1. Present and future activities of the Garching group (E15)
JRA1 meeting Paris
J.-C. Lanfranchi

2. 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‘

3. 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

4. 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

5. 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

6. 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

7. Quenching Factor Measurement @ ~10mK
new KELVINOX400 dilution refrigerator was set 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

8. 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

9. 71Ge longterm measurements with composite detectors
Time [d]
Pulse height [channels]
K-capture
L-capture
71Ge measurement
 measurements performed in UGL Garching

10. 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

11. 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

12. 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, …