OMC rates in different nuclei related to 2β-decay. K.Ya. Gromov, D.R. Zinatulina, C. Briançon, V.G. Egorov, A.V. Klinskih, R.V. Vasiliev, M.V.Shirchenko,I. Yutlandov, C. Petitjean. MATRIX elements workshop, Dresden, Germany

 (n,p)-likecharge--exchangereactions

Ordinary Muon Capture (OMC)  Electron Capture: e - + (A,Z)  (A, Z-1) + e Q ~ m e  0.5 MeV  Muon Capture:  - + (A,Z)  (A, Z-1) +  Q ~ m   100 MeV

OMC

2β-decay2β-exp’ts μ - capture Status 76 Ge Gerda Majorana 76 Se CaTGV, NEMO3 48 Ti CdTGV 106 Cd Se NEMO3, SuperNEMO 82 Kr MoNEMO3 100 Ru− 116 CdNEMO3 116 Sn NdSuperNEMO 150 Sm2002, 2006 Candidates for 2β decay and status of μ-capture:

Setup (solid target)

PSI,2006

Setup (gas target) Vessel walls   plastic scintillator C3 Entrance window  C1 & C2

PSI, 2006

Distribution of N (E, t):

Time evolution (method) The fragment number (each fragment corresponds to 10 ns time period)

Muon life-time in Kr isotopes ns yield

Our results for Kr and Sm: IsotopeE γ, keVLife-time, nsλ c, 1/μs 82 Kr (isotopic- enriched) ± ± ± ± ± ± Kr (57%) ± ± Kr (17.3%) ± ± Sm (isotopic- enriched) ± ± ± ± ± ± 0.14

Distribution of N (E, t)

What do we observe?  Prompt muonic X-rays (cascade) - Prompt spectrum give us: identification, normalization, and isotopic shifts.  Delayed γ-rays following μ-capture - Delayed spectrum give us: identification and partial rates  -(Background) -uncorrelated to muon capture- Uncorrelated spectrum give us: identification, calibration and isotopic yields.

Spectra with Kr:

S P D K-series Muonic X -rays Normalization: Number of Incoming muons ~ ~ sum of KX-lines

Isotopic shift in Cd: K  ( 106 Cd) K   ( 106 Cd)

OMC

Detector efficiency: Small detector with Be window High-volume detector E[keV] eff‘cy

48 Sc IfIf IiIi Extraction of partial rates - Intensity of gamma line incoming to level keV - Intensity of gamma line outgoing from level keV -The sum of intensities mu-X-rays K-series. - Enrichment of our target.

, –2– , , 2, ,3 <3 48 Sc <3 ~ 7.37% (0.24 ± 0.04) % (1.10 ± 0.06) % (0.35 ± 0.09) % (0.40 ± 0.03) % (0.37 ± 0.04) % (0.47 ± 0.07) % < 0.31 % < % (0.11 ± 0.05) % (0.35 ± 0.08) % < 1.55 % <1.25% <0.194 %

E_level, keV Partial rates (experiment) Charge- excharge reactions 06+T1/2= h < < 1.25high < medium ± < ± 0.07medium ± 0.08high , ± , 2-< ± , 2, ± , ± ± 0.04medium < Partial rates for 48 Sc (% per μ-stop)

E_level, keV Partial rates E_level, keV Partial rates E_level, keV Partial rates 44.4(1) + T 1/2 =1.8*10 -6 sec 457.3(2;3)745.0(1 + ;2 + ) (1) (2) (0 - ;1;2) (1) + < (2÷5) (0 + ;3 + ) (1) (1;2 + ) (1;2;3 + ) (3) - < (2;3) < 3> (0;1) + < (2÷6) (1;2;3) (4) - < (1;2 + ) (1 - ;2 - ;3 + ) (1;2) (1 - ;2;3 + ) (1;2;3) + ~ (1;2) + < (2;3) (1 - ;2 - ;3 + ) (3;4) - ~ (1;2 - ) (1;2) (2;3;4)< (1;2;3)924.7(< 3) (2;3) (1;2;3 + ) < (2)+(2)+ < < 4< (1;2;3) (3;4) (1;2;3 - )~ < (3) (1 + ;2 + ) < 3~ (1;2 - ) (1 - ;2 - ) (1;2;3) (2÷5) (1 + ;2 + )~ < (2÷5)681.1(1÷4) (1;2) + ~ (1;2) (1÷4)~ (1;2;3) (1;2;3) (< 4) (1 + ;2 + ) (1;2) < Partial rates for 76 As (% per μ-stop)

Decay of the nuclei produced in OMC n OMC 2n A, ZTarget: aγaγ aγaγ aγaγ aβ-aβ- aβ-aβ- aβ-aβ-

76As75As 74As Uncorrelated spectrum measured with the 76 Se target

Isotopes yields for 150 Sm: A, Element Type of decay T 1/2 λ i /10 4, c Pm g.s β h * Pm IT μs Pm g.s β h * Pm IT d * Pm IS β d Pm g.s β d Nd g.s β h<78

Conclusions and plans:  OMC presently seems to be a bit off the main stream of physics But: it can provide important information about the high-q component of the weak nuclear response, i.e. it is relevant for the neutrinoless double beta decay (here in particular the 2- and 3+ states) Further: the connection between mucap and double beta decay has been fully worked out theoretically (Suhonen et al)  Several double beta decay nuclei ( 48 Ti, 76 Se, 82 Kr, 106 Ag, 150 Sm) have been studied in mu-cap by our group and results are consistent with chargex and also complementary to chargex  The analyses are difficult and require a strong concerted effort (level scheme of 150 Pm is unknown, difficult spectrum of 82 Kr with many lines which including different isotopes in this reaction)  New and forceful initiatives are needed to advance the field -- the initiative of Prof. Ejiri is very much appreciated!!

Thank you for your attention!

 Conclusion   1) Mucap presently seems to be a bit off the main stream of physics  2) But: it can provide important information about the high-q component of the weak nuclear response, i.e. it is relevant for the neutrinoless double beta decay (here in particular the 2- and 3+ states)  3) Further: the connection between mucap and double beta decay has been fully worked out theoretically (Suhonen et al)  4) several double beta decay nuclei (48-Ti, 76Se, 82Kr, 106Ag, 116Sn, 150Sm) have been studied in mucap by our group and results are consistent with chargex and also complementary to chargex.  5) The analyses are difficult and require a strong concerted effort  6) New and forceful initiatives are needed to advance the field -- the initiative of Prof. Ejiri is very much appreciated!!

 here are my thoughts about mu-capture 1) mucap tells us what states respond to the weak interaction at high momentum transfer 2) the information gives us a way to connect these states to hadronic interaction and may be allow to find some common scaling between mucap and chargex 3) strong interaction processes in chargex are complicated and contain components which are not relevant for weka interaction -- may be mucap can tell us more about the selectivity of the excitation in chargex