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 nuclear recoil v ~ 230 km/s 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 WIMP Searches – Evolution
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M. Schumann (U Zürich) – Liquid Noble Gas Detectors 6 WIMP Searches – Evolution
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M. Schumann (U Zürich) – Liquid Noble Gas Detectors 7 WIMP Searches – Evolution
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M. Schumann (U Zürich) – Liquid Noble Gas Detectors 8 WIMP Searches – Evolution
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M. Schumann (U Zürich) – Liquid Noble Gas Detectors 9 WIMP Searches – Evolution
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M. Schumann (U Zürich) – Liquid Noble Gas Detectors 10 WIMP Searches – Evolution
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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 even when only measuring light = 4 x 10 – 4 3 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 ● scalability to larger detectors = 4 x 10 cm²
● 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 measure relative to 5 7 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
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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 Background Suppression
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Use of radiopure materials .
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self Shielding → fiducialization
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 20 Background Suppression
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Use of radiopure materials .
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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. Schumann (U Zürich) – Liquid Noble Gas Detectors 21 Pulse Shape Discrimination
C. Regenfus (ArDM) Singlet and triplet excimer states have characteristic lifetimes:
Ar: 5 ns, 1.6 µs Xe: 4 ns, 22 ns
The ratio Ntrip/Nsing depends on the ionization density → the particle type
Signal Size
LAr Discrimination levels of – 8
3x10 achieved in test setups ]
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arXiv:0904.2930, PRC 78, 035801 (2008) t
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→ mandatory because of huge e Ar39 background (~1Bq/kg) H
LXe O(10)% rejection at low E NIM A 612, 328 (2010) Better for very high LY n (8x10– 2 @ 50% NR acc.) NIM A 659, 161 (2011) log(Time) [ns] DEAP collaboration M. Schumann (U Zürich) – Liquid Noble Gas Detectors 22 E excitation + ionization Charge/Light Ratio atom Xe* Xe+ + e-- motion +Xe +Xe Charge/Light ratio depends on dE/dx → discrimination Xe*2 Xe+2 +e-- PRL 105, 131302 (2010) 2Xe + h Xe** + Xe Co60 scintillation ionization PRD 80, 052010 (2009) light electrons E=3.90 kV/cm
Cs137 E=0.53 kV/cm
AmBe
AmBe
ZEPLIN-III XENON100 ~99.99% rejection @ 50% acceptance ~99.5% rejection @ 50% acceptance
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 23 Detector Concepts
Single Phase Detector
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 24 Detector Concepts
Single Phase Detector
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 25 Detector Concepts
Single Phase Detector
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 26 Detector Concepts
Single Phase Detector
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 27 Detector Concepts
Single Phase Detector
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 28 Detector Concepts
Single Phase Detector Time Projection Chamber
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 29 Detector Concepts
Single Phase Detector Time Projection Chamber
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Single Phase Detector Time Projection Chamber
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A Time M. Schumann (U Zürich) – Liquid Noble Gas Detectors 31 Detector Concepts
Single Phase Detector Time Projection Chamber
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A Time M. Schumann (U Zürich) – Liquid Noble Gas Detectors 32 Detector Concepts
Single Phase Detector Time Projection Chamber
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A Time M. Schumann (U Zürich) – Liquid Noble Gas Detectors 33 Detector Concepts
Single Phase Detector Time Projection Chamber
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A Time M. Schumann (U Zürich) – Liquid Noble Gas Detectors 34 Dual Phase TPC
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3dim vertex reconstruction Astropart. Phys. 35, 573 (2012) ER charge signal S2
151 µs light signal S1
NR
Figures from XENON100 M. Schumann (U Zürich) – Liquid Noble Gas Detectors 35 Single Phase Detector
proper vertex reconstruction needs huge number of very high light yield photons
very low background
Figures from XMASS
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 36 The WIMP Landscape - today
XENON10 Note: many experiments are not shown!
ZEPLIN-III CDMS-II
XENON100
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 37 A bit more information...
SIMPLE (2011)
CRESST (2011) CRESST (2007, reanalysis)
ZEPLIN-III (2011)
some results are missing! M. Schumann (U Zürich) – Liquid Noble Gas Detectors 38 A bit more information...
Recent CoGeNT news:
J. Collar @ TAUP old „signal“
new „background“
SIMPLE (2011) remaining „signal“ PRL 106, 131301 (2011) CRESST (2011) CRESST (2007, reanalysis)
90% signal acceptance for bulk events
Kopp, Schwetz,some Zupan, results arXiv:1110.2721 are missing! Kelso, Hooper, Buckley, arXiv:1110.5338 M. Schumann (U Zürich) – Liquid Noble Gas Detectors 39 The WIMP Landscape - today
XENON10 Note: many experiments are not shown!
ZEPLIN-III CDMS-II
XENON100
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 40 ZEPLIN III
12kg LXe target 5.1 kg fiducial mass
● LXe dual phase detector
● was operated at Boulby mine (UK)
● science run 2011: arXiv:1110.4769 1344 kg x days raw exposure 8 events observed in the ROI (7-29 keVr) → compatible with background expectation
● ZEPLIN program has come to an end
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 41 XENON100
Quick Facts ● 62 kg LXe target ● Dual phase TPC ● active LXe veto ● 242 PMTs ● running @ LNGS (IT)
PRL 107, 131302 (2011)
Last science run: PRL 107, 131302 (2011)
4800 kg x d raw exposure 1471 kg x d acpt. corrected (100 GeV/c²)
3 events observed → fully compatible with background lowest published → best WIMP limit over large mass range background of all running DM experiments PRD 83, 082001 (2011)
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 42 XENON100
Quick Facts ● 62 kg LXe target ● Dual phase TPC ● active LXe veto ● 242 PMTs ● running @ LNGS (IT)
PRL 107, 131302 (2011)
Last science run: PRL 107, 131302 (2011)
4800 kg x d raw exposure 1471 kg x d acpt. corrected (100 GeV/c²)
3 events observed → fully compatible with background lowest published → best WIMP limit over large mass range background of all running DM experiments PRD 83, 082001 (2011)
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 43 XENON100
Quick Facts ● 62 kg LXe target ● Dual phase TPC ● active LXe veto ● 242 PMTs ● running @ LNGS (IT)
PRL 107, 131302 (2011)
Current Science Run
● decreased background ● lower threshold ● more than 2x of 2010 dark matter data (and still taking data) lowest published ● much more calibration data background of all running DM → data analysis is almost done experiments → expect new results very soon PRD 83, 082001 (2011)
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 44 The WIMP Landscape
XENON10
ZEPLIN-III CDMS-II
XENON100
XENON100
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 45 The WIMP Landscape
XENON10
ZEPLIN-III CDMS-II
XENON100
XENON100 XMASS
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 46 XMASS
20 ● single phase LXe detector
● 800kg total, 100kg fiducial mass
● 60% of surface covered with 642 hexagonal PMTs
● very high LY (~7x higher than Xe100)
● located in Kamioka (JP)
● running since end of 2010; ultra low Kr85 background
● higher Rn background reported at TAUP2011; study on S1 PSD published (92% rej @ 50% acc)
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 47 XMASS
20 ● single phase LXe detector
● 800kg total, 100kg fiducial mass
● 60% of surface covered with 642 hexagonal PMTs
● very high LY (~7x higher than Xe100)
● located in Kamioka (JP)
● running since end of 2010; ultra low Kr85 background
● higher Rn background reported at TAUP2011; study on S1 PSD published (92% rej @ 50% acc)
first results will be announced at the Japanese Physical Society meeting, March 23, 2012 → expect results from 1 year exposure
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 48 LUX DarkSide
● dual-phase LXe TPC @ Sanford Lab (US) ● dual-phase LAr TPC @ LNGS (IT)
● 350 kg LXe, 100 kg fiducial mass ● DarkSide-10 (10 kg prototype) currently installed at LNGS ● low background Ti cryostat, water shield → testbench for larger detectors ● LY 2x higher than Xe100 ● DarkSide-50 (50 kg) ● currently being operated above ground, → commissioning by end of 2012 move UG scheduled for end of April ● use Ar depleted in Ar39 (x0.01?) ● underground science starts fall 2012, ● scintillator neutron-veto and water aim for 300 days exposure Figs. from E. Bernard muon veto (Borexino CTF) Figs. from L. Grandi
S1 data!
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 49 The WIMP Landscape
XENON10
ZEPLIN-III CDMS-II
XENON100
XMASS XENON100 DarkSide-50
LUX
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 50 The WIMP Landscape
XENON10
ZEPLIN-III CDMS-II
XENON100
MiniCLEAN 50 XMASS XENON100 DarkSide-50
LUX DEAP-3600
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 51 DEAP-3600 and MiniClean
Figs. from A. Hime
● single phase LAr ● 3.6t total, 1t fiducial mass ● excessive R&D on PSD ● single phase LAr and LNe ● in acrylic vessel @ SNOLab (CA) ● 500 kg total, 150 kg fiducial mass ● first filling expected end of 2013 ● Rn-free assembly ● operation with Ar 39 depleted Ar (x0.04) ● installation at SNOLab (CA) ● Goal: run for 3 years: 2013-2017 ● expected to run end of 2012-2014
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 52 The Beauty of 2 Targets
MiniCLEAN will be able to operate with LAr and LNe
Note: due to the smaller Mass number A, the sensitivity of LNe is ~10x lower than for LAr
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 53 XENON1T
● dual phase LXe TPC
1.05m ● 2.4t LXe ("1m³ detector") 1t fiducial mass 1.9m ● 0.95m 100x lower background than Xe100 (self shielding, low radioactivity components) Low Radioactivity Photon Detectors ● Timeline: 2010 – 2015
(3”, Total ~270) ● start construction at LNGS this year Low rad. Cryostat
1.3m
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 54 The WIMP Landscape
XENON10
ZEPLIN-III CDMS-II
XENON100
MiniCLEAN 50 XMASS XENON100 DarkSide-50
LUX DEAP-3600
XENON1T
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 55 The WIMP Landscape
XENON10
ZEPLIN-III CDMS-II
XENON100
MiniCLEAN 50 XMASS XENON100 DarkSide-50
LUX DEAP-3600
XENON1T
ultimate WIMP facilities: DARWIN, MAX, LZ
M. Schumann (U Zürich) – Liquid Noble Gas Detectors 56 Summary
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Liquid noble gas detectors currently dominate the field of direct dark matter searches
Very likely, this will not change in the future. M. Schumann (U Zürich) – Liquid Noble Gas Detectors 57