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 EDELWEISS-SubGeV: Scientific context A widening search domain eV keV MeV GeV TeV Absorption DM-electron scattering DM-Nucleus scattering Electronic recoil Electronic recoil Nuclear recoil Hidden sector Dark Matter and others Standard WIMP 8B 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 (IPNL) J. Billard, New Directions in the Search for Light Dark Matter Particles, Fermilab 2019 2 Sept. 10th, 2019 EDELWEISS @ TAUP2019 2 This talk EDELWEISS-III EDELWEISS-Surf axion-like particle SIMP results results Evolution of the detectors from EDELWEISS- III to EDELWEISS-SubGeV EDELWEISS-III Sept. 10th, 2019 EDELWEISS @ TAUP2019 3 EDELWEISS-III Setup Sept. 10th, 2019 EDELWEISS @ TAUP2019 4 EDELWEISS-III detectors 210 210 [JINST 12 (2017) P08010]Pb β Pb β 210 210 206 Po α 206 Po α Heat: DT = E/Ccal + Ionization: Npairs = E/eg orPb en Pb <2x10-5 rejection of electron/nuclear recoils Readout of all electrodes provides a <4x10-5 surface event rejection. yield 18000 kg.day equivalent 18000 kg.day equivalent 210Pb β Ionization 210Po 206Pb α Sept. 10th, 2019 EDELWEISS @ TAUP2019 5 18000 kg.day equivalent Axion-Like Particle searches n Starting point: ER spectrum of tritium paper: For solid-state detector, optimal combination of • low background (Compton < 0.1 DRU), • and resolution (baseline s = 190 eVee, proportional term = 1.2%), important in case of signal • 287/1149 kgd with 0.8/2.0 keVee threshold n Line search from threshold up to 500 keVee • Observed peak intensities consistent with known 232Th, 226Ra, 235U lines from chain n Best sensitivity for solid-state detectors for the detection of solar axions via the Compton- Counts Bremsstrahlung-Recombination/Deexcitation-like processes (CBRD), or via the 57Fe 14.4 keV state PRD 98 (2018) 082004 082004 (2018) 98 PRD Sept. 10th, 2019 EDELWEISS @ TAUP2019 6 ALPs & dark photons limits n Best Ge-based limits <6 keV, thanks to surface rejection very important to reduce low-energy ER backgrounds n Prospect to reach sensitivity in the 100 eV – 1 keV region competitive 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 bounds Stellar [PLB 747 (2015) 331] Kinetic coupling kFF’ of dark photon Sept. 10th, 2019 EDELWEISS @ TAUP2019 7 Context: EDELWEISS SubGeV program n Current+future projects: background limited n For searches involving nuclear recoils (NR), event-by-event identification down to 1 GeV/c2 and 10-43 cm2 ~1 kg.y requires sphonon = 10 eV and sion = 20 eVee n The ionization resolution is key to particle identification + surface rejection (already seen as key in axion-like searches) n Keeping the ability to apply HV to EDELWEISS detectors is important to reduce thresholds in ER searches n New strategy for EDELWEISS: reducing the detector mass from 860 to 33 g is key to meet resolution goals First milestones in this program: EDELWEISS-Surf Sept. 10th, 2019 EDELWEISS @ TAUP2019 8 Motivations for DM surface searches n Relevance of strong interactions of ~GeV DM particles • Main focus of direct DM searches so far: DM-nucleon cross-sections below 10-31 cm2: 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) cm2 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) cm2 DM-nucleon interactions [e.g. Chen et al, PRD 65 123515 (2002)] n Technological: • 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) Sept. 10th, 2019 EDELWEISS @ TAUP2019 9 EDELWEISS-Surf Above-ground DM search n Context: EDELWEISS and Ricochet common R&D for low-threshold detectors performed in easy- access surface lab @ IPN-Lyon n <1 m overburden: ideal for SIMP search (strongly interacting DM) n Dry cryostat (CryoConcept) with RED20 (33g) <30h cool-down (fast turnover RED11 (200g) ideal for detector R&D) [NIM A858 (2017) 73] n < µg/√Hz vibration levels (spring-suspended tower). [JINST 13 (2018) No.8 T08009] n RED20: 33g Ge with NTD sensor, with no electrode • No ER/NR discrimination, but no uncertainty due to ionization yield or charge trapping) n 55Fe source for calibration Sept. 10th, 2019 EDELWEISS @ TAUP2019 10 EDELWEISS-Surf data n Streamed data processed PSD from 137 h displayed 26 0.65 ] Hz 24 0.6 with optimum filter 10-7 1 n Stability of noise & 22 0.55 20 0.5 Trigger rate [Hz] resolution over 137h 10-8 10-1 (6 days) of data taking 18 0.45 16 0.4 n -9 -2 Baseline energy resolution [eV] 1 day set aside a priori Linear power spectrum [V/ 10 10 Measured Noise 14 0.35 Signal template Optimal filter transfer function [a.u.] Expected from OF theory for blind search Optimal filter 12 0.3 1 10 102 0 20 40 60 80 100 120 n Baseline: s = 17.8 eV Frequency [Hz] Time [hour] Calibration and Resolution 12 n @5.9 keV: s = 36 eV 7 10 Data Noise induced triggers 6 6 1018 eV RMS10 energy resolutionResidual 105 4 0.4 105 10 Efficiency 0.05 0.1 0.15 0.2 0.3Event rate [evts/kg/keV/day)] 104 0.2 0 1 2 3 Trigger4 and Livetime5 6 7 8 Calibrated[PRD with 99 low 082013 energy X-rays (2019)]from 55Fe + ∆χ2 cuts 0.1 Energy [keV] + χ2 cut normal Sept. No10th, ionisation 2019 read-out (only phonons) - EDELWEISS @ TAUP2019 Analysis threshold 11 total deposited energy is collected, 0 allowing for a low threshold 10−1 1 60 eV energy threshold Energy [keV] Bradley J Kavanagh (GRAPPA) Tiny, tough WIMPs with EDELWEISS-surf LHC Results Forum - 3rd June 2019 Efficiency, signal prediction: pulse simulation 0.4 60 eV analysis n Efficiency (including deadtime, pileups and threshold c2 cuts) obtained by inserting pulses at Efficiency 0.3 random times in actual data stream 0.2 n Same technique used to evaluate response Trigger and Livetime + Dc2 cuts 0.1 to WIMPs of given masses + c2 cut normal Analysis threshold • Case 1: NR from standard WIMPs 0 10-1 1 • Case 2: ER+NR including Migdal effect Energy [keV] 2 GeV/c2 Unsmeared Background Model Background Model 5 Analysis Threshold (60 eV) 105 Analysis Threshold (60 eV) 10 Data Data 2 35 2 2 29 2 Excluded WIMP model: 0.7 GeV/c ,9.8 10− cm Excluded WIMP model: 50 MeV/c ,9.0 10− cm ⇥ ⇥ 2 37 2 2 30 2 Excluded WIMP model: 2.0 GeV/c ,4.5 10− cm Excluded WIMP model: 100 MeV/c ,7.0 10− cm ⇥ ⇥ 2 37 2 2 32 2 Excluded WIMP model: 10.0 GeV/c ,1.1 10− cm Excluded WIMP model: 1.0 GeV/c ,1.6 10− cm 104 ⇥ 104 ⇥ Standard Spectra Migdal Spectra 103 103 2 Number of counts [evts/keV] Number of102 counts [evts/keV] 2GeV/c 102 After pulse simulation 0.03 0.1 1 2 0.03 0.1 1 2 Energy [keV] Energy [keV] Sept. 10th, 2019 EDELWEISS @ TAUP2019 12 ...filling the gap between ground & space searches n Shaded regions: with full Earth-Shielding (ES) calculation n Lines: underground limits (w/o ES calculation, ~ok for <10-31 cm2) 10-24 Stronger upper -25 CMB cutoff for Migdal 10 10-26 XQC rocket -27 (subleading ] 2 10 component) 10-28 EDELWEISS-surf Migdal 10-29 10-30 -31 2 10 EDELWEISS-surf Sharp 45 MeV/c -32 10 CRESST – n-cleus cutoff due to ES -33 EDELWEISS-Surf (Standard) 10 EDELWEISS-Surf (Migdal) effect on velocity 10-34 EDELWEISS-III LT 10-35 CRESST Surface -36 CRESST-II + CRESST-III 10 SuperCDMS LT -37 10 CDMSLite 10-38 LUX (Standard) -39 LUX (Migdal) 10 XENON1T (Standard) 10-40 XENON100 LT -41 NEWS-G 10 DarkSide (Standard) WIMP-nucleon cross section [cm -42 10 XQC -43 CMB * Also: 10 10-44 Neutrino discovery limit spin-dependent CDEX Migdal Underground 10-45 limits 10-2 2´10-2 10-1 2´10-1 1 2 3 4 5 6 7 10 2 [PRD 99 082013 (2019)] WIMP Mass [GeV/c ] Sept. 10th, 2019 EDELWEISS @ TAUP2019 13 1 kg Ge array with: 1. 10 eV phonon resolution 2. 20 eVee ionization resolution 3. Possibility of applying large Luke-Neganov amplification NEXT STEPS TOWARDS THE EDELWEISS-SUBGEV GOALS Sept. 10th, 2019 EDELWEISS @ TAUP2019 14 Goal 1: 10 eV phonon resolution n Results with 33g + Ge-NTD detectors confirm that these sensors are a reliable choice EDELWEISS R&D: heat sensors to reproducibly reach s=20 eV NbSi transition edge sensor NbSi TES on thermal chip: n Replacing JFETs @ 100K with high impedance on sapphire or germanium chip HEMTs @ 1K should provideEDELWEISS R&D: heat sensors additional x2 needed in should reach <10 eV resolution (RMS) with standard JFET pre-amplifiers resolution NbSi transition edge sensor NbSi TES on thermal chip: high impedance n Also being investigated: on sapphire or germanium chip NbSi transition edge sensors NbSi sensor should reach <10 eV resolution (RMS) transition 100 nm thick, @ 45 mK 20mm diameter spiral NbSi S.