1. Nuclear matrix elements 1 / T 1/2 = PS * NME 2 * (m / m e ) 2 measured quantityquantity of interest The big unknown Started worldwide effort for a coherent program to reduce NME uncertainty down to 30%, summary report available nucl-ex/0511009 Needs international coherent effort http://www.ippp.dur.ac.uk/0NU2B/2005.html

2. Nuclear matrix elements 1 / T 1/2 = PS * ME 2 * (m / m e ) 2 0+0+ 1+1+ (A,Z) (A,Z+1) (A,Z+2) 0+0+ charge exchange (p,n), (3He,t) muon capture beta- decays antineutrino- capture nu N scattering Theory: Shopping list what to measure to improve calculations Experiment: Where can it be measured, who? „Ultimate dream“: coherent effort, strategy paper to get things done Q - values charge exchange (n,p), (d,2He) EC/beta+ decays

3. Phase space   decay rate scales with Q 5  2  decay rate scales with Q 11 Q-value (keV) IsotopeNat. abund. (%) (PS 0v) –1 (yrs eV 2 ) (PS 2v) –1 (yrs) Ca 4842710.1874.10E242.52E16 Ge 7620397.84.09E257.66E18 Se 8229959.29.27E242.30E17 Zr 9633502.84.46E245.19E16 Mo 10030349.65.70E241.06E17 Pd 110201311.81.86E252.51E18 Cd 11628027.55.28E241.25E17 Sn 12422885.649.48E245.93E17 Te 130252934.55.89E242.08E17 Xe 13624798.95.52E242.07E17 Nd 15033675.61.25E248.41E15

4. Matrix elements 2 matrix elements determined by intermediate 1 + states 0 matrix elements different

5. Outcome: Working packages Working package 1: Charge exchange reactions Working package 2: Q-value measurements Working package 3: Muon capture Working package 4: Double elecron capture Working package 5: Neutrino nucleus scattering Working package 6: Nucleon exchange reaction Urgency: Some facilities might vanish in the near future!!!

6. WP1: Charge exchange Currently: (d, 2 He) and ( 3 He,t) Further: ft-values of EC fixing g_pp EM transitions to IAS nuclear deformation s.r.c.

7. WP2: Q-values Only 76 Ge known very accurate Atomic traps Reasons: - Good energy resolution detectors - Presence of nearby background lines - Enhancement in EC/EC modes if levels are degenerate

8. WP3: Ordinary Muon capture

9. NNR05-Workshop Neutrino nuclear responses in particle and astro nuclear physics -- Double beta decays and low-energy astro neutrinos----- Dec. 1-4, CASTHarima, Osaka Japan Neutrinos involved in  and astro nuclear physics are mostly low- energy(0.01-0.1 GeV) neutrinos, and accordingly the responses are spin isospin responses with low multi-polarities of L= 0~3. In fact the spin isospin responses for the lowest multi-pole of L=0 have extensively been studied at RCNP, MSU, KVI, TUDA and others. High E-resolution systems there are very powerful. http://www.spring8.or.jp/e/conference/appeal/nnr05/