First Data from DM-Ice17, Prospects for DM-Ice

First Data from DM-Ice17, Prospects for DM-Ice

Reina Maruyama, Yale University on behalf of the DM-Ice Collaboration

IBS Mini Workshop on Direct Search of Dark Matter July 7, 2015 Daejeon, Korea

IBS, Korea - July 7, 2015Reina Maruyama

Dark Matter Signal or Background?

2

arXiv:1308.5109

Cou

nts

/ 30

days

DAMA Max

arXiv:1401.3295

DAMA

CRESST

CoGeNTCDMS-Si

arXiv:1304.4279

Eur. Phys. J. C (2012) 72:1971

Pettus Thesis Defense

3

A World of Dark Matter Searches

Homestake:*•*LUX

Soudan:*•*CDMS*•*CoGeNT

SNOLAB:*•*DEAP/CLEAN*•*PICASSO*•*COUPP*•*DAMIC

Boulby:*•*DRIFT

Canfranc:*•*ANAIS*•*ArDM*•*Rosebud

Modane:*•*EDELWEISS

Gran*Sasso:*•*CRESST*•*DAMA/LIBRA*•*DarkSide*•*XENON

Kamioka:*•*XMASS

YangYang:*•*KIMS

Jinping:*•*PandaNX*•*CDEX

South*Pole:*•*DMNICE

ANDES:*(planned) Stawell:*

(planned)

7 May 2015


Northern Hemisphere

Gran SassoDAMA/Libra

250kgrunning

Y2LKIMS

~200kg

Gran SassoSaBRE

R&D

CanfrancANAIS 250 kg

KamiokaKamLAND-PICO

Southern Hemisphere

South PoleDM-Ice

17 kg runningR&D for 250 kg

Stawell Mine, AustraliaSaBRE

R&D, lab ready ~ 2018

icerock

4

Several Groups conducting ultra-pure crystal with several vendors to go to the full scaleDM-Ice: • NaI dark matter search in an entirely different environment• South Pole offers:

• Ultra-clean and ultra-stable environment• Seasonal variation unambiguously different from dark matter modulation• IceCube offers muon monitoring and veto as well as experience• NSF-run South Pole Station for logistical support

Annual Modulation Dark Matter Searcheswith NaI Detectors

Reina Maruyama P5 @ SLAC, Dec 2-4, 2014

Phased Program for DM-Ice

DM-Ice17

Operating since 2011 17 kg of NaI(Tl) at 2450m depth at South Pole

DM-Ice 250 North

Northern Hemisphere Run portable 250 kg NaI(Tl) detector, first deployment in the Northern Hemisphere

Directly test DAMA’s assertion that the observed annual modulation is due to dark matter & understand its origin

- probes longest-standing dark matter claim- NaI(Tl) target- aims to understand origin of DAMA’s signal - only experiment with access to both Northern & Southern Hemispheres

A Phased Experimental Program

150 cm

DM-Ice 250 South

Deployment at South Pole if modulation seen in North &ice drilling becomes available

BoulbyDM-Ice 37 North

see#also##Cherwinka*et#al.**Astroparticle*Physics*35*(2012)*749

Rome, May 12, 2014Reina Maruyama

South Pole with IceCube

South Pole

runway

AMANDA

Amundsen-Scott South Pole Station

IceCube

South Pole with IceCube

South Pole

runway

AMANDA


IceCube

SPT, BICEP II

IceCube Control Lab


ARA

Science and Facilities

at the South Pole

1 km

IBS, Korea - July 7, 2015Reina Maruyama Pettus Thesis Defense

Advantages of South Pole

• Same dark matter signal in both hemispheres• Seasonal variation reversed in phase

- Muon tagging with IceCube/DeepCore- Spallation neutrons moderated by ice

• Overburden: 2450 m ice (2200 m.w.e.)- Clean Ice

‣ ppt 238U/232Th, ppb 40K- Enclosed space

• Stable environment under ice• Support infrastructure of Amundsen-Scott South Pole Station

7 May 2015 7

see#also##Cherwinka*et#al.**Astroparticle*Physics*35*(2012)*749

IBS, Korea - July 7, 2015Reina MaruyamaReina Maruyama

DM-Ice17: An NaI Detector in IceCube/DeepCore

50m

bedrock

IceCube lab

1450m

2450m

2820m

Demonstrated:• Feasibility of deploying a

remotely-operable dark matter detector in the Antarctic Ice

• Stability of the environment• Radiopurity of the antarctic

ice / hole ice• Explore the capability of

IceCube to veto muons

8

DM-Ice-17 AMANDA (decommissioned)

DeepCore

IceCube

Deployed at the South Pole in December 2010• A 17 kg NaI detector • Operation since Feb. 2011• Data run from June 2011

DM-Ice-17 Detector

NAIAD NaI Crystal (5”x5”, 8.5 kg)

quartz light guides

2 IceCube mainboards + HV control boards

Stainless Steel Pressure Vessel

1.0 m

36 cm (14”)

PMTs: 5” ETL 9390UKB

IceCube DOM 59

IceCubeDOM 60

7 m

DM-Ice

PTFE light reflectors

DM-Ice-17 Construction & Deployment

10

Shipment to Antarctica

Detector in the hole

Deployment

Detector assembly

July 2010

Revive NAIAD xtals

Sep - Oct. 2010 Dec. 1, 2010

Dec. 11, 2010

Design begin Feb. 2010


DM-ICE17 Assembly

11


Pressure Vessel Testing

7 May 2015 12

Integrity#of#steel#pressure#vessel#tested#against#>7000#psi#(freeze9in#test)


DM-ICE17 Assembly

13

Final#assembly#and#wiring.#Lower#volume#purged#with#nitrogen#and#sealed#from#electronics.

IBS, Korea - July 7, 2015Reina Maruyama 14

IceCube Below

IceCube Lab

SPT/BICEP-II

IceTop

DM-Ice17 Below

Data from DM-ICE17


DM-Ice17: Detector Operations

data run

data run

• Monitored quantities:• Temperature of the boards

• ~10°C above surrounding ice• Fast (2-3 weeks) decrease

during freeze-in• slower decrease over a few

months after freeze-in• Pressure follows similar trend as

temperature (ADC resolution limited)

• Values recorded every 2 sec. before March 2012. Every 60 sec. since March 2012.

• Physics data taking since June 2011 DM-Ice CollaborationarXiv:1401.4804v1


Low Energy Spectrum

• Spectrum below 10 keV dominated by “thin” pulses.

• Below 2 keV: combination of single-photoelectrons & electronics noise

16

20-5 0 5 10 15 25

coun

ts /

day

/ keV

/ kg

1

10

210

310

410 Data (no cuts)

Data (cuts applied)

Thin Pulse Model

EMI Noise Model

SPE Noise Model

Energy (keVee)

thin

EMI

Signal: < 100 keVSignal: > 100 keV Energy

SPE

DM-Ice CollaborationarXiv:1401.4804v1


Event Selection: “Thin” pulses• Characteristics:

• high pulse-height relative to charge• asymmetric between two PMTs

• 90% of events between 5-10 keV are “thin”

• Current cut effective above 7 keV

17

Before cutAfter cut

Pulse

Hei

ght

Energy (keV)

Charge: PMT-1

Char

ge: P

MT-

2

pulse height vs. charge

charge: PMT1 vs. PMT2

energy spectrum: before & after thin pulse cut

Low Energy Background Model

April 7, 201518

210Pb

210Pb

125I

125I X-rays212Pb

keV

40K

Largest contamination from NaI(Tl) and PMTs

7.9±0.4 dru

DM-Ice 2014


Energy (keV)4000 4500 5000 5500 6000 6500 7000 7500 8000

coun

ts /

day

/ keV

/ kg

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45 Det-1 Alphas

Simulation Alphas

Th232

Pb212Ra-228

U238

Th230U-234

Po218Ra-226

Po210

Spectrum vs. Simulation

19

208Tl&(Th)chain)

208Tl&(Th)chain)&+&214Bi&(U)chain) 40K

213Bi&(U)chain)

214Pb&(U)chain)

• Good agreement with simulation• Simulation based on:

• NaI from alphas and K from data• radioassay of spare parts

alphas&in&DM)Ice17&NaI&(5&mBq/kg)

DM-Ice CollaborationarXiv:1401.4804v1

gamma alpha

Bi-Po

Pulse-shape discrimination (1 - 9 MeVee)


Cosmogenic Activation for DM-Ice17

20

44

Commercial*flights*at*~36,000+*ft*

Storage*at*9,301*ft*

Polar*program*flights*

Low*geomagnetic*rigidity*

Madison,*WI,*USA*Boulby,*GBR*

McMurdo*Station*

South&Pole&Station&

Sandiviken,*SWE*

Christchurch,*NZL*

Location(Relative(Neutron(

Rate((to(sea(level)(

Madison,)WI) 1.38)

South)Pole) 11.1)

Commercial)Flight)

100)–)600)


Cosmogenic Decay Peaks

21

Energy (keV)0 20 40 60 80 100 120 140

Rat

e (d

ru)

0

50

100

150

200

250

300

Energy (keV)0 20 40 60 80 100 120 140

Rat

e (d

ru)

5

10

15

20

25

30

2013 Data July 2011 Sept 2011

Energy (keV)0 20 40 60 80 100 120 140

Rat

e (d

ru)

-2

0

2

4

6

8 July 2011 Residual Sept 2011 Residual Triple-Gaussian Fit

Time (days)200 250 300 350 400 450 500 550 600

Peak

Rat

e (c

ount

s / k

g / d

ay)

0

20

40

60

80

100

120 Det-1 Det-2 Det-1 Fit Det-2 Fit

Rate%(cou

nts%/%k

g%/%k

eV%/%da

y)%

Det41%t1/2%=%59.2%±%1.8%days%Det42%t1/2%=%60.9%±%2.6%days%Lit.%t1/2%=%59.400%±%0.010%days%

DM4Ice17%Det41%Data%and%Residual%

125I%full4energy%

113Sn,%121mTe%X4rays%

125I%L4capture%

Confirm*identity*of*cosmogenic*peaks:*Match*simulated*spectral*features*

Expect*65.3*keV*fullNenergy*and*37.6*keV*LNshell*capture*peaks*for*125I*

Measuring*decay*time*Expect*59.4*day*halfNlife*for*125I*

Count*Rate*for*125I*Peak


Looking Ahead: Activation for DM-Ice

22

Transport)by)sea/overland)

Reduce)storage)time)at)9,301)ft)

Polar)program)flights)remain)

Low)geomagnetic)rigidity)

Madison,)WI,)USA)Boulby,)GBR)

McMurdo)Station)

South&Pole&Station&

Sandiviken,)SWE)

Christchurch,)NZL)


Simulated Activation Event Rate

23

Energy (keV)0 20 40 60 80 100 120 140 160 180 200

Rat

e (c

ount

s / k

g / k

eV /

day)

-110

1

10

210 NaI CosmogenicsSn113

Te121m Te125m Te127m

I125 I126

Time (days)0 50 100 150 200 250 300 350

Rat

e (c

ount

s / k

g / k

eV /

day)

-110

1

10

2-6 keV RateSn113

Te121m I126

L"shell'X"ray'or'Auger'e"'

K"shell'X"ray'or'Auger'e"'

126I,'113Sn,'121mTe'

• Multiple*strong*cosmogenic*lines*• Significant*contributions*to*2*–*6*keV*region*of*interest*&*must*be*minimized

Cosmogenic*contribution*to*ROI:*• 126I*(t1/2*=*13*days)*• lead*contribution*at*deployment*

• 113Sn*(t1/2*=*115*days)*• dominates*rate*over*physics*run*

Event(rate(one(month(after(deployment Event(rate(vs.(time


Cosmogenic Mitigation

24

“Exposure budget” for 113Sn in*DM-Ice250S:*

After “easy” 40% reductionMajor contributions remain from NZL-McM flight and South Pole

Further reductions:*50% reduction in low-altitude NZL-McM cargo flight (15% of total)*

90% reduction in South Pole activation from under-ice storage:


Antarctic Ice: Overburden at -2500 m (2200 m.w.e.)

Muon flux vs. depth in the ice, total and those untriggered by IceCube/DeepCore.

• ~85 muons/m2/day at bottom of IceCube (2/day for DM-Ice17)

• IceCube/DeepCore veto reduces rate by ~1-2 orders of magnitude.

25

PreliminaryDUSEL Homestake

IceCube/ DeepCore veto


Identifying Muons in DM-Ice

26

Muons are identified with their high energy depositions and pulse shape variable using the pulse height (hi) at time (ti):

Expect 0 α, 3 γ in muon sample/year


IceCube - DM-Ice Coincidence

28

December 2012 – Event #142012-12-21 RunID: 121431, EventID 79868923

DM-Ice

Muon rate in DM-Ice (appear as mip): 2/day

81 events in 11 months pass IceCube’s muon trigger.(expect more events in less stringent triggers)

Muon events result in elevated event rate at low energies in DM-Ice17 persisting for > 10 sec.

Events that trigger both DM-Ice and IceCube Found!

Time From Muon Event [s]-10 0 10 20 30 40 50

Coi

ncid

ent r

ate

[Hz]

050

100150200250300350400450500

DM0 LC Rate

Time From Muon Event [s]-10 0 10 20 30 40 50

Mon

itorin

g ra

te [k

Hz]

0

20

40

60

80

100

120

140PMT-1a Coincident Run!PMT-1b Coincident Run!PMT-1a Monitoring Run!PMT-1b Monitoring Run!Muon Event!

DM-Ic

e/Ic

eCub

e


The muon rate at the South Pole well measured by IceCube

Seasonal Muon Rate Modulation

Tilav et al, arXiv:astro-ph/1001.077629

Temperature of the stratosphere in pressure layers, TP [K]

IceCube muon rate [Hz] (black) & Teff [K] (red)

IceCube Collaboration, arXiv:1108.0171

Muon rate modulation with a single IceCube DOM


Muon Rate in DM-Ice and IceCube

• The muon rate observed in DM-Ice tracks IceCube’s rate

30

200 400 600 800 1000 1200

DM

-Ice

Muo

n R

ate

[day

-1]

2

2.5

3

3.5

4

Days from January 1, 2011200 400 600 800 1000 1200

SMT8

Rat

e [k

Hz]

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

DM-Ice DM-Ice Fit IceCube

DM-Ice17: 14±3% mod.!IceCube: 8.6±1.2% mod.!


Muon Energy Distribution

• Energy & direction of the muons measured by IceCube• DM-Ice anchors muons in IceCube to 13 cm• Studies underway to help improve IceCube

reconstruction

31

Energy Estimate [GeV]2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

Cou

nts

1

10

210Det-1 MPE

Det-1 Seed

Energy Estimate [GeV]2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

Res

idua

l

-505

10152025

]°Zenith [^0 10 20 30 40 50 60 70 80 90

Cou

nts

0

20

40

60

80

100

120

140Det-1 MPE

Det-1 Seed

]°Zenith [0 10 20 30 40 50 60 70 80 90

Res

idua

l

-202468

101214

]°Azimuth [^0 50 100 150 200 250 300 350

Cou

nts

0

5

10

15

20

25

30

35

40

Det-1 MPE

Det-1 Seed

]°Azimuth [0 50 100 150 200 250 300 350

Res

idua

l-10

-5

0

5

10

Energy Zenith Azimuth

32

inner crystal

outer crystal

Sensitivity to DAMA Modulation Signalassume 225 kg exposure/yr (90% livetime)

1 year: 3.3σ2 years: 4.6σ3 years: 5.7σ

Based on MC sample of modulated signal, using same binning and analysis method as DAMA, fit to fixed phase and period.

DM-Ice250 Background 2-6 keV region: 3 dru w/o xtal-xtal veto, 1.75 dru average with veto

DM-Ice250 Simulations

DM-Ice250

DAMA

Close-Packed Detector Array Inner Crystal Vetoed Spectrum

GeVΧm1 10 210 310

2 c

mσ

-4410

-4310

-4210

-4110

-4010

-3910

-3810

-3710

-3610 )σ, 5σDAMA allowed region (90%C.L., 3500 kg*years, 1.0 dru, 2-4 keV (Previous Projection)500 kg*years, 1.0 dru, 0.25-20 keV500 kg*years, 1.0 dru, 0.5-20 keV500 kg*years, 1.0 dru, 1.0-20 keV500 kg*years, 1.0 dru, 1.5-20 keV500 kg*years, 1.0 dru, 2.0-20 keV

New Low-Background NaI(Tl) Crystals

33

Development of NaI(Tl) detectors with Alpha Spectra, Inc (ASI) in CO, USAThree groups work with Alpha Spectra: DM-Ice, ANAIS, KIMS. Communication and sharing of R&D results

Backgrounds are within acceptable levels for an experiment with 2 counts/day/keV/kg.

- 2 x 18 kg crystals from Alpha Spectra, first ran at Fermilab MINOS near hall for testing, then moved to Boulby

New DM-Ice crystal


DM-Ice37 Contamination

• Collective NaI(Tl) effort (DM-Ice, ANAIS, KIMS)• Goal set by DAMA: 1 dru in ROI• Currently: 3 dru above noise energies

• Noise removal in progress• DM-Ice17: 8 dru

• 2 mBq/kg alphas

35


What do we need to test DAMA?

• 500 kg-yr, 1 cnt/keV/kg/day at various thresholds

36

GeVΧm1 10 210 310

2 c

mσ

-4410

-4310

-4210

-4110

-4010

-3910

-3810

-3710

-3610 )σ, 5σDAMA allowed region (90%C.L., 3500 kg*years, 1.0 dru, 2-4 keV (Previous Projection)500 kg*years, 1.0 dru, 0.25-20 keV500 kg*years, 1.0 dru, 0.5-20 keV500 kg*years, 1.0 dru, 1.0-20 keV500 kg*years, 1.0 dru, 1.5-20 keV500 kg*years, 1.0 dru, 2.0-20 keV


What do we need to test DAMA?

• 500 kg-yr, 1, 2 & 5 cnt/keV/kg/day, 2 - 20 keV

38

GeVΧm1 10 210 310

2 c

mσ

-4410

-4310

-4210

-4110

-4010

-3910

-3810

-3710

-3610 )σ, 5σDAMA allowed region (90%C.L., 3500 kg*years, 5.0 dru, 2.0-20 keV500 kg*years, 2.0 dru, 2.0-20 keV500 kg*years, 1.0 dru, 2.0-20 keV


What If…

39

• 1000 kg-yr, 0.1 cnt/keV/kg/day

41

Summary

1

DM-Ice17 DM-Ice 250 North

Directly test DAMA’s assertion that the observed annual modulation is due to dark matter & understand its origin

150 cm

DM-Ice 250 South

• Successful installation and running of DM-Ice17 at the South Pole• IceCube gives additional information on muons in DM-Ice, DM-Ice may help

IceCube’s reconstruction• DM-Ice37 at Boulby, crystal R&D going forward• 11x reduction in 40K, 8x in 210Pb• DM-Ice250: unique position in global effort to definitively test DAMA


Yale University Reina Maruyama, Karsten Heeger, Kyungeun Lim, Walter Pettus, Zachary Pierpoint, Antonia Hubbard

University of Wisconsin – Madison Francis Halzen, Albrecht Karle, Matthew Kauer, Mike DuVernois, Bethany Reilly

University of Sheffield Neil Spooner, Vitaly Kudryavtsev, Anthony Cole, Anthony Ezeribe, Calum Macdonald, Christopher Oates, Frederic Mouton, Matt Robinson, Sam Telfer, Dan Walker

University of Alberta Darren Grant

University of Illinois at Urbana-Champaign Liang Yang

DM-Ice Collaboration

42

Fermilab Lauren HsuShanghai Jiao Tang University Xiangdong Ji, Changbo Fu

NIST-Gaithersburg Pieter Mumm

University of Stockholm Chad Finley, Per Olof Hulth, Klas Hultqvist, Christian Walck

DigiPen Charles Duba, Eric Mohrmann

Boulby Underground Science Facility Sean Paling

Documents

First Data from DM-Ice17, Prospects for DM-Ice