1. Nasim Fatemi-Ghomi, Group Christmass Meeting December 2006 1 Nasim Fatemi-Ghomi Double Beta Decay Study of 150 Nd at NEMO3 (The magic isotope!!)

2. Nasim Fatemi-Ghomi, Group Christmass Meeting December 2006 2 Introduction 150 Nd is one of the seven double beta decay isotopes of the NEMO3 detector. It has a high nuclear transition energy,Q , and it is therefore easier to reduce the radioactive background. This makes it interesting and a strong candidate for SuperNemo!! Nd 2 O 3 has 57g mass (37g pure 150 Nd). Nd 2 O 3

3. Nasim Fatemi-Ghomi, Group Christmass Meeting December 2006 3 Internal Background BgAct(mBq/kg)Ge measurement Modane-Baksan Found from 1e channel 210 Bi368.42- 207 Tl163.0- 211 Pb163.0- 234m Pa84.4- Found from e  Channel 207 Bi235128 - 120 Found from e  +  214 Bi15.3< 3 - 20 V.Tretyak(Aussoi s 2005) 40 K66.7< 6.6 - 9.6 V.Vasiliev (Dubna 2004) 208 Tl7.959.6 - 5 228 Ac22.120 - 15 212 Bi22.1- Ge measurement 152 Eu38.3(modane)21.6(Baksan) External Background & Background on the Surface Background on the Surface of the Wires and Foils. of the Wires and Foils. BgAct(Bq) SW 214 Bi0.623 SW 214 Pb0.623 SF 214 Bi0.0185 SF 214 Pb0.0185 PM 214 Bi374 PM 214 Pb374 PM 228 Ac515 PM 60 Co50.7 PM 40 K954 Air 214 Pb702 Air 214 Bi702

4. Nasim Fatemi-Ghomi, Group Christmass Meeting December 2006 4 Data taking time =422.665 days = 1.16 yr. Events should come from Nd 2 O 3. Data Selection Pre-selection for 150 Nd to 2  events: Two electrons with E 1,E 2 > 0.2 MeV. Both electrons originate from a common vertex. Track starts from layers 1 & 2 of the tracker. No alpha decay in the event. No gamma cluster with energy >0.15 MeV.

5. Nasim Fatemi-Ghomi, Group Christmass Meeting December 2006 5

6. 6 Final Half-life Result for 150 Nd to 2  T 12 = 9.46 -0.37 +0.41 (stat)  0.85(syst) x 10 18 y Number of data events: 1271 Number of total background: 412 Efficiency 6.74%

7. Nasim Fatemi-Ghomi, Group Christmass Meeting December 2006 7 Plan for Future: Put limit on using this measured half-life. Put limit on T 12 0 using this measured half-life. More data has to be added to have more statistics!! More data has to be added to have more statistics!! Just started working with 160 Cd. Just started working with 160 Cd. + The first draft of a technical note on The first draft of a technical note on 150 Nd  2  analysis is written! Has to be approved by the collaboration to become part of a paper!