[PPT] - EDELWEISS searches for low-mass Dark Matter particles EDELWEISS-III PowerPoint Presentation

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Jules Gascon

IPNLyon (IP2I), Université Lyon 1 + CNRS/IN2P3

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

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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A widening search domain

Sept. 10th, 2019

EDELWEISS @ TAUP2019

TeV GeV MeV keV eV

Absorption Electronic recoil DM-electron scattering Electronic recoil DM-Nucleus scattering Nuclear recoil

Standard WIMP Hidden sector Dark Matter and others

8B neutrinos (~ 6 GeV)

Reactor neutrinos (~ 2.7 GeV)

EDELWEISS-SubGeV program

High Voltage single e/h Low Voltage

Part. ID + Fid

High Voltage single e/h Low Voltage

Part. ID + Fid

Not competitive with noble gases experiments

EDELWEISS-III

J. Billard, New Directions in the Search for Light Dark Matter Particles, Fermilab 2019

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This talk

Sept. 10th, 2019

EDELWEISS @ TAUP2019

EDELWEISS-III

EDELWEISS-III axion-like particle results EDELWEISS-Surf SIMP results Evolution of the detectors from EDELWEISS- III to EDELWEISS-SubGeV

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EDELWEISS-III Setup

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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EDELWEISS-III detectors

Sept. 10th, 2019

EDELWEISS @ TAUP2019

Heat: DT = E/Ccal + Ionization: Npairs = E/eg or en

[JINST 12 (2017) P08010]

210Pb β 206Pb 210Po α

Ionization yield

Readout of all electrodes provides a <4x10-5 surface event rejection.

18000 kg.day equivalent

<2x10-5 rejection of electron/nuclear recoils

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Axion-Like Particle searches

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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

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Line search from threshold up to 500 keVee

Observed peak intensities consistent with known

232Th, 226Ra, 235U lines from chain

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Best sensitivity for solid-state detectors for the detection of solar axions via the Compton- Bremsstrahlung-Recombination/Deexcitation-like processes (CBRD), or via the 57Fe 14.4 keV state

Sept. 10th, 2019

EDELWEISS @ TAUP2019

Counts PRD 98 (2018) 082004

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ALPs & dark photons limits

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Best Ge-based limits <6 keV, thanks to surface rejection very important to reduce low-energy ER backgrounds

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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

Sept. 10th, 2019

EDELWEISS @ TAUP2019

ALP coupling

EDELWEISS-III

Kinetic coupling kFF’

f dark photon

EDELWEISS-III S t e l l a r b

u

n d s

[ P L B 7 4 7 ( 2 1 5 ) 3 3 1 ]

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Context: EDELWEISS SubGeV program

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Current+future projects: background limited

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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

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The ionization resolution is key to particle identification + surface rejection (already seen as key in axion-like searches)

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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Keeping the ability to apply HV to EDELWEISS detectors is important to reduce thresholds in ER searches

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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

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Motivations for DM surface searches

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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)]

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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

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EDELWEISS-Surf Above-ground DM search

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Context: EDELWEISS and Ricochet common R&D for low-threshold detectors performed in easy- access surface lab @ IPN-Lyon

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<1 m overburden: ideal for SIMP search (strongly interacting DM)

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Dry cryostat (CryoConcept) with <30h cool-down (fast turnover ideal for detector R&D)

[NIM A858 (2017) 73]

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< µg/√Hz vibration levels (spring-suspended tower).

[JINST 13 (2018) No.8 T08009]

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RED20: 33g Ge with NTD sensor, with no electrode

No ER/NR discrimination, but no

uncertainty due to ionization yield or charge trapping)

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55Fe source for calibration

Sept. 10th, 2019

EDELWEISS @ TAUP2019 RED20 (33g) RED11 (200g)

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EDELWEISS-Surf data

Sept. 10th, 2019

EDELWEISS @ TAUP2019

Frequency [Hz] 1 10

2

10 ] Hz Linear power spectrum [V/

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Optimal filter transfer function [a.u.]

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Noise Signal template Optimal filter

PSD from 137 h displayed Energy [keV] 1 2 3 4 5 6 7 8 Event rate [evts/kg/keV/day)]

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0.05 0.1 0.15 0.2

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Data Noise induced triggers Residual

Time [hour] 20 40 60 80 100 120 Baseline energy resolution [eV] 12 14 16 18 20 22 24 26

Measured Expected from OF theory

Trigger rate [Hz]

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65

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Streamed data processed with optimum filter

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Stability of noise & resolution over 137h (6 days) of data taking

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1 day set aside a priori for blind search

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Baseline: s = 17.8 eV

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@5.9 keV: s = 36 eV

[PRD 99 082013 (2019)]

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Efficiency, signal prediction: pulse simulation

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Efficiency (including deadtime, pileups and c2 cuts) obtained by inserting pulses at random times in actual data stream

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Same technique used to evaluate response to WIMPs of given masses

Case 1: NR from standard WIMPs
Case 2: ER+NR including Migdal effect
Sept. 10th, 2019

EDELWEISS @ TAUP2019

Energy [keV]

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1 Efficiency 0.1 0.2 0.3 0.4

Trigger and Livetime cuts

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c D + cut

normal 2

c + Analysis threshold

0.03 0.1 1 2 Energy [keV] 102 103 104 105 Number of counts [evts/keV] Migdal Spectra

Background Model Analysis Threshold (60 eV) Data Excluded WIMP model: 50 MeV/c2, 9.0 × 10−29 cm2 Excluded WIMP model: 100 MeV/c2, 7.0 × 10−30 cm2 Excluded WIMP model: 1.0 GeV/c2, 1.6 × 10−32 cm2

0.03 0.1 1 2 Energy [keV] 102 103 104 105 Number of counts [evts/keV] Standard Spectra

Background Model Analysis Threshold (60 eV) Data Excluded WIMP model: 0.7 GeV/c2, 9.8 × 10−35 cm2 Excluded WIMP model: 2.0 GeV/c2, 4.5 × 10−37 cm2 Excluded WIMP model: 10.0 GeV/c2, 1.1 × 10−37 cm2

2 GeV/c2 Unsmeared 2 GeV/c2 After pulse simulation

60 eV analysis threshold

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...filling the gap between ground & space searches

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Shaded regions: with full Earth-Shielding (ES) calculation

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Lines: underground limits (w/o ES calculation, ~ok for <10-31 cm2)

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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WIMP Mass [GeV/c

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WIMP-nucleon cross section [cm

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EDELWEISS-Surf (Standard) EDELWEISS-Surf (Migdal) EDELWEISS-III LT CRESST Surface CRESST-II SuperCDMS LT CDMSLite LUX (Standard) LUX (Migdal) XENON1T (Standard) XENON100 LT NEWS-G DarkSide (Standard) XQC CMB Neutrino discovery limit + CRESST-III

Sharp 45 MeV/c2 cutoff due to ES effect on velocity Stronger upper cutoff for Migdal (subleading component)

EDELWEISS-surf Migdal EDELWEISS-surf CRESST – n-cleus XQC rocket CMB

CDEX Migdal Underground

[PRD 99 082013 (2019)] * Also: spin-dependent limits

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NEXT STEPS TOWARDS THE EDELWEISS-SUBGEV GOALS

1 kg Ge array with:

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10 eV phonon resolution

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20 eVee ionization resolution

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Possibility of applying large Luke-Neganov amplification

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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Goal 1: 10 eV phonon resolution

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Results with 33g + Ge-NTD detectors confirm that these sensors are a reliable choice to reproducibly reach s=20 eV

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Replacing JFETs @ 100K with HEMTs @ 1K should provide additional x2 needed in resolution

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Also being investigated: NbSi transition edge sensors

Sept. 10th, 2019

EDELWEISS @ TAUP2019

100 nm thick,

20mm diameter spiral NbSi sensor lithographied

n a 200 g Ge

NbSi sensor transition @ 45 mK

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Goal 2: 20 eVee ionization resolution

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Transition from JFET to HEMT

[ new arXiv:1909.02879 ]

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Lower intrinsic noise + reduce cabling capacitance by working at 1K or 4K

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Data driven HEMT models show that the goal of 20 eVee is reachable with ~20 pF total input impedance

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Ongoing HEMT characterizations

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HEMT-based preamp tests end of 2019

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Cryogenics + cabling challenges ahead

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Work done in synergy with the Ricochet-CryoCube collaboration

Sept. 10th, 2019

EDELWEISS @ TAUP2019

1.09712)

Optimization of 33g FID design: large fiducial volume & low capacitance

FET to HEMT Goal

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Goal 3: High voltage operation

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Luke-Neganov boost to amplify signal (and not electronic noise)

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Already tested on existing FID800 detectors

Sept. 10th, 2019

EDELWEISS @ TAUP2019

EDELWEISS

Preliminary

133Ba

356 keV line

FWHM (keVee) Luke boost = 1 + V/3 1 0.1 2.5 keV NR 0.6 keV NR Same detector Same source Different biases (8V or 90 V)

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Goal 3: High voltage operation

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Current run @ LSM : obtaining near single-electron sensitivity on 33 and 200 g detectors: exploration of DM interactions with electrons & nuclei

Sept. 10th, 2019

EDELWEISS @ TAUP2019

DM search zone 160 eV 1.3 keV 10.4 keV

66 Volt s = 5 eVee

NbSi209 Preliminary

160 eV 1.3 keV 10.4 keV DM search zone

RED30

70 Volt s = 1.8 eVee

Preliminary

First EDELWEISS DM-electron scattering and absorption results expected by fall 2019.

High-impedance NbSi TES Ge-NTD

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Goal 3: High voltage operation

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Current run @ LSM : obtaining near single-electron sensitivity on 33 and 200 g detectors: Calibration of nuclear recoils down to low thresholds

Sept. 10th, 2019

EDELWEISS @ TAUP2019

15V 66V 66V 66V

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Conclusions

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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

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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)

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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

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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

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BACKUP

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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EDELWEISS-III

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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Search extended to spin-dependent cases

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14N has both p and n spin à shielding from atmosphere

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Large cross-section → dramatic ES effects (especially on Migdal limits)

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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SD WIMP-Proton Cross Section (cm

EDELWEISS-Surf RRS-Balloon CMB CDMSLite LUX PandaX-II XENON1T PICO-60-II 1

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WIMP Mass (GeV/c

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SD WIMP-Neutron Cross Section (cm

EDELWEISS-Surf EDELWEISS-Surf Migdal RRS-Balloon XQC CDMSLite LUX PandaX-II XENON1T

Ge Ge Ge+Migdal CaWO4 Li2MoO4 Li2MoO4 Ge Ge Si Si Si H

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Current EDELWEISS run at LSM

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Continuous running at <21 mK since January 2019

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Eleven Ge detectors

Rest of cryostat used for joint

physics run with CUPID-Mo

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Compare detector physics in 32g, 200g and 800g detectors

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Compare performance of NTD and NbSi-TES heat sensors

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Study of low-energy backgrounds in Ge detectors

perated with large Luke-

Neganov amplification

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Limits on Dark Matter using ER and NR spectra of detectors with large Luke- Neganov amplification

Sept. 10th, 2019

EDELWEISS @ TAUP2019

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Current measurements

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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 the detectors, or in the bulk (via trapped space charges)

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EDELWEISS purely capacitive ionization readout (gate & detector reset via mechanical relays at fixed time intervals): continuous measure of charge on all electrodes: I = DQ/Dt slope.

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So far measurement of currents <0.1 fA achieved on 800g detector, up to 90V bias (~1000 electrons/second/kgGe)

Sept. 10th, 2019

EDELWEISS @ TAUP2019

Drain Electrode Feedback Polarization Source 5 pF 2 nF [JINST12 P08010 (2017)]