BETA(-)-DECAY AND COSMIC-RAY HALF-LIFE OF MN-54

A superconducting solenoid electron spectrometer operated in the lens mode was adapted to search for the beta(-) decay of Mn-54. The Compton electron and other instrumental backgrounds were largely reduced by s pecial shielding of the absorber system. An improved procedure was dev eloped to select the events by momenta. An upper limit of less than 3. 9 x 10(-5) has been established for the intensity of the beta(-)branch . This would define the partial half-life of the Mn-54 beta(-) decay t o be greater than 2.2 x 10(4) yr. The implications of this result for the Mn-54 cosmic-ray chronometry problem are discussed.