Further gamma-spectroscopic inquiry into the decay scheme of Fe59

Abstract

The gamma-rays in the decay of Fe 59 were examined by the sum-coincidence method. The measurements definitely confirm the existence of the 1.432 MeV level and the 143 as well as the 335 kcu gamma-lines. It appcars on the other hand that the 1.189, 1.458 and 1.479 McV levels known from the (p, p') scattcring aro not involved in the decay of Fe ~'. In the case of the 192--1097 keV cascade, the results of the preliminary angular correlation measurements diffr from those rcported by SC~FF and Mr.TZGER. IntroduetionIn the summer of last year, the decay scheme of Fe 59 was examined at this Institute. The necessity for the investigation was motivated by the fact that the reports in the literature on the beta-spectrum were not in agreement. While M. DEUTSCH et al.[1] and F. METZGER [2] found two beta groups of ncarly identical intensity with 257 and 460 keV end-point energy, K. MANN and G. HA~soN [3] could not demonstrate one of these groups. In order to clear up the question, the radiations of Fe 59 were investigated by means of the beta-gamma-coincidence method, which in this case had not yet been applied. The results of measurement clearly showed that there were two betagroups of 275 -{-5 and 455 ~ 5 keV end-point energies in 44.6 and 55.4% ratios, respectively. These ate in coincidence with the gamma-rays of 1.283 and 1.097 MeV energies, respectively. The details of these investigations were reported in the "Nuclear Physics" [4].During last year, J. M. FEar [5] also examined the decay scheme of Fe s9 by scintillation gamma-coincidence spectroscopie methods. His results gire rise to the supposition that the heretofore known decay scheme is supplemented by a new level of 1.439 MeV energy, which decays by emitting 143 or 335 keV gamma-rays through 1.283 or 1.097 MeV levels into the ground state (Fig. 1). Fs.Rcusor~'s decay scheme represents also the levels obtained by BUV.CHr~ER et al. by means of (p, p') scattering.The tnvestigations reported here on the decay of Fe 59 had the purpose of deciding through the sum-coincidence method [6] whether there were further transitions of incidental levels involved in the decay. The arrangement of the measuring apparatuses is shown in Fig. 2. (Regarding some experimental experiences on the HoocErr sum-coincidence method ef. [7].) 3 .4eta Phys. Htmg. Toro. XII. Fase. 4.