New ideas in Conventional Detectors T. Shutt SLAC TAUP 2019, - PowerPoint PPT Presentation

New ideas in Conventional Detectors T. Shutt SLAC TAUP 2019, Toyama Sept 11, 2019

Big New Idea: Stop Looking Down PDG 2018 No annual modulation signal in other experiments 2 T . Shutt - TAUP 2019, Sept 11, 2019

Big New Idea: Stop Looking Down PDG 2018 No annual modulation signal in other experiments 3 T . Shutt - TAUP 2019, Sept 11, 2019

Big New Idea: Stop Looking Down PDG 2018 Symmetric DM? SIMPS? No annual modulation signal in other experiments 4 T . Shutt - TAUP 2019, Sept 11, 2019

New Ideas: How to do it. • Detector mass 1 kg 100 pp solar 10 4 10 tons b n s d , m t a No annual modulation signal in other • Measured energy m χ = 500 MeV × [ 2 16 GeV ] E nr M N 0.19 keV × 5 T . Shutt - TAUP 2019, Sept 11, 2019

Conventional, in this talk • Dark matter acts like a particle - Acts like a wave: G. Rybka, next session • Detectors - Liquid noble TPCs - Cryogenic - Not covered in next talk 6 T . Shutt - TAUP 2019, Sept 11, 2019

Low energy “Nuclear” Recoils • Lindhard - “adiabatic” overlap of electron shells • Most energy goes to heat • Bigger effect at low energy (PDB, 2016) Mass stopping power [MeV cm 2 /g] µ + on Cu µ − 100 Bethe Anderson- Ziegler Lindhard- Radiative Scharff effects 10 reach 1% Minimum ionization Nuclear losses 1 0.001 0.01 0.1 1 10 100 1000 βγ Electron velocity in target atoms 7 T . Shutt - TAUP 2019, Sept 11, 2019

e e e e e e New Idea: different channel - Migdal: nuclear kick relative to electron shell generates ionization. (Ibe, et al., arXiv:1707.07258) χ X-ray ~ ~ Bremsstrahlung ~ ~ ~ • Small probability, depends on shells ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Ionization electron ~ ~ • Boosted energy in ER channel χ • Also “Bremsstrahlung” (Kouvaris, Pradler, arXiv: + + 1607.01789) Auger electron arXiv:1907.12771 (LUX, arXiv:1811.11241) NR Migdal Brehm 1.2 keVer threshold 8 T . Shutt - TAUP 2019, Sept 11, 2019

e e e e e e New Idea: different channel - Migdal: nuclear kick relative to electron shell generates ionization. (Ibe, et al., arXiv:1707.07258) χ X-ray ~ ~ Bremsstrahlung ~ ~ ~ • Small probability, depends on shells ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Ionization electron ~ ~ • Boosted energy in ER channel χ • Also “Bremsstrahlung” (Kouvaris, Pradler, + + arXiv:1607.01789) Auger electron arXiv:1907.12771 (LUX, arXiv:1811.11241) Big penalty in rate 9 T . Shutt - TAUP 2019, Sept 11, 2019

Newish Idea: S2 only in LXe/Ar TPCs • # electrons, photons comparable • Light collection ~10%, e - collection ~100% • Substantially reduce E threshold • Time Projection Chamber (XENON1T - 1907.11485) 100 12 NEST Charge Yield NEST Light Yield 10 LUX DD Charge Yield Yield (quanta/keV) LUX DD Light Yield LLNL Charge Yield 8 6 4 2 (LUX - 1907.06272) 0 5 0 1 2 3 4 5 Nuclear recoil energy (keV) 10 T . Shutt - TAUP 2019, Sept 11, 2019

S2 only electron background (Sorensen, Kamdin, arXiv:1711.07025) “e-train” in LUX LBECA prototype - sealed • Several sources of electrons chamber with high chemical purity • LBECA: dedicated S2 only experiment K. Ni, DM14 - Electron reduction methods under study - 100 kg LXe detector planned LZ grid under test • LZ: major program to reduce emission from grids (Stifter, DM16) - electron signal ~4 times larger than LUX 11 T . Shutt - TAUP 2019, Sept 11, 2019

Very new idea: doping • Dissolve H2 in LXe TPC • Proton is best low mass target H - 3 e - E nr ~100 eV: m x ~ 100 MeV • Lindhard nullified by m H, m Xe Xe imbalance look like? • H2 and D2: odd n and p - or He, if ok with PMTs • HydroX - new experiment, currently LZ-based 12 T . Shutt - TAUP 2019, Sept 11, 2019

HydroX • LZ fiducial becomes shield To/From 222 Rn removal To/From Main Circula0on Loop Outer Cryostat Vessel Xenon Tower • Modify purification to cope Dis0lla0on Column with H2 x6 • Need to check - H2 solubility - charge yield Preliminary Projections - effect of H2 on S2 13 T . Shutt - TAUP 2019, Sept 11, 2019

Calibrating Nuclear Recoils • Lindhard - successful at high energies B. Lenardo, April APIS, 2019 - Recent lower yields in Si, Xe. Generic? Xe response • Must calibrate down to (or below) DM measurement energy • Prediction: increasingly active area - Beams with variety of reactions - Photo-nuclear sources + gamma shield - Notch filters 124 Sb- 9 Be • Move beam or detector? - Cryo detectors + dilution refrigerator? Sc Fe ~2 keV 24 keV - In-situ calibration ideal • Need ~ 1 keV neutrons to calibrate H! Photo-nuclear source + filters (HydroX, unpublished) 14 T . Shutt - TAUP 2019, Sept 11, 2019

Superfluid 4 He • Low mass target HERALD, Hertel et al., arXiv: 1810.06283 • Complex set of excitations He Atom - Excimers, singlet ~ns, triplet 13 s Vacuum Interface (lost) n o t o h P Recoil - IR light Triplet Excimer - Phonons / Rotons Quasiparticle - Should provide discrimination • Early work on HERON, Nuclear Recoil Electron Recoil 1 proposed solar exp. Rotons/phonons ν Singlet photons 0.8 Energy Fraction - Significant advances in Triplet photons 0.6 IR photons sensors and cryogenic 0.4 technology since then 0.2 0 15 T . Shutt - TAUP 2019, Sept 11, 2019 1

Superfluid 4 He • EFT response modeling. (Esposito, DM14) Field ionization • Field ionization to measure He atom. tip (Osterman, DM14) • Collective modes in He and superconductors push to lower E, m x 10 -24 - Hochberg, Zhao, Zurek arxiV:1504.07237 10 -26 - Schutz, Zurek, arXiiv:1604.08206 10 -28 • “Wild West” of approaches to E~m eV, m x ~ keV 10 -30 100 m Dark Matter-nucleon σ SI [cm 2 ] 10 -32 1478 m - Superconductors+TES (Hochberg, Zhao, Zurek arxiV: 10 -34 1504.07237) 10 -36 - Magnetic bubble chambers (Bunting et al., arXiv: 10 -38 1701.06566) 10 -40 - Optical phonons (Knapen et al., arXiv:1712.06598) 10 -42 - Diamond (Kurinsky, et al., PRD 2019) 10 -44 - Absorption in superconductor (Hochberg et al., arXiv: 10 -46 1604.06800) 10 -48 - 3D dirac materials (Hochberg et al., arXiv:1708.08929) HERALD 10 -50 - …. 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 Dark Matter mass [MeV/c 2 ] 16 T . Shutt - TAUP 2019, Sept 11, 2019

Backgrounds • Backgrounds below ~keV are Hochberg et al., arXiv:1512.04533 1 / terra incognita kg/ keV/ • Little self shielding at ~kg mass day - Rates better than 1/kg/keV/day only with enormous effort • Robinson: coherent Compton scattering rises at low energy • Non particle 'backgrounds” - PICO particles - T. Noble talk, Robinson, arVix:1610.07656 DM10 - Differential cross section d σ /dE r (b/eV) 0.1 GeV/c 2 Dark Matter on Si - CRESST crackophonics ~ca. 2000 10 0 - Ge Coherent Si Coherent 10 -2 He Coherent - These may well proliferate at low Ge Compton - 10 -4 Si Compton - May be subject energy 10 -6 to structure effects or 10 -8 • DM backgrounds session - DM4 at - 10 -10 en- 10 -3 10 -2 10 -1 10 0 10 1 10 2 10 3 Recoil Energy E r (eV) - 17 T . Shutt - TAUP 2019, Sept 11, 2019 a-

Predictions are hard, especially about the future Niels Bohr Yogi Berra 18 T . Shutt - TAUP 2019, Sept 11, 2019

PDG 2018 ~1988 Tomorrow Today No annual modulation signal in other experiments 19 T . Shutt - TAUP 2019, Sept 11, 2019

Summary • As we approach neutrino floor for WIMPs, new frontier has opened at low mass • Building on existing technologies, wide variety of new ideas • Exciting time for hunting dark matter 20 T . Shutt - TAUP 2019, Sept 11, 2019