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

T . Shutt - TAUP 2019, Sept 11, 2019

Big New Idea: Stop Looking Down

2

No annual modulation signal in other experiments

PDG 2018

T . Shutt - TAUP 2019, Sept 11, 2019

3

No annual modulation signal in other experiments

PDG 2018

Big New Idea: Stop Looking Down

T . Shutt - TAUP 2019, Sept 11, 2019

No annual modulation signal in other experiments

PDG 2018

4

Big New Idea: Stop Looking Down

Symmetric DM? SIMPS?

T . Shutt - TAUP 2019, Sept 11, 2019

• Detector mass
• Measured energy

New Ideas: How to do it.

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mχ = 500 MeV × [ Enr 0.19 keV × MN 16 GeV ]

2

No annual modulation signal in other

10 tons 104 100 1 kg

pp solar a t m , d s n b

T . Shutt - TAUP 2019, Sept 11, 2019

Conventional, in this talk

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• Dark matter acts like a particle
• Acts like a wave: G. Rybka, next session
• Detectors
• Liquid noble TPCs
• Cryogenic
• Not covered in next talk

T . Shutt - TAUP 2019, Sept 11, 2019

Low energy “Nuclear” Recoils

7

• Lindhard - “adiabatic” overlap of electron shells
• Most energy goes to heat
• Bigger effect at low energy

(PDB, 2016)

1 10 100

Mass stopping power [MeV cm2/g]

Lindhard- Scharff

Bethe Radiative effects reach 1%

βγ

0.001 0.01 0.1 1 10 100 1000 Minimum ionization Nuclear losses

µ− µ+ on Cu

Anderson- Ziegler

Electron velocity in target atoms

T . Shutt - TAUP 2019, Sept 11, 2019 χ χ

Bremsstrahlung Auger electron X-ray Ionization electron e e e e

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

e

~ ~ ~ ~ ~ ~ ~

e

arXiv:1907.12771

New Idea: different channel

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• Migdal: nuclear kick relative to electron shell generates
• ionization. (Ibe, et al., arXiv:1707.07258)
• Small probability, depends on shells
• Boosted energy in ER channel
• Also “Bremsstrahlung” (Kouvaris, Pradler, arXiv:

1607.01789)

Migdal Brehm NR 1.2 keVer threshold

(LUX, arXiv:1811.11241)

T . Shutt - TAUP 2019, Sept 11, 2019

New Idea: different channel

9

• Migdal: nuclear kick relative to electron shell generates
• ionization. (Ibe, et al., arXiv:1707.07258)
• Small probability, depends on shells
• Boosted energy in ER channel
• Also “Bremsstrahlung” (Kouvaris, Pradler,

arXiv:1607.01789)

χ χ

Bremsstrahlung Auger electron X-ray Ionization electron e e e e

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

e

~ ~ ~ ~ ~ ~ ~

e

arXiv:1907.12771

(LUX, arXiv:1811.11241)

Big penalty in rate

T . Shutt - TAUP 2019, Sept 11, 2019

Newish Idea: S2 only in LXe/Ar TPCs

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• # electrons, photons comparable
• Light collection ~10%,

e- collection ~100%

• Substantially reduce E threshold
• Time Projection Chamber

(XENON1T - 1907.11485)

1 2 3 4 5 Nuclear recoil energy (keV) 2 4 6 8 10 12

NEST Charge Yield NEST Light Yield LUX DD Charge Yield LUX DD Light Yield LLNL Charge Yield

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(LUX - 1907.06272)

100 Yield (quanta/keV)

T . Shutt - TAUP 2019, Sept 11, 2019

S2 only electron background

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• Several sources of electrons
• LBECA: dedicated S2 only experiment
• Electron reduction methods under study
• 100 kg LXe detector planned
• LZ: major program to reduce emission from

grids (Stifter, DM16)

• electron signal ~4 times larger than LUX

(Sorensen, Kamdin, arXiv:1711.07025)

“e-train” in LUX

LBECA prototype - sealed chamber with high chemical purity

• K. Ni, DM14

LZ grid under test

T . Shutt - TAUP 2019, Sept 11, 2019

Very new idea: doping

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• Dissolve H2 in LXe TPC
• Proton is best low mass target
• 3 e- Enr~100 eV: mx~100 MeV
• Lindhard nullified by mH, mXe

imbalance

• H2 and D2: odd n and p
• or He, if ok with PMTs
• HydroX - new experiment,

currently LZ-based

look like?

H Xe

T . Shutt - TAUP 2019, Sept 11, 2019

HydroX

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• LZ fiducial becomes shield
• Modify purification to cope

with H2

• Need to check
• H2 solubility
• charge yield
• effect of H2
• n S2

Preliminary Projections

To/From Main Circula0on Loop To/From 222Rn removal

x6

Xenon Tower Outer Cryostat Vessel Dis0lla0on Column

T . Shutt - TAUP 2019, Sept 11, 2019

Calibrating Nuclear Recoils

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• Lindhard - successful at high energies
• Recent lower yields in Si, Xe. Generic?
• 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
• Move beam or detector?
• Cryo detectors + dilution refrigerator?
• In-situ calibration ideal
• Need ~ 1 keV neutrons to calibrate H!
• B. Lenardo, April APIS, 2019

Xe response

124Sb-9Be

Sc ~2 keV Fe 24 keV

Photo-nuclear source + filters (HydroX, unpublished)

T . Shutt - TAUP 2019, Sept 11, 2019

Superfluid 4He

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• Low mass target
• Complex set of excitations
• Excimers, singlet ~ns, triplet 13 s

(lost)

• IR light
• Phonons / Rotons
• Should provide discrimination
• Early work on HERON,

proposed solar exp.

• Significant advances in

sensors and cryogenic technology since then

ν

He Atom Vacuum Interface Quasiparticle P h

• t
• n

Recoil Triplet Excimer

0.2 0.4 0.6 0.8 1

Energy Fraction Nuclear Recoil Electron Recoil

1

Rotons/phonons Singlet photons Triplet photons IR photons

HERALD, Hertel et al., arXiv: 1810.06283

T . Shutt - TAUP 2019, Sept 11, 2019

Superfluid 4He

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• EFT response modeling. (Esposito, DM14)
• Field ionization to measure He atom.

(Osterman, DM14)

• Collective modes in He and

superconductors push to lower E, mx

• Hochberg, Zhao, Zurek arxiV:1504.07237
• Schutz, Zurek, arXiiv:1604.08206
• “Wild West” of approaches to E~meV, mx~keV
• Superconductors+TES (Hochberg, Zhao, Zurek arxiV:

1504.07237)

• Magnetic bubble chambers (Bunting et al., arXiv:

1701.06566)

• Optical phonons (Knapen et al., arXiv:1712.06598)
• Diamond (Kurinsky, et al., PRD 2019)
• Absorption in superconductor (Hochberg et al., arXiv:

1604.06800)

• 3D dirac materials (Hochberg et al., arXiv:1708.08929)
• ….

Field ionization tip

10-1 100 101 102 103 104 105 106 10-50 10-48 10-46 10-44 10-42 10-40 10-38 10-36 10-34 10-32 10-30 10-28 10-26 10-24

Dark Matter-nucleon σSI [cm2] Dark Matter mass [MeV/c2]

100 m 1478 m

HERALD

T . Shutt - TAUP 2019, Sept 11, 2019

Backgrounds

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• Backgrounds below ~keV are

terra incognita

• Little self shielding at ~kg mass
• Rates better than 1/kg/keV/day
• nly with enormous effort
• Robinson: coherent Compton

scattering rises at low energy

• Non particle 'backgrounds”
• PICO particles - T. Noble talk,

DM10

• CRESST crackophonics ~ca. 2000
• These may well proliferate at low

energy

• DM backgrounds session - DM4
• r

at

• en-
• a-

10-10 10-8 10-6 10-4 10-2 100 10-3 10-2 10-1 100 101 102 103 May be subject to structure effects Differential cross section dσ/dEr (b/eV) Recoil Energy Er (eV) 0.1 GeV/c2 Dark Matter on Si Ge Coherent Si Coherent He Coherent Ge Compton Si Compton

Robinson, arVix:1610.07656

Hochberg et al., arXiv:1512.04533

1 / kg/ keV/ day

T . Shutt - TAUP 2019, Sept 11, 2019

Predictions are hard, especially about the future Niels Bohr Yogi Berra

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T . Shutt - TAUP 2019, Sept 11, 2019

19

No annual modulation signal in other experiments

PDG 2018

~1988 Today Tomorrow

T . Shutt - TAUP 2019, Sept 11, 2019

Summary

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• 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