A Search for Neutrinoless Double Beta Decay with NEMO-3

Kiyotaka Yamazaki

150Nd

A source foil contains Nd2O3 with 37.0±0.1g of 150Nd (~90% of the foil)

150Nd is a 2νββ isotope with Qββ=3367keV -Second highest of all 2νββ isotopes (Qββ (48Ca)=4271kev)

The highest phase factor in all 2νββ isotopes.

Phase 1 and Phase 2

Nuclear Instruments and Methods in Physics Research A 606 (2009) 449–465

Radon diffusion through the joints of the sectors

Radon-free facility was installed in September 2004

Phase1: A(Rn) = 37.7±0.1 mBq/m3

Phase1: A(Rn) = 6.46±0.02 mBq/m3

Background analysis -1e1γ channel

EC (e.g. 207Bi, 152Eu) -daughter nucleus de-excites by emission of photon and electron is ejected via internal conversion. β-decay to an excited states (e.g. 152Eu, 154Eu) -daughter nucleus de-excites by emission of photon

β-decay and 2γ emission (e.g. 208Tl) -daughter nucleus de-excites by emission of 2 photons but it is possible that one of photon is not detected.

Background analysis -1e1γ channel

Phase 1 Phase 2

Energy Sum

Energy ofElectron

But…

Nasim FATEMI-GHOMI thesis 2009

A(208Tl)= 0.47±0.05 mBq

924.7days

1402.1days in Total

A(208Tl)= 1.25±0.1 mBq

2e channel

T1/2=(9.03±0.04)×1018 years

Next year…

• Main goal is to publish all the 150Nd results

• Analysis of full-set of the data• Radon Problem• More background analysis

- with 1e, 1e2γ channel• And 0νββ analysis…