Present and Future Cryogenic Dark Matter Search in

Europe

Wolfgang Rau, Technische Universität München

CRESST

EURECAEURECA

ryogenicareventearch withuperconductinghermometers

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 2

CRESST• Max-Planck-Institut for physics (Munich)• Technical University Munich• University of Oxford• Laboratori Nazionali del Gran Sasso• University of Tübingen• University of Warwick

EDELWEISS• CEA-Saclay DAPNIA/DRECAM• CRTBT Grenoble• CSNSM Orsay• FZK/Univ. Karlsruhe• IAP Paris• IPN Lyon• Laboratoire Souterrain de Modane

EURECA + CERN + MPIK (Heidelberg) + ...

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 3

ILIASIntegrated Large Infrastructures for Astroparticle Science

• Financed by EU• Infrastructure for astroparticle physics in

Europe (not complete, but a good start)• Contains different structures:

– Networks (Dark Matter, Double Beta, Underground Science, Gravitational Waves, Theory)

– Joint Research Activities (Double Beta, Low Background, Gravitational Waves)

– Transnational Access (Underground laboratories)

• 12 Countries, 20 Contractors / ~140 Institutes, > 1000 scientists

• Forum for discussion of future plans in Europe

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 4

Overview

• CRESST– Technique– Status– Next Future

• EDELWEISS– Technique– Status– Next Future

• EURECA– Idea– Plans– Status

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 5

CRESST – TechniqueW-TES: (Tc = 6-10 mK)

Heater for stabilization (DC)and calibration (test pulses)

6 8 mm²

Al contact

W

Au heater

Target: CaWO4

• Cylindrical, /h: 4 cm• Mass: 300 g• Light output: ~1 % (’s)

Thresholds• Phonons: 2 keV• Light: 20 eV

~2 keVee• Discrimination: 12 keV

Light detector• 30 30 0.4 mm Si

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 6

CRESST – Technique

W-band

-band

Recoil energy

Lig

ht e

nerg

y

Quenching

• Different light yield for different nuclei (O, Ca, W)?

Two experiments to measure Quenching (so far room temp.):• Neutron scattering• Ion beamBoth indicate: less light for heavy nuclei

Additional support from data

ReflectorC

aWO

4

• -band between - and n-band• recoiling nuclei from -decay

-band

n-band

• Nuclear recoil less light than electron recoil!

(O)

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 7

CRESST – Technique

3600 m w.e.

Gran Sasso

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 8

CRESST – Status

Spring 2004: 2 months run with 2 detectors

sensitivity limited by neutrons

if high QF applies for WIMP recoils:

results comparable to EDELWEISS (10-6 pb)

Light

yie

ld

Run 28, Daisy

Energy in Phonon Channel [keV]

Light

yie

ld

Energy in Phonon Channel [keV]

Run 28, Julia (bad light resolution)

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 9

CRESST – StatusSince April 2004: upgrade• Install neutron moderator

(30-50 cm PE, 11 t); µ-veto• Increase number of readout

channels (4 66)• Enlarge target mass

(600 g 10 kg)

Shielded cryostat

PE neutron moderator

Plastic scintill. -veto66 SQUIDs on

He-flange

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 10

CRESST – Next Future

• Finish major work by beginning of 2005

• Restart with few detectors

• Install new detector holder late spring

• Increase target mass to 10 kg within 2005

• Situation in Gran Sasso not clear(major construction work expected – influence on CRESST so far unknown)

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 11

EDELWEISS - TechniqueTarget:cyl. Germanium crystal, 320 g 7.0 cm, height 20 mm (beveled)

Ionization: Inner disk / outerring (“guard”)with -Si / -Ge

Thermal:NTD(~ 20 mK)

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 12

EDELWEISS - Technique

Thresholds Heat: 0.4 – 2 keV Ionization: 1.1 – 1.5 keV Analysis

Ion. trigger: 20 – 30 keVPhon. trig.: 15 keV

Resolution Heat: 0.6 – 2 keV @ 10 keV

2 – 4 keV @ 122 keV Ion.: 2 – 3 keV @ 122 keV

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 13

EDELWEISS - Status

Ion. trigger• 20 kg d• Thr:

20/30 keV• 3 events

Phonon trigger• 22 kg d• Thr:

15 keV• 18 events• 1 coinc. (n-n)

2000 – 2003: 62 kg d, 40 events (only 3 for 30–100 keV)

2003 Data (3 new detectors)

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 14

EDELWEISS - StatusNbSi sensors for athermal phonons

• NbSi: metal-isolator transition (high R)

• 2 surfaces covered (ionization + heat sensors)

• Two-component signal: - Thermal (energy)- Athermal (surface

discrimination)• Successful test with

200 g modules in EW I:

- 90 % rejection- 50 % efficiency

Outer electrodeNbSi meander

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 15

EDELWEISS – Next Future

• Aim for sensitivity improvement 100

• Installation started 04/04 – expected to finish summer 05

• 1st phase: 21 NTD detectors (320 g), 7 NbSi detectors (400 g)

Edelweiss II @ Modane (4800 m w.e.)

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 16

EDELWEISS – Next Future

• Large new cryostat – low activity– inverse geometry– up to 120 detectors

• Improved shielding – 20 cm lead– 50 cm PE– Muon veto

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 17

EURECA

uropeannderground

arevent search with

alorimeterrray

EURECA

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 18

EURECA – Idea

• Next generation DM search to explore most of SUSY parameter space

• Cryogenic experiments very promising

• Target mass in the 1 ton range

• Different targets (WIMP signature)

• Collect European competence

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 19

EURECA – Plans

• Discriminating cryogenic detector to reach a sensitivity 10-10 pb for coherent interaction

• Better sensitivity for spin-dependent interaction• Design study to investigate requirements and

technical challenges:– Detector development (larger modules, better

discrimination, other targets)– Optimal shielding strategies– Background reduction (handling/cleaning) and

modeling (Monte Carlo simulations)– Cryogenics, electronics, cabling, DAQ

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 20

EURECA – Plans

Structured in Working groups:• Detector Development• Low Radioactivity• Neutron Background, µ-veto and Shielding• Cryogenics• Cabling• DAQ• Underground site issues

ILIAS

ILIAS

Wolfgang Rau, TUM Future Direct Detection, Chicago 12/04 21

EURECA – Status

• Letter of Intent to ApPEC summer 2004

• Start proposal process September 2004

• Present Proposal to ApPEC January 2005

• Present Proposal to Funding Agencies

• Start work 2005/06 ???