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Low Energy WIMP Search Results from

CDMSLauren Hsu

Fermilabfor

the CDMS CollaborationSlide material contributed by David Moore

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Low Mass WIMPs

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Lowering the CDMS Threshold• Lowering analysis threshold below 10 keV yields sensitivity to low

mass WIMPs in region of contention.• The cost = sacrifice some background rejection due to worsening

timing resolution. Accept > 1 event background.

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Low Threshold Dataset

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Energy Calibration

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Candidate Events

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90% C.L. Limits

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Background Composition

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Comparison to CoGeNT Data

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Naive Energy Rescaling

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Summary• Presented analysis of CDMSII data with threshold

lowered from 10 to 2 keV• Backgrounds present in this analysis have been

characterized. No excess events over expected background were observed

• Despite no background subtraction, observed rate of events is incompatible with interpretation of CoGeNT and DAMA data as evidence for spin-independent elastic scattering of WIMPs

• Compatibility between CDMS and CoGeNT data requires majority of CoGeNT excess to be due to background and unexpectedly small CDMS background

Ahmed et al., PRL 106 131302 (2011), arXiv: 1011.2482

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Shallow Site Comparison

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Zero Charge Events

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Background Composition

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Candidate Events

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Rate by Detector

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CDMSLITE

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