Decay of 90Kr and 90Rb

Abstract

The decay of 32 s 90Kr and 154 s 90Rb has been studied using NE102 beta detectors and NaI(Tl) and Ge(Li) gamma-ray detectors, singly and in coincidence. Thirteen excited states of 90Rb involving 35 transitions have been identified with excitation energies of 0.1064, 0.1215, 0.2419, 0.3557, 0.6144, 0.6610, 0.7408, 0.8375, 1.2402, 1.6740(1+), 1.7798(1+), 2.1261(1+), and 3.0937(1+) MeV. The 256 s isomeric state at an excitation of 0.1064 MeV (probably 4–) feeds high spin states of 90Sr at 2.2068, 2.4972, 2.5712, 2.9275, 3.5835, 4.1485, 4.3355, and 5.0397 MeV with a total intensity of 12%. The 154 s ground state of 90Rb feeds many low spin states in 90Sr, including the levels at 0.8315, 1.6555, 1.8921, 2.5271, 3.0385, 3.3833, 3.4497, 3.8985, 4.0325, 4.0360, 4.1360, 4.3660, 4.6466, 4.891, 4.921, 4.974, 5.070, 5.091, 5.163, 5.1876, 5.2540, 5.285, and 5.3336 MeV. Sixty-four transitions in 90Sr have been classified in this manner. The decay energy of 90Kr is 4.41 ± 0.03 MeV.