Nuclear transparency and double beta decay of molybdenum 100. Annual progress report, March 1, 1992--January 31, 1993

Abstract

Data taking is now complete on a double beta decay experiment which has been carried out with collaborators from the Lawrence Berkeley Laboratory, the University of New Mexico, and the Idaho National Engineering Laboratory, and work is continuing on a second collaborative experiment, AGS experiment 850 at the Brookhaven National Laboratory to study nuclear color transparency. In March, the experimental apparatus used to search for double beta decay in molybdenum 100 in the Consil silver mine in Osburn, Idaho was dismantled, and the data analysis is in its final stages. No evidence has been seen for the O{sup +} {yields} O{sup +} mode of zero neutrino double beta decay collaborators with a 1{sigma} lifetime limit of 3 {times} 10{sup 22} years. This limit is 7.5 times greater than the limit we published previously in Physical Review Letters in 1989. Backgrounds have been simulated and fits are currently underway to a simulated O{sup +} {yields} 2{sup +} mode of zero neutrino double beta decay to improve on a very preliminary 1{sigma} lifetime limit of 2.3 {times} 10{sup 21} years presented at the April, 1992 meeting of the APS in Washington. A scintillating fiber detector with three Hamamatsu, H4140, 256 channel multianode phototubes has been built, instrumented, and tested in the May--July 1992 run in the EVA detector at Brookhaven Laboratory`s AGS. Preliminary results from this detector have been disappointing. it is likely that the detector will have to be substantially redesigned before the 1993 AGS run.