Nuclear matrix elements

1 / T1/2 = PS * NME2 * (m / me)2

measured quantity quantity of interest

The big unknownStarted worldwide effort for a coherentprogram to reduce NME uncertainty down to 30%, summary report availablenucl-ex/0511009

Needs international coherent efforthttp://www.ippp.dur.ac.uk/0NU2B/2005.html

Nuclear matrix elements1 / T1/2 = PS * ME2 * (m / me)2

0+

1+

(A,Z)

(A,Z+1)

(A,Z+2)0+

charge exchange(p,n), (3He,t)

muon capturebeta- decays

antineutrino-capture

nu N scattering

Theory: Shopping list what to measure to improve calculationsExperiment: 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

Phase space decay rate scales with Q5

2 decay rate scales with Q11

 

Q-value (keV)

Isotope Nat. abund. (%)

(PS 0v)–1 (yrs eV2)

(PS 2v) –1 (yrs)

Ca 48 4271 0.187 4.10E24 2.52E16Ge 76 2039 7.8 4.09E25 7.66E18Se 82 2995 9.2 9.27E24 2.30E17Zr 96 3350 2.8 4.46E24 5.19E16Mo 100 3034 9.6 5.70E24 1.06E17Pd 110 2013 11.8 1.86E25 2.51E18Cd 116 2802 7.5 5.28E24 1.25E17Sn 124 2288 5.64 9.48E24 5.93E17Te 130 2529 34.5 5.89E24 2.08E17Xe 136 2479 8.9 5.52E24 2.07E17Nd 150 3367 5.6 1.25E24 8.41E15

Matrix elements2 matrix elements determined by intermediate 1+ states

0 matrix elements different

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!!!

WP1: Charge exchangeCurrently: (d,2He) and (3He,t)

Further:ft-values of EC fixing g_ppEM transitions to IASnuclear deformations.r.c.

WP2: Q-valuesOnly 76Ge known very accurate

Atomic traps

Reasons:

- Good energy resolution detectors- Presence of nearby background lines

- Enhancement in EC/EC modes if levels are degenerate

WP3: Ordinary Muon capture

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/