Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for...

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Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016

Transcript of Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for...

Page 1: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Down-to-earth searches for cosmological dark matterCarter Hall, University of Maryland

October 19, 2016

Page 2: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Astrophysical evidence for dark matter

Ω Galaxy cluster collisions Rotation curves

Page 3: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

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380,000 years after the big bang

Today

1970’s - 1980’s: Cold dark matter is needed to seed the formation of galaxy clusters

13.9 billion years

Credit: Andrey Kravtsov, KICP, U. Chicago

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Temperature and density fluctuations are 1 part in 105.

The cosmic microwave background anisotropy imaged Planck (2014).

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CMB multipole expansion - measured by Planck (2014)

Prominent 3rd peak indicates presence of matter which did not rebound.

~ 1°

~ 1/2°~ 1/3°

Page 6: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Neutrinos? – not heavy enough

‘Weakly Interacting Massive Particle’

generalize

Page 7: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Early universe plasma

Age of universe ~ 1 nanosecond;Temperature ~ 100 GeV

?

Dark matter

Dark matter

Normalmatter

Normal matter

Dark matter annihilation

Dark matter creation

The thermal hypothesis:Was the dark matter an interacting component in the very early universe?

Page 8: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Correct dark

matter abundance

Large annihilation cross section

Small annihilation cross section

Typical weak nuclear force cross sections

J. Feng, Annu. Rev. Astron. Astrophys. 2010. 48:495–545

The thermal hypothesis:Was the dark matter an interacting component in the very early universe?

Page 9: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

The Milky Way’s dark matter halo

•  Typical orbital vel. = 230 km/sec~ 0.1% speed of light

•  Density: ~ 300 mproton / liter•  WIMPs (~100 GeV): 3 per liter

•  deBroglie wavelength:•  WIMPs: larger than a nucleus.

Coherent scalar scattering on ordinary nuclear matter, σ ~ A2

•  Production: •  WIMPs: thermal

Page 10: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

?

Dark matter

Dark matter

Normalmatter

Normal matter

Dark matter annihilation

Dark matter creation

Page 11: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .
Page 12: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

HAWC projected five-year sensitivity (start 2015)

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?

Dark matter

Dark matter

Normalmatter

Normal matter

‘Direct detection’

Page 16: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

WIMP γ,β

‘Direct Detection’

nuclear recoil signal

electron recoil background

Page 17: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

The parameter space of direct detection

& XENONNT

Page 18: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Nuclear recoil energy spectra

From: arXiv:1107.1295

A2 dependence

Page 19: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Calibration of LUX: Beta spectrum of Carbon-14

Carbon-14 beta decay

Xenon-131 Gamma line

(164 keV)

Detector threshold = 1.3 keV

1- 8 keV: x-ray region

Page 20: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

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Target

scintillating bolometers (CRESST)

Cryogenic semiconductors

(CDMS)

Light

Phonons/heat 100% energy slowest cryogenics

Ionization

WIMP

WIMP

• Nuclear recoils vs. electron recoils ◆ "Division of energy ◆ "Timing ◆ "Stopping power

Two-phase noble liquids (PandaX, XENON, LUX)

Detection modes for ionizing radiation

Single-Phase noble liquids (XMASS, DEAP/CLEAN)

Page 21: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .
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Typical Event in LUX

S1S2

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Strong background rejection from kinematics

~ MeV γ

must cross

full volume without

interacting again

~ keV deposition

forward scattering

Page 24: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

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Simulation of self-shielding in liquid xenon

Volume cut rejects most gamma backgrounds.

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Particle ID: recoil discrimination in LUX

Light

Charge/Light

Charge/Light

Charge/Light

Electron recoils (background)

Nuclear recoils (signal)

Difference

Electron recoil rejection factor:

200 -500

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LUX assembly – 2010 - 2011

370 kg of liquid xenon

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Page 28: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Sanford Underground Research Facility

Davis Cavern 1480 m (4200 mwe)

LUX Water Tank South Dakota USA

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Davis Cavern @ SURF, March 2011

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Davis Campus dedication, May 30, 2012

Ana Davis, widow of Ray Davis

Davis Campus water tank, home of LUX

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On top of the water shield, Sept. 2012

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LUX installed underground, Sept. 2012

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LUX recoil bands and energy scales

more charge recombination

less charge recombination

electron recoil band

nuclear recoil band

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0 10 20 30 40 501

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

log 10

(S2 b/S

1) x

,y,z

cor

rect

ed

S1 x,y,z corrected (phe)

3 6 9 12 15 18 21 24 27 30 keVnr

1.3

1.8

3.5

4.65.9

7.1

keVee

LUX WIMP search data (2013) 160 events observed 85.3 days × 118.3 kg = 10,090 kg�days

2013 initial results (Run 3): Phys.Rev.Lett. 112 (2014) 091303. 2015 re-analysis of Run 3: Phys.Rev.Lett. 116 (2016) 161301.

Light

Charge Light

_______

Page 35: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

October 30, 2013

Page 36: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Calibration: external gamma sources (137Cs)

Calibration source guide tubes

Self-shielding makesexternal gamma sources

mostly ineffectual

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Tritium: an ideal electron-recoil band calibration source

0 2 4 6 8 10 12 14 16 18 200

0.5

1

1.5

2

Electron Kinetic Energy [keV]

Coun

ts/k

eV/d

ay/1

0000

0 at

oms

Tritium Beta Spectrum (Q=18.6 keV, T1/2=12.3 years)

WIMP search range

C

H

H H

T

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Injection and removal of tritium from LUX, August 2013

−300 −200 −100 0 100 200 300 400 500

10−4

10−3

10−2

10−1

100

Time (hours)

Rat

e (H

z)

S1 <150 [Phe]. Fiducial Volume

Rateτ 1=6.0 ±0.5Hoursτ 2=6.4 ±0.1 Hours

August 8, 2013

Success

10/21/16

Fiducial count rate for S1 < 150 PE

Page 39: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

0 100 200 300 400 500 600

0

50

100

150

200

250

300

radius squared (cm2)

drift

tim

e (µ

s)

−20 −10 0 10 20−25

−20

−15

−10

−5

0

5

10

15

20

25

x (cm)

y (c

m)

Tritium event locations in LUX – August 2013

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Page 40: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Charge vs Light from tritium in LUX at 170 V/cm

178,000 fiducial tritium events 10/21/16 40

Page 41: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Tritium “combined-energy” spectrum

178,000 fiducial tritium events 41

Page 42: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Light yield of liquid xenon

LUX – tritium (100 & 180 V/cm)

Page 43: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Nuclear-recoil calibration w/mono-energetic neutronsD + D → n + 3He En = 2.45 MeV

Page 44: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Nuclear-recoil calibration of LUX Neutron scattering with a neutron generator

Page 45: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

LUX final WIMP search results – Run 3 & 4 combined, 2013 - 2016

LUX Run 3 & 4 (2016): arXiv:1608.07648

Page 46: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

LUX -> LZ (2020) Scale up LUX fiducial mass by x40

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LUX

LZ:TotalXe-10TonAc5veXe–7TonFiducialXe–5.6Ton

LUX

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Xe TPC

Gd-doped liquid

scintillator outer

detector

50 kV high voltage

existing LUX water shield

The LZ Experiment – coming in 2020

Page 48: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

LZ Sensitivity (5.6 Tonnes, 1000 live days)

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2.5×10-48cm2

Page 49: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

History of WIMP sensitivity @ 50 GeV

LUX & PandaX-II (2016) LZ

Ge, NaI no discrimination

Ge, w/discrim.

LXe, w/discrim. ZEPLIN

XENON 1T

XENON100

LUX (2013)

Page 50: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .
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Uranium-238 decay chain

Thorium-232 decay chain

end end

start

start

gamma sources

Page 52: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

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Tl-208 (Th-232) Bi-214

(U-238) K-40

Ge-76

Xe-136 Te-130

ββ0ν Q values:

Ordinary radioactive decay here on earth

WIMP scattering

Page 53: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Two problems from particle physics 1) Why is the weak scale so light? è New weak physics? è WIMPs

2) Why no CP violation in QCD ? è Peccei-Quinn symmetry?è Axions

Page 54: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

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Electron-recoil and nuclear-recoil calibration data

Page 55: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

Is LUX a success?

Page 56: Down-to-earth searches for cosmological dark matter · 2016. 10. 21. · Down-to-earth searches for cosmological dark matter Carter Hall, University of Maryland October 19, 2016 .

July 22, 2016