 40 – 1985 1 evt/ton/day 1 evt/ton/year 1 evt/kg/year Homestake Oroville 1990 Liquid Noble Gases Detectors Cryogenic Crystals 1995 HDMS 94 HDMS DAMA 98 DAMA Ge / UKDMC CDMS I 99 I CDMS HDMS 98 HDMS NaI EDELWEISS03 EDELWEISS 98 2000 Xe DAMA 00 DAMA IGEX / Ar EDELWEISS01 Year CDMS I 02 I CDMS ZEPLIN I ZEPLIN 2005 CDMS II 04 II CDMS CDMS II 10 II CDMS XENON100 10 XENON100 XENON100 11 XENON100 WARP ZEPLIN II ZEPLIN XENON10 DAMA/Libra 08 DAMA/Libra 2010 EDELWEISS 09 ZEPLIN III ZEPLIN EDELWEISS 11 CRESST 11 CRESST 2015 2020 Plot adadped from R. Gaitskell 9 WIMP Searches – Evolution l l e 1e– 40 k s t EDELWEISS 98 i Oroville a G HDMS 94 . R UKDMC Homestake m ² HDMS 98 o r c 1e– 41 IGEX f / d V DAMA 98 DAMA 00 DAMA/Libra 08 e e p CDMS I 99 EDELWEISS 01 d G a d 0 CDMS I 02 a 6 1 evt/ton/day WARP t ~ o 1e– 42 EDELWEISS 03 l ZEPLIN I ZEPLIN II P @ n CDMS II 04 CRESST 11 o i t c e 1e– 43 EDELWEISS 09 S XENON10 s EDELWEISS 11 s CDMS II 10 o ZEPLIN III r XENON100 10 C t 1e– 44 1 evt/kg/year SuperCDMS Soudan n XENON100 11 e d n e Crystals Ge/NaI p XMASS XENON100 e d 1e– 45 Cryogenic Detectors DarkSide-50 n I MiniClean - n Liquid Noble Gases Xe/Ar i p LUX S 1e– 46 DEAP-3600 XENON1T 1e– 47 1 evt/ton/year 1985 1990 1995 2000 2005 2010 2015 2020 Year M. Schumann (U Zürich) – Liquid Noble Gas Detectors 10 WIMP Searches – Evolution l l e 1e– 40 k s t EDELWEISS 98 i Oroville a G HDMS 94 . R UKDMC Homestake m ² HDMS 98 o r c 1e– 41 IGEX f / d V DAMA 98 DAMA 00 DAMA/Libra 08 e e p CDMS I 99 EDELWEISS 01 d G a d 0 CDMS I 02 a 6 1 evt/ton/day WARP t ~ o 1e– 42 EDELWEISS 03 l ZEPLIN I ZEPLIN II P @ n CDMS II 04 CRESST 11 o i t c e 1e– 43 EDELWEISS 09 S XENON10 s EDELWEISS 11 s CDMS II 10 o ZEPLIN III r XENON100 10 C t 1e– 44 1 evt/kg/year SuperCDMS Soudan n XENON100 11 e d n e Crystals Ge/NaI p XMASS XENON100 e d 1e– 45 Cryogenic Detectors DarkSide-50 n I MiniClean - n Liquid Noble Gases Xe/Ar i p LUX S some experiments are missing! 1e– 46 DEAP-3600 expect results within the next weeks! XENON1T 1e– 47 1 evt/ton/year 1985 1990 1995 2000 2005 2010 2015 2020 Year M. Schumann (U Zürich) – Liquid Noble Gas Detectors 11 Outline Motivation: Dark Matter ✓ Noble Liquid Detectors: Concepts Noble Liquid Detectors: Experiments M. Schumann (U Zürich) – Liquid Noble Gas Detectors 12 Noble Liquid Targets Target LXe LAr LNe Atomic Number 54 18 10 Atomic mass 131.3 40.0 20.2 Boiling Point Tb [K] 165.0 87.3 27.1 Liq. Density @ Tb [g/cm³] 2.94 1.40 1.21 Fraction in Atmosphere 0.09 9340 18.2 Price $$$$ $ $$ Scintillator Ionizer W (E to generate e-ion pair) [eV] 15.6 23.6 Wph (,) [eV] 17.9 / 21.6 27.1 / 24.4 Experiments ~5 ~5 ½ [stopped, running, in preparation] M. Schumann (U Zürich) – Liquid Noble Gas Detectors 13 Why Argon? ● large abundance → modest price → can think about gigantic detectors ● relatively compact detectors →exploit self shielding ● cryogenics @ –180°C (above LN2) Argon ● scalability to larger detectors ● excellent background discrimination m = 100 GeV/c² – 4 3 even when only measuring light = 4 x 10 cm² ● well established technology BUT: - low threshold possible??? - very high background from Ar39 (~1 Bq/kg) - need to „shift“ light ArDM M. Schumann (U Zürich) – Liquid Noble Gas Detectors 14 Why Xenon? ● scintillation light in VUV (178nm) ● high mass number A~131 SI: high WIMP rate @ low theshold ● high Z=54, high ~3 kg/l: self shielding, compact detector ● 50% odd isotopes ● no long lived Xe isotopes Argon Kr-85 can be removed to ppt Xenon ● "easy" cryogenics @ –100°C m = 100 GeV/c² – 4 3 ● = 4 x 10 cm² scalability to larger detectors ● good background discrimination when measuring light and charge BUT: - very expensive - only fair signal/background discrimination compared to Ar M. Schumann (U Zürich) – Liquid Noble Gas Detectors 15 Scintillation and Ionization ● energy deposition produces Astropart. Phys 35, 573 (2011) electron-ion pairs and excited atom states; both processes can lead to scintillation ● anti-correlation between charge and light improvement of energy resolution possible ● E-field dependence (field quenching) ● response depends on particle type and energy E excitation + ionization PRB 76, 014115 (2007) atom Xe* Xe+ + e-- motion +Xe +Xe Xe*2 Xe+2 +e-- 2Xe + h Xe** + Xe scintillation ionization light electrons M. Schumann (U Zürich) – Liquid Noble Gas Detectors 16 Nuclear Recoil Energy Scale ● WIMPs interact with target nucleus arXiv:1203.0849 nuclear recoil (nr) scintillation LAr ( and 's produce electronic recoils) ● absolute measurement is difficult 5 7 measure relative to Co (122keV) ● relative scintillation efficiency Leff: measurement principle: PRL 107, 131302 (2011) D LXe e t s h n ie ld n LXe M. Schumann (U Zürich) – Liquid Noble Gas Detectors 17 Backgrounds Experimental Sensitivity without background: (mt)-1 with background: (mt)-1 / 2 ] 1 - y 2 - m [ Background Sources x u l F environment: U, Th chains, K n o u 2 3 8 2 3 4 2 3 4 m 2 3 4 2 3 0 2 2 6 2 2 2 2 1 8 U → Th → Pa → U → Th → Ra → Rn → Po … M α β β α α α α 2 3 2 Th → 2 2 8 Ra → 2 2 8 m Ac → 2 2 8 Th → 2 2 4 Ra → 2 2 0 Rn → 2 1 6 Po … α β β α α α ● and Decays (electronic recoil) Depth [mwe] → „intrinsic“ bg most dangerous (Kr85, Ar39, Rn) ● neutrons from (,n) and sf in rocks and detector parts ● neutrons from cosmic ray muons ● alphas irrelevant for noble liquids Electronic Recoils Nuclear Recoils (gamma, beta) (neutron, WIMPs) M. Schumann (U Zürich) – Liquid Noble Gas Detectors 18 Laboratori Nazionali del Gran Sasso (LNGS) XENON100 DarkSide XENON1T LNGS: 1.4km rock (3700 mwe) Other laboratories: Boulby (UK), LSM (F), Canfranc (E), Soudan (US), CRESST Sanford (US), SNOLab (CA), Kamioka (JP), Jinping (CN), ... XENON100 M. Schumann (U Zürich) – Liquid Noble Gas Detectors A Shielding Useofradiopure materials Backgrounds Avoid Background Suppression selfShielding → fiducialization active(µ,veto largeshield poly) (Pb, water, deepunderground location coincidence) Astropart. Phys. 012) 35, 573 (2 20 Background Suppression ) 2 1 0 2 ( A Avoid Backgrounds 3 7 5 , 5 3 Use of radiopure materials . s y h P . t r a Shielding p o r t s deep underground location A large shield (Pb, water, poly) active veto (µ, coincidence) self Shielding → fiducialization B Use knowledge about expected WIMP signal WIMPs interact only once → single scatter selection require some position resolution Scintillation Pulse Shape WIMPs interact with target nuclei → nuclear recoils exploit different dE/dx from Charge/Light Ratio signal and background M.