The GERDA Experiment at Gran Sasso Grzegorz Zuzel

The GERDA Experiment at Gran Sasso Grzegorz Zuzel Institute of Physics, Jagiellonian University, Cracow, Poland on behalf of the GERDA Collaboration Half Day Io. P 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 nat. Ge - Background for enr. Ge - Liquid argon instrumentation: LAr. Ge - GERDA phase II • Conclusions and future plans Half Day Io. P 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 China GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 76 Ge GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions - Ge mono-crystals are very pure - Ge detectors have excellent energy resolution - Detector = source - Enrichment required (7. 4 % 86 %) • Background level: 10 -2 – 10 -3 cts/(ke. V kg y) • Realization in phases: - Phase I: 17. 8 kg (8 diodes) of enr. Ge from Hd. M & IGEX experiments available (15. 3 kg of 76 Ge) - Phase II: adding new detectors, 37. 5 kg of enriched material in hand, p-type BEGe detectors (~20 kg) will be produced - Phase III: world-wide collaboration, O(500 kg) of 76 Ge Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Bare high purity enr. Ge detectors GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Sensitivities phase II GERDA’s goals Deign <mßß> ~ 0. 1 e. V Present status Bcg for nat. Ge Bcg for enr. Ge phase I LAr. Ge GD Phase II. KKDC Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Sensitivities KK claim GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 h 8. 9 m Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions t = 3/6 cm copper Ø 4. 2 m Half Day Io. P 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 Bcg for nat. Ge control room Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions water plant Rn monitor water tank + veto Half Day Io. P 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 nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Construction of water tank 19 May 08 Water tank: GERDA’s goals Ø 10 m h = 9. 5 m V = 650 m 3 VH 2 O = 590 m 3 Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

GERDA milestones GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions • 2005 – 2010: GERDA funded, designed and constructed in LNGS Hall A • June 2010: Commissioning started. One string (3 nat. Ge detectors, 7. 6 kg) deployed for the first time. Checking the detector’s performance • June 2010 – June 2011: Detailed investigation of background sources with nat. Ge (42 Ar, 228 Th, cosmogenics) • June 2011: Deployment of the first string of enr. Ge (3 detectors, 6. 7 kg) Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Background for nat. G: 42 Ar 92 d exposure (July – November 2010) 2. 1 cts/kg/day @ 1525 ke. V GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Background for nat. G: 42 Ar GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Background for nat. G: 42 Ar • • 42 Ar production: 40 Ar(a, 2 p)42 Ar reaction in atmosphere and fall-out from atmospheric nuclear explosions 42 Ar concentration: measured < 50 m. Bq/l < 0. 094 cts/(kg d) in GERDA geometry, for an homogeneous distribution around the detectors. GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions q I @ 1524 ke. V < 0. 094 Background @ Qbb (cts/kg*d) • From 42 K -s when I @ Q <1. 7 10 -3 decays happen in the (cts/ke. V kg y) detector borehole or @ Li layer • Hard bremssthralung of > 2 Me. V -s in LAr Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Background for nat. G: other sources GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions GERDA Rate @ 2614 ke. V = 4. 83 cts/(kg y) Hd. M Rate @ 2614 ke. V = 26 cts/(kg y) GERDA Rate @ Q = 2. 2 10 -2 cts/(ke. V kg y) Hd. M Rate @ Q = 1. 1 10 -1 cts/(ke. V kg y) Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

NEW: spectrum for enr. G 39 Ar: 1. 01 Bq/kg from WARP NIM A 574: 83 -88, 2007 GERDA’s goals Deign 76 Ge: 1. 74 · 1021 y from Hd. M ref. NIM A 522, 371 -406, 2004 Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions 42 Ar spectrum normalized to peak assumin homogeneous distribution Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P 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 nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Q : R ~ 104 Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

42 Ar spike in LAr. Ge Added 42 Ar activity ~ 5 Bq GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

GERDA phase II: BEGe detectors - Low capacitance high energy resolution. E ~ 1. 6 ke. V @ 1. 332 Me. V - Increased field near electrode improved - S/B rejection capability by ID event topologies - Pulse Shape cuts accepting 90 % of 232 Th DEP - (mostly Single Site Events 0 -like) - ~10% survival of the g-line 212 Bi line (mostly - Multi-Site Events -like) GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge 0 -like LAr. Ge GD Phase II. DEP 89 -bgd Conclusions 11% Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

GERDA phase II: BEGe detectors 3 nat. Ge + 4 depl. Ge BEGe detectors produced and tested in 2009 -2010 in vacuum cryostat: all show excellent resolution (1. 6 ke. V @ 1332 ke. V) and Pulse Shape discrimination performances GERDA’s goals depl. Ge. O depl. Ge (6 N) 2: Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. crystal slice Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

GERDA phase II: BEGe detectors 3 nat. Ge + 4 depl. Ge BEGe detectors produced and tested in 2009 -2010 in vacuum cryostat: all show excellent resolution (1. 6 ke. V @ 1332 ke. V) and Pulse Shape discrimination performances GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

GERDA phase II: enr. Ge GERDA’s goals ü 97 % of the available 37. 5 kg of enr. Ge is now 6 N material. The integrated exposure to cosmic ray is 5. 2 days. Deign ü All the material was stocked underground. Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions ü Contract with the industrial partner to grow enr. Ge crystals & produce BEGe diodes following the process of depl. BEGe: signed. ü Current schedule: Phase II detectors produced and tested by Summer 2013. Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Conclusions and future plans • GERDA is taking data since June 2010 • Phase I detectors perform well: – LC < 50 p. A and stable – E @ 2. 614 ke. V 208 Tl: (3. 6 – 6. 0) ke. V GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions • Background: – – – Unexpected 42 Ar, but background from 42 K aviodable Th/U for nat. Ge smaller than in previous 0 experiments At Q nat. Ge (1839 -2239 ke. V): 0. 06 ± 0. 02 cts/(ke. V kg·y) At Q enr. Ge < 0. 06 cts/(ke. V kg·y) (90 % C. L. ) For enr. Ge observed spectrum well reproduced by overlapping of 39 Ar, 2 of 76 Ge and 42 Ar • Deployment of 8 enr. Ge detectors by the end of 2011 • Instrumentation of LAr in GERDA Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

GERDA vs BOREXINO B = 10 -3 cts/(ke. V kg y) B = 10 -6 cts/(ke. V kg y) ! GERDA’s goals Deign Present status Bcg for nat. Ge Bcg for enr. Ge LAr. Ge GD Phase II. Conclusions GERDA BOREXINO Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Backup slides Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

0 • No bg: • With bg: Backup slides M t b E = = detector mass (active) measurement time background energy resolution Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

Shroud/Mini Shroud Outer shroud: diameter 760 mm Mini shroud: diameter 115 mm Backup slides MS Run 10 with Mini Shroud Many field configurations tested! Half Day Bologna, Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain 20 th September 2010

3 nat. Ge no M 3 nat. Ge With M 3 enr. Ge With M 3 nat. Ge With M no M Attrack ions to M run 1 Run 3 w/o M M 0 V S 0 V h+700 Tested several electrostatic and shields config 4 Reverted bias 10 17/09/2020 M 0 V S 3. 0 k. V h +700 12 TAUP 2011 - Munich M’ 0 V S 0 V M 0 V S 0 V h 0 14 36 Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge Backup slides Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge Backup slides Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge Backup slides Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain

LAr. Ge Backup slides Half Day Io. P Meeting: Neutrinoless Double Beta Decay, 12. 10. 2011 University College London, Great Britain