EDELWEISS searches for low-mass Dark Matter particles EDELWEISS-III results on Electron Recoil searches with 860g detectors [PRD 98 082004 (2018)] SubGeV WIMP/SIMP search results with a 33g detector [PRD 99 082013 (2019)] Recent EDELWEISS-SubGeV developments Jules Gascon IPNLyon (IP2I), Université Lyon 1 + CNRS/IN2P3 Sept. 10th, 2019 EDELWEISS @ TAUP2019
A widening search domain eV keV MeV GeV TeV Absorption DM-electron scattering DM-Nucleus scattering Electronic recoil Electronic recoil Nuclear recoil Standard WIMP Hidden sector Dark Matter and others 8 B neutrinos (~ 6 GeV) Reactor neutrinos (~ 2.7 GeV) EDELWEISS-SubGeV program EDELWEISS-III Not competitive with High Voltage Low Voltage High Voltage Low Voltage noble gases experiments single e/h Part. ID + Fid single e/h Part. ID + Fid J. Billard, New Directions in the Search for Light Dark Matter Particles, Fermilab 2019 2 Sept. 10th, 2019 EDELWEISS @ TAUP2019
This talk EDELWEISS-III EDELWEISS-Surf axion-like particle SIMP results results Evolution of the detectors from EDELWEISS- III to EDELWEISS-SubGeV EDELWEISS-III 3 Sept. 10th, 2019 EDELWEISS @ TAUP2019
EDELWEISS-III Setup 4 Sept. 10th, 2019 EDELWEISS @ TAUP2019
EDELWEISS-III detectors [JINST 12 (2017) P08010] Heat: D T = E/C cal + Ionization: N pairs = E/ e g or e n <2x10 -5 rejection of electron/nuclear recoils Readout of all electrodes provides a Ionization yield <4x10 -5 surface event rejection . 18000 kg.day equivalent 210 Pb β 210 Po α 206 Pb 5 Sept. 10th, 2019 EDELWEISS @ TAUP2019
Axion-Like Particle searches Starting point: ER spectrum of tritium paper: n For solid-state detector , optimal combination of low background ( Compton < 0.1 DRU ), • and resolution (baseline s = 190 eV ee , • proportional term = 1.2%) , important in case of signal 287/1149 kgd with 0.8/2.0 keV ee threshold • Line search from threshold up to 500 keV ee n Observed peak intensities consistent with known • 232 Th, 226 Ra, 235 U lines from chain Counts Best sensitivity for solid-state detectors for the n detection of solar axions via the Compton- Bremsstrahlung-Recombination/Deexcitation-like PRD 98 (2018) 082004 processes (CBRD), or via the 57 Fe 14.4 keV state 6 Sept. 10th, 2019 EDELWEISS @ TAUP2019
ALPs & dark photons limits Best Ge-based limits <6 keV, thanks to surface rejection very important n to reduce low-energy ER backgrounds Prospect to reach sensitivity in the 100 eV – 1 keV region competitive n with XENON: improve ionization resolution on single electrodes from present ~300 eV (200 eV fiducial) to 20 eV with HEMT readout Green-dashed: projection for 50 eV resolution & present backgrounds ALP coupling EDELWEISS-III EDELWEISS-III ] 1 3 3 s ) d 5 n 1 u 0 o 2 b ( 7 r 4 a 7 l l e B t L S P [ Kinetic coupling k FF’ of dark photon 7 Sept. 10th, 2019 EDELWEISS @ TAUP2019
Context: EDELWEISS SubGeV program Current+future projects: background limited n For searches involving nuclear recoils (NR), n event-by-event identification down to 1 GeV/c 2 and 10 -43 cm 2 ~1 kg.y requires s phonon = 10 eV and s ion = 20 eV ee The ionization resolution is key to particle n identification + surface rejection (already seen as key in axion-like searches) Keeping the ability to apply HV to n EDELWEISS detectors is important to reduce thresholds in ER searches New strategy for EDELWEISS: reducing the n detector mass from 860 to 33 g is key to meet resolution goals First milestones in this program: EDELWEISS-Surf 8 Sept. 10th, 2019 EDELWEISS @ TAUP2019
Motivations for DM surface searches Relevance of strong interactions of ~GeV DM particles n Main focus of direct DM searches so far: DM-nucleon cross-sections below 10 -31 cm 2 : • Shielding from Earth + atmosphere can be neglected, i.e. experiments are located in deep underground sites, to reduce cosmic-ray induced backgrounds O(10 -24 ) cm 2 DM-DM cross-section of ~GeV DM particles could actually help CDM problems • at small-scale (DM halo, satellites...) [Spergel+Steinhardt PRL 84 3760 (2000)] Natural extension: test for O(10 -24 ) cm 2 DM-nucleon interactions [e.g. Chen et al, PRD 65 • 123515 (2002)] Technological: n Detector development program based in surface laboratory • Proof that relatively massive EDELWEISS-like detectors can be used in surface experiment, • i.e. relevant for the study of the coherent elastic scattering of reactor neutrinos on nucleons (like Ricochet) 9 Sept. 10th, 2019 EDELWEISS @ TAUP2019
EDELWEISS-Surf Above-ground DM search Context: EDELWEISS and Ricochet n common R&D for low-threshold detectors performed in easy- access surface lab @ IPN-Lyon <1 m overburden : ideal for SIMP n search (strongly interacting DM) Dry cryostat (CryoConcept) with n RED20 (33g) <30h cool-down (fast turnover RED11 (200g) ideal for detector R&D) [NIM A858 (2017) 73] < µ g/ √ Hz vibration levels n (spring-suspended tower). [JINST 13 (2018) No.8 T08009] RED20: 33g Ge with NTD sensor, n with no electrode No ER/NR discrimination, but no • uncertainty due to ionization yield or charge trapping) 55Fe source for calibration n 10 Sept. 10th, 2019 EDELWEISS @ TAUP2019
EDELWEISS-Surf data Streamed data processed PSD from 137 h displayed n 26 0.65 Baseline energy resolution [eV] Trigger rate [Hz] with optimum filter ] Optimal filter transfer function [a.u.] Hz 24 0.6 - 7 10 1 Linear power spectrum [V/ Stability of noise & 22 0.55 n resolution over 137h 20 0.5 - - 8 10 1 10 (6 days) of data taking 18 0.45 16 0.4 1 day set aside a priori n - 9 - 2 10 10 Measured Noise 14 0.35 for blind search Expected from OF theory Signal template Optimal filter 12 0.3 0 20 40 60 80 100 120 Baseline: s = 17.8 eV 2 10 1 10 n Frequency [Hz] Time [hour] @5.9 keV: s = 36 eV Event rate [evts/kg/keV/day)] n 7 10 Data Noise induced triggers 6 6 10 10 Residual 5 10 4 10 5 10 0.05 0.1 0.15 0.2 4 10 [PRD 99 082013 (2019)] 0 1 2 3 4 5 6 7 8 Energy [keV] 11 Sept. 10th, 2019 EDELWEISS @ TAUP2019
Efficiency, signal prediction: pulse simulation Efficiency 60 eV analysis 0.4 Efficiency (including deadtime, pileups and n threshold c 2 cuts) obtained by inserting pulses at 0.3 random times in actual data stream 0.2 Same technique used to evaluate response n Trigger and Livetime D c 2 + cuts to WIMPs of given masses 0.1 c 2 + cut normal Analysis threshold Case 1: NR from standard WIMPs • 0 - Case 2: ER+NR including Migdal effect 1 • 10 1 Energy [keV] 2 GeV/c 2 Unsmeared Background Model Background Model Analysis Threshold (60 eV) Analysis Threshold (60 eV) 10 5 10 5 Number of counts [evts/keV] Number of counts [evts/keV] Data Data Excluded WIMP model: 50 MeV/c 2 , 9 . 0 × 10 − 29 cm 2 Excluded WIMP model: 0.7 GeV/c 2 , 9 . 8 × 10 − 35 cm 2 Excluded WIMP model: 100 MeV/c 2 , 7 . 0 × 10 − 30 cm 2 Excluded WIMP model: 2.0 GeV/c 2 , 4 . 5 × 10 − 37 cm 2 Excluded WIMP model: 1.0 GeV/c 2 , 1 . 6 × 10 − 32 cm 2 Excluded WIMP model: 10.0 GeV/c 2 , 1 . 1 × 10 − 37 cm 2 10 4 10 4 Migdal Spectra Standard Spectra 10 3 10 3 2 GeV/c 2 10 2 10 2 After pulse simulation 0.03 0.1 1 2 0.03 0.1 1 2 Energy [keV] Energy [keV] 12 Sept. 10th, 2019 EDELWEISS @ TAUP2019
...filling the gap between ground & space searches Shaded regions: with full Earth-Shielding (ES) calculation n Lines: underground limits (w/o ES calculation, ~ok for <10 -31 cm 2 ) n - 24 Stronger upper 10 CMB - 25 10 cutoff for Migdal - XQC rocket 26 10 (subleading - 27 10 ] 2 component) - 28 WIMP-nucleon cross section [cm EDELWEISS-surf Migdal 10 - 29 10 - 30 10 - 31 EDELWEISS-surf 10 Sharp 45 MeV/c 2 - 32 10 CRESST – n -cleus cutoff due to ES - EDELWEISS-Surf (Standard) 33 10 EDELWEISS-Surf (Migdal) effect on velocity - 34 10 EDELWEISS-III LT - 35 CRESST Surface 10 - CRESST-II + CRESST-III 36 10 SuperCDMS LT - 37 10 CDMSLite - 38 LUX (Standard) 10 - LUX (Migdal) 39 10 XENON1T (Standard) - 40 10 XENON100 LT - 41 NEWS-G 10 DarkSide (Standard) - 42 10 XQC - 43 10 CMB * Also: - 44 Neutrino discovery limit 10 spin-dependent - CDEX Migdal Underground 45 10 - - - - ´ ´ limits 2 2 1 1 10 2 10 10 2 10 2 3 4 5 6 7 1 10 2 WIMP Mass [GeV/c ] [PRD 99 082013 (2019)] 13 Sept. 10th, 2019 EDELWEISS @ TAUP2019
1 kg Ge array with: 10 eV phonon resolution 1. 20 eV ee ionization resolution 2. Possibility of applying large Luke-Neganov amplification 3. NEXT STEPS TOWARDS THE EDELWEISS-SUBGEV GOALS 14 Sept. 10th, 2019 EDELWEISS @ TAUP2019
Goal 1: 10 eV phonon resolution Results with 33g + Ge-NTD n detectors confirm that these sensors are a reliable choice to reproducibly reach s =20 eV Replacing JFETs @ 100K with n HEMTs @ 1K should provide � additional x2 needed in resolution Also being investigated: n NbSi transition edge sensors NbSi sensor � transition 100 nm thick, @ 45 mK 20mm diameter spiral NbSi sensor lithographied on a 200 g Ge 15 Sept. 10th, 2019 EDELWEISS @ TAUP2019
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