Doppler Shift Lifetime and Gamma-Ray Angular Measurements in 93NB

• Main Authors: Tapphorn,R M, Shnidman,R
• Format: Report
• Language: English
• Subjects: ALPHA PARTICLES; COMPUTATIONS; COMPUTER PROGRAMS; DOPPLER EFFECT; GAMMA RAYS; Li drifted Ge detectors; NIOBIUM; Niobium 93; NUCLEAR ENERGY LEVELS; Nuclear Physics & Elementary Particle Physics; NUCLEAR STRUCTURE

Mean lifetimes for four levels in 93Nb have been measured by the Doppler-shift attenuation method. Gamma-ray angular distributions have been measured for the gamma decay of excited levels in 93Nb up to 1127 keV in excitation. The levels were excited by the 90Zr(alpha, p gamma)93Nb reaction at a bombarding energy of 14.77 MeV. Spectra of gamma rays in coincidence with protons were obtained with a 55-cc Ge(Li) detector. Spin assignments obtained from the present results for the low-lying positive-parity levels in 93Nb are in agreement with previous assignments. A spin of 3/2(-) has been assigned to a level at 685 keV in excitation and a spin of 5/2(-) (3/2-) has been assigned to an 809-keV negative-parity level. Gamma-ray mixing ratios measured for the gamma decay of excited low-lying levels in 93Nb have been combined with lifetime measurements to calculate the electromagnetic transition strengths. The experimental E2 transition strengths are shown to be consistent with those predicted by a weak-coupling model.