Update on the EDELWEISS Dark Matter Search
Klaus Eitel on behalf of the EDELWEISS collaboration
heat
Ge c ionization
KIT – The Research University in the Helmholtz Association www.kit.edu Update on the EDELWEISS Dark Matter Search
Klaus Eitel on behalf of the EDELWEISS collaboration
heat EDELWEISS-III New result: ALP limits Ge EDELWEISS-LT program c New result: Sub-GeV WIMP limit at surface ionization
KIT – The Research University in the Helmholtz Association www.kit.edu (low mass) WIMP searches
) CRESST n-cleus 2
CDMSLite
DAMIC
EDELWEISS-III
nucleon SI cross section (cm section cross SI nucleon
- WIMP PANDA-X LUX XENON-1t
0.1 1 10 WIMP Mass (GeV/c2)
3 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin (low mass) WIMP searches
) CRESST n-cleus 2 threshold
CDMSLite
DAMIC EDELWEISS-III
threshold,
nucleon SI cross section (cm section cross SI nucleon mass & -
bgd red./discr. WIMP PANDA-X LUX mass & XENON-1t discrimination 0.1 1 10 WIMP Mass (GeV/c2)
4 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin EDELWEISS low mass WIMP searches
EDELWEISS-III
Exploitation of results with 20 kg array ) 2 EPJC 76 (2016) 548 (x20-150 better than EDW-II) EDELWEISS-Surf Ionization R&D Improving discrimination to explore the 8B region with resolution (DMB8) Exploring non-WIMP DM with smaller array
(MELODI)
nucleon SI cross section (cm section cross SI nucleon - Heat channel R&D DMB8
Improving the heat channel resolution to reach WIMP lower WIMP masses 0.1 1 10 WIMP Mass (GeV/c2) Above-ground R&D (Surf) and deployment at LSM (LT)
5 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin EDELWEISS-III setup LSM: ~4800m.w.e. rock overburden (deepest in Europe) 5 µ/m2/d active muon veto (100m2, 98% geom. coverage); ≥20cm Pb & ≥50cm PE shield (int+ext) clean room; de-radonised air 10-20 mBq/m3 cryostat hosting up to 40kg of detectors at 18mK Selection of radiopure material
Performance of the EDELWEISS-III experiment for direct dark matter searches JINST 12 (2017) P08010
6 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin EDELWEISS-III detectors measuring heat & ionisation: surface event suppression:
Fully InterDigitized ~870g HPGe detectors Bulk: charges collected by C1 and C2; V and V act as veto Top=18mK 1 2 Surface: charges collected by either C1V1 or C2V2
C1:+4V V1:-1.5V NTD 2 GeNTD heat sensors - electrodes: e concentric Al rings (2mm spacing) B covering all faces FID800 h+ S J Low Temp Phys (2014)176:182 Ø=70mm, h=40 mm NTD Phys.Lett.B 681 (2009) 305 C2:-4V V2:+1.5V 7 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin EDELWEISS-III detectors -5 measuring heat & ionisation: surface event suppression210Pb b ~10 : Fully InterDigitized ~870g HPGe detectors 210 206 Po a Top=18mK Pb
210Pb source near surface
yield Ionization 18000 kg.day equivalent 210Pb b 210Po a 206Pb
recoil energy (keV) recoil energy (keV)
Ø=70mm, h=40 mm J Low Temp Phys (2014)176:182 Phys.Lett.B 681 (2009) 305
8 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin 18000 kg.day equivalent 10
Axion-like particle searches day /kg/
1 keV Starting point: study of electron recoil spectrum / of tritium paper Astropart. Phys. 91 (2017) 51
1149 kgd with 2 keVee threshold counts -1 287 kgd with 0.8 keVee threshold 10
Analysis extended to higher energy for line search up to 500 keVee Intensities of observed peaks consistent with known Th/U lines Resolution: 10-2
Baseline 193 eVee energy (keV)
Proportional term = 1.23%
continuum
counts residual/
energy (keV) energy (keV)
9 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin ALP and dark photon results
arXiv:1808.02340 Emission of axions/ALPs from the sun
10-10
EDELWEISS-II Solar neutrinos EDELWEISS-III 10-11 -16 XENON100 10 PandaX-II LUX
10-12 EDELWEISS-III Red giants
10-17 10-13 CBRD signal 57Fe 14.4 keV line 10-5 10-4 10-3 10-2 10-1 1 0 2 4 6 8 10 12 14 16
-11 gae < 1.1 x 10 (90%CL) (90%CL)
for ma << 14keV 10 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin ALP and dark photon results
keV-scale Bosonic DM
ALP coupling gae kinetic coupling k of dark photon
ae k . Best Ge-based limits <6 keV g EDELWEISS-III (thanks to surface rejection) EDELWEISS-III . Start to explore <1 keV
Stellar bounds PLB 747 (2015) 331
arXiv:1808.02340
11 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin ALP and dark photon perspective with improved ionization resolution
keV-scale Bosonic DM
ALP coupling gae kinetic coupling k of dark photon
ae k g EDELWEISS-III
EDELWEISS-III
Stellar bounds PLB 747 (2015) 331
. Improvements foreseen in the 100 eV – 1 keV region with improved ionization (new FE electronics & lower det. capacitance) arXiv:1808.02340
12 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin prospects for GeV-range masses
Complete study based on present measured backgrounds and resolutions vs possible improvements:
PRD 97 (2018) 022003 ) 2 1. Use of Neganov-Luke boost to lower thresholds (up to 100V bias)
2. Improve heat resolution, objective of 800g detectors: PRD 97 (2018) 022003 PRD (2018) 97
sphonon = 500 eV 100 eV (50 eV resolution already achieved on 200 g detector) Projection for 4x800g 100 eV – 100V
150 days / current bgd
nucleon SI cross section (cm section cross SI nucleon -
3. Reduction x100 of heat-only background WIMP 0.1 1 10 WIMP Mass (GeV/c2)
13 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin EDELWEISS-LT: NL-boost & improved heat
E 퐸푖표푛 NL= 휀 ∙ 푉푏푖푎푠
Prompt phonons Charge propagation Vbias NL amplified phonons
✔ 100V bias already achieved J. Billard et al., JLTP(2016)184:299 ✔ Observe nucl. recoils down to ~0.1 keVee ✔ Full ion.+heat readout possible at any V
NTD-B event 133
Ba 356 keV line ) ee
1
keV
( heat
0.1 FWHM
0 4000 8000 12000 Total phonon energy (keV) Luke boost = 1 + V/3
14 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin resolution improvements on a 32g HPGe
R&D with 32g HPGe combined with the objective of testing the above-ground sensitivity to sub-GeV WIMPs
optimized NTD heat sensor on a 32g crystal, no electrodes (i.e. 1keV = 1keVNR) kept at 17 mK in IPNL low-vibration dilution fridge [arXiv:1803.03463] one day blinded for WIMP search in [0-2] keV region 60eV analysis threshold
s =18 eV baseline
15 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin unblinding the data
No surprise: blinded day = carbon copy of preceding + following days
analysis region
8000 dru 0.6-2.0 keV
4000 dru > 7 keV
Find maximal WIMP rate compatible with total number of counts observed in the pre-defined windows 90% CL on WIMP signals as fctn of WIMP mass
16 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin
EDELWEISS surface limit
) 2 CRESSTn-cleus (above ground) Achieved resolution on a smaller detector exceeds by x5 the original LT goal with 800g detectors EDELWEISS-Surf (above ground) Best above-ground limit down to 600 MeV/c2: SIMP
First sub-GeV limit with Ge, down to 500 MeV/c2 section(cm SIcross
EDELWEISS-III nucleon Small detectors with lower thresholds to be -
combined with expertise acquired on HV: WIMP threshold reduction by factor (1+Vbias/3) in keVee
0.1 1 10 WIMP Mass (GeV/c2)
17 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin Conclusions & outlook
EDELWEISS-III : large detectors with rejection Excellent rejection performance, but not competitive with large Ar/Xe detectors above 6 GeV Exploitation of excellent surface event rejection from FID to get best Ge ALP limits, and enter the sub-keV range EDELWEISS-MELODI : develop large detectors with FID design Exploring non-WIMP DM with prototype: ALPs in the 0.1-1 keV range,
and direct sensitivity to quenching at ~0.4 keVNR Building block for a much larger search experiment (DMB8, suited for future SNOLAB program) addressing specifically the region where the DM signal needs to be spectrally resolved from a solar 8B neutrino signal Prospects in the sub-GeV-WIMP range: beyond EDELWEISS-LT Going beyond original [PRD] goal: 100 eV 18 eV (~500 eV EDW-III) Best surface limit for WIMPs above 0.6 GeV/c2 Resolutions achieved on 32g detectors + expertise acquired in HV runs open the way for the 0.1-1 GeV range
18 29 August 2018 Klaus Eitel - Update on the EDELWEISS DM Search TeVPA 2018, Berlin