The Germanium Observatory for Dark Matter (GEODM)...overall misid 10-4 → < 3 x 10-7, far better than needed for GEODM 12 M. Pyle, B. Serfass Yield Recoil Energy [keV] 0 10 20 30

The Germanium Observatory forDark Matter (GEODM)

Sunil GolwalaCaltech

DUSEL Lead WorkshopOct 2, 2009

SuperCDMS/GEODM Sunil Golwala

Outline

• Cryogenic Dark Matter Search (CDMS) II summary• From CDMS II to SuperCDMS and GEODM

• Backgrounds• Background rejection• Detector fab/test costs and timescales• Status/Timeline

2


Caltech: S. R. GolwalaFermilab: D. A. Bauer, R. SchmittMIT: E. Figueroa-FelicianoNIST: K. IrwinQueens University: W. Rau, P. di StefanoSanta Clara University: B. A. Young SLAC National Accelerator Lab: E. do Couto e Silva, J. WeisandSouthern Methodist University: J. CooleyStanford University: P.L. Brink, B. Cabrera, S. YellinSt. Olaf College: A. ReisetterSyracuse University: R.W. SchneeTexas A&M: R. Mahapatra, M. PlattUniversity of California, Berkeley: N. Mirabolfathi, B. Sadoulet, D. SeitzUniversity of Colorado at Denver: M. E. HuberUniversity of Florida: T. SaabUniversity of Minnesota: P. Cushman, V. Mandic

The GEODM Collaboration

3


Z-sensitive Ionization- and Phonon-mediated detectors: Phonon signal measured using photolithographed superconducting phonon absorbers and transition-edge sensors.

CDMS ZIP Detectors

!

AlW

qp-trap

Si or Gecrystal

quasiparticle diffusion

Q inner

Q outer

A

B

D

C

Rbias

I bias

SQUID array Phonon D

Rfeedback

Vqbias

40 60 80 100 120

0

1

2

3

T [mK]

R [!

]

athermal phononspropagate

ballistically

TES = transitionedge sensor

4



CDMS ZIP Detectors

!

AlW

qp-trap

Si or Gecrystal


Q inner

Q outer

A

B

D

C

Rbias

I bias


Rfeedback

Vqbias

40 60 80 100 120

0

1

2

3

T [mK]

R [!

]


ballistically


1 µm tungstenTES

380 µm x 60 µm aluminum fins

4



CDMS ZIP Detectors

!

AlW

qp-trap

Si or Gecrystal


Q inner

Q outer

A

B

D

C

Rbias

I bias


Rfeedback

Vqbias

40 60 80 100 120

0

1

2

3

T [mK]

R [!

]


ballistically


1 µm tungstenTES

380 µm x 60 µm aluminum fins

4

Ionization measurement

Inner electrode(85%)

Outerelectrode(15%)

Two ionization channels:! Inner fiducial volume! Outer electrode where field lines are not uniform

!!

"#$%$&'()*+$

%,#$%$-.-/0'(+-

e- and h+ drift to surfaces in 3 or 4 V/cm applied field

FET amp

Ionization measurement

Inner electrode(85%)

Outerelectrode(15%)

Two ionization channels:! Inner fiducial volume! Outer electrode where field lines are not uniform

!!

"#$%$&'()*+$

%,#$%$-.-/0'(+-

e- and h+ drift to surfaces in 3 or 4 V/cm applied field

FET amp


Backgrounds in the CDMS II Experiment

5

Photons (γ)

primarily Compton scatteringof broad spectrum up to 2.5 MeV

small amount of photoelectric effect from low energy gammas

Neutrons (n)

radiogenic: arising from fission and (α,n) reactions in surrounding materials (cryostat, shield, cavern)

cosmogenic: created by spallation of nuclei in surrounding materials by high-energy cosmic ray muons.

Surface events (“β”)

radiogenic: electrons/photons emitted in low-energy beta decays of 210Pb or other surface contaminants

photon-induced: interactions of photons or photo-ejected electrons in dead layer

γ

γ

γ

β

n

γ

e-


• Recoil energy• Phonon (acoustic

vibrations, heat) measurements give full recoil energy

• Ionization yield• ionization/recoil energy

strongly dependent on type of recoil (Lindhard)

• Primary discriminationagainst photon bgndby ionization yield

CDMS II Background Discrimination

6

• bulk electron recoils (gamma source)• bulk nuclear recoils (neutron source)X surface electron recoils (NND selection)

1.5

1.0

0.5

0.00 10 20 30 40 50 60 70 80 90 100

Ioni

zatio

n Y

ield

Recoil Energy [keV]


• Photon rejection• Bulk photon rate (bulk ER)

= 300/kg/day. Single-scatters = 90/kg/day

• Single-scatter surface ERs= 0.3/kg/day

• Surface ER singles/bulk ER singles = 4 x 10-3

• Surface ER singles misid’d asnuclear recoils (NRs)/surface ER singles = 0.2(ionization dead layer)

• Phonon timing rejects surface events: 0.006 misid. prob.

• Overall misid probability: 2 x 10-6 for bulk ER, 6 x 10-6 for single-scatter bulk ER

• Beta rejection• Comparable single-scatter ER rate of low-energy beta emitters (mainly 210Pb)• 0.2 misid by yield and 0.006 misid by timing: 1 x 10-3 misid probability

CDMS II Background Discrimination

7

Dan Bauer, Fermilab April 30, 2009

Current results from CDMS II

Photons

Surface events

No WIMPS found in this

signal ‘box’

4 x 10-3

0.2nuclear recoil (WIMP)

acceptance region0.006

6 x10-6

1 x 10-3

single scatters


• 398 kg-d raw exposure(4 kg Ge at Soudan mine, 2000 mwe, 10/06-7/07)

• Single-scatter events• Estimated leakage of misid’d

surface events based on• photon cal data• WIMP-search multiples• Cuts defined to obtain ~0.5

misid’d events: optimal balance of efficiency and leakage

• Expect 0.6 +0.5-0.3 (stat) +0.03-0.02 (syst) misid’d surface events

• Expect < 0.1 unvetoed single-scatter neutrons (conservative)

• 0 events observed

CDMS II 2008 Results

8

Dan Bauer, Fermilab April 30, 2009

Current results from CDMS II

Photons

Surface events

No WIMPS found in this

signal ‘box’

single scatters


Spin-Independent Exclusion Limit

9

• Zero events observed• Including reanalysis of

prior data set, obtain best spin-independent limit for M > 40 GeV/c2;published in PRL, Filippini thesis

• 2.5X exposure in hand and being analyzed• many analysis

improvements• should reach

CDMS II target sensitivity of 2 x 10-44 cm2

CDMS II target sensitivity


χ10 Mass [GeV/c2]

σSI

[cm

2 ]

C D M S II F ina l

15kg @ S oudan

100kg @ S N O LAB

1.5T @ D U S E L

101 102 10310−47

10−46

10−45

10−44

10−43

10−42From CDMS II to SuperCDMS and GEODM

10

Staged three-prong program toexplore MSSM or study a signal:• (mildly) decreased backgrounds• (vastly) improved background rejection• increase in mass/detector and decrease in

cost/detector< 1 event misid’d bgnd at each stage

CDMS II (2008)

∅7.5cm x 1cm ZIP0.25 kg/detector

16 detectors = 4 kg2 yr, 1700 kg-d

SuperCDMS Soudan (2012)∅7.5cm x 2.5cm mZIP

0.64 kg/detector25 detectors = 15 kg

2 yr, 8000 kg-d

SuperCDMSSNOLAB

(2016)

∅10cm x 3.5cm iZIP1.5 kg/detector

70 detectors = 105 kg3 yr = 100,000 kg-d

GEODM DUSEL(2021)

∅15cm x 5cm iZIP5.1 kg/detector

300 detectors = 1.5 T4 yr, 1.5 M kg-d

x5

x12

x15


Improving Background Rejection

• Interdigitated ZIP (iZIP) design meets needs for SuperCDMS SNOLAB and GEODM

• Interleaved ionization electrodes cause ionization to partition differently for surface and bulk events

• High field near surface increases ionization yield for surface events

• Top/bottom phonon sensors (ground rails) provide simpler, more direct z information

11

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K<'8R'!((%I/6W'<%86R%3'8<%

/')!6*(%*64%.%I/6X8'@%

0V +V 0V

negativeversion

on other face

M. Pyle!"!#$%&'()*+$#,-*-*'$•! %-./0&$1(2&2$#,-*-*$3&42-.5$

•! 6$#,-*-*$7,4**&0'$–! 8*409'('+$:.5&;$7,4**&0'$1.<<&2$

=>$?$

•! @AAB$CDE'$(*$F4;400&0GH,4**&0$–! 3*$@$IJK$

–! L$ED1$MNNB.<ON.<OPB*<Q$$

–! $RB$80$H-00&HS-*$T*'$$•! UAB*<$5,(HV$

•! W&*)5,$X$UNA.<$

–! EH$@$6B<Y$M4Z&;$(-*$(<F04*54S-*Q+$$•! [$\$P?<Y$$$

•! ]$\$RB^<Y$M#,4'&$1&F4;45&2Q$

•! DOH&00&*5$D*&;)9$3&'-0.S-*$

–! [+$!"#$%&'&&$M_N`G=N`Q$

–! ]+$a\$RAB&`&&$M_N`G=N`Q$

()*&'#+,--#./01#2&3456#783-9:;:#<64&:6=->#



• Interdigitated ZIP (iZIP) design appears to meet needs of SuperCDMS SNOLAB and GEODM• High field at

surfaces increasesionization yield:0.2 misid →< 3 x 10-4 misid

• Surface events share charge differently than bulk events:< 10-3 misid

• Phonon partition and timing z position:< 10-3 misid

• All measurements limited by neutron background in surface test facilities• Ionization yield and Q/P asymmetry likely uncorrelated; if true, then

overall misid 10-4 → < 3 x 10-7, far better than needed for GEODM

12

M. Pyle, B. Serfass

Ioni

zatio

n Y

ield

Recoil Energy [keV]0 10 20 30 40 50 60 70 80

1.2

1.0

0.8

0.6

0.4

0.2

0.0

133Ba photon source

109Cd e− source









12

M. Pyle, B. Serfass

400

350

300

250

200

150

100

50

00 50 100 150 200 250 300 350 400

Q on one side [keV]

Q o

n bo

th s

ides

[ke

V]

109Cd e− source

133Ba photon source









12

M. Pyle, B. Serfass

arct

an(Q

bott

om/Q

top)

[de

g]

arctan(Pbottom/Ptop) [deg] phonon delay (bottom − top) [µs]20 25 30 35 40 45 50 55 60 -40 -30 -20 -10 0 10 20 30 40

100

90

80

70

60

50

40

30

20

10

0

-10

133Ba photon source 109Cd e− source


Reducing Cost/Time: Larger Substrates

• Larger substrates provide gains in bgnds and in cost/time per kg• Step 1: 10-cm HPGe substrates for SNOLAB (Ortec)• Step 2: Dislocation-free Ge for GEODM

• deep (Ev + 0.080 eV) V2H impurity ruins 77K HPGe γ spectrometers; inhibited via dislocations at 102-4 cm-3 created bythermal gradients during crystal pulling

• impurities no problem for CDMS: they can be neutralized

• dislocation-free xtals available up to30 cm diameter!

13

77K4.2K


Reducing Cost/Time: Larger Substrates

• Proof-of-principle from Haller sample ofdislocation-free Ge (3 cm x 1 cm)• Good collection at 1 V/cm (reasonable field)

• Working with Umicore and Photonic Senseto demonstrate 15-cm fab at necessarypurity/compensation levels• DUSEL R&D grant, DUSEL S4 grant• Germanium workshop in Berkeley this fall

14

0 20 40 60 80 1000

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Q IO Fvolts (keV )

H aller S ample , !2V

0 20 40 60 80 1000

500

1000

1500

2000

2500

3000

3500

Q IO Fvolts (keV )

H aller S ample , 2V

0 20 40 60 80 1000

500

1000

1500

2000

2500

3000

3500

4000

Q IO Fvolts (keV )

H aller S ample , !1V

0 20 40 60 80 1000

500

1000

1500

2000

2500

Q IO Fvolts (keV )

H aller S ample , 1V

Figure 2: Charge Spectra for di!erent bias values.

2

0 20 40 60 80 100

4000

3500

3000

2500

2000

1500

1000

500

0

coun

ts

Energy [keV]

!8 !6 !4 !2 0 2 4 6 80.6

0 .65

0.7

0 .75

0.8

0 .85

0.9

0 .95

1

1.05

Bias (V )

Ch

arg

e E

ffic

ien

cy

H a ller S ample

!8 !6 !4 !2 0 2 4 6 80

0.5

1

1.5

2

2.5

3

3.5

Bias (V )

60!

ke

V w

idth

(k

eV

)

H a ller S ample

Figure 6: Top: Charge e!ciency vs charge bias. Bottom: Width of the 60keV peak (1!) vs charge bias. Note: Charge e!ciency is estimated using thecalibration factor for QIOFvolts, as determined using the 60 keV peak, andassuming that the collection e!ciency is 100% for the +6V case.

6

-8 -6 -4 -2 0 2 4 6 8

1.05

1.00

0.95

0.90

0.85

0.80

0.75

0.70

0.65

0.60

colle

ctio

n ef

ficie

ncy

Bias [V/cm]


Backgrounds and Background Rejection: Photons

• Consider together bulk scattering and surface events due to photon background• Moderate improvements in raw rates; already shown in CDMS I• Moderate reductions in surface area/volume ratio via increased mass/detector• More significant improvements in background rejection via iZIP

15

StageRate

[/kg/d]Relative

RateSgl. Scatter x Misid. Prob.

Relative Misid. Prob.

Misid. Rate [/kg/d] Gain σ [cm2]

CDMS II published

296 1 1.2 x 10−6 1 7.2 x 10−4 1 4.5 x 10−44

CDMS IIfinal

296 1 5.9 x 10−7

(analysis)0.5 3.6 x 10−4 2 2.3 x 10−44

SuperCDMS Soudan

296 1 1.9 x 10−7

(mZIP)0.17 1.2 x 10−4 6 5 x 10−45

SuperCDMS SNOLAB

90(CDMS I rate)

0.3internal shield, better stock

< 1.7 x 10−8

(iZIP)< 0.014 1.5 x 10−6 > 250 3 x 10−46

GEODMDUSEL

90(CDMS I rate)

0.3internal shield, better stock

< 1.2 x 10−11 ?(iZIP)

< 10−5 ? 1.1 x 10−9 ? > 3.3 x 105 ? 2 x 10−47

reduction of raw background rate via better shielding/reduced contamination

improvement in background rejection via better discrimination


Backgrounds and Background Rejection: Betas

• Surface events from low-energy beta decays• Significant reductions in raw rate/kg-d from reduced surface area/volume ratio

and best CDMS II detector 210Pb rate• More significant improvements in background rejection via iZIP• No reduction in 210Pb beyond already achieved is required!

16

StageRate

[/kg/d]Relative

RateSgl. Scatter x Misid. Prob.

Relative Misid. Prob.

Misid. Rate [/kg/d] Gain σgoal [cm2]

CDMS II published

3.4 1 1.0 x 10−4 1 7.6 x 10−4 1 4.5 x 10−44

CDMS IIfinal

3.4 1 5.3 x 10−5

(analysis)0.5 3.8 x 10−4 2 2.3 x 10−44

SuperCDMS Soudan

0.83x0.6 210Pb

2.5cm thickness

0.25 4.4 x 10−5 (mZIP)

0.42 7.9 x 10−5 10 5 x 10−45

SuperCDMS SNOLAB

0.603.5cm thickness

0.18 < 5 x 10−6

(iZIP)< 0.05 < 3 x 10−6 250 3 x 10−46

GEODMDUSEL

0.415cm thickness

0.12 < 5 x 10−9 ?(iZIP)

< 5 x 10−5 ? < 2 x 10−9 ? > 3.7 x 105 ? 2 x 10−47

reduction of raw background rate via better shielding/reduced contamination

improvement in background rejection via better discrimination


Backgrounds and Background Rejection: Neutrons

• Radiogenic neutrons: U/Th fission and (α,n)• Cryostat Cu:

• 0.2 ppb U, 0.6 ppb Th currently, predicts 7.4 x 10-5 single n/kg/day, expected to be the limiting bgnd for SuperCDMS Soudan

• Electroformed Cu should have < 0.1 ppt U/Th (EXO < few ppt already demonstrated);don’t need underground fab

• Pb in shield• 50 ppt upper limit on U/Th in existing shield, expected levels much lower• 1 ppt U/Th (Heusser upper limit) yields 6 x10-6 single n/kg/day for SuperCDMS Soudan;

ok for SNOLAB, need to improve upper limit by x15 for GEODM• Polyethylene:

• 0.2 ppb U, 0.2 ppb Th upper limits on existing material yield 1.6 x 10-5 single n/kg/day• Need

improved poly (x3 and x45) or replace with water

17

Stage Rate[/kg/d]

Relative Rate

Gain σ [cm2]

CDMS II published 1.2 x 10−4 1 1 4.5 x 10−44

CDMS II final 1.2 x 10−4 1 1 2.3 x 10−44

SuperCDMS Soudan 1.2 x 10−4 1 1 5 x 10−45

SuperCDMS SNOLAB 6.0 x 10−6 0.05 20 3 x 10−46

GEODM DUSEL 4.0 x 10−7 0.003 300 2 x 10−47


Backgrounds and Background Rejection: Neutrons

• Cosmogenic neutrons: • cosmic-ray muon spallation

of nuclei in rock walls• muon rate is >1000x lower

than Soudan at DUSEL 7400 ft level• showering greatly aids in vetoing• Would need to go to DUSEL

7400 ft level to reduce cosmogenicvs. SNOLAB

18

Depth (mwe)Lo

g 10(

Muo

n Fl

ux)

(/m

2 /s)

DUSEL 7400 ft = 7000 mwe

DUSEL 4850 ft = 4200 mwe

Soudan= 2000 mwe


Reducing Backgrounds: SNOLAB/GEODM Cryostat/Shield

19

SNOLAB design

50 cm cold dimension(150 kg)

inner shielding layer internal to cryostat vacuum wall• allows stronger/

thicker vacuum wall• keeps final layer of

shielding clean• reduces mass of

final shield (esp. Pb)

internal moderator

internal ancient

Pb shield

cryogen-freedilution

refrigerator

expandedtails for betteraccess/pumping

cryocooler on electronics

feedthrough stem

scale to 100 cm cold dimension for 1.5T GEODM


• Costs for fab and test; product = detector ready for installation in experimentHas driven experiment cost in past.

Reducing Cost/Time: Doing the Numbers

20

CDMS II SuperCDMS Soudan

SuperCDMS SNOLAB GEODM

Cost basis actual approved to be proposed

totalmass 4 kg 16 kg 105 kg 1500 kg

# detectors, mass 16 x 0.25 kg(+ 14 x 100g Si) 25 x 0.64 kg 70 x 1.5 kg 300 x 5.1 kg

cost/detector $200K-$300K $225k $225k $120k

rate [det/mo] 0.5-0.75/mo 1/mo 2/mo 8/mo

cost/kg $800k-1200k $350k $150k $24k

rate [kg/mo] 0.1-0.2 kg/mo 0.64 kg/mo 3 kg/mo 40 kg/mo

totaldetector cost

$4.8M (+ $4.2M) $5.6M $16M $36M

totaldetector time

2.7 yrs(+ 2.3 yrs) 2 yrs 3 yr 3 yrs


Status/Schedule

• CDMS II: • data taking complete• final analysis proceeding, expected to be out this fall

• SuperCDMS Soudan:• First 3.2 kg of detectors installed in Soudan (along with existing 2.4 kg),

second 3.2 kg of detectors fab’d and awaiting surface testing• Approved in Aug 2008 to fab remaining 9.6 kg of detectors and run for 2 yrs

21

Activity Name 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

CDMS IIOperations

4kg, 2E-44 cm2Expected Sensitivity

SuperCDMS SoudanDetector R&D

Construction

Operations

Expected Sensitivity 15 kg, 5E-45 cm2

SuperCDMS SNOLABDetector R&D

Construction

SNOLAB facility

~100 kg detectors

Operations

Ramp up to ~100 kg

Expected Sensitivity

100 kg sensitivity 100 kg, 3E-46 cm2

GEODMConceptual Design

Technical Design

Construction

Operations

DUSEL Construction Start

DUSEL 4850'

DUSEL 7400'

Expected Sensitivity = 2E-47 cm2

1500 kg, 2E-47 cm2


SuperTower 1 Running at Soudan!

• ST1 installed April 16, 2009, cold June 4, and in stable running by Aug 1• Best 3/5 of CDMS II also remains in place: total 4 kg → 5.6 kg

• 210Po α rate verified; surface-event rates and rejection need more data• will run ST1 alone until ST2-5 ready

22

Preliminary!

J. H

all,

L. H

su


Status/Schedule

• SuperCDMS SNOLAB:• R&D funding likely in FY10, proposal to be submitted in FY10 for FY11 start• Cryostat/shield and electronics design proceeding at FNAL under base funding;

critical to get release of funds to order long-lead-time dilution refrigerator ASAP• SNOLAB is enthusiastic, space has been set aside, initial test setup in FY10• Overlap with DUSEL provides prototyping in v. similar environment

23

Activity Name 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

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24

25

26

27

28

29

30

CDMS IIOperations



Construction

Operations



Construction

SNOLAB facility

~100 kg detectors

Operations

Ramp up to ~100 kg




Technical Design

Construction

Operations


DUSEL 4850'

DUSEL 7400'


1500 kg, 2E-47 cm2


Status/Schedule

• DUSEL GEODM• Design through 2014• Construction 2015-2017

• 7400 ft level occupancy in 2018 would be a substantial delay; were aiming for 2017• Operations 2018-2021 (4 yrs running)

24

Activity Name 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

1

2

3

4

5

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7

8

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13

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30

CDMS IIOperations



Construction

Operations



Construction

SNOLAB facility

~100 kg detectors

Operations

Ramp up to ~100 kg




Technical Design

Construction

Operations


DUSEL 4850'

DUSEL 7400'


1500 kg, 2E-47 cm2


Status/Schedule

• DUSEL GEODM• Conceptual design and initial cost estimate ($50M construction) in hand• DUSEL S4 engineering study phase

• $2.1M proposed over 3 yrs, $1.3M funded • Goal: arrive at “preliminary design” of experiment by end of funding in 2012,

with infrastructure needs incorporated in DUSEL preliminary design in 2010.• SNOLAB development work under DOE R&D and NSF/DOE project funding would

also contribute positively ‣ Completion of SNOLAB cryostat/shield design (scale-up for GEODM)‣ Study of active neutron veto for SNOLAB (radiogenic backgrounds)‣ Development of SLAC and TAMU fab capabilities and testing setup‣ Reengineering of cold hardware for iZIP, better reliability, easier fabrication‣ Screening of materials with aim to SNOLAB and GEODM needs

25


Conclusions

• CDMS II reaching successful completion• SuperCDMS Soudan ramping up

• 7.5-cm x 2.5-cm ZIP, 15 kg, 5 x 10-45 cm2

• ST1 installed and 210Po verified, ST2 to be tested• approved for ST3/4/5 + science running• reach: 5 x 10-45 cm2

• SuperCDMS SNOLAB to be proposed soon• 10-cm x 3.5-cm iZIP, 105 kg, 3 x 10-46 cm2

• new SLAC involvement

• GEODM• 15-cm x 5-cm iZIP, 1.5T, 2 x 10-47 cm2

• conceptual design in place• preliminary design beginning• fleshing out lab interface details for DUSEL PDR

26


Caltech: S. R. GolwalaFermilab: D. A. Bauer, R. SchmittMIT: E. Figueroa-FelicianoNIST: K. IrwinQueens University: W. Rau, P. di StefanoSanta Clara University: B. A. Young SLAC National Accelerator Lab: E. do Couto e Silva, J. WeisandSouthern Methodist University: J. CooleyStanford University: P.L. Brink, B. Cabrera, S. YellinSt. Olaf College: A. ReisetterSyracuse University: R.W. SchneeTexas A&M: R. Mahapatra, M. PlattUniversity of California, Berkeley: N. Mirabolfathi, B. Sadoulet, D. SeitzUniversity of Colorado at Denver: M. E. HuberUniversity of Florida: T. SaabUniversity of Minnesota: P. Cushman, V. Mandic

The GEODM Collaboration

27

The Germanium Observatory for Dark Matter (GEODM)...overall misid 10-4 → < 3 x 10-7, far better than needed for GEODM 12 M. Pyle, B. Serfass Yield Recoil Energy [keV] 0 10 20 30

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