Search for double beta-decay products of /sup 136/Xe in liquid xenon

In order to probe the 2/spl nu/-mode of the double beta-decay of /sup 136/Xe, decay daughters (/sup 136/Ba) were accumulated under an electric field on the surface of a spherical electrode in a positive ion collector filled with liquid xenon, and were then observed with a time-of-flight mass spectrometer. The positive ion collector was operated for 847 hours using natural liquid xenon of 3 liters. No /sup 136/Ba isotopes were detected with the time-of-flight mass spectrometer. However, it was found that a collector electrode made of stainless steel was free from contamination of natural barium isotopes as background.<
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