GERDA Phase II Detectors and Acceptance Tests

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1 Detectors and Acceptance Tests Victoria Wagner for the WG Max-Planck-Institut für Kernphysik

2 The Experiment Phase I started Nov. 1 st 2011 Currently running with 9 coaxial germanium detectors Total mass: 15.57kg (enriched) kg (natural) Germanium

3 Goal 1: Increase sensitivity: T 1/2 a M a: enrichment fraction M: mass of active material additional total mass approx. 20kg use of enriched material that contains about 87% of 76 Ge (nat. abundance 7.6%) Goal 2: Active background rejection with pulse shape analysis Broad Energy Germanium detectors planned to start end of 2012 with approximately 25 enriched BEGe detectors

4 Detector 2. Crystal pulling at Canberra, Oak Ridge, USA Cut into 3-4 slices, each approx. 700 g 3. Diode production at Canberra Olen, Belgium and acceptance tests in underground laboratory in Mol, Belgium 1. Enrichment process at ECP in Zelenogorsk, Russia 4. Final destination: Gran Sasso, Italy

5 Current of Diode Delivery of first 7 enriched BEGes by Canberra February for acceptance tests in underground laboratory enr BEGe

6 A full characterization of the enriched detectors Possibility of close study of enriched detectors before deployment into Do the detectors have the required characteristics for? acceptance or rejection of detectors in case of rejection: send back diodes to Canberra for refurbishing/ regrowing

7 of at MPIK Characterization of 5 depleted BEGe during the last 2 years Optimization of DAQ and measurement procedure as well as analysis tools at Max-Planck-Institut für Kernphysik Special interest in pulse shape analysis: Scan with 228 Th in different DAQ modes 60 Co measurements for PSA

8 of at MPIK Th228 measurement with depleted BEGe for pulse shape discrimination SSE A A MSE SSE MSE

9 223 m New elevator Overburden: ~ 175 m sand ~ 50 m clay Old elevator 39 m 84 m of acceptance test in = High Activity Disposal Experimental Site at SCK, the Belgian Nuclear Research Center Approx. 20km to Canberra Olen

10 in Data acquisition with two parallel systems: I I Struck FADC with 8 channels enr BEGe FADC: pulses and energy spectrum MCA: only energy spectrum MCA with 6 channels

11 at Standard test protocol for : HV Scan Energy resolution Leakage current monitoring with USB loggers Active volume measurement with 60 Co Dead layer measurement with 133 Ba and 241 Am Pulse shape discrimination with 228 Th and 90 Sr Short term measurement to test stability Charge collection study with collimated 241 Am source

12 First results from acceptance tests in In the last 2 weeks measurements of the first 4 detectors have begun Energy resolution of ARGO (FWHM): keV: (1.60±0.01)keV keV: (1.69±0.01)keV Energy resolution of ANDROMEDA (FWHM): keV: (1.57±0.01)keV keV: (1.66±0.01)keV both enriched BEGe detectors have a very good energy resolution! evaluated by Sabine Hemmer

13 Conclusion of test: successful Start of acceptance test with 7 enriched detectors: successful requirements: 2 detectors/week : possible Installation of several setups: possible, partly implemented : Finish test of first seven detectors Green light for production of second batch of detectors Bonding, holder production AND finally deployment of detectors in

14 Thank you for your attention!