1. Harry Nelson UCSB DUSEL Henderson at Stony Brook May 5, 2006
CDMS/SuperCDMS
Harry Nelson
UCSB
DUSEL Henderson at Stony Brook
May 5, 2006

2.  0 WIMP Direct Detection Signal Background Er Er Density/Sparsity
Electron
Recoils
Background
v/c  0.3
Sparse Energy Deposition Er
Nucleus
Recoils Er
v/c  10-3
Dense Energy Deposition
v/c small; <Bragg
Neutrons same, but 1020 higher – eliminate by going deep, shielding well 0
Density/Sparsity
Basis of Discrimination
5/4/2006
Stonybrook DUSEL Workshop

3. Stonybrook DUSEL Workshop
Out of date (2002)… the impact of background
10-39
10-40
CDMS - 16 kg-d
(at shallow site)
Edelweiss - 12 kg-d
ZEPLIN I kg-d
DAMA - 58,000 kg-d
WIMP – nucleon  (cm2)
10-41
10-42 1 10
100
1000
104
Mass (GeV)
5/4/2006
Stonybrook DUSEL Workshop

4. Sort of Deep Facility Soudan Mine Hosts: State of Minn., U Minn.,
Fermilab
690 meters underground
2090 meters water equivalent
5/4/2006
Stonybrook DUSEL Workshop

5. Stonybrook DUSEL Workshop
5/4/2006
Stonybrook DUSEL Workshop

6. Stonybrook DUSEL Workshop
A Cold Heart
Results from first…
ZIP 1 (Ge)
ZIP 2 (Ge)
ZIP 3 (Ge)
ZIP 4 (Si)
ZIP 5 (Ge)
ZIP 6 (Si)
4 K
0.6 K
0.06 K
0.04 K
SQUID cards
FET cards
14C
poorer resolution
Two `towers’
6 detectors…
10 cm
Tower 1: 4 Germanium (0.25 kg each), 2 Silicon (0.1 kg each)
5/4/2006
Stonybrook DUSEL Workshop

7. First Year of Running CDMS II at Soudan
Oct Jan “Tower 1”
53 livedays, 1 kg Ge, 0.2 kg Si
Mar.-Aug “The Two Towers”
74 livedays 1.5 kg of Ge, 0.6 kg of Si
More Barium Calibration
Date
Towers 1 & 2
Tower 1
Livetime (days)
5/4/2006
Stonybrook DUSEL Workshop

8. Nuclear Recoil bad at making Ionization0
Holes e-
Germanium
more ionization!
Need a second, `fair’ measure of deposited energy… sound! 
Both deposit, say, 20 keV
5/4/2006
Stonybrook DUSEL Workshop

9. Separation of the types of recoils
Sound
5/4/2006
Stonybrook DUSEL Workshop

10. Stonybrook DUSEL Workshop
Latest Search Plot…
Small Circles: prior to surface rejection
beta emitters
Color: passing surface rejection
Star: one candidate
5/4/2006
Stonybrook DUSEL Workshop

11. Stonybrook DUSEL Workshop
Surface rejection
2 based analysis significantly improves the surface event rejection
CDMS will not be background limited soon. Can indefinitely tighten cuts with increased exposure to maintain a discovery potential
Surface events from calibration source
neutrons from calibration source
5/4/2006
Stonybrook DUSEL Workshop

12. Two Papers Just Published
5/4/2006
Stonybrook DUSEL Workshop

13. New Limits (Spin Independent)
Silicon: low mass
90% CL
About twice more sensitive than 1-tower
5/4/2006
Stonybrook DUSEL Workshop

14. Stonybrook DUSEL Workshop
The Near Future
Installed 3 additional towers in November
CDMS- Soudan
CDMS -projected
Edelweiss
ZEPLIN-1
PRELIMINARY
Improvements
Cryogenics, backgrounds, DAQ
Currently commissioning
30 detectors in 5 towers of 6
4.75 kg of Ge, 1.1 kg of Si to run through 2007
Improve sensitivity x10
Last fall we installed 18 additional detectors in 3 additional towers, for a total of 4 kilograms of germanium. Running these 5 towers of detectors for 9 months should improve our sensitivity by another order of magnitude. (0:15)
5/4/2006
Stonybrook DUSEL Workshop

15. SuperCDMS: Move south to balmy Sudbury
Henderson
5/4/2006
Stonybrook DUSEL Workshop

16. Stonybrook DUSEL Workshop
5/4/2006
Stonybrook DUSEL Workshop

17. Stonybrook DUSEL Workshop
Scale up: 25 kg, 150 kg stages
25 kg 2008 start Soudan
2010/11 SNOLAB
150 kg – beyond 2011
5/4/2006
Stonybrook DUSEL Workshop

18. Stonybrook DUSEL Workshop
5/4/2006
Stonybrook DUSEL Workshop

19. Detectors in `Super Towers’
CDMS II ZIPs:
3” diameter x 1 cm = 0.25 kg Ge
SuperCDMS ZIPs:
3” diameter x 1” = 0.64 kg Ge
Thicker Detectors – less surface per volume
Revert electrode design – better rejection
5/4/2006
Stonybrook DUSEL Workshop

20. Stonybrook DUSEL Workshop
5/4/2006
Stonybrook DUSEL Workshop

21. Elements leading to increased sensitivity
Thicker Detectors
Less surface/volume, factor of 2.5
Better Analysis Rejection
Variety of improvements factor of 4
Cleaner Detectors
Lead-210… (?) Radon Daughter, factor of 10
Redesign detectors for better rejection
Factor of 10
Factor of 1000, total…
5/4/2006
Stonybrook DUSEL Workshop

22. Sensitivity Expectations: Distant Future
Jun 07
2009
5/4/2006
Stonybrook DUSEL Workshop

23. Projected Sensitivies
5/4/2006
Stonybrook DUSEL Workshop

24. Stonybrook DUSEL Workshop
Time Line
5/4/2006
Stonybrook DUSEL Workshop

25. Stonybrook DUSEL Workshop
Infrastructure
Lower Campus (neutrons)
20 m L  10 m W  10 m H (60  30  30 feet)
Liquid He and Nitrogen (compressor plant? 100 m2, 1000
sqft)
… cryocooling reducing need…
100 kVA electrical power
200 m3/minute air flow (6000 cfm)
low Radon capability (details need work)
5-ton crane
5/4/2006
Stonybrook DUSEL Workshop