-> to worldwide experiments searching for neutrinoless double beta decay

Transcription

1 From Baksan to -> A.Smolnikov International Session-Conference of RAS "Physics of fundamental interactions dedicated to 50th anniversary of Baksan Neutrino Observatory, Nalchik, Russia, June 6-8, 2017

2 -> to worldwide experiments searching for neutrinoless double beta decay A.Smolnikov, International Session-Conference of RAS "Physics of fundamental interactions dedicated to 50th anniversary of Baksan Neutrino Observatory, Nalchik, Russia, June 6-8, 2017

3 Dedicated to the memory of the first Director of Baksan Neutrino Observatory Alexander Alexandrovich Pomansky

4 Double Beta Decay DBD unique tool to study neutrino properties: Majorana vs. Dirac, mass scale, hierarchy, CP phases 2νββ: (A,Z) (A,Z+2) + 2e - + 2ν e 0νββ: (A,Z) (A,Z+2) + 2e - (Observed for several nuclei, test of nuclear matrix elem. calculations) d u e - d W - W - u ν e ν e L=2 e - 1/τ = G(Q,Z) M nucl 2 m ee2, m ee = i U ei ² m i

5 0νββ decay rate Light neutrino exchange Phase space factor (~Q bb5 ) Nuclear matrix element Effective Majorana neutrino mass = m 1 U e1 2 + m 2 U e2 2.e iα1 + m 3 U e3 2.e iα2 coherent sum α 1,2 - complex CP-violating Majorana phases

6 9 physical parameters in neutrino mass matrix m ν θ 12 and m 2 2 m 2 1 θ 23 and m 2 3 m 2 2 θ 13 (or U e3 ) m 1, m 2, m 3 sgn (m 2 3 m 2 2 ) Dirac phase δ Majorana phases α and β (or α1 and α2, or φ1 and φ2, or...) 0νββ (see, for instant, 7 out W.Rodejohann, of 9 parameters J.Phys.G. 39 (2012) ) of neutrino mass matrix!

7 KKGH claim GERDA, EXO200, SNO+ CUORE, SuperNEMO Ton-scale

8 Sterile Neutrinos: the usual plot for double beta decay gets completely turned around!

9 What we should observe in experiments? 2νββ 0νββ Light neutrino exchange L=0

10 What we can observe in experiments?

11 The experimental challenge Experimental approach: reduce background b, improve resolution E, increase exposure (M T), Controversy V. Egorov, JINR

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13 IGEX-DB / Baksan Phase in the Laboratory for Low Background Experiments BNO INR RAS 660 м в.э. NEMO-3

14 IGEX-Baksan in operation from > up to now

15 IGEX Baksan

16 IGEX Baksan + IGEX - Canfranc

17 IGEX Baksan > now IGEX Canfrank GERDA - I GERDA - II > LEGEND > LEGEND 1 ton MAJORANA - D >

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19 Available experimental techniques: Ionization detectors, Scintillation detectors, Time Projection Chambers, Cryogenic bolometers, Multilevel Multilevel Ge diodes ε, E 106 Cd, TGV -2 TGV -3

20 Multilevel Ge diodes ε, E 106 Cd, TGV -2 TGV -3

21 Presently used isotopes No favorite isotope / experimental techniques Several experiments using different isotopes and methods are needed

22 Completed, operating, under construction and R&D Table adopted from presentation of O.Cremonesi at TAUP-2015

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24 GERDA: the GERmanium Detector Array Located at LNGS, Italy 3400 m w.e. Neutrinoless Double Beta Decay Experiment Clean room: Detector handling The main conceptual design of the GERDA experiment is to operate with naked HPGe detectors (enriched in Ge-76) submerged in high purity liquid argon supplemented by a water shield. Lock system: Detector insertion Liquid Ar cryostat: Shielding, cooling of detectors Cu shield Phase I detector array Water tank instrumented with PMTs: Shielding, Cherenkov muon-veto Eur. Phys. J. C (2013) 73:2330

25 Results of GERDA Phase I M. Agostini et al., (GERDA Collaboration), Phys. Rev. Lett.111, (2013).

26 Phase II started Dec strings of HPGe detectors deployed: 37 detectors enriched in 76Ge (35.8 kg) 3 natural detectors (7.6 kg)

27 Liquid Argon veto for GERDA Phase II

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29 M. Agostini et al., (GERDA Collaboration), Nature, (2017).

30 GERDA-PhaseII: first background-free 0νββ experiment

31 LEGEND (Large Enriched Germaium Experiment for Neutrinoless ββ Decay)

32 NEMO-3

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34 Majorana Demonstrator started in 2015

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36 Plan to start in 2017

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40 Nearest future

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42 Far future -> Proposals for ton scale experiments

43 Many other experimental R&D efforts that can not be discussed in detail: Lucifer phonons and scintillation COBRA pixelized CdZnTe semiconductor detector, SuperNEMO full scale, SNO+, Moon, DCBA, NEXT,.. Super NEMO COBRA NEXT LUCIFER SNO+ MAJORANA

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46 Summary kg of 136 Xe very far future? Controversy S. Schönert, NME WS, LNGS Nov. 2011

47 Conclusion New sensitive experiments are starting operation -> -> new important information is expected 5 experiments have reached [m ββ]< 1 ev sensitivity with 4 isotopes: GERDA - EXO - KamLAND-Zen CUORE, NEMO Upgrades and new experiments coming to investigate the inverted hierachy region of [m ββ] < mev

48 Extra slides