Nuclear Reactions for Neutrinoless Double Beta Decay

Transcription

1 Nuclear Reactions for Neutrinoless Double Beta Decay Manuela Cavallaro INFN LNS (Italy) Unraveling the complexity of nuclear systems: singleparticle and collective aspects through the looking glass 6-10 February 2017

2 0νββ decay Open problem in modern physics: Neutrino absolute mass scale Neutrino nature 0νββ is considered the most promising approach Process mediated by the weak interaction Occurring in even-even nuclei where the single -decay is energetically forbidden

3 Double β-decay Two-neutrino double beta decay Neutrinoless double beta decay Observed in 11 isotopes since 1987 Still not observed M. Goeppert-Mayer, Phys Rev. 48 (1935) 512 E. Majorana, Il Nuovo Cimento 14 (1937) 171 W. H. Furry, Phys Rev. 56 (1939) 1184 A ZX N A Z+2 Y N 2 + 2e + 2 ν A ZX N A Z 2 Y N+2 + 2e + + 2ν 1. Within standard model 2. T 1/ to yr 1. Beyond standard model 2. Violation of lepton number conservation 3. CP violation in lepton sector 4. A way to leptogenesis and GUT 5. Access to effective neutrino mass

4 Search for 0 decay: A worldwide race Experiment Isotope Lab Status GERDA 76 Ge LNGS [Italy] Operational CUORE 130 Te LNGS [Italy] Construction Majorana 76 Ge SURF [USA] Construction KamLAND-Zen 136 Xe Kamioka [Japan] Operational EXO/nEXO 136 Xe WIPP [USA] Operational SNO+ 130 Te Sudbury [Canada] Construction SuperNEMO 82 Se (or others) LSM [France] R&D CANDLES 48 Ca Kamioka [Japan] R&D COBRA 116 Cd LNGS [Italy] R&D Lucifer 82 Se LNGS [Italy] R&D DCBA many [Japan] R&D AMoRe 100 Mo [Korea] R&D MOON 100 Mo [Japan] R&D List not complete

5 Nuclear Matrix Elements 0νββ decay half-life Phase space factor contains the average neutrino mass T (0 0 ) G M f ( m i, U ) 1 0 ei 2 Nuclear Matrix Element (NME) M 0 2 ˆ 0 f O i 2 Transition probability of a nuclear process Nuclear physics plays a key role!

6 Nuclear Matrix Elements Nuclear Matrix Element (NME) M 0 2 ˆ 0 f O i 2 Calculations (still sizeable uncertainties): QRPA, Large scale shell model, IBM, EDF E. Caurier, et al., PRL 100 (2008) N. L. Vaquero, et al., PRL 111 (2013) J. Barea, PRC 87 (2013) T. R. Rodriguez, PLB 719 (2013) 174 F.Simkovic, PRC 77 (2008)

7 Z The idea Is there an experimental way to access the NME? The ERC project NURE: 76 Se 77 Se 78 Se Nuclear reactions Double Charge Exchange reactions (DCE) to stimulate in the laboratory the same nuclear transition occurring in 0νββ 74 Ge 75 Ge 76 As 75 As 77 As 76 Ge N

8 0νββ vs HI-DCE Differences DCE mediated by strong interaction, 0νββ by weak interaction DCE includes sequential transfer mechanism Similarities Same initial and final states: Parent/daughter states of the 0 decay are the same as those of the target/residual nuclei in the DCE Similar operator: Short-range Fermi, Gamow-Teller and rank-2 tensor components are present in both the transition operators, with tunable weight in DCE Large linear momentum (~100MeV/c) available in the virtual intermediate channel Non-local processes: characterized by two vertices localized in a pair of valence nucleons Same nuclear medium: Constraint on the theoretical determination of quenching phenomena on 0 Off-shell propagation through virtual intermediate channels

9 The context Weak interaction probes β, 2νββ, μ-capture, ν-nucleus scattering, Double charge-exchange induced by pions (π ±, π ) abandoned in the 80 s due to the large differences in the momentum transfer and lack of direct GT component in the operators Single charge-exchange reactions induced by light ions ( 3 He,t), (d, 2 He), Other researches to extract information on NME from experimental data and/or constrain the theory Interesting for β-decay and 2νββ! Heavy-ion induced double charge-exchange limited in the past due to low cross-sections Transfer reactions for constraining Ψ i, Ψ f Renewed interest (RIKEN, Osaka) but low resolution ( 1.5 MeV)

10 The project NURE plans to measure the absolute cross section of HI-DCE reactions on nuclei candidates for 0νββ and to extract «data-driven» NME the measured quantity isthe cross section dσ dω q, ω = f(nme) details of the reaction The extraction of nuclear structure information from measured cross sections is not trivial e.g. for single charge-exchange: NME extracted within 2-5% accuracy by proportionality relation dσ dω q, ω = σ E p, A F q, ω NME(α) E p incident energy q momentum transfer ω excitation energy

11 Connection between -decay and Single CEX Single β-decay strenghs are proportional to single CEX cross-sections under specific conditions For (p,n), (n,p), (d, 2 He) F. Osterfeld Rev. Mod. Phys. 64 (1992) 491 T.N. Taddeucci Nucl. Phys. A 469 (1997) 125 H. Ejiri Phys. Rep. 338 (2000) 256 H.M. Xu, et al., Phys. Rev. C 52 (1995) R1161 H. Ejiri Phys. Rep. 338 (2000) 256 ( 3 He,t) Y. Fujita Prog. Part. Nuc. Phys. 66 (2011) B(GT) [(3He,t);q=0] B(GT) [β decay] = 1 ± 0.05 Strong interaction Weak interaction (In general for B(GT)>0.05)

12 Connection between -decay and Single CEX For heavier projectiles: ( 7 Li, 7 Be) B(GT) [(7 Li,7Be);q=0] B(GT) [β decay] = 1 ± 0.2 Confirmed on different nuclei: 11 Be, 12 B, 15 C, 19 O (less precision) Microscopic and unified theory of reaction and structure is mandatory for quantitative analyses S. Nakayama PRC 60 (1999) F. Cappuzzello et al., Nucl. Phys. A 739 (2004) F.Cappuzzello et al. Phys.Lett B 516 (2001) F.Cappuzzello et al. EuroPhys.Lett 65 (2004) S.E.A.Orrigo, et al. Phys.Lett. B 633 (2006) C.Nociforo et al. Eur.Phys.J. A 27 (2006) M.Cavallaro Nuovo Cimento C 34 (2011) 1

13 Z Z The project 76 Se 77 Se 78 Se Only two transitions of interest for 0νββ: 76 Ge 76 Se and 116 Cd 116 Sn Two directions: ββ + via ( 18 O, 18 Ne) and ββ - via ( 20 Ne, 20 O) Complete net of reactions which can contribute to the DCE cross-section: 1p-, 2p-, 1n-, 2n-transfer, single cex, DCE Two (or more) incident energies to study the reaction mechanism GERDA, MAJORANA, COBRA ( 18 O, 20 Ne) 74 Ge 75 Ge 76 As 75 As 77 As N 76 Ge 116 Sn 117 Sn 118 Sn ( 18 O, 20 Ne) 114 Cd 115 Cd 116 In 115 In 117 In N 116 Cd

14 The pilot experiment 40 Ca( 18 O, 18 Ne) MeV Catania 18 O 7+ beam from Cyclotron at 270 MeV (10 pna, 3300 C in 10 days) 40 Ca target 300 μg/cm 2 Ejectiles detected by the MAGNEX spectrometer 0 < θ lab < 10 corresponding to a momentum transfer ranging from 0.17 fm -1 to 2.2 fm -1 K800 Superconducting Cyclotron MAGNEX magnetic spectrometer

15 The MAGNEX spectrometer Measured resolution: Energy E/E 1/1000 Angle θ 0.3 Mass m/m 1/160 Optical characteristics Measured values Angular acceptance (Solid angle) 50 msr Angular range Momentum (energy) acceptance -14%, +10% (-28%,+20%) Momentum dispersion for k= (cm/%) 3.68 Maximum magnetic rigidity 1.8 T m F. Cappuzzello et al., Eur. Phys. Journ. A (2016) 52:167 15

16 Zero-degree measurement Θ MAGNEX = +4-1 < θ lab < +10 Faraday-cup ejectiles beam TARGET beam

17 Particle Identification MeV 20 Z identification Br = p q X 2foc µ m Eresid 2 q A identification Ne Na 21Ne 20Ne 19Ne Ne Ne F Xfoc(m) Eresid (ch) F. Cappuzzello et al., NIMA621 (2010) 419 F. Cappuzzello, et al. NIMA638 (2011) 74 M.Cavallaro et al. EPJ A 48: 59 (2012) D.Carbone et al. EPJ A 48: 60 (2012) Eresid (ch)

18 The pilot experiment 18 O + 40 Ca at 270 MeV 40 Ca( 18 O, 16 O) 42 Ca 2n-transfer 40 Ca( 18 O, 20 Ne) 38 Ar 2p-transfer 40 Ca 41 Ca 42 Ca ( 18 O, 20 Ne) 39 K 41 K 40 K 38 Ar 39 Ar 40 Ar 40 Ca( 18 O, 18 Ne) 40 Ar DCE 40 Ca( 18 O, 18 F) 38 K CEX Experimental feasibility: zero-deg, resolution (500 kev), low cross-section (μb/sr) Limitations of the past HI-DCE experiments are overcome! Data analysis feasibility: the analysis of the DCE cross-section has lead to NME compatible with the existing calculations F. Cappuzzello, et al., Eur. Phys. J. A (2015) 51:145

19 Preliminary NME extraction In the lack of «real» theory dσ dω DCE Under the hypothesis of validity of the factorization q, ω = σ α DCE E p, A F α DCE q, ω B T DCE α B P DCE α σ α DCE E p, A = K(E p, 0) J ST 2 NST D M 40 2 Ca Just to speculate: removing Pauli blocking one can roughly estimate 0 M 48 2 Ca Pauli blocking about 0.14 for F and GT F. Cappuzzello, et al., Eur. Phys. J. A (2015) 51:145

20 A broader view Limitations of NURE: Only two systems can be studied in 5 years (due to the low cross-sections) A more accurate job on the theory is needed 20

21 A broader view The NUMEN project NUclear Matrix Elements for Neutrinoless double beta decay TeBe CS-upgrade NURE Operating in a wider context, in a longer time scale (10-15 yr), in close synergy with NURE SiCILIA INFN call

22 A broader view The NUMEN project NUclear Matrix Elements for Neutrinoless double beta decay The collaboration Spokespersons: F. Cappuzzello and C. Agodi E. Aciksoz, L. Acosta, C. Agodi, X. Aslanouglou, N. Auerbach, J. Bellone, R. Bijker, S. Bianco, D. Bonanno, D. Bongiovanni, T. Borello, I. Boztosun, V. Branchina, M.P. Bussa, L. Busso, S. Calabrese, L. Calabretta, A. Calanna, D. Calvo, F. Cappuzzello, D. Carbone, M. Cavallaro, E.R. Chávez Lomelí, M. Colonna, G. D Agostino, N. Deshmuk, P.N. de Faria, C. Ferraresi, J.L. Ferreira, P. Finocchiaro, A. Foti, G. Gallo, U. Garcia, G. Giraudo, V. Greco, A. Hacisalihoglu, J. Kotila, F. Iazzi, R. Introzzi, G. Lanzalone, A. Lavagno, F. La Via, J.A. Lay, H. Lenske, R. Linares, G. Litrico, F. Longhitano, D. Lo Presti, J. Lubian, N. Medina, D. R. Mendes, A. Muoio, J. R. B. Oliveira, A. Pakou, L. Pandola, H. Petrascu, F. Pinna, F. Pirri, S. Reito, D. Rifuggiato, M.R.D. Rodrigues, A. Russo, G. Russo, G. Santagati, E. Santopinto, O. Sgouros, S.O. Solakcı, G. Souliotis, V. Soukeras, S. Tudisco, R.I.M. Vsevolodovna, R. Wheadon, V. Zagatto Italy, Brazil, Greece, México, Germany, Turkey, Israel, Romania 73 members, 8 countries

23 A broader view The NUMEN project NUclear Matrix Elements for Neutrinoless double beta decay Phase1: The experimental feasibility (completed) Phase2: Experimental exploration of few cases (NURE) and work on theory (running until 2021) Phase3: Facility upgrade (Cyclotron, MAGNEX, beam line, ) to work with two orders of magnitude more intense beam Phase4: Systematic experimental campaign on all the systems with the upgraded facility

24 Upgrade of LNS facilities: The CS accelerator LNS CS accelerator current (from 100 W to 5-10 kw); Existing extraction channel From electrostatic extraction (low efficiency 50%) to extraction by stripping (>99%) New extraction channel beam transport line transmission efficiency to nearly 100% 24

25 Upgrade of the MAGNEX FPD: The gas tracker MAGNEX focal plane detector rate (from few khz to MHz) From multi-wire tracker To micro-pattern tracker Wire-Based Detector: Secondary effects Gain limits Space charge Counting-rate limits Aging Damage after long-term operation Micro-pattern gas detectors: Move down in size & add cathodes very close to anodes to evacuate ions produced during the avalanche process

26 NU M EN Upgrade of the MAGNEX FPD: The Particle Identification SiCILIA INFN call A radiation tolerant stopping wall for particle identification Radiation hardness ions in ten years activity (silicon detector dead at 10 9 implanted ions/cm 2 (heavy ions not MIP!!)) From wall of 60 Si pad detectors (7 cm X 5 cm) To????? What isthe right material?? Radiation hard Heavy ions Working in gas environment Large area High energy resolution (1%) Timing resolution (few ns) SiC SiC telescope

27 NU M EN Typical present target ladder Reaction targets for high intensity Target technology for intense heavy-ion beam (10pμA) Isotopes candidate for 0νββ: 116 Sn, 116 Cd, 76 Ge, 76 Se, 130 Te, 48 Ca, Most of them have low melting temperature and low thermal conductivity Idea: Evaporation on a backing material with good properties (Graphen, Diamond, Graphite) and cooling Politecnico Torino and INFN-Torino 27

28 NU M EN NUMEN is a challenging program Targets: For intense heavy-ion beams Integration 28

29 The Goals of the Research Program Main goal (Holy Graal): Extract data-driven information on NME from measured cross-sections of for all the systems candidate for 0νββ Secondary goals: Constraints to the existing theories of NMEs Comparative information on the sensitivity of half-life experiments Complete study of the reaction mechanism

30 Conclusions and Outlooks Many experimental facilities for 0 half-life, but not for the NME Pioneering experiments shown that DCE cross sections can be suitably measured First results for the ( 18 O, 18 Ne) and ( 20 Ne, 20 O) are encouraging, showing that quantitative information on 0 NME are not precluded Experimental campaign on nuclei candidates for 0νββ and work on the theory in the next 5 years The upgrade foreseen for the INFN-LNS cyclotron and the MAGNEX spectrometer will allow to build a unique facility for a systematic exploration of all the nuclei candidate for 0νββ

31 Conference on Neutrinos and Nuclear Physics (CNNP2017) October 2017 Catania (Italy) - Nuclear double beta decays - Nuclear structure in connection with neutrino physics - Nuclear reactions as a probe for weak decays - Neutrino-nucleus interaction at low and high energy - Supernova models and detection of supernova neutrinos - Solar models and detection of solar neutrinos - Direct and indirect dark-matter searches - Rare beta decays of nuclei for neutrino-mass measurements - Neutrino oscillations and matter effects - Anomalies in reactor neutrinos - New related detection technologies

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