The GERDA Experiment at Gran Sasso Grzegorz Zuzel Institute of Physics, Jagiellonian University, Cracow, Poland on behalf of the GERDA Collaboration Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Overwiew • Goals of GERDA • Design of the experiment • Present status - Background for natGe - Background for enrGe - Liquid argon instrumentation: LArGe - GERDA phase II • Conclusions and future plans Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain The Collaboration 95 physicists from 17 institutions from Germany, Italy, Russia, Poland,Belgium,Switzerland and China GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Goals of GERDA • GERDA (GERmanium Detector Array) has been designed to investigate neutrino-less double beta decay of 76Ge - Ge mono-crystals are very pure - Ge detectors have excellent energy resolution GERDA’s goals - Detector = source Deign - Enrichment required (7.4 % 86 %) Present status • Background level: 10-2 – 10-3 cts/(keV kgy) Bcg for natGe enr • Realization in phases: Bcg for Ge enr LArGe - Phase I: 17.8 kg (8 diodes) of Ge from HdM & IGEX experiments available (15.3 kg of 76Ge) GD Phase II. - Phase II: adding new detectors, 37.5 kg of enriched Conclusions material in hand, p-type BEGe detectors (~20 kg) will be produced 76 - Phase III: world-wide collaboration, O(500 kg) of Ge Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Bare high purity enrGe detectors GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Sensitivities phase II GERDA’s goals Deign <mßß> ~ 0.1 eV Present status Bcg for natGe Bcg for enrGe phase I LArGe GD Phase II. KKDC Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Sensitivities KK claim GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Design of the experiment Active cooling GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe h 8.9 m 8.9 h LArGe GD Phase II. t = 3/6 cm copper Conclusions Ø 4.2 m Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Design of the experiment clean room lock cryo-mu-lab GERDA’s goals cryostat Deign Present status control room Bcg for natGe Bcg for enrGe LArGe GD Phase II. water plant Rn monitor Conclusions water tank + veto Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Design of the experiment GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Unloading of cryostat 6 Mar 08 GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Construction of water tank 19 May 08 Water tank: Ø 10 m h = 9.5 m V = 650 m3 GERDA’s goals 3 VH2O = 590 m Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Construction of clean room 27 Feb 09 GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Muon veto in water tank 12 aug 09 GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA in Hall C GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA milestones • 2005 – 2010: GERDA funded, designed and constructed in LNGS Hall A • June 2010: Commissioning started. One string (3 natGe GERDA’s goals detectors, 7.6 kg) deployed for the first time. Checking Deign the detector’s performance Present status • June 2010 – June 2011: Detailed investigation of Bcg for natGe background sources with natGe (42Ar, 228Th, Bcg for enrGe cosmogenics) LArGe • June 2011: Deployment of the first string of enrGe GD Phase II. (3 detectors, 6.7 kg) Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Background for natG: 42Ar 92 d exposure (July – November 2010) 2.1 cts/kg/day @ 1525 keV GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Background for natG: 42Ar GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Background for natG: 42Ar • 42Ar production: 40Ar(a,2p)42Ar reaction in atmosphere and fall-out from atmospheric nuclear explosions • 42Ar concentration: measured < 50 Bq/l < 0.094 cts/(kgd) in GERDA geometry, for an homogeneous distribution around the detectors. GERDA’s goals Deign I @ 1524 keV < 0.094 Background @ Qbb Present status (cts/kg*d) • From 42K b-s when nat -3 Bcg for Ge I @ Qbb <1.7 10 decays happen in the Bcg for enrGe (cts/keV kgy) detector borehole or LArGe @ Li layer GD Phase II. • Hard bremssthralung of Conclusions > 2 MeV b-s in LAr Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Background for natG: other sources GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GERDA Rate @ 2614 keV = 4.83 cts/(kgy) GD Phase II. HdM Rate @ 2614 keV = 26 cts/(kgy) Conclusions -2 GERDA Rate @ Qbb = 2.210 cts/(keV kgy) -1 HdM Rate @ Qbb = 1.110 cts/(keV kgy) Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain NEW: spectrum for enrG 39 Ar: 1.01 Bq/kg from WARP NIM A 574:83-88,2007 GERDA’s goals Deign 76Ge: 1.74 ·1021 y Present status from HdM ref. NIM A 522,371-406, 2004 Bcg for natGe Bcg for enrGe LArGe GD Phase II. 42Ar spectrum normalized to peak Conclusions assumin homogeneous distribution Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Background suppression by LAr instrumentation 228 Th GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. 4 Conclusions Qbb: R ~ 10 Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain 42Ar spike in LArGe Added 42Ar activity ~ 5 Bq Rnat Anat Aspiked Rspiked GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA phase II: BEGe detectors GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe - Low capacitance high energy resolution. 0bb-like E ~ 1.6 keV @ 1.332 MeV LArGe - Increased field near electrode improved DEP -bgd GD Phase II. 89 - S/B rejection capability by ID event topologies - Pulse Shape cuts accepting 90 % of 232Th DEP Conclusions - (mostly Single Site Events 0bb-like) 11% - ~10% survival of the g-line 212Bi line (mostly - Multi-Site Events -like) Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA phase II: BEGe detectors 3 natGe + 4 deplGe BEGe detectors produced and tested in 2009-2010 in vacuum cryostat: all show excellent resolution (1.6 keV @ 1332 keV) and Pulse Shape discrimination performances deplGe (6N) GERDA’s goals depl GeO2: Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. crystal slice Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA phase II: BEGe detectors 3 natGe + 4 deplGe BEGe detectors produced and tested in 2009-2010 in vacuum cryostat: all show excellent resolution (1.6 keV @ 1332 keV) and Pulse Shape discrimination performances GERDA’s goals Deign Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II. Conclusions Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA phase II: enrGe 97 % of the available 37.5 kg of enrGe is now 6N material.