SuperCDMS Searches for Low-Mass Particle Dark Matter - Noah Kurinsky Lederman Fellow, Fermi National Accelerator Laboratory ICHEP Virtual ...
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SuperCDMS Searches for Low-Mass Particle Dark Matter Noah Kurinsky Lederman Fellow, Fermi National Accelerator Laboratory ICHEP Virtual Conference July 29, 2020
Overview • Low Mass Dark Matter Technical Challenges • Recent SuperCDMS Results - ERDM w/ HVeV (arXiv:2005.14067 submitted to PRD) - NRDM w/ PD2 (arXiv:2007.14289, submitted to PRL) - ALP/Dark Photon Constraints from SuperCDMS Soudan (arXiv:1911.11905, Phys. Rev. D 101, 052008) • Upcoming Results - HVeV @ 0V - HVeV @ NEXUS (FNAL) - PD2 @ CUTE (SNOLAB) - IMPACT @ TUNL (Nuclear recoil yield calibration) • APS Talk Video • Future Plans - Pre-SNOLAB Science - First Science from SuperCDMS SNOLAB 2 7/29/2020 Noah Kurinsky
Collision Kinematics • Recoil energy for a typical dark matter particle velocity depends on target mass and recoil type • Electron and nuclear recoils have different kinematics; nuclear recoils are Low Mass High Mass simple elastic collisions, electron recoils are largely inelastic and depend on electron orbital and kinematics within the bound electron-atom system • In addition to momentum transfer for a fixed velocity, using a velocity and angular distribution yields an expected energy spectrum p 2mT E ✓ ◆2 m ,N R 1 2 mN v 2 2m v EN R qmax = 2 E 2mN 2 m + mN ✓ ◆ m ,ER EER 1 2 µN v = mN v 2 m v2 2 2 m + mN 5 7/29/2020 Noah Kurinsky
SuperCDMS Athermal Phonon Sensors • Crystal targets made of Si/Ge • In any recoil event, all energy eventually returns to the phonon system • Prompt phonons produced by interaction with nuclei • Indirect-gap phonons produced by charge carriers reaching band minima • Recombination phonons produced when charge carriers drop back below the band-gap • Phonons are also produced when charges are drifted in an electric field; makes sense by energy conservation alone • Total phonon energy is initial recoil energy plus Luke (NTL) phonon energy, as shown at right Ephonon = Erecoil + V ⇤ neh ✓ ◆ y(Erecoil ) = Erecoil 1 + V ⇤ "eh • Athermal phonons collected in superconducting aluminum fins and channeled into Tungsten TES, effectively decoupling crystal heat capacity from calorimeter (transition edge sensor) heat capacity Romani et. al. 2017 (https://arxiv.org/abs/1710.09335 ) 6 7/29/2020 Noah Kurinsky
Science Leading to SuperCDMS SNOLAB Electron Recoil (Charge Readout) Nuclear Recoil (Heat Readout) Lower Backgrounds, Larger Exposure Surface R&D (Lower Threshold, Improve Reconstruction) (Stanford, Northwestern, Berkeley, Texas A&M) NEXUS @ FNAL CUTE @ SNOLAB SuperCDMS SNOBOX @ SNOLAB 7 7/29/2020 Noah Kurinsky
Science Leading to SuperCDMS SNOLAB First Results Published Electron Recoil (Charge Readout) Nuclear Recoil (Heat Readout) Lower Backgrounds, Larger Exposure Surface R&D (Lower Threshold, Improve Reconstruction) (Stanford, Northwestern, Berkeley, Texas A&M) Currently Running NEXUS @ FNAL CUTE @ SNOLAB Installation In Progress SuperCDMS SNOBOX @ SNOLAB 8 7/29/2020 Noah Kurinsky
Science Leading to SuperCDMS SNOLAB Electron Recoil (Charge Readout) Nuclear Recoil (Heat Readout) Lower Backgrounds, Larger Exposure Surface R&D (Lower Threshold, Improve Reconstruction) (Stanford, Northwestern, Berkeley, Texas A&M) NEXUS @ FNAL CUTE @ SNOLAB SuperCDMS SNOBOX @ SNOLAB 9 7/29/2020 Noah Kurinsky
Science Leading to SuperCDMS SNOLAB Electron Recoil (Charge Readout) Nuclear Recoil (Heat Readout) Lower Backgrounds, Larger Exposure Surface R&D (Lower Threshold, Improve Reconstruction) (Stanford, Northwestern, Berkeley, Texas A&M) NEXUS @ FNAL CUTE @ SNOLAB SuperCDMS SNOBOX @ SNOLAB 10 7/29/2020 Noah Kurinsky
Electron-Recoil Searches • SuperCDMS HVeV - gram-scale, single-charge resolving detectors - Run 1 - 2018 - Run 2 - 2020 - Run 3 - 2021 (underground, lower backgrounds) • Long-term: HV detectors @ SNOLAB • Challenges - Charge leakage - Understanding quantized backgrounds - Maximizing charge collection efficiency - Removing surface backgrounds 11 7/29/2020 Noah Kurinsky
Experimental Setup (Run 1 @ Stanford) 12 7/29/2020 Noah Kurinsky
HVeV v1 0.5 Gram-Day Science Spectrum • Ran the detector for ~12 hours with SuperCDMS Collaboration 2018 (https://arxiv.org/abs/1804.00088 ) a 1 Hz laser calibration (black line) • Background consistent with infrared photon background at low energy, high-energy tail was not anticipated • Device had 10-14 eV resolution, and the ability to distinguish between ‘true’ events and impurity- mediated events (unlike CCDs which only measure electrons or holes) • Very simple analysis; it’s easy to see how one rules out a quantized signal in light of this background 13 7/29/2020 Noah Kurinsky
Experimental Setup (Run 2 @ Northwestern) V. Novati, APS April 2020 14 7/29/2020 Noah Kurinsky
SuperCDMS Collaboration 2020 (arXiv:2005.14067) HVeV Run 2 Supplemental Plots • HVeV second run taken with 3 eV resolution detector over the course of 3 weeks: - 60V and 100V spectra show identical backgrounds; signal seen not voltage dependent - Different prototype, run in a different lab, in a different state - 0V data acquired with ~12 eV threshold, results still being analyzed - Rates in every charge bin consistent with Run 1…that is completely unexpected 15 7/29/2020 Noah Kurinsky
SuperCDMS Collaboration 2020 (arXiv:2005.14067) HVeV Run 2 Results Supplemental Plots V. Novati, APS April 2020 16 7/29/2020 Noah Kurinsky
Low-Mass Nuclear Recoil Searches • Phonon readout - SuperCDMS CPD (10g, operated at SLAC) - 2020 - HVeV @ 0V (1g, operated at NU) - 2020 (in prep) - SNOLAB detectors and CPD at CUTE • Challenges - Unexplained low-energy excesses persist - Detectors w/ thresholds below 10 eV highly sensitive to environmental noise - Science reach driven by threshold and trigger accuracy - Few calibration points below 1 keV 17 7/29/2020 Noah Kurinsky
Design of a Large Area Photon Detector Design of a Large Area Photon Detector • The detector is a CDMS-style athermal phonon sensor • The detector is a CDMS-style athermal phonon - 1 mm thick silicon wafer, 45.6 cm^2 surface area sensor - Mass ofmm – 1 10.6 grams thick silicon wafer, 45.6 cm# surface area – Mass of 10.6 grams • The • The device device hashasbeen been optimized optimized for forphoton photondetection – Distributed athermal sensor array read out by TESs detection – Single distributed channel gives a fast collection time - Distributed athermal sensor array read out by TESs of athermal phonons - Single distributed – This channel penalties reduces efficiency gives a fast collection due to athermal time of athermal phononphonons down conversion $% = 41.5 mK, - This–reduces lowering efficiency the expected penalties dueenergy resolution to athermal • Designed phonon downoriginally conversionfor degraded alpha rejection in neutrinoless - T_c=41.5 double beta mK, lowering decay andenergy the expected for an active photon veto for dark matter experiments resolution • Designed originally for degraded alpha rejection in neutrinoless double beta decay and for an 22 July 2019 LTD-18, Milano 4 active photon veto for dark matter experiments https://agenda.infn.it/event/15448/contributions/95785/ 18 7/29/2020 Noah Kurinsky
arXiv:2004.10257 Reducing Readout Noise • Readout noise limited by thermal fluctuation shot noise between sensor and crystal - Can reduce this only by weakening the link between the sensor and absorber, or dropping the sensor temperature - Power noise at the level of 1e-17 aW/sqrt(Hz) - Hitting readout limitations • Power to current gain impacted by total heat capacity of the sensor - Make smaller sensors • Massive on-sensor multiplexing - Readout smaller sections of the detector - Use MKIDs or other naturally multiplexed sensors rather than DC TES arXiv:2007.14289 19 7/29/2020 Noah Kurinsky
CPD Dark Matter Search Results arXiv:2007.14289 • Detector threshold (online FPGA-based trigger) of 20 eV • World-leading limits below ~150 MeV - First NR result with
Future Prospects • Following up HVeV and CPD at underground facilities • Preparing for SuperCDMS SNOLAB 21 7/29/2020 Noah Kurinsky
Pre-SNOLAB Science • HVeV @ NEXUS - Larger exposures - Understanding leakage currents and low- energy backgrounds - NR/ER calibrations NEXUS Sensitivity Study - New readout techniques (e.g. mKIDs) Cryogenic Underground TEst Facility (CUTE) @ SNOLAB • NR Searches @ CUTE - 10g R&D Detectors with
Plans ER/NR for Follow-up • 1 gram-day of 0V data taken - Determine whether background is NR, ER, or detector-related - Continuous readout will allow NR limit with 9eV energy threshold - Coming late 2020 • More data taking at NEXUS - Currently operating underground, constructing lead shield - 3 eV resolution maintained in new facility • Plans for larger payload, additional studies w/ high-energy gamma sources, different detector Preliminary packaging 23 7/29/2020 Noah Kurinsky
NEXUS: Underground Experimental Site for R&D • Northwestern EXperimental Underground Site at Fermilab (NEXUS@FNAL) - Underground cryogenic detector testing facility in class 10,000 clean room - 106 m (300 mwe) depth + lead shielding (in progress) - expected
NEXUS: Underground Experimental Site for R&D • Northwestern EXperimental Underground Site at Fermilab (NEXUS@FNAL) - Underground cryogenic detector testing facility in class 10,000 clean room - 106 m (300 mwe) depth + lead shielding (in progress) - expected
From APS April Meeting SuperCDMS SNOLAB Detectors 26 7/29/2020 Noah Kurinsky
From APS April Meeting SuperCDMS SNOLAB Layout 27 7/29/2020 Noah Kurinsky
SuperCDMS SNOLAB Science Targets 28 7/29/2020 Noah Kurinsky
SuperCDMS SNOLAB Science Targets 29 7/29/2020 Noah Kurinsky
SuperCDMS SNOLAB Science Targets 0V arrays of small to medium-sized detectors High Voltage NTL-based Phonon + Ionization 30 7/29/2020 Noah Kurinsky
Summary • SuperCDMS Detectors are seeing significant backgrounds at low energy - Comparison between HV and 0V will elucidate source - Runs at NEXUS/CUTE underway will gauge depth/background dependence - See Yoni Kahn’s talk for a phenomenological take on this question - See Lauren Hsu’s talk next week for a broader overview of light DM detection • Upcoming results with ~9 eV threshold will probe new DM masses below 100 MeV, and provide a direct comparison with Run 2 results • SuperCDMS SNOLAB detectors will substantially improve exposure and benefit from these early background studies • Many calibration programs underway to understand nuclear recoils in the
Thanks! 32 7/29/2020 Noah Kurinsky
Questions? • Zoom info: - Topic: Noah Kurinsky ICHEP Questions - Time: Jul 29, 2020 01:00 PM Central Time (US and Canada) - Link - Meeting ID: 991 4345 0731 - Passcode: 688639 33 7/29/2020 Noah Kurinsky
Backup 34 7/29/2020 Noah Kurinsky
HVeV v1.5: Edge-Dominated Leakage ArXiv:1903.06517 • Prototype demonstrated position dependence in the non-quantized data hinted at during HVeV Run 1 • Nearly contact-free biasing scheme isolates contact along the crystal edge, preventing charge tunneling through most of the high-voltage face • Surface events have a distinct pulse shape and can be removed using a cut in the pulse-shape plane. • Non-quantized leakage is dominant at high radius; 95% of non-quantized events removed by 50% radial cut efficiency. 80% of quantized events removed by the same cut 35 7/29/2020 Noah Kurinsky
HVeV v1.5: Edge-Dominated Leakage ArXiv:1903.06517 • Prototype demonstrated position dependence in the non-quantized data hinted at during HVeV Run 1 ArXiv:1903.06517 • Nearly contact-free biasing scheme isolates contact along the crystal edge, preventing charge tunneling through most of the high-voltage face • Surface events have a distinct pulse shape and can be removed using a cut in the pulse-shape plane. • Non-quantized leakage is dominant at high radius; 95% of non-quantized events removed by 50% radial cut efficiency. 80% of quantized events removed by the same cut 36 7/29/2020 Noah Kurinsky
HVeV v2: Combining Lessons https://agenda.infn.it/event/15448/contributions/95710/ • Maintain 3 eV resolution, scale back to 1g Device paper in prep - High coverage for higher dynamic range • Still seeing some issues with sidewall trapping and incomplete neutralization - We observe ~15% trapping • Physics results from Nuclear Recoil calibration at TUNL coming soon! 37 7/29/2020 Noah Kurinsky
R&D ‘HVeV’ Prototype Progress HVeV v2 (NF-C) HVeV v1 HVeV v1.5 Device: In Prep ERDM: Device: https://arxiv.org/abs/1710.09335 Device: https://arxiv.org/abs/1903.06517 NRDM: In Prep DM: https://arxiv.org/abs/1804.10697 • 3 eV Resolution • 3 eV Resolution • 10 eV Resolution • 0.06 electron-hole pairs • 30% energy efficiency • 1 gram mass • 0.25 gram mass, contact-free • 1 gram mass, backside design contact • No position resolution • High position resolution • High position resolution • ~1.2 Ohm Resistance • ~400-900 mOhm Resistance • ~300 mOhm Resistance • ~55 mK Tc • 65 mK Tc • 65 mK Tc • Amorphous Layer • No Amorphous Layer • No Amorphous Layer 38 7/29/2020 Noah Kurinsky
Scaling Up in Mass 39 7/29/2020 Noah Kurinsky
Scaling Up in Mass Faster Signal Lower Sensor Noise 40 7/29/2020 Noah Kurinsky
Scaling Up in Mass Faster Signal Large-Scale Multiplexing Lower Sensor Noise Sets Operating Voltage for NTL Single-Charge Readout 41 7/29/2020 Noah Kurinsky
Detector R&D Groups • HVeV (1g Detector Chips) - Caltech: Sunil Golwala, Yen-Yung Chang, Taylor Aralis, Osmond Wen - Fermilab: Noah Kurinsky, Dan Bauer - Northwestern: Enectali Figueroa-Feliciano, Ziqing Hong, Tom Ren, Ran Chen - Stanford/SLAC: Blas Cabrera, Betty Young, Francisco Ponce, Chris Stanford, To Chin Yu - University of Minnesota: Matt Fritts, Nick Mast - University of Florida: Tarek Saab, Corey Bathurst, Tyler Reynolds • Large Area Photon Detectors - UC Berkeley: J. Camilleri, C. Fink, Y. Kolomensky, M. Pyle, B. Sadoulet, B. Serfass, S. Watkins - Texas A&M: Nader Mirabolfathi, Rupak Mahapatra, Fedja Kadribasic • QET Fabrication R&D - Mark Platt (TAMU), Paul Brink (SLAC) 42 7/29/2020 Noah Kurinsky
HVeV v2 1cm Designs • Best for NR - UCB A/C - low coverage, single channel NF-H - 600 mOhm normal state resistance • Best for ERDM UCB-C - Optimized for baseline resolution with varying levels of Al coverage - 900 mOhm Rn - NF F, G, H - 300 mOhm Rn - NF A, D, E NF-C • NF-A is roughly the same as QP.4, i.e. AR64 • Best for Calibrations - Sacrifice baseline resolution for higher dynamic range - 300 mOhm normal state - NF-B/C https://confluence.slac.stanford.edu/display/CDMS/HVeV+v2+Design 43 7/29/2020 Noah Kurinsky
NEXUS Si/Ge Dark Matter Search Timeline • Spring-Fall 2019 (ADR Demonstrator): 1 gram - 1 gram, 4 eV resolution (20 eV threshold) - 0.01 electron-hole pair resolution (
Future for HVeV Program • Mounting issues damaged some prototypes (X’s) • 2 1g v2 detectors, optimized X for dynamic range, now successfully operated X X • 2 4g detectors currently being mounted (both optimized for low energy resolution) • Many more prototypes to help test the resolution and efficiency models that go into this detector design X X - Multiple designs with sub-eV projected resolutions 45 7/29/2020 Noah Kurinsky
Broad Picture: Detection Media for Lower Mass US Cosmic Visions, arXiv:1707.04591 • Looking at current/future technologies, we have a mix of materials with different work functions, to limit dark counts and maximize energy to carrier conversion • Extent of these arrows driven by fundamental limitations from kinematics and material properties, and assumes large current hurdles can be overcome in energy and charge noise across all experiments • June 2019 workshop at FNAL explored much more than cosmic visions: https://astro.fnal.gov/ldm/ 46 7/29/2020 Noah Kurinsky
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