supercdms at snolab wolfgang rau, queen’s university for the supercdms collaboration
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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
SuperCDMS at SNOLAB – W. Rau – SNOLAB workshop 2010 15
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