Investigation ofRe186via radiative thermal-neutron capture onRe185

Abstract

Partial γ-ray production cross sections and the total radiative thermal-neutron capture cross section for the 185 Re(n, γ) 186 Re reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched 185 Re target. The 186 Re cross sections were standardized using well-known 35 Cl(n, γ) 36 Cl cross sections from irradiation of a stoichiometric nat ReCl3 target. The resulting cross sections for transitions feeding the 186 Re ground state from low-lying levels below a cutoff energy of Ec = 746 keV were combined with a modeled probability of ground-state feeding from levels above Ec to arrive at a total cross section of σ0 = 111(6) b for radiative thermal-neutron capture on 185 Re. A comparison of modeled discrete-level populations with measured transition intensities led to proposed revisions for seven tentative spin-parity assignments in the adopted level scheme for 186 Re. Additionally, 102 primary γ-rays were measured, including 50 previously unknown. A neutron-separation energy of Sn = 6179.59(5) keV was determined from a global least-squares fit of the measured γ-ray energies to the known 186 Re decay scheme. The total capture cross section and separation energy results are comparable to earlier measurements of these values.

In-beam γ -ray spectroscopy studies of medium-spin states in the odd-odd nucleus Re186

“…The newly observed 150.3-keV transition was in prompt (±40 ns) coincidence with the 74.7-keV one, known to depopulate the 174.1-keV level [7,8]. This relationship permitted determination of a precise value of 324.4 keV for the excitation energy of the K π = 5 + band head, which was known previously as ∼330 keV [4,6,7,10]. The 144.0-keV γ ray was observed to terminate at the 180.4-keV level, implying that the latter is a long-lived isomeric state.…”

“…From earlier work, it was determined that the 141.1-keV γ ray has M 1 character [7], and this γ ray was proposed to depopulate an intrinsic K π = 4 + state [8,10]. Matters et al [6] revised the assignment to J π = 6 + on the basis of a statistical analysis of the 185 Re(n, γ) 186 Re γ-ray cascade intensities. Here, the 141.1-keV γ ray is assigned as the first cascade transition within the K π = 5 + band, which is established for the first time in the present study.…”

“…An al-ternative approach to determine the 185 Re(n, γ) 186m Re cross section, which is independent of the isomer half-life, is to apply statistical modeling to the observed capture-γ cascades feeding the isomer. This procedure, recently demonstrated by Matters et al [6], relies on detailed knowledge of level structures above the isomer.…”

“…Recently, Matters et al [10] used the (n,2n) reaction to reveal several new levels and γ-ray transitions assessed as feeding the long-lived, K π = (8 + ) isomer. These authors have also studied low-spin states using the 185 Re(n,γ) reaction [6].…”

Radiative-capture cross sections for the La139(n,γ) reaction using thermal neutrons and structural properties of LaHurst1, Sweet2, Goldblum3 et al. 2019Phys. Rev. CSelf Cite3000View full textAdd to dashboardCite

“…Low-energy transitions (E γ 200 keV) can be significantly attenuated in high-density materials, e.g., tungsten [30] and rhenium [31], requiring significant corrections for photon attenuation [32]. Because the thick samples used in this measurement are rather bulky, however, to ensure low-energy γ rays are treated appropriately for photon attenuation, two additional measurements using thin samples of the exact same lanthanum compounds were subsequently performed.…”