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

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

S. Belogurov, ITEP/INR Moscow GERDA experiment  :(A,Z)  (A,Z+2) + 2e - d d u u e-e- e-e- W-W- W-W- e e  L=2 Primary Objective:  Effective mass: m ee = |  i U ei ² m i | (decay generated by (V-A) cc-interaction via exchange of light Majorana neutrinos)  Majorana nature

S. Belogurov, ITEP/INR Moscow GERDA experiment

76 Ge results IGEX, HD-M bcg ~0.2 ev/kg/keV/y T 1/2 >2 ·10 25 y Klapdor’s claim T 1/2 ~1.2· y (big errors)

S. Belogurov, ITEP/INR Moscow GERDA experiment Previous large scale projects GENIUS – MAJORANA - GEM M = 1 (10?), 0.5, 1 ton (86% enriched 76 Ge) 0 -DBD sensitivity T 10y ~ 2, 0.4,1 ·10 28 y ~ 10 – 80 meV Assumed bkg: ~ 0.04, 0.4, 0.2 count/keV ton y ~ 0.04, 0.4, 0.2 count/keV ton y

S. Belogurov, ITEP/INR Moscow GERDA experiment 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 LN 2 or LAr Stepwise strategy

S. Belogurov, ITEP/INR Moscow GERDA experiment 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. Jochum l, 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. Zuzel c 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

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 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. Simulations of external gamma background

S. Belogurov, ITEP/INR Moscow GERDA experiment

Cosmogenic Co-60 inside diodes T 0 for cosmic ray exposure: completion of mono-zone refinement  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 β 11 22 2+β2+β 1+1+ 2+β2+β Q ββ

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

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

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

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

S. Belogurov, ITEP/INR Moscow GERDA experiment Shielding Spallation reactions are produced by nuclear active component of CR (mostly neutrons) Attenuation length for this component is 150 g/cm 2 for air Relevant cross sections behave like A 0.6 -A 0.8, e.g. for Fe – attenuation length is ~200 g/cm 2 Optimizing the shape of the shielding, taking into account angular distribution of nuclear active component may reduce flux times with mass of shielding 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 seems realistic anyway. Tests with Bi fission chamber may be usefull.

S. Belogurov, ITEP/INR Moscow GERDA experiment Dependence of the shielding mass on the material Let take for (effective)  A ~A 0.73 l~1/(  A n A )~1/  A ·A/  A 0.27 /  M~ l 3  A 0.81 /  2 PE7.5 Al1.98 Fe 0.41 Pb 0.59 Another argument – neutron production by muons

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

S. Belogurov, ITEP/INR Moscow GERDA experiment Ionization loss, fluctuation of ionization loss and multiple Coulomb scattering of charged hadrons and nuclear fragments and 3-particle modes of meson decay. 6. Modeling of hA- и AA-interactions in exclusive approach (MSDM-generator) Transport of N, , K, N and arbitrary nuclei (A,Z) up to 1 TeV/u. 2. Extended target as a combination of bodies limited by second order.surfaces (CG-compatible) 3. Arbitrary chemical and isotope composition of materials in the target zones. 7. Memorizing of each hadron cascade tree during its simulation without loss of physical information. 8. Storing of sources of , e , e+ and of neutrons (E n <14.5 MeV) during simulation of the hadron cascade Neutron transport (E n <14.5 MeV) on the basis of the28-groups ABBN neutron data library. 10. Analog and weighted simulation modes, open architecture of the code Recent version of the SHIELD code (from N. Sobolevsky)

S. Belogurov, ITEP/INR Moscow GERDA experiment Fast, cascade stage 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 up of light nuclei [5] Evaporation/Fission [5,6] Multifragmentation of higly excited nuclei (SMM) [7] 1.V.D.Toneev, K.K.Gudima, Nucl. Phys. A400 (1983) 173c. 2.N.S.Amelin, К.К.Gudima, V.D.Toneev. Yad.Fiz. 51 (1990) 1730 (in Russian). 3.N.S.Amelin, К.К.Gudima, S.Yu.Sivoklokov, V.D.Toneev. Yad.Fiz. 52 (1990) 272 (in Russian). 4.K.K.Gudima, S.G.Mashnik, V.D. Toneev, Nucl. Phys. A401 (1983) A.S.Botvina, A.S.Iljinov, I.N.Mishustin et al., Nucl. Phys. A475 (1987) G.D.Adeev, A.S.Botvina, A.S.Iljinov et al. Preprint INR, 816/93, Moscow, Botvina, A.S. Iljinov and I.N. Mishustin, Nucl.Phys. A507 (1990) 649. Cross sections of NA-,  A- and AA-interactions: V.S.Barashenkov, A.Polanski. Electronic Guide for Nuclear Cross Sections. JINR E2 ‑ 94 ‑ 417, Dubna, Cross sections of KA- и NA-interactions: B.S.Sychev et al. Report ISTC, Project 187, Modeling of inelastic hA- и AA-interactions (MSDM – Multi Stage Dynamical Model, from N. Sobolevsky)

S. Belogurov, ITEP/INR Moscow GERDA experiment 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 · y, eV Phase II: enlarge to ~35-40 kg (background <10 -3 / keV kg y) –within 4 years: ~100 kg y –sensitivity: 2 · y, 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 Expected results for DM

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