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New experiment for the search of neutrinoless double beta decay of 76 Ge at LNGS

New experiment for the search of neutrinoless double beta decay of 76 Ge at LNGS. GERmanium Detector Array (GERDA). Outline. General DBD situation and motivation Technical details Expected sensitivity of the experiment. u. e -. d. n e. L=2. W -. n e. W -. d. e -. u.

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New experiment for the search of neutrinoless double beta decay of 76 Ge at LNGS

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  1. New experiment for the search of neutrinoless double beta decay of 76Ge at LNGS GERmanium Detector Array (GERDA) S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  2. Outline • General DBD situation and motivation • Technical details • Expected sensitivity of the experiment S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  3. u e- d ne L=2 W- ne W- d e- u Primary Objective: 0: (A,Z)  (A,Z+2) + 2e- Majorana nature mee= |iUei ²mi | • Effective mass: (decay generated by (V-A) cc-interaction via exchange of light Majorana neutrinos) S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  4. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  5. 76Ge results • IGEX, HD-M bcg ~0.2 ev/kg/keV/y • T1/2>2 ·1025 y • Klapdor’s claim T1/2~1.2· 1025y (big errors) S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  6. Previous large scale projects GENIUS – MAJORANA - GEM M =1 (10?),0.5,1 ton (86% enriched 76Ge) 0n-DBD sensitivity T10y ~ 2,0.4,1·1028 y <mn> ~ 10–80meV Assumed bkg: ~ 0.04, 0.4, 0.2 count/keV ton y S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  7. Basic ideology of GERDA • To collect most of the existing enriched detectors (11 kg from Hd-M, KI; 8kg IGEX, ITEP/INR) • Background of existing detectors is mostly due to surface contaminations (contacts, housing) repacking with minimum material around • High Z materials to be put as far as possible from the diodes, the closest shield - high purity LN2 or LAr • Stepwise strategy S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  8. GERDA collaboration • I. Abt j , M. Altmann j , A.M. Bakalyarov i, I. Barabanov g, C. Bauer c, M. Bauer l, • E. Bellotti f , S. Belogurov g,h, S.T. Belyaev i, A. Bettini k, L. Bezrukov g, V. Brudanin b, • C. Büttner j , V.P. Bolotsky h, A. Caldwell j , C. Cattadori a,f , M.V. Chirchenko i, • O. Chkvorets c, H. Clement l, E. Demidova h, A. Di Vacri a, J. Eberth d, V. Egorov b, • E. Farnea k, A. Gangapshev g, G.Y. Grigoriev i, V. Gurentsov g, K. Gusev b, • W. Hampel c, G. Heusser c, W. Hofmann c, L.V. Inzhechik i, J. Jochuml, M. Junker a, • S. Katulina b, J. Kiko c, I.V. Kirpichnikov h, A. Klimenko b,g, K.T. Knöpfle c, • O. Kochetov b, V.N. Kornoukhov g,h, R. Kotthaus j , V. Kusminov g, M. Laubenstein a, • V.I. Lebedev i, X. Liu j , H.-G. Moser j , I. Nemchenok b, L. Pandola a, P. Peiffer c, • R.H. Richter j , K. Rottler l, C. Rossi Alvarez k, V. Sandukovsky b, S. Schönert c, • S. Scholl l, J. Schreiner c, B. Schwingenheuer c, H. Simgen c, A. Smolnikov b,g, • A.V. Tikhomirov i, C. Tomei a, C.A. Ur k, A.A. Vasenko h, S. Vasiliev b,g, D. Weißhaar d, • M. Wojcik e, E. Yanovich g, J. Yurkowski b, S.V. Zhukov i, G. Zuzelc • a INFN Laboratori Nazionali del Gran Sasso, Assergi, Italy • b Joint Institute for Nuclear Research, Dubna, Russia • c Max-Planck-Institut für Kernphysik, Heidelberg, Germany • d Institut für Kernphysik, Universität Köln, Germany • e Jagiellonian University, Krakow, Poland • f Università di Milano Bicocca e INFN Milano, Milano, Italy • g Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia • h Institute for Theoretical and Experimental Physics, Moscow, Russia • i Russian Research Center Kurchatov Institute, Moscow, Russia • j Max-Planck-Institut für Physik, München, Germany • k Dipartimento di Fisica dell’Università di Padova e INFN Padova, Padova, Italy • l Physikalisches Institut, Universität T¨ubingen, Germany S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  9. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  10. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  11. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  12. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  13. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  14. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  15. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  16. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  17. Figure 26: Scintillator module using a WLS fiber light guide for readout as well as a set of black strips for equalizing light collection. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  18. Simulations of external gamma background Fig. 1 presents dependence of background index as a function of diameter of the vessel: for single crystal and for 252 crystal assembly. In the case of 252 crystal assembly a mode of Ar active shielding was also calculated. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  19. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  20. 1 2 β 2+β 2+β 1+ Cosmogenic Co-60 inside diodes Qββ • T0 for cosmic ray exposure: completion of mono-zone refinement • 0.017 Bq/kg per day exposure [Miley 92] • Benchmark test: detector production with 7.4 days exposure • assumption: 30 days  2.5 ·10-3 / (keV·kg·y) • Kurchatov enriched crystals: ~5·10-3 / (keV·kg·y) in 2006 S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  21. Background summary Phase I: external ~ 10-3 / (keV kg y) internal < 10-2 / (keV kg y) Units: 10-3 / (keV kg y) Phase II: (No segmentation) (With segmentation) S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  22. Relations with Majorana • Coordination and sharing of simulations • Coordination of R&D e.g. on segmentation • Participation in meetings • At the phase of 500-1000 kg experiment merging is possible S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  23. Procurement of enriched material • Funding for ~30 kg of enriched Ge-76 secured • Contract with ECP close to signing: • Basic contract: enrichment, underground storage, optional purification • 2 kg pre-sample for quality control  28 kg • Non-enriched sample (15 kg) for reference • Special transport container designed to minimize activation • Optional waste enrichment to Ge-74 for “zero” detector S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  24. From Majorana WP S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  25. Shielding against cosmogenic activation at transport S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  26. Shielding • Spallation reactions are produced by nuclear active component of CR (mostly neutrons) • Attenuation length for this component is 150 g/cm2 for air • Relevant cross sections behave like A0.6-A0.8 , e.g. for Fe –attenuation length is ~200 g/cm2 • Optimizing the shape of the shielding, taking into account angular distribution of nuclear active component may reduce flux 20-50 times with mass of shielding 15-20 ton, it is feasible for lend transport • But, hadron cascade generation by muons in the shielding material is a limitation (no Pb hence) carefull investigation of this phenomenon is underway. Shielding efficiency of 10-20 seems realistic anyway. Tests with Bi fission chamber may be usefull. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  27. Dependence of the shielding mass on the material • Let take for (effective) sA~A0.73 • l~1/(sAnA)~1/sA ·A/r ~ A0.27/r • M~ l3r~ A0.81/r2 PE 7.5 Al 1.98 Fe 0.41 Pb 0.59 Another argument – neutron production by muons S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  28. Neutron generation by muons (From M. Bauer) S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  29. Recent version of the SHIELD code (from N. Sobolevsky) 1. Transport ofN, , K, N and arbitrary nuclei(A,Z) up to 1 TeV/u. 2. Extended targetas a combination of bodieslimited by second order.surfaces (CG-compatible) 3. Arbitrarychemical andisotopecomposition of materialsin the target zones. 4. Ionization loss, fluctuation of ionization lossandmultipleCoulomb scattering of charged hadrons and nuclear fragments. 5. 2- and3-particlemodesof meson decay. 6. Modeling ofhA- и AA-interactionsin exclusive approach (MSDM-generator). 5 7. Memorizingof each hadron cascade treeduring its simulationwithout loss of physical information. 8. Storing of sourcesof , e, e+ andof neutrons (En<14.5 MeV) during simulationof the hadron cascade.55 9. Neutron transport (En<14.5 MeV) on the basis ofthe28-groups ABBN neutron datalibrary. 10. Analog and weighted simulation modes, open architecture of the code S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  30. Modelingof inelastichA- и AA-interactions(MSDM – Multi Stage Dynamical Model, from N. Sobolevsky) • Fast, cascadestage of nuclear reaction: • DCM (Dubna Cascade Model ) [1] • Independent Quark-Gluon String Model (QGSM) [2,3] • Coalescence model [1] Pre-equilibrium emission of nucleons and lightest nuclei[4] • Equilibrium deexitation of residual nucleus: • Fermi break upof light nuclei[5] • Evaporation/Fission [5,6] • Multifragmentation of higly excited nuclei (SMM) [7] • V.D.Toneev, K.K.Gudima, Nucl. Phys. A400 (1983) 173c. • N.S.Amelin, К.К.Gudima, V.D.Toneev. Yad.Fiz.51 (1990) 1730 (in Russian). • N.S.Amelin, К.К.Gudima, S.Yu.Sivoklokov, V.D.Toneev. Yad.Fiz.52 (1990) 272 (in Russian). • K.K.Gudima, S.G.Mashnik, V.D. Toneev, Nucl. Phys. A401 (1983) 329. • A.S.Botvina, A.S.Iljinov, I.N.Mishustin et al., Nucl. Phys. A475 (1987) 663. • G.D.Adeev, A.S.Botvina, A.S.Iljinov et al. Preprint INR, 816/93, Moscow, 1993. • Botvina, A.S. Iljinov and I.N. Mishustin, Nucl.Phys. A507 (1990) 649. Cross sections ofNA-, A- and AA-interactions: V.S.Barashenkov, A.Polanski. Electronic Guide for Nuclear Cross Sections. JINR E2‑94‑417, Dubna, 1994. Cross sections of KA- иNA-interactions: B.S.Sychev et al. Report ISTC, Project 187, 1999. S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  31. Expected sensitivity of GERDA • Phase I: implementation of existing Ge-76 diodes (~15 kg) of HdM and IGEX in new experiment (“background free”) • operation in LN2 with background <10-2 / keV kg y • >15 kg y (free of background): scrutinize claim (97.8% excl. or 5 sigma confirmation) • sensitivity: 3·1025 y, 0.24-0.77 eV • Phase II: enlarge to ~35-40 kg (background <10-3 / keV kg y) • within 4 years: ~100 kg y • sensitivity: 2·1026 y, 0.09-0.29 eV • Phase III: (depending on physics results of Phase I+II and on the understanding of backgrounds) • world-wide collaboration (Majorana): 500 kg S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  32. Expected results for DM S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

  33. conclusions • New well thought out experiment is born • Let’s wish it buon voyage S. Belogurov, ITEP/INR Moscow GERDA experiment 21.10.04

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