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 Feilitzsch W. Potzel J.-C. Lanfranchi W. 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 Feilitzsch L. Oberauer W. Potzel M. Goeger-Neff T. 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‘

CRESST Detector Development Reflector ca. 5- 50 mK CaWO4-Crystal SPT (Superconducting Phase-transition- Thermometer) Phonon-detector Silicon-Substrate SPT Light-detector  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 Growth production 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

Light Detectors with Neganov-Luke Amplification Combination of the calorimetric and the ionization measurement techniques 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 electron recoils nuclear 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

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: Neutron detectors Pulsed Neutron source Energy measurement via time of light TOF Scattering angle Cryostat with detector

Composite Detectors development performed for GALLEX/GNO prefabricated & tested Ir/Au TES on Si-substrate separation of main absorber & TES low energy threshold Al2O3 (20x10x1 mm3) Detector A Pulse shape allows attribution of events in the composite detector powerful tool: surface background rejection possibility preselection of (best) TESs possible mass production of micro TESs feasible  detector design for CNNS ? Si Al2O3

71Ge longterm measurements with composite detectors Time [d] Pulse height [channels] K-capture L-capture 71Ge measurement  measurements performed in UGL Garching

UGL Garching (15 m.w.e.): testsite for cryogenic detectors 3 Ge-detectors for material analysis Cryostat (KELVINOX100) External lead shielding (10-15cm) m-veto

Experimental setup in the UGL External Pb shielding, Thickness: 15cm upper part: 10cm 3He/4He dilution refrigerator Dewar (OVC) lq. Helium Internal shielding: Sintimid Cu 5mm Pb 23mm Cu 10mm Detector holder Low-activity Pb (<5Bq/kg) m-Veto, 15 plastic scintillator panels Inner vacuum (IVC) He pumping lines Electrical contactation ports 3He/4He mixing chamber (~10mK) channel for external g-sources Experimental setup in the UGL

New Underground Laboratory 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: g-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, …