 Decay of 48 Ca, Preliminary Results Shiva King NEMO Meeting Aussois December 2005

Introduction Selection criteria Analysis Results Runs processed from Feb – Sept. 2004, total run time = s = 0.92yrs

Selection Criteria (preliminary) Two tracks with –ve charge associated with different scintillator hits Energy deposit in each scintillator E > 100 keV For counters on petals use front face only Do not use PMTs with a low gain: >6 Two tracks must have a common vertex in the source foil  r| < 4cm |  z| < 4cm TOF cut: int. > 1%; ext. < 0.1% There must be at least 1 hit in layer 0 or 1 Track length > 30cm Alphas:  Refiring time > 70  s  Not more than 2 unused fast geiger hits <20cm from vertex  Single and group hits

MC Background BgGen. EventsActivityExp. Events 214 Bi sfoil1.0e70.74mBq/m Bi swire4.7e8857mBq Bi foil2.0e60.254mBq/Kg Eu foil2.0e630mBq/Kg Pa foil2.0e6<15mBq/Kg Pb foil2.0e64.17mBq/Kg Tl foil2.0e60.3mBq/Kg Tl PMT2.0e940.41Bq Y2.0e61746mBq/Kg681.02

Eee and Ee (before energy cuts)

Cos  (before energy cuts)

Eee/Ee (EeeMin>1.5Mev; EeMin>0.6Mev) Events: 61 Bg Events:21.73 S/B:1.81 Events: 41 Bg Events:2.64 S/B:14.54 T 1/2 =3.29 x10 19 yrs

Cos  (EeeMin>1.5Mev; EeMin>0.6Mev )

Eee/Ee (EeeMin>1.5Mev; EeMin>0.7Mev) Events: 41 Bg Events:11.26 S/B:2.64 Events: 30 Bg Events:2.13 S/B:13.10 T 1/2 =3.46 x10 19 yrs

Cos  (EeeMin>1.5Mev; EeMin>0.7Mev )

Results E cuts Cos  Half-Life (x10 19 yrs)EvntsBg EvntsS/BEff. EeMin>0.6 All cos  % EeMin>0.6 Cos  < % EeMin>0.7 All cos  % EeMin>0.7 Cos  < %