1. Clarence Chang CDMS Collaboration Meeting Feb 11-12, 2005 UCSB
R118 Odds and Ends
Clarence Chang
CDMS Collaboration Meeting
Feb 11-12, 2005
UCSB

2. Outline
Efficiency variations in time
Leakage numbers
PRD

3. Outline
Efficiency variations in time
Leakage numbers
PRD

4. What we want to do
Estimate the impact on our efficiencies due to potential time variations and differences between calibration and WIMP search data
Problem : Few Nuclear Recoils in the WIMP search data
Proposal : Use Electron Recoils
Take pass fraction from ER band cut as estimate of variation in NR band cut efficiency
Need to be trickier with timing parameters
Bin WIMP search data into 5 time bins and compare with Cf data

5. Approach for Timing parameters

6. The Algorithim Fit NR and ER of Cf data to Gaussians
Fit ER of WIMP search data to Gaussian
Determine a shift and a stretech parameter to match Cf ER Gaussian to WIMP search Gaussian
ERµWIMP = ERµCf + ∆µ
ERWIMP = ERCf∆
Shift and Stretch timing parameter by
 = ( - NRµCf ) ∆ + NRµCf + ∆µ
What fraction passes the timing cut?

7. The Efficiencies

8. Relative Differences

9. Average over Time bins

10. Relative Difference (Averaged over time)

11. Outline
Efficiency variations in time
Leakage numbers
PRD

12. Single Scatter Gammas
From sample from which Timing cuts are not defined
Z1 : 1/21, ~ %
Z2+3+5 : 0/13,632 ( ) <0.017% (90% UL)
Single scatter gammas in WIMP search data
Z1 has 1,702 events
Z2+3+5 have 4,528 ( )
Expected 0.08 events (in Z1)

13. Neutrons MC simulations from Sharmila
Include more than MC for SUF… so have new numbers!
Coincident neutrons : 1.9 0.4
Anti-Coincident (punch through) neutrons : 0.05 0.02

14. Betas Using data from which timing cut is defined
Recoil Z1 Z2 Z3 Z5
10-20 -
0.11
0.16
0.08
20-40
0.03
0.25
0.12
40-100
0.02
0.1
0.04
Using data from which timing cut is defined
Recoil Z1 Z2 Z3 Z5
10-20 -
20-40
0.03
0.14
40-100
Using data from which timing cut is not defined

15. Expected leakage summary
Neutrons : 0.050.02
Ambient gammas : 0.07
Betas : 1.05 0.36

16. Outline
Efficiency variations in time
Leakage numbers
PRD

17. Blind vs Intended analysis?
What plots to show
Only Z5’s Qinner efficiency varies. All others the same. Will show difference for Z5 Qin. This is moot.
Both for overall efficiency and limits
Scatter plots? (blind, intended, both?)
Cut numbers? (blind, intended, both?)
Arguments for showing only intended analysis
Can anyone outside of me reconstruct the blind analysis easily? Are these RQs available? Will we make these RQs public?
Arguments for showing only the blind analysis
More consistent with PRL story
Still, really just arguing over wording
“Oh, you just f**ked up, but it didn’t matter…”