Beta+-delayed proton (or α) emission is a typical decay mode of very neutron-deficient nuclei. Valuable information for the ground state in the precursor, such as half-life, spin, and parity, can be ...obtained by studying the β+-p decay properties. The high efficiency and unique experimental signature for detecting protons allow one to study states in the β+-decay daughter that are not accessible through other means. By measuring the properties of protons emitted to a known state in the daughter, information on the structure of the proton-unbound state can be obtained.
The known nuclei that exhibit this decay mode are evaluated to give the recommended values for the nuclear properties of these nuclei. This includes branching ratios, and half-lives. In addition for those nuclei with known resolved proton transitions, proton energies, intensities, and the energies of the proton-emitting states are compiled. A list of experimental references for each β+-p precursor is also given.
All papers published prior to June 2019 have been considered in adopting the properties given in this work.
The β decays of neutron-rich nuclei near the doubly magic (78)Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of (82)Zn ...(228±10 ms), (83)Zn (117±20 ms), and (85)Ga (93±7 ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the (78)Ni region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A>140 nuclei.
An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in the observation of two ...α-decay chains, produced via the ^{243}Am(^{48}Ca,xn)^{291-x}Mc reaction, that were separated by mass-to-charge ratio (A/q) and identified by the combined BGS+FIONA apparatus. One event occurred at A/q=284 and was assigned to ^{284}Nh (Z=113), the α-decay daughter of ^{288}Mc (Z=115), while the second occurred at A/q=288 and was assigned to ^{288}Mc. This experiment represents the first direct measurements of the mass numbers of superheavy elements, confirming previous (indirect) mass-number assignments.
The β-delayed neutron emission of 83,84Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high ...above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to 78Ni core-excited states in 83,84Ge favored by shell effects. We developed shell model calculations in the proton fpg9/2 and neutron extended fpg9/2 + d5/2 valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. Furthermore, this leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models.
A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich $^{110}$Ru (t$_{1/2}$= 12 s) isotope produced at the ...CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.
By studying the (109)Xe→(105)Te→(101)Sn superallowed α-decay chain, we observe low-lying states in (101)Sn, the one-neutron system outside doubly magic (100)Sn. We find that the spins of the ground ...state (J=7/2) and first excited state (J=5/2) in (101)Sn are reversed with respect to the traditional level ordering postulated for (103)Sn and the heavier tin isotopes. Through simple arguments and state-of-the-art shell-model calculations we explain this unexpected switch in terms of a transition from the single-particle regime to the collective mode in which orbital-dependent pairing correlations dominate.
Men who have sex with men (MSM) disproportionately experience childhood sexual abuse (CSA) compared with heterosexual men, often resulting in continued trauma-related sequelae, including symptoms of ...posttraumatic stress disorder (PTSD) such as avoidance. The variability in trauma-related sequelae may be associated with chronicity or duration of CSA. The relationship between duration of CSA and later PTSD symptom severity is not well understood, including the extent coping strategies account for these relationships. We used linear regression to examine these relationships and to assess the indirect effects of avoidance (behavioral disengagement and denial) and adaptive coping strategies on the relationship between CSA duration and adult PTSD symptom severity on a diverse sample included 290 MSM with a history of CSA. In adjusted models, CSA duration was significantly associated with adult PTSD symptom severity (standardized β = .23, p < .000) and with avoidance coping (standardized β = .19, p = .002). Separating this out, behavioral disengagement was significantly associated with CSA duration (standardized β = .20, p = .001) but denial was not. In adjusted analyses assessing indirect effects, avoidance coping partially accounted for the relationship between CSA duration and total trauma symptom severity (standardized β reduced from .23 to .17; Sobel = 2.90, p = .004). Similarly, behavioral disengagement partially accounted for the association between CSA duration and total symptoms (standardized β reduced from .23 to .18; Sobel = 2.68, p = .007). Avoidance coping, and behavioral disengagement specifically, may play a role in the severity of PTSD symptoms experienced by MSM with CSA histories. This work emphasizes the need for clinicians to consider behavioral disengagement in understanding PTSD symptom severity among MSM with histories of CSA.
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