Status of the CRESST Dark Matter Search Anja Tanzke - - PowerPoint PPT Presentation

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Status of the CRESST Dark Matter Search Anja Tanzke - - PowerPoint PPT Presentation

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Status of the CRESST Dark Matter Search Anja Tanzke Max-Planck-Institute for Physics YSW Ringberg 2015, 7.7.2015 Detector Module light detector (with TES) reflective and scintillating housing target crystal TES holding clamps

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SLIDE 1

Status of the CRESST Dark Matter Search

Anja Tanzke

Max-Planck-Institute for Physics

YSW Ringberg 2015, 7.7.2015

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SLIDE 2

Detector Module

reflective and scintillating housing light detector (with TES) target crystal TES holding clamps

Non-scintillating surfaces on reflective bronze holding clamps!

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 2 / 20

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SLIDE 3

Background from surface contamination with 210Po

210Po → 206Pb(103 keV) + α (5.3 MeV)

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 3 / 20

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SLIDE 4

Background from surface contamination with 210Po

210Po → 206Pb(103 keV) + α (5.3 MeV)

crystal clamp 1

Decay inside clamp material

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 3 / 20

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SLIDE 5

Background from surface contamination with 210Po

210Po → 206Pb(103 keV) + α (5.3 MeV)

crystal clamp 1

Decay inside clamp material

2

Decay on or slightly below surface of clamp (a) α hitting clamp → no scintlillation light

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 3 / 20

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SLIDE 6

Background from surface contamination with 210Po

210Po → 206Pb(103 keV) + α (5.3 MeV)

crystal scintillator 1

Decay inside clamp material

2

Decay on or slightly below surface of clamp (a) α hitting clamp → no scintlillation light (b) α hitting scintillating material → additional scintlillation light (with different

pulse shape)

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 3 / 20

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SLIDE 7

CRESST-II Phase 2

Data-taking since July 2013 18 detector modules (5 kg target mass) Upgraded Detector Modules: 3 new detector designs Focus on one detector module TUM40

29 kg days of data nonblinded data set from August 2013 to December 2013

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 4 / 20

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SLIDE 8

TUM40

light detector (with TES) target crystal reflective and scintillating housing

conventional module

crystal held by non-scintillating reflective bronze clamps

TUM40

crystal held by CaWO4 sticks pressed by clamps outside the reflective housing → fully-scintillating housing

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 5 / 20

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SLIDE 9

Veto of Surface Events

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 6 / 20

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SLIDE 10

Veto of Surface Events

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 7 / 20

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SLIDE 11

TUM40: Radiopurity

CaWO4 crystal production at TUM improvement of e−/γ background below 50 keV by a factor of 2-10 TUM40: average rate 3.44/(kg keV day) γ-lines caused by cosmogenic activation Energy resolution σ ∼100 eV all lines agree within <5 eV to tabulated values

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 8 / 20

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SLIDE 12

TUM40: Trigger Threshold

extremely low trigger threshold of Eth ∼ 603 eV

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 9 / 20

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SLIDE 13

TUM40: Results after 29 kg days

Fully-efficient veto of surface backgrounds Unprecedented radiopurity Very low trigger threshold of ∼600 eV Excellent resolution of ∼100 eV → Low-threshold Dark Matter analysis

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 10 / 20

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SLIDE 14

Low Threshold Analysis - Motivation

WIMP Mass (GeV) 1 10

2

10

3

10 Counts per kg d and pb 1 10

2

10

3

10

4

10

5

10

6

10

O W Ca 10-40keV 10-40keV

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 11 / 20

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SLIDE 15

Low Threshold Analysis - Motivation

WIMP Mass (GeV) 1 10

2

10

3

10 Counts per kg d and pb 1 10

2

10

3

10

4

10

5

10

6

10

O W Ca 1-40keV 10-40keV 10-40keV

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 11 / 20

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SLIDE 16

TUM40: Acceptance Region

WIMP-Acceptance region:

600 eV < E < 40 keV LY < 50% O-band

all events are considered as WIMP scatters

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 12 / 20

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SLIDE 17

WIMP-Landscape Summer 2014

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 13 / 20

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SLIDE 18

Results from 29 kg days of TUM40

M2 completely ruled out New parameter space explored for WIMP masses below 3 GeV/c2

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 13 / 20

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SLIDE 19

Data vs. Simulation

M2 completely ruled out New parameter space explored for WIMP masses below 3 GeV/c2 Events in acceptance region can be explained with e−/γ background only

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 13 / 20

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SLIDE 20

Goal for CRESST II Phase 2

500 kg days reached end

  • f May

threshold of several detectors lowered <400 eV → further improvement in low mass WIMP region possible Analysis strategy: use non-blinded data set (115 live days) for definition of data quality cuts, trigger efficiencies and selection of detectors Apply to blinded data set (since January 2014)

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 14 / 20

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SLIDE 21

Future Strategy for CRESST III

CRESST proved high potential for low-mass WIMP search → Increase Performance of detectors

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 15 / 20

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SLIDE 22

CRESST III: Low-mass WIMP search

Increase performance of detectors with small crystals (m∼24 g) with at least TUM40 quality

scale down size by a factor of 10 TUM40 m=250g m=24g

phonon detector threshold ∼ 400 eV improvement by factor of 5 light detector resolution ∼ 5 eV improvement by factor of 2

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 16 / 20

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SLIDE 23

CRESST III: Detector modules for low-mass WIMP search

light detector (with TES) block-shaped target crystal reflective and scintillating housing CaWO4 stick (with holding clamps)

Prototype successfully tested (threshold of 100 eV reached) Production of detector modules ongoing CRESST III will start end of this year

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 17 / 20

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SLIDE 24

Projection for CRESST III Phase 1

CRESST III Phase 1

50 kg days: 10 small crystals (m=24 g) operated for 1 year

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 18 / 20

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SLIDE 25

Projection for CRESST III Phase 2

CRESST III Phase 2

1 tonne days: 100 modules, 2 years crystal radiopurity improved by a factor of 100

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 19 / 20

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SLIDE 26

Conclusions

CRESST II Phase 2

CRESST technology proved high potetial for low-mass WIMP search CRESST II Phase 2 probed new region of parameter space below 3 GeV/c2

CRESST III

Potential to explore low-mass WIMP region Starting end of 2015

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 20 / 20

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SLIDE 27

Backup Slides

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 20 / 20

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SLIDE 28

Crystal Growth via Czochralski Method

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 20 / 20

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SLIDE 29

Radon decay chain

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 20 / 20

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SLIDE 30

Multi-Element Target CaWO4

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 20 / 20

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SLIDE 31

TUM40: Cut Efficiency

  • A. Tanzke (MPP)

Status of CRESST YSW Ringberg 2015 20 / 20