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. Marnieros, HDR (2014) with standard JFET pre-amplifiers sensor lithographied http://hal.in2p3.fr/tel-01088881/document on a 200 g Ge 14 Bernhard Siebenborn - EDELWEISS dark matter search Institut für Kernphysik Sept. 10th, 2019 EDELWEISS @ TAUP2019 15
S. Marnieros, HDR (2014) http://hal.in2p3.fr/tel-01088881/document
14 Bernhard Siebenborn - EDELWEISS dark matter search Institut für Kernphysik 7
1 2 Goal 2: 20 eVee ionization resolution 3 4 n Transition from JFET to HEMT Goal #3: EM background[ rejectionnew arXiv: 1909.02879of O(103) ] FET to 5 n Lower intrinsic noise + reduce cabling HEMT 20 eV ionization resolution: HEMT preamplifiers + new electrode design 6 capacitance by working at 1K or 4K n Data driven HEMT models show that the 7 FET to HEMT goal of 20 eVee is reachable with ~20 pF 8 Goal Goal 9 total input impedance n Ongoing HEMT characterizations • As initiated by the CDMS-Berkeley group10 (arXiv:1611.09712) we are transitioning to HEMT based preamplifiers. • HEMT have lower intrinsic noise than11 JFET • Work @ 4/1 K allowing to reduce the stray capacitance • Based on our data driven HEMT model12, O (10) eV rms reachable with ~20 pF total input impedance • HEMT characterizations are ongoing 13 • First HEMT-based preamp to be tested in winter 2019 ! • Cryogenic and cold cabling challenges14 ahead ! Left: Contribution to the ionization resolution of the voltage noise, current noise, bias • Synergie with the Ricochet-CryoCube collaboration Fig. 5 J. Billard (IPNL) 8 15 n HEMTresistor-based (10 preamp GW @ tests 20mK). end The of 2019 total detector + cabling capacitance is 20 pF. 5 pF and 100 pF geometries have been studied. FFT of 1 keV event are shown. Right: Evolution of the resolution 16 n Cryogenics + cabling challenges ahead with the detector + cabling capacitance for the 5 HEMT geometries and the IF1320 Si-JFET 17 n Workfrom done InterFET. in synergy Noise ofwith the biasthe resistor is included.Optimization (Color figureof 33g online.) FID design: large 18 Ricochet-CryoCube collaboration fiducial volume & low capacitance
19 Sept. 10th, 2019 EDELWEISS @ TAUP2019 16 20 Ge-NTD Thermal Sensor Heat 21 Veto Top Interdigitized Al Electrodes 22 Fiducial Top 23 24 25
26 (V) Field 27 10mm 28 29 15 mm 30 31 Fig. 6 Electrostatic simulation of a Full Inter-Digitized electrodes scheme on a 38 g germanium 32 crystal (F = 30 g, h = 10mm). The crystal is surrounded at 2 mm distance by a chassis connected 33 to the ground (not shown). The capacitance of the 4 electrodes with respect to the ground is about 20 pF (Color figure online.) 34 35 36 37 38 tector. Electrostatic simulations (Fig. 6) show that the EDELWEISS Fully Inter- 39 Digitized (FID) 800g detector [1] ionization electrode pattern can be adapted to 40 match the 20 pF capacitance requirement with a 30 g detector. This FID detec- ⇠ 41 tor geometry has been shown to efficiently reject surface events, which may be 42 advantageous for CEnNS and low-mass WIMP searches where the low energy 43 backgrounds are unknown. Future work will address the issues of very low ca- 44 pacitance cabling and optimization the balance between individual detector mass, 45 fidicual volume, and detector capacitance when considering the 10 eV heat and 46 20 eVee ionization baseline RMS resolutions required to the upcoming Ricochet 47 and EDELWEISS-SubGeV experiments. The development of HEMT-based am- 48 plifiers represents a clear path to achieving the energy resolution requirements of 49 cryogenic semiconductor detectors for pursuing new physics in the low mass Dark 50 Matter and CEnNS sectors. 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Goal 3: High voltage operation n Luke-Neganov boost to amplify signal (and not electronic noise) n Already tested on existing FID800 detectors
EDELWEISS Preliminary
133Ba 2.5 keV NR 356 keV line
0.6 keV NR ) 1 ee keV Same detector 0.1 Same source
Different biases FWHM ( (8V or 90 V)
Luke boost = 1 + V/3
Sept. 10th, 2019 EDELWEISS @ TAUP2019 17 Goal #4: Operation Goalat high 3: voltageHigh voltage (~100 operationV)
n Current run @ LSM : obtaining near single-electron sensitivity on 33 and High Voltage: Exploring DM-electron/nucleus interactions with near single-electron sensitivity achieved 200 g detectors: exploration of DM interactions with electrons & nuclei in massive bolometers operated underground (low-background environment ~ 1 - 0.1 DRU). High-impedance NbSi TES Ge-NTD
10.4 keV NbSi209 Preliminary 10.4 keV RED30 Preliminary 66 Volt 70 Volt 1.3 keV s = 5 eVee 1.3 keV s = 1.8 eVee 160 eV DM 160 eV DM search search zone zone
First EDELWEISS DM-electron scattering and absorption results expected by fall 2019. 18 J. BillardSept. (IPNL)10th, 2019 EDELWEISS10 @ TAUP2019 Goal 3: High voltage operation n Current run @ LSM : obtaining near single-electron sensitivity on 33 and 200 g detectors: Calibration of nuclear recoils down to low thresholds
15V 66V
66V 66V
Sept. 10th, 2019 EDELWEISS @ TAUP2019 19 Conclusions n Increasing interest in the low-mass dark matter region motivated by lack of evidence of new physics at LHC (e.g. SUSY): Beyond the standard WIMP Dark Matter scenario
n EDELWEISS-SubGeV program aims at probing MeV-GeV particles via ER and NR interactions with detectors able to provide: • Reduce detector mass to improve resos & thresholds -> confirmed by EDELWEISS-Surf
• Particle ID and surface event rejection down to 50 eVNR (Low Voltage) • Single-e/h sensitivity on massive bolometers (High Voltage) n Low-voltage R&D program focusing on front-end HEMT preamplifier and low- capacitance electrode design, in synergy with Ricochet/Cryocube
Design objective: s = 10 eV (phonon) + 20 eVee (ionization) Goal is to reach O(10-43) cm2 with background rejection at 1 GeV, with 1 kg payload in one year at LSM n High-voltage R&D program, advancing well with near single-e/h sensitivity achieved on 33.4 g and 200 g Ge crystals operated at Modane. Science results expected end 2019
Sept. 10th, 2019 EDELWEISS @ TAUP2019 20 BACKUP
Sept. 10th, 2019 EDELWEISS @ TAUP2019 21 EDELWEISS-III
Sept. 10th, 2019 EDELWEISS @ TAUP2019 22 Search extended to spin-dependent cases n 14N has both p and n spin à shielding from atmosphere n Large cross-section → dramatic ES effects (especially on Migdal limits)
-23 -23 ) )
10 2 10 2 Si H Si 10-25 10-25
Li2MoO4 10-27 Ge+Migdal 10-27 Si Ge 10-29 Ge 10-29
10-31 10-31 Li2MoO4 -33 -33 10 10 EDELWEISS-Surf EDELWEISS-Surf CaWO4 Ge EDELWEISS-Surf Migdal RRS-Balloon -35 -35
10 RRS-Balloon SD WIMP-Proton Cross Section (cm 10 CMB SD WIMP-Neutron Cross Section (cm XQC CDMSLite -37 Ge -37 10 CDMSLite 10 LUX
LUX PandaX-II - - 10 39 PandaX-II 10 39 XENON1T XENON1T PICO-60-II 10-41 10-41 2´10-1 1 2 3 4 5 6 7 10 20 30 2´10-1 1 2 3 4 5 6 7 10 20 30 WIMP Mass (GeV/c 2) WIMP Mass (GeV/c 2)
Sept. 10th, 2019 EDELWEISS @ TAUP2019 23 Current EDELWEISS run at LSM n Continuous running at <21 mK since January 2019 n Eleven Ge detectors • Rest of cryostat used for joint physics run with CUPID-Mo n Compare detector physics in 32g, 200g and 800g detectors n Compare performance of NTD and NbSi-TES heat sensors n Study of low-energy backgrounds in Ge detectors operated with large Luke- Neganov amplification n Limits on Dark Matter using ER and NR spectra of detectors with large Luke- Neganov amplification
Sept. 10th, 2019 EDELWEISS @ TAUP2019 24 Current measurements
n Luke-Neganov amplification: the value of the applied bias is usally limited by leakage currents
• Few fA current sufficient to degrade heat measurement in Ge detectors cooled down at 20 mK
• Need to investigate if these currents are at the surface of thecontrol, detectors, sampling or frequency in the bulk and clock (via allows trapped easy identification and subtraction of common noise space charges)patterns due to electronic interference. n EDELWEISS purely capacitive ionization readout Polarization (gate & detector reset via mechanical relays at Feedback 5 pF fixed time intervals): continuous measure of Drain Electrode Source charge on all electrodes: I = DQ/Dt slope. 2 nF
[JINST12 P08010 (2017)] 2017 JINST 12 P08010 n So far measurement of currents <0.1 fA
achieved on 800g detector,Figure 7. EDELWEISS-III up to 90V signal bias readout: heat (left) and ionization (right) channels. (~1000 electrons/second/kgGe) 5.1 Heat channel readout
Sept. 10th, 2019 The experimental optimalEDELWEISS heat energy @ TAUP2019 resolution is obtained with impedances of the NTD25 thermis- tors of a few M⌦ and a current bias of a few nA at 18 mK. These values are a compromise between the sensitivity to microphonics at such high impedance and non-linearity of the VNTD I responses ( ) (NTD voltage versus bias current). These non-linearities appear due to thermal decoupling of the detectors from the bath via the heat sink, thermal decoupling of the NTD from the germanium crystal via the glue in between them and electron-phonon decoupling within the NTD [32]. The typical heat capacity for a fully equipped FID detector is about 2 nJ/K at 18 mK, so the expected temperature elevation for an energy deposition of 1 keV is roughly 0.1 µK. With a typical heat response of 0.5 V/K, an energy sensitivity of 50 nV/keV is obtained. Typical time constants at 18 mK are 10 ms for the rise time and 10 and 100 ms for the two main decay times respectively (see [32] for details). EDELWEISS-III heat pre-amplification electronics is based on IFN860 bi-JFETs with a noise plateau at about 1–2 nV/pHz rms. The white noise contribution of the NTD Johnson noise is in the same range. Considering only these two sources of white noise and a decay time constant of 100 ms lead to an electronic baseline resolution of about 300 eV FWHM. Heat current excitation is modulated in the 500 Hz range: at both ends of the NTD two opposite current squares are created by di erentiating a triangular voltage pulse on a 5 pF capacitance (figure 7, left). This square modulation technique has been originally developed for the Archeops balloon and Planck satellite [33]. The demodulation is done after the digitization at 100 kHz either online or o ine by means of software. All noise that has not been modulated is rejected and the noise level is the one at the modulation frequency. The electronics 1/f noise is thus e ciently rejected by the modulation and the common-mode noise is rejected by the di erential measurement. A reference square could be subtracted before the second stage of amplification to enhance the dynamic range.
5.2 Ionization channel readout The mean energy to generate an electron-hole pair is 3 eV in germanium [34]. Therefore a 1 keV ionization energy baseline resolution corresponds to a charge of 330 electrons equivalent at the input. If an electric field is applied through the detector, the electron-hole pairs drift through the detector
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