The GERDA Experiment at Gran Sasso

Grzegorz Zuzel

Institute of , Jagiellonian University, Cracow, Poland

on behalf of the GERDA Collaboration

Half Day IoP Meeting: Neutrinoless , 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 () has been designed to investigate -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 kgy) 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 - Phase III: world-wide collaboration, O(500 kg) of 76Ge

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 ~ 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/(kgd) 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 kgy) 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/(kgy) GD Phase II. HdM Rate @ 2614 keV = 26 cts/(kgy) Conclusions -2 GERDA Rate @ Qbb = 2.210 cts/(keV kgy) -1 HdM Rate @ Qbb = 1.110 cts/(keV kgy)

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. 0bb-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  0bb-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. The integrated exposure to cosmic ray is 5.2 days. GERDA’s goals

Deign  All the material was stocked underground. Present status  Contract with the industrial partner to grow Bcg for natGe enrGe crystals & produce BEGe diodes Bcg for enrGe following the process of deplBEGe: signed. LArGe GD Phase II.  Current schedule: Phase II detectors produced Conclusions and tested by Summer 2013.

Half Day IoP 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 pA and stable – E @ 2.614 keV 208Tl: (3.6 – 6.0) keV GERDA’s goals • Background: Deign – Unexpected 42Ar, but background from 42K aviodable Present status – Th/U for natGe smaller than in previous 0bb experiments Bcg for natGe – At Q natGe (1839-2239 keV): 0.06 ± 0.02 cts/(keV kg·y) Bcg for enrGe bb – At Q enrGe < 0.06 cts/(keV kg·y) (90 % C.L.) LArGe bb enr GD Phase II. – For Ge observed spectrum well reproduced by overlapping of 39Ar, 2bb of 76Ge and 42Ar Conclusions • Deployment of 8 enrGe detectors by the end of 2011 • Instrumentation of LAr in GERDA

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain GERDA vs BOREXINO B = 10-3 cts/(keVkg y)

B = 10-6 cts/(keVkg y) ! GERDA’s goals

Deign

Present status Bcg for natGe Bcg for enrGe LArGe GD Phase II.

Conclusions

GERDA BOREXINO

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain Backup slides

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain 0bb

• No bg:

• With bg:

Backup slides

M = detector mass (active) t = measurement time b = background E = energy resolution

Half Day IoP 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

Run 10 with Mini Shroud MS Backup slides

Shroud

Many field configurations tested!

Half DayBologna, IoP Meeting: 20th September Neutrinoless 2010 Double Beta Decay, 12.10.2011 University College London, Great Britain 3 natGe 3 natGe 3 enrGe no M With M no M With M 3 natGe Attrack run1 ions to M With M

Run 3 w/o M M 0V Tested several S 0 V h+700 electrostatic and shields config M 0V S 3.0 kV h +700

4 Reverted bias M 0V M’ 0V S 0 V S 0V h 0 10 12 14

13/10/2011 TAUP 2011- Munich 36

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe

Backup slides

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe

Backup slides

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe

Backup slides

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain LArGe

Backup slides

Half Day IoP Meeting: Neutrinoless Double Beta Decay, 12.10.2011 University College London, Great Britain