SuperCDMS at SNOLAB

Wolfgang Rau, Queen’s Universityfor the

SuperCDMS Collaboration

2

SUF, 10 mwe

Soudan, 2100 mwe

SNOLAB, 6000 mwe

1998 - 2002 CDMS I6 detectors1 kg Ge (30 kgd ) < 3.5e-42 cm2

2003 - 2013

CDMS II (until 2009) 30 detectors~4 kg Ge (300 kgd) < 3.5e-44 cm2

SuperCDMS @ Soudan~20 detectors 10-15 kg Ge (~1200 kgd) < 9e-45 cm2

2011 - 2017

SuperCDMS @ SNOLAB 80-90 detectors100 kg Ge (~35000 kgd) < 3e-46 cm2

SuperCDMS test facility @ SNOLAB (2011)

CDMS / SuperCDMS TimelineSuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010

exposures areafter all cuts!

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 3

SuperCDMS Collaboration

California Institute of TechnologyZ. Ahmed, J. Filippini, S.R. Golwala, D. Moore

Fermi National Accelerator LaboratoryD. A. Bauer, F. DeJongh, J. Hall, D. Holmgren, L. Hsu, E. Ramberg, R.L. Schmitt, J. Yoo

Massachusetts Institute of TechnologyE. Figueroa-Feliciano, S. Hertel, S.W. Leman, K.A. McCarthy, P. Wikus

NIST *K. Irwin

Queen’s UniversityC. Crewdson *, P. Di Stefano *, J. Fox *, S. Liu *, C. Martinez *, P. Nadeau *, W. Rau

Santa Clara UniversityB. A. Young

SLAC/KIPAC *M. Asai, A. Borgland, D. Brandt, W. Craddock, E. do Couto e Silva, G.G. Godrey, J. Hasi, M. Kelsey, C. J. Kenney, P. C. Kim, R. Partridge, R. Resch, J.G. Weisend, D. Wright

Southern Methodist UniversityJ. Cooley

Stanford UniversityP.L. Brink, B. Cabrera, M. Cherry *, R. Moffatt*, L. Novak, R.W. Ogburn , M. Pyle, M. Razeti*, B. Shank*, A. Tomada, S. Yellin, J. Yen*

Syracuse UniversityM. Kos, M. Kiveni, R. W. Schnee

Texas A&MK. Koch*, R. Mahapatra, M. Platt *, K. Prasad*, J. Snader

University of California, BerkeleyM. Daal, T. Doughty* , N. Mirabolfathi, A. Phipps, B. Sadoulet, D. Seitz, B. Serfass, D. Speller*, K.M. Sundqvist

University of California, Santa BarbaraR. Bunker, D.O. Caldwell, H. Nelson

University of Colorado DenverB.A. Hines, M.E. Huber

University of FloridaT. Saab, D. Balakishiyeva, B. Welliver *

University of MinnesotaH. Chagani*, J. Beaty, P. Cushman, S. Fallows, M. Fritts, T. Hoffer*, O. Kamaev, V. Mandic, X. Qiu, R. Radpour*, A. Reisetter, A. Villano*, J. Zhang

University of ZurichS. Arrenberg, T. Bruch, L. Baudis, M. Tarka* new collaborators or new institutions in SuperCDMS

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 4

Overview

• CDMS Technology

• SuperCDMS at Soudan

• iZIP Detectors

• SuperCDMS at SNOLAB

• SuperCDMS Detector Test Facility at SNOLAB

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 5

CDMS Technology

Thermal couplingThermalbath

Phonon sensor

Target

+++ +

-- --

++

+ +

-- - - -

- -

++ +en

Phonon energy [keV]

Ioni

zatio

n en

ergy

[keV

eeq

]

Nuclear recoilsfrom neutrons

Electron recoilsfrom β’s and γ’s

• Phonon signal: measures energy deposition

• Ionization signal: distinguishes between electron (large) and nuclear recoils (small)

• Surface events have reduced ionization: need additional information to identify

Phon

on s

igna

lCh

arge

sig

nal

Electron recoil Nuclear recoil

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 6

SuperCDMS at SoudanDetectors

New detectors: • larger mass (240 g 610 g), larger volume-to-surface ratio (x 2.5)• New phonon sensor design: mZIP

improve position reconstruction and pulse shape discrimination for surface events• New electrode design: iZIP

discriminate surface events based on charge distribution between electrodes• iZIPs have more readout channels per detector (both, phonon and charge sensors

on top and bottom) than mZIPs fewer detectors, but larger fiducial volume/detector

ZIP

mZIP

iZIP

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 7

SuperCDMS at SoudanStatus

Status at Soudan:• mZIP detectors tested underground (2009), data analyzed, performance satisfactory• iZIP detectors: test run underground will start this fall

tests so far (above ground) indicate MUCH better discrimination

Next Dark Matter Run• Probably using both, mZIP and iZIP• Start with full pay load in summer 2011• ~20 detectors, 10-15 kg Ge• Expected sensitivity: 5e-45 cm2

(spin-independent WIMP-nucleon cross section)

15 kg @ Soudan

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 8

iZIP Technology

Basic configuration

+3 V 0 V

-3 V 0 VElectric field calculation

Phonon sensors on top and bottom

Mostly neutron background

Recoil energy [keV]

Ioni

zatio

n yi

eld

Surface events

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 9

SuperCDMS at SNOLAB

Milestone (DOE) FY2010 FY2011 FY2012 FY2013 FY2014

CD-0 mission need 10/1/10

CD-1 prelim. design, cost range 10/1/11

CD-2 baseline design and cost 10/1/12

CD-3 start of construction 10/1/12

CD-4 start of operations 10/1/14

• Scientific goal: sensitivity for WIMP-nucleon interaction cross section of 3e-46 cm2

• Target mass: ~100 kg of germanium• Total exposure: ~100 kg y• Detector type: 100 mm diameter iZIPs• Number of detectors: 75-100• Start of construction possible in 2012 (subject to positive funding decision)• Start of operation in 2014

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 10

Detectors

CD-010/10

CD-110/11

CD-2/310/12

CD-410/12

SuperCDMS@ Soudan

: 3”h: 1”

SuperCDMS@ SNOLAB: 100 mmh: 33 mm

CDMStower

SuperCDMS @ SNOLABtowers

iZIP 100 mmionization test

New ReadoutDevelopment

Engineering Model

Operation

Install towers

Detector Production

Design improvements

First SuperCDMS100 mm Ge crystal

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 11

Cryogenics and Shield Layout

• Cryogen free dilution refrigerator save on He cost and operations

• Pb and inner poly within the OVC minimize contamination of shield / external gamma background

• Thick copper cans provide clean shielding

• Removable inner can mount detectors in ultra-clean room: minimize exposure to Rn / dust

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 12

Ladder LabTentative Layout

SuperCDMS100 kg experiment

Utilities

Utilities

TF

PICASSO

COUPP60 kg

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 13

SuperCDMS Test FacilityMotivation

• Need to quantify strongly improved background discrimination• iZIPs seem to be good enough, BUT cannot be tested in above ground facility

Need underground facility with very good neutron shielding

• Larger detectors have longer pulses• Interaction rate from environmental gammas increases with mass• Leads to pile-up, may not be able to operate detectors above ground at all

Need underground facility with good gamma shielding

• May be able to use test facility at SNOLAB with variable shielding to study neutron environment (input for SuperCDMS shielding design or background Monte Carlo simulations)

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 14

Cab

S uperC DMSU ndergroundN eutronfreeC ryogenic

T estF acility

Water Tank

New Cu Tails

Cryostat Gas handling

Pumps

SuperCDMS Test FacilityConcept

Mag

netic

Shi

eldi

ng

He

Liqu

efier

LN L

ique

fier Will be replaced

by new remote controlled system

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X X

(X) X X X X X X

X X (X) X X (X) (X) X

(X) X X (X) X X (X) (X)

X X X X

(X) X X X

Man

agem

ent

Tails

Ther

momet

ryAut

omati

onGas

hand

ling

Lique

fiers,

impl.

Mag

netic s

hieldi

ng

Shiel

ding (

tank

)Dry

well, d

eck

Cold ha

rdwar

e

Detec

tor W

iring

SUF c

ryoge

nic te

st

FNAL s

yste

m test

SNOLA

B wor

k

Berkeley

FNAL

Queen’s

SLAC

SNOLAB

Stanford

SuperCDMS Test FacilitySystems / Tasks

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 16

SuperCDMS Test FacilitySchedule

June 2011

December 2010Shipping to FNAL

September 2010Start SUF work

SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 17

Conclusions

SuperCDMS @ Soudan:• First engineering run completed• Second engineering run 2010/11• Restart dark matter search in 2011• iZIPs performance promising

SuperCDMS @ SNOLAB• Design is well underway• Entering DOE’s CD process hopefully later this year• Earliest possible start of construction: 2012• Start of operation: 2014

SuperCDMS Detector Test Facility at SNOLAB• Cryostat refurbishment underway• Most system components are at hand• Few open questions (magnetic shielding, detector wiring)• Commissioning at SNOLAB: mid 2011