Present and future activities of the Garching group (E15)

JRA1 meeting Paris 20.02.2007 J.-C. Lanfranchi

E15 cryogroup:

CRESST, EURECA, CNNS

F. von FeilitzschW. PotzelJ.-C. LanfranchiW. Westphal (PhD)C. Coppi (PhD)Ch. Isaila (PhD)Ch. Ciemniak (PhD)S. Pfister (PhD)S. Roth (Dipl.)A. Gütlein (Dipl.)H. Hagn (Tech.)

E15 scintillator development:

BOREXINO, DoubleCHOOZ, LENA

F. von FeilitzschL. OberauerW. PotzelM. Goeger-NeffT. Marrodan (PhD)M.Wurm (PhD)J. Winter (Dipl.)T. Wiebke (Dipl.)P. Pfahler (Dipl.)M. Hofmann (Dipl.)H. Hagn (Tech.)

SFB375 (finished), TR27 ‚Neutrinos and Beyond‘ (transregional researchprogram)excellence cluster ‚Structure and Origin of the Universe‘

Reflectorca. 5-50 mK

CaWO4-Crystal

SPT (Superconducting Phase-transition-Thermometer)

Phonon-detector

Silicon-Substrate

SPT Light-detector

CRESST Detector Development

heat + scintillation light measurement for background rejection

@ E15:

- reproducibility of W and Ir/Au SPTs- CaWo4 crystal growth / radiopurity aspects- enhancement of light detector via Neganov-Luke effect- test of detector modules in UGL Garching

Crystal Growthproduction of CaWO4 crystals (PhD, Ch. Ciemniak)for CRESST ( EURECA?)

collaborational work with crystallab in Garching (Dr.A. Erb)

investigation of scintillating properties

investigation of radiopurity

first cryodetector made from such a crystal in preparation

Scintillation light

Phonons E lectron-hole pairs

T herm al signal Charge drift and co llection by

the applied vo ltage

Generation of additionalN eganov-Luke phonons

Am plification of thetherm al signal

Combination of the calorimetric and the ionization measurement techniques

Light Detectors with Neganov-Luke Amplification

Neganov-Luke Effect: charges drifting across the detector generate heat

by measuring this heat the amount of ionization can be determined

Present detector design involves composite TES technique

Application of the Neganov-Luke Effect

Vb=0V Vb=50V

Result: improvement of FWHM base line noise of the light signal from 17 keV 6 keV

improved discrimination of the different recoil bands powerful tool for neutron rejection ongoing development in cooperation with KETEK GmbH

electronrecoils

nuclearrecoils

Neutron detectors

Pulsed Neutron source

Energy measurement via

time of light

TOF

Scattering angle

Cryostat with detector

Quenching Factor Measurement@ ~10mK

• new KELVINOX400 dilution refrigerator was set up @ MLL Garching first beam time forseen in June 2007 after mounting of SQUIDs and electronics• additionally: new table top neutron source acquired for test purposes

Experimental setup:

Composite DetectorsComposite Detectors

Al2O3 (20x10x1 mm3) Detector A

• development performed for GALLEX/GNO • prefabricated & tested Ir/Au TES on Si-substrate• separation of main absorber & TES• low energy threshold

Pulse shape allows attribution of events in the composite detector

Si Al2O3

powerful tool:• surface background rejection possibility• preselection of (best) TESs possible• mass production of micro TESs feasible

detector design for CNNS ?

71Ge longterm measurementswith composite detectors

Time [d]

Pul

se h

eigh

t [c

hann

els]

K-capture

L-capture

71Ge measurement

measurements performed in UGL Garching

External lead shielding(10-15cm)

Cryostat(KELVINOX100)

-veto

• testsite for cryogenic detectors• 3 Ge-detectors for material analysis

UGL Garching (15 m.w.e.):

Experimental setup in the Experimental setup in the UGL UGL

External Pb shielding,Thickness: 15cmupper part: 10cm

3He/4He dilution refrigerator

Dewar (OVC)

lq. Helium

Internal shielding:

SintimidCu 5mm

Pb 23mm

Cu 5mm

Pb 23mm

Cu 10mm

Sintimid

Detectorholder

Low-activityPb (<5Bq/kg)

-Veto,15 plastic scintillatorpanels

Inner vacuum (IVC)

He pumpinglines

Electrical contactation ports

3He/4He mixing chamber (~10mK)

channel for external-sources

New Underground LaboratoryNew Underground Laboratoryin Garching (UGL2) in Garching (UGL2)

• new underground laboratory to be built in 2007 in the framwork of the excellence cluster ‚ Structure and Origin of the Universe‘

• ~15 m.w.e. ~6m of rock overburden

• ~100m2, ~400m3: -spectroscopy for material analysis, scintillator development and low temperature experiments: - 2-3 Ge-detectors - 2 cryostats - ~6m long tube for investigating scintillator properties (DoubleChooz, LENA)

• investigation of growing crystals (CaWO4) underground ?

• storage area for low background materials: Cu, Pb, crystals, …