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The Cl35(n,p) and Cl35(n,α) cross sections at incident neutron energies between 2.42 and 2.74 MeV were measured using the Berkeley High Flux Neutron Generator. The cross sections for Cl35(n,p) were more than a factor of 3 to 5 less than all of the values in the neutron absorption data libraries, while the Cl35(n,α) cross sections are in reasonable agreement with the data libraries. The measured energy-differential cross section is consistent with a single resonance with a width of 293(46) keV. This result suggests that, despite the high incident neutron energy, any attempt to model (n,x) cross sections in the vicinity of the N=Z=20 shell gap requires a resolved resonance approach rather than a Hauser-Feshbach approach.

A set of prompt partial γ-ray production cross sections from thermal neutron capture were measured for the La139(n,γ) reaction using a guided beam of subthermal (thermal and cold) neutrons incident on a La2natO3 target at the Prompt Gamma Activation Analysis facility of the Budapest Research Reactor. Absolute La140 cross sections were determined relative to the well-known comparator Cl35(n,γ) cross sections from the irradiation of a stoichiometric LaCl3nat sample. The total cross section for radiative thermal neutron capture on La139 from the sum of experimentally measured cross sections observed to directly feed the La140 ground state was determined to be σ0expt=8.58(50) b. To assess completeness of the decay scheme and as a consistency check, the measured cross sections for transitions feeding the ground state from levels below a critical energy of Ec=285 keV were combined with a modeled contribution accounting for ground-state feeding from the quasicontinuum to arrive at a total cross section of σ0=9.36(74) b. In addition, a neutron-separation energy of Sn=5161.001(21) keV was determined from a least-squares fit of the measured primary γ-ray energies to the low-lying levels of the La140 decay scheme. Furthermore, several nuclear structure improvements are proposed for the decay scheme. The measured cross-section and separation-energy results are comparable to earlier measurements of these quantities.

Background: The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Purpose: Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in Cd106. Methods: In an inverse kinematics reaction, a Cd106 beam impinging on a C12 target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for Cd106. Results: The g factors of the 21+ and 41+ states in Cd106 were measured to be g(21+)=+0.398(22) and g(41+)=+0.23(5). A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ(Cd106;21+)=7.0(3)ps and τ(Cd106;41+)=2.5(2)ps. The mean life τ(Cd106;22+)=0.28(2)ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ(Cd106;43+)=1.1(1)ps and τ(Cd106;31-)=0.16(1)ps were determined for the first time. Conclusions: The newly measured g(41+) of Cd106 is found to be only 59% of the g(21+). This difference cannot be explained by either shell-model or collective-model calculations.

Partial γ-ray production cross sections and the total radiative thermal-neutron capture cross section for the Re185(n,γ)Re186 reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched Re185 target. The Re186 cross sections were standardized using well-known Cl35(n,γ)Cl36 cross sections from irradiation of a stoichiometric natReCl3 target. The resulting cross sections for transitions feeding the Re186 ground state from low-lying levels below a cutoff energy of Ec=746keV 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 Re185. 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 Re186. 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 Re186 decay scheme. The total capture cross section and separation energy results are comparable to earlier measurements of these values.

Background: The structure of the semimagic Sn50 isotopes were previously studied via measurements of B(E2;21+→01+) and g factors of 21+ states. The values of the B(E2;21+) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. Purpose: This work presents the first measurement of the 21+ and 41+ states' magnetic moments in the unstable neutron-deficient Sn110. The g factors provide complementary structure information to the interpretation of the observed B(E2) values. Methods: The Sn110 nuclei have been produced in inverse kinematics in an α-particle transfer reaction from C12 to Cd106 projectiles at 390, 400, and 410 MeV. The g factors have been measured with the transient field technique. Lifetimes have been determined from line shapes using the Doppler-shift attenuation method. Results: The g factors of the 21+ and 41+ states in Sn110 are g(21+) = +0.29(11) and g(41+) = +0.05(14), respectively. In addition, the g(41+) = +0.27(6) in Cd106 has been measured for the first time. A line-shape analysis yielded τ(110Sn;21+) = 0.81(10) ps and a lifetime of τ(110Sn;31-) = 0.25(5) ps was calculated from the fully Doppler-shifted γ line. Conclusions: No evidence has been found in Sn110 that would require excitation of protons from the closed Z=50 core.