The EDELWEISS-III Experiment Silvia Scorza on behalf of the - PowerPoint PPT Presentation

The EDELWEISS-III Experiment Silvia Scorza on behalf of the EDELWEISS collaboration Institut für Experimentelle Kernphysik, Karlsruhe Institute of Technology KIT – University of the State of Baden-Wuerttemberg and 
 www.kit.edu National Research Center of the Helmholtz Association

Direct Detection Principle Detection of the WIMP WIMP Target Nucleus energy deposited from galactic halo in laboratory Elastic collision due to elastic scattering off target θ R v~220 km/s v~0 km/s nuclei E R ~30 keVr • Elastic scattering of a WIMP deposits small amount of energy into recoiling nucleus 
 (~ few 10s of keV) • Expected rate: 
 < 0.1 interaction per ton per day 
 (7.6 x 10 -46 cm 2 for m χ = 33 GeV) • Radioactive background of most materials gives higher rate • Event ID from measurements of ionization and phonon energies Silvia Scorza Astroparticle Physics 2014 2

The EDELWEISS Experiment 5 µ /m 2 /day e + ,e - , γ , Pb shield 4800 mwe (deepest in Europe) n, polyethylene shield µ -n, Neutron counter µ , Muon Veto Silvia Scorza Astroparticle Physics 2014 3

Low WIMP Mass Analysis 
 EDELWEISS-II 95% rejecton (ID3) • Total fiducial exposure : 113 kg.d neutron calibration � • 3 evts observed in the WIMP box 
 (one event for M χ = 10 GeV) • Estimated background (5-20 keV): Neutron < 1.7 evt, most probable 1.0 evt 
 (based on Monte-Carlo + activity meas.) Gamma < 1.2 evt • Limits on σ SI derived from Poisson 
 statistics • Significantly extends EDW limits 
 for M χ = 7-30 GeV PRD, 86, 051701(R), (2012) Silvia Scorza Astroparticle Physics 2014 4

EDELWEISS-III Improvement Goal: 10 -45 cm 2 with FID800 (24 kg fiducial) - Improved material selection PE - Extra internal PE shield: 
 ca.10 cm below bolometers 
 ca. 5 cm around and on top - Upgrades of muon veto, cryogenics, 
 PE cabling, thermal screens - Modify electronics and DAQ (scalability): 
 lead 360 channels + auxiliary detectors - New event-based readout - More analysis tools: Kdata: ROOT-based, multi-tier, db, … NIM A 684 (2012) 63 Background (20 – 200 keV) EDW-2 (evt / kg.d) EDW-3 (evt / kg.d) Improvement Gamma rate 82 14 – 44 up to 6 Ambient neutrons < 8.1·10 -3 (0.8 – 1.9)·10 -4 up to 100 Muon-induced neutrons < 2·10 -3 < 2·10 -4 up to 10 Astropart. phys. 47 (2013) 1 - Astropart. Phys. 44 (2013) 28 Silvia Scorza Astroparticle Physics 2014 5

EDELWEISS-III Improvement Kapton cables New PE 
 (1 K) Thermal 
 Detector 
 screen plate Digitization 
 New PE 
 300 K (1 K) FETs 
 100 K Roman Pb • Additional PE shield, new Cu thermal screens • Kapton cables and connectors between 1 K-10 mK (Steel) and 10 mK-10 mK (Cu) • ALL cold electronics at 100 K: relays instead of resistors for feedback and detector biases J Low Temp Phys 167 (2012) 645 Silvia Scorza Astroparticle Physics 2014 6

FID detector scheme +4V Full Inter-Digitized � 800 g HP-Ge Detector � Height: 4 cm Width: 7 cm Silvia Scorza Astroparticle Physics 2014 7

Background Rejection ID400 Fiducial Events Most backgrounds (e, γ ) produce electron recoils Yield (Ionization/recoil) ~1 WIMPs and neutrons produce nuclear recoils Yield (Ionization/recoil) ~0.3 NTD e- e- h+ Surface Events 
 10 Bulk Event 
 Charge collection shared � between one veto and its Charge collected h+ neighbor fiducial on fiducial electrodes, e.g. C & D electrodes B & D � NTD Silvia Scorza Astroparticle Physics 2014 8

FID Gamma Rejection 133 Ba Calibration Ionization Yield EDELWEISS-II 
 ID Rejection 
 factor: 3+-1 x 10 -5 � ID 400 g with 10x 160 g fiducial mass ID (350000 γ ) Ionization Yield EDELWEISS-III FID 800 g with 36x ~ 600 g fiducial mass NTD Fiducial Volume 75 % FID Rejection 
 factor < 6 x 10 -6 � FID (411000 γ ) Recoil Energy (keV) NTD Silvia Scorza Astroparticle Physics 2014 9

FID Surface Rejection 210 Bi 210 Pb 210 Po 206 Pb β ! β ! α Ionisation Yield FID 800 Cu 210 Bi 210 Pb 210 Po β ! β ! α γ 206 Pb 10 5 Kg.d equivalent 10keV 100keV 1MeV 5,3MeV 100keV Al Ionisation Yield amGe 50 nm 350 nm 20 µm 700 µm Ge Surface zone rejected 2 mm Fiducial Volume Recoil Energy (keV) 4·10 -5 misidentified events/(kg.d) (90% CL, Er >15 keV) � Silvia Scorza Astroparticle Physics 2014 10

Time Resolved Ionization Channel C 1 +4 V V 1 -1.5 V • Additional spatial information on z-axis of NTD bolometer • Improved understanding of charge migration • Identifying double scatter events • Surface event rejection � Event based readout needed for 40 MHz channel → Trigger on ionization channel � � NTD C 2 -4 V V 2 +1.5 V 90 1 80 C 1 70 Amplitude normalized Amplitude in ADU 60 V 2 50 0 40 30 20 C 2 -1 10 0 1 5 7.5 12.5 15 0 2.5 10 17.5 20 22.5 25 Time in µ s Time in µ s (40 MS/s) Silvia Scorza Astroparticle Physics 2014 11


 Upgrades - Resolution/Threshold Cryogenics 
 Electronics � Resistors removed, no Pulse Tubes close to the cryostat active feedback, removed and replaced by GM replaced by a relay thermal machines outside of the system shields (cryoline upgraded) 
 � -> Microphonic noise reduced 
 Silvia Scorza Astroparticle Physics 2014 12


 Upgrades - Resolution/Threshold Cryogenics 
 Electronics � Resistors removed, no Pulse Tubes close to the cryostat active feedback, removed and replaced by GM replaced by a relay thermal machines outside of the system shields (cryoline upgraded) 
 � -> Microphonic noise reduced 
 Baseline Resolution FWHM (keV) EDELWEISS II EDELWEISS III Ionization 900 600 Heat 1.2 1.0 Silvia Scorza Astroparticle Physics 2014 12


 Upgrades - Resolution/Threshold Cryogenics 
 Electronics � Resistors removed, no Pulse Tubes close to the cryostat active feedback, removed and replaced by GM replaced by a relay thermal machines outside of the system shields (cryoline upgraded) 
 � -> Microphonic noise reduced 
 R&D (JFET -> HEMT) 
 Baseline Resolution FWHM (keV) EDELWEISS II EDELWEISS III X 300 Ionization 900 600 Heat 1.2 1.0 Silvia Scorza Astroparticle Physics 2014 12

2014 Status November 2013 - January 2014: 15 x 800 g, commissioning phase 
 February 2014 : 36 x 800 g detectors installed in cryostat 
 (+ 3 Lumineu double beta decay detectors) 
 24 kg of fiducial mass in germanium Facility able to acquire Baseline resolution: <650 eV> 
 3000 kg.d per 6 months Ba 356-keV resolution: <10 keV> � Expected background from internal neutrons limits total exposure with <1 bkg event from 
 4500 kg.d (2.5x10 -9 pb) to 12 000 kg.d (10 -9 pb) � Silvia Scorza Astroparticle Physics 2014 13

2014 Status November 2013 - January 2014: 15 x 800 g, commissioning phase 
 February 2014 : 36 x 800 g detectors installed in cryostat 
 (+ 3 Lumineu double beta decay detectors) 
 24 kg of fiducial mass in germanium Facility able to acquire 3000 kg.d per 6 months � Expected background from internal neutrons limits total exposure with <1 bkg event from 
 4500 kg.d (2.5x10 -9 pb) to 12 000 kg.d (10 -9 pb) � Silvia Scorza Astroparticle Physics 2014 13


 
 Within the Cryostat … The LUMINEU project: tests of ZnMoO4 crystals within EDWIII cryostat for ββ measurement. 0 νββ of 100 Mo -> information on neutrino nature, mass and hierarchy � Light vs. heat @ LSM background measurement 313g ZnMo04 bolometer operated at LSM in the EDELWEISS setup and its light detector. 2014: 2 enriched Zn 100 MoO 4 crystals (~60g each) have been produced at NIIC and successfully tested aboveground. They are now installed at LSM, ready to take data. � A.S. Barabash et al., arXiv:1405.6937 Silvia Scorza Astroparticle Physics 2014 14

Installation of 36 FIDs Silvia Scorza Astroparticle Physics 2014 15


 
 
 Current Status • Commissioning of FID detectors • 36 detectors installed, 24 being read out • Cool down ongoing Timeline End of 2014/ Early 2015 � Reach 3000 kg.d 
 (6 months of data taking) 2016 � Reach 12000 kg.d (10 -9 pb) Low Mass WIMP 1200 kg.d (4 FID) 
 Er > 3 keV, 300 eV FWHM with HEMT Standard WIMP 12000 kg.d no event 
 Er > 15 keV (10%efficiency at 6 keV) 
 Silvia Scorza Astroparticle Physics 2014 16

Next Step: EURECA � � -39 10 ] XENON10 (2011) 2 WIMP-Nucleon Cross Section (SI) [cm •Ge/CaWO 4 detectors DAMA (Savage, 2009) -40 10 CoGeNT (2012) CRESST-II (2012) � SIMPLE (2012) -41 COUPP (2012) 10 ZEPLIN-III (2011) •Cooperation with CDMS-Si (2013) CDMS (2010/2011) -42 10 EDELWEISS (2010/2011) SuperCDMS XENON100 (2012) -43 10 3 ) 1 0 1 ) 2 0 1 ( r ( 2 X l l e U u e L � h m u c B Edelweiss 3 SCDMS at Soudan -44 10 SCDMS at SNOLAB XENON1T (2017) •200kg low mass phase -45 Neutrino background 10 Roszkowski (2013) EURECA followed by ton-scale -46 10 upgrade 
 -47 10 3 4 5 6 7 10 20 30 40 100 200 1000 2000 10000 2 WIMP Mass [GeV/c ] •Conceptual Design 200kg phase 
 standard high under investigation with new Report 
 mass search performances ( ton-scale ) Physics of the Dark Universe, (EDW-III & CRESST update) Volume 3, p. 41-74. Silvia Scorza Astroparticle Physics 2014 17