Status and Progress of GERDA The GERmanium Detector Array Karl - PowerPoint PPT Presentation

Status and Progress of GERDA ‘The GERmanium Detector Array’ Karl Tasso Knöpfle MPI Kernphysik, Heidelberg on behalf of the GERDA collaboration ktkno@mpi-hd.mpg.de T 2 ν = 1.5·10 21 y ½ β - β - T 0 ν = ? ½ Int. Workshop on Double Beta Decay & Related Neutrino Measurements (DBD09) Hawaii, October 11 – 13, 2009

double beta decay 2 ν ßß 0 ν ßß e e e e ν ν <m ßß > ≠ 0 ν i ν i Σ i W W W W A,Z A,Z+2 A,Z A,Z+2 nuclear process nuclear process > 10 25 yrs, conventional 2 nd order process hypothetical process , T 1/2 only possible if observed in various nuclei neutrino is massive Majorana particle ~ 10 19 – 10 21 T 1/2 yrs ► lepton number violation Δ L=2 ► access to absolute ν mass scale ► physics beyond s.m. DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 2 sum of kinetic energies

double beta decay 2 ν ßß 0 ν ßß e e e e ν ν <m ßß > ≠ 0 ν i ν i Σ i W W W W A,Z A,Z+2 A,Z A,Z+2 nuclear process nuclear process Ge-76 : Q ββ =2039 keV exp. signature > 10 25 yrs, conventional 2 nd order process hypothetical process , T 1/2 exp. signature only possible if observed in various nuclei Ge-76 : Q ββ =2039 keV neutrino is massive Majorana particle ~ 10 19 – 10 21 T 1/2 yrs ► lepton number violation Δ L=2 observed observed ► access to absolute ν mass scale ► physics beyond s.m. DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 3 searched for sum of kinetic energies

halflife – effective mass relation measured deduced nuclear matrix element Schönert taup2009 DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 4

dbd isotopes in comparison 48 Ca isotope specific quantity 76 Ge lowest / ave / highest Q Q ββ -value / MeV 2.04 76 Ge / 2.8 / 48 Ca: 4.3 G 0 ν phase space / (10 25 y eV 2 ) 0.2 76 Ge / 2.4 / 150 Nd: 8 48 Ca: 0.19% / 9.6% / 130 Te: 35% a isotopic abundance 7.4 % DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 5

dbd isotopes in comparison 48 Ca isotope specific quantity 76 Ge lowest / ave / highest Q Q ββ -value / MeV 2.04 76 Ge / 2.8 / 48 Ca: 4.3 G 0 ν phase space / (10 25 y eV 2 ) 0.2 76 Ge / 2.4 / 150 Nd: 8 48 Ca: 0.19% / 9.6% / 130 Te: 35% a isotopic abundance 7.4 % experiment specific detection efficiency ( =1 if source=detector) exposure [kg y] sensitivity* instrumental spectral width molecular weight background index [cts/(keV kg y)] of source *RevModPhys 80(08)481 DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 6

dbd isotopes in comparison 48 Ca isotope specific quantity 76 Ge lowest / ave / highest Q Q ββ -value / MeV 2.04 76 Ge / 2.8 / 48 Ca: 4.3 G 0 ν phase space / (10 25 y eV 2 ) 0.2 76 Ge / 2.4 / 150 Nd: 8 48 Ca: 0.19% / 9.6% / 130 Te: 35% a isotopic abundance 7.4 % experiment specific detection efficiency ( =1 if source=detector) 86% 70 kg y exposure [kg y] sensitivity* 76 Ge achieved with 3.3 keV instrumental spectral width molecular weight background index [cts/(keV kg y)] of source *RevModPhys 80(08)481 0.1 DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 7

<m ßß > best limits* / value Bi-214 Bi-214 Q ββ Heidelberg – Moscow Experiment 5 enriched Ge-76 diodes (EPJ A12 (’01) 147) ? background index ~0.1 cts/ (kev · kg · y) 1.9 ·10 25 35.5 kg y : T 1/2 ≥ y (90% CL) <m ββ > < 0.3 – 1 eV (similar limit by IGEX , NP B87 (’00) 278) part of collaboration claims signal (PL B586 (‘04) 198) = 1.2 (0.7-4.2)·10 25 71.7 kg y : T 1/2 (3 σ range) <m ββ > = 0.44 (0.24 – 0.58) eV Claimed 4 σ significance dependent on background model ( Strumia&Vissani ’06, O. Chkvorets, PhD th. ’08) Cuoricino Co-60 sum Cuoricino 62 TeO 2 bolometers (PR C7 (’08) 035502) Q ββ (Te-130) background index ~0.2 cts/ (kev · kg · y) 3.0 ·10 24 11.8 kg y : T 1/2 ≥ y (90% CL) 0 ν 4.18) ٠ 10 25 y (3 σ range) T 1/2 = (0.69 - <m ββ > < 0.19 – 0.68 eV ► < m ßß > = 0.44 (0.3 – 1.24) eV DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 8

<m ßß > best limits* / value Bi-214 Bi-214 Q ββ Heidelberg – Moscow Experiment 5 enriched Ge-76 diodes (EPJ A12 (’01) 147) ? background index ~0.1 cts/ (kev · kg · y) 1.9 ·10 25 35.5 kg y : T 1/2 ≥ y (90% CL) <m ββ > < 0.3 – 1 eV (similar limit by IGEX , NP B87 (’00) 278) part of collaboration claims signal (PL B586 (‘04) 198) = 1.2 (0.7-4.2)·10 25 71.7 kg y : T 1/2 (3 σ range) <m ββ > = 0.44 (0.24 – 0.58) eV Claimed 4 σ significance dependent on background model ( Strumia&Vissani ’06, O. Chkvorets, PhD th. ’08) Cuoricino Co-60 sum Cuoricino 62 TeO 2 bolometers (PR C7 (’08) 035502) Q ββ (Te-130) background index ~0.2 cts/ (kev · kg · y) 3.0 ·10 24 11.8 kg y : T 1/2 ≥ y (90% CL) 0 ν 4.18) ٠ 10 25 y (3 σ range) T 1/2 = (0.69 - <m ββ > < 0.19 – 0.68 eV ► < m ßß > = 0.44 (0.3 – 1.24) eV Evidence remains unclear - confirmation needed with same & different isotopes DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 9 ► reduce background by O (100) for better sensitivity

GERDA goals & sensitivity GERDA’s goal : reach background index at Q ββ = 2039 keV of 0.01 / 0.001 cts / (keV ٠ kg ٠ y) phase II : add new enriched Ge-76 detectors, 20 kg B ~ 0.001 cts / (keV ٠ kg ٠ y) 0.001 ► 37.5 kg enriched Ge-76 bought 3 y ٠ 35 kg exposure <m ßß > ~ 0.2 eV phase I : 0.01 use Ge-76 diodes of HD-Moscow & IGEX ~18 kg B ~ 0.01 cts / (keV ٠ kg ٠ y) intrinsic background expected KKDC phase III: depending on results worldwide collaboration for real big experiment close contacts & MoU with MAJORANA collaboration DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 10

GERDA goals & sensitivity GERDA’s goal : reach background index at Q ββ = 2039 keV of 0.01 / 0.001 cts / (keV ٠ kg ٠ y) mass hierarchy phase II : degenerate add new enriched Ge-76 detectors, 20 kg B ~ 0.001 cts / (keV ٠ kg ٠ y) A.Strumia & F.Vissani, hep-ph / 0503246 ► 37.5 kg enriched Ge-76 bought 3 y ٠ 35 kg exposure inverted phase I : use Ge-76 diodes of HD-Moscow & IGEX Majorana mass normal ~18 kg B ~ 0.01 cts / (keV ٠ kg ٠ y) intrinsic background expected phase III: depending on results worldwide collaboration for real big experiment close contacts & MoU with MAJORANA collaboration DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 11

GERDA background reduction EXTERNAL bgnds: γ (Th, U), n, μ INTRINSIC or VERY CLOSE bgnds : cosmogenic - 60 Co (5.3 a), 68 Ge (270 d)- contaminated holders, FE, cables … DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 12

GERDA background reduction EXTERNAL bgnds: γ (Th, U), n, μ Gran Sasso 3800 m w.e. GERDA in Hall A of LNGS LNGS: Laboratori Nazionali del Gran Sasso

GERDA background reduction EXTERNAL bgnds: γ (Th, U), n, μ INTRINSIC or VERY CLOSE bgnds : cosmogenic - 60 Co (5.3 a), 68 Ge (270 d)- contaminated holders, FE, cables … Shielding possible water: γ & n shield, Cherenkov medium bare Ge for μ veto diodes source=detector H 10 m LAr stainless steel cryostat w Cu shield, Rn tight Ø 4 m also active shield ! Ø 10 m α (LAr) = 0.050/cm α (Cu) = 0.34/cm α (Pb) = 0.48/cm α (H 2 O) = 0.043/cm DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 14

GERDA background reduction EXTERNAL bgnds: γ (Th, U), n, μ INTRINSIC or VERY CLOSE bgnds : cosmogenic - 60 Co (5.3 a), 68 Ge (270 d)- contaminated holders, FE, cables … Shielding possible Discriminate single & multi site events ! water: γ & n shield, ► SSE: ßß, DEP ► MSE: Compton Cherenkov medium bare Ge for μ veto diodes signal background source=detector H 10 m LAr stainless steel cryostat w Cu shield, γ Rn tight Ø 4 m also array of segmented Ge detectors active shield ! Ø 10 m ► anti-coincidence of detectors & detector segments α (LAr) = 0.050/cm α (Cu) = 0.34/cm ► pulse shape analysis (PSA) α (Pb) = 0.48/cm α (H 2 O) = 0.043/cm DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 15

clean room – rdy status status: phase I lock – under test cryo-mu-lab μ veto rdy FE electronics phase I array under test rdy (scaled:) control room cryostat - rdy water plant Rn monitor water tank - rdy DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 16 GERDA bldg - rdy LAr fill : Oct/Nov 09

unloading of cryostat t DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 17 6 mar 08

construction of water tank water tank: Ø 10 m h = 9.5 m V = 650 m 3 designed for external γ ,n, μ background DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 18 ~10 -4 cts /(keV ٠ kg ٠ y) 19 may 08

construction of clean room status: construction of water tank DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 19 27 feb 09

clean room, active cooling device getting prepared for installation muon veto in water tank status: muon veto DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 20 12 aug 09

muon veto in water tank status: muon veto DBD09, Oct 13 K.T.Knöpfle: 'GERDA' 21 12 aug 09