Precise measurements of theBk97249ground state half-life and theβ−-decay end-point energy

Abstract

The half-life of the 249 Bk ground state was determined by means of γ-ray spectroscopy, following for 728 days the growth of its α-decaying daughter nuclide 249 Cf. Using a chemically-purified source containing 249 Bk and 137 Cs nuclides, γ-ray singles measurements were carried out using a 25% coaxial Ge detector. The areas of the strongest 333.37-and 388.17-keV γ-ray peaks, produced in the α decay of 249 Cf, and the 661.66-keV peak, produced in the β − decay of 137 Cs, were determined.The measured activity of the latter was used to account for geometrical and dead-time corrections to the efficiency of the spectrometer, thus minimizing the systematic uncertainties associated with

Fusion reaction Ca48+Bk249 leading to formation of the element Ts ( Z=117Khuyagbaatar1, Yakushev2, Düllmann3 et al. 2019Phys. Rev. C321170View full textAdd to dashboardCite

“…Four target segments with thicknesses of 0.37(4), 0.53 (5), 0.53 (5), 0.50(5) mg/cm 2 were produced by electrodeposition on 0.99(5) mg/cm 2 Tibacking foils with an area of 6 cm 2 each [25]. Because the half-life of 249 Bk is only 327.2(3) d [26], its amount in the target was continuously decreasing with time via β − decay to 249 Cf (y, [27]), which primarily decays via α particle emission. Initially these targets were first used for an attempt at the synthesis of the element 119 for about four months [28].…”

Search for the heaviest atomic nuclei among the products from reactions of mixed-Cf with a Ca48 beam

“…Long irradiations of 249 Bk from ORNL with 48 Ca were performed throughout 2009-2012 at JINR in Dubna yielded the identification of a new element, with 117 protons, known now as tennessine as well as an observation of one event of 294 Og [14]. The isotope 249 Bk beta decays with a half-life of 327 days [15] to 249 Cf. This is [14].…”

Actinide targets for the synthesis of super-heavy elements

“…249 Bk targets from ORNL have also been used for single-atom chemistry studies [47] of element 117 decay chain products at Dubna, and for a search [48] for element 119 using a 50 Ti beam at GSI. 249 Bk decays by beta emission to 249 Cf with a half-life of 327 days [49]. As a result, 249 Bk must be freshly produced for each experiment, and significant ingrowth of 249 Cf can occur, ∼30% after six months.…”