An above-barrier narrow resonance in F-15

Intense and purified radioactive beam of post-accelerated O-14 was used to study the low-lying states in the unbound F-15 nucleus. Exploiting resonant elastic scattering in inverse kinematics with a thick target, the second excited state, a resonance at E-R = 4.757(6)(10) MeV with a width of Gamma = 36(5)(14) keV was measured for the first time with high precision. The structure of this narrow above-barrier state in a nucleus located two neutrons beyond the proton drip line was investigated using the Gamow Shell Model in the coupled channel representation with a C-12 core and three valence protons. It is found that it is an almost pure wave function of two quasi-bound protons in the 2s(1/2) shell. (C) 2016 The Authors. Published by Elsevier B.V

Toward the limit of nuclear binding on the N=Z line : Spectroscopy of Cd 96

A γ-decaying isomeric state (τ1/2=197-17+19 ns) has been identified in Cd96, which is one α particle away from the last known bound N=Z nucleus, Sn100. Comparison of the results with shell-model calculations has allowed a tentative experimental level scheme to be deduced and the isomer to be interpreted as a medium-spin negative-parity spin trap based on the coupling of isoscalar (T=0) and isovector (T=1) neutron-proton pairs. The data also suggest evidence for the population of a 9+ T=1 state, which is predicted by shell-model calculations to be yrast. Such a low-lying T=1 state, which is unknown in lighter mass even-even self-conjugate nuclei, can also be interpreted in terms of the coupling of T=0 and T=1 neutron-proton pairs

Narrow resonances in the continuum of the unbound nucleus 15^{15}F

The structure of the unbound $^{15}$F nucleus is investigated using the inverse kinematics resonant scattering of a radioactive $^{14}$O beam impinging on a CH$_2$ target. The analysis of $^{1}$H($^{14}$O,p)$^{14}$O and $^{1}$H($^{14}$O,2p)$^{13}$N reactions allowed the confirmation of the previously observed narrow $1/2^{-}$ resonance, near the two-proton decay threshold, and the identification of two new narrow 5/2$^{-}$ and 3/2$^{-}$ resonances. The newly observed levels decay by 1p emission to the ground of $^{14}$O, and by sequential 2p emission to the ground state (g.s.) of $^{13}$N via the $1^-$ resonance of $^{14}$O. Gamow shell model (GSM) analysis of the experimental data suggests that the wave functions of the 5/2$^{-}$ and 3/2$^{-}$ resonances may be collectivized by the continuum coupling to nearby 2p- and 1p- decay channels. The observed excitation function $^{1}$H($^{14}$O,p)$^{14}$O and resonance spectrum in $^{15}$F are well reproduced in the unified framework of the GSM

High natural radiation exposure in radon spa areas: a detailed field investigation in Niska Banja (Balkan region)

The measurement campaigns have been done in the rural community of Niska. Banja, a spa town located in southern Serbia, to evaluate population exposure to natural radioactivity. After a screening survey in 200 houses, annual radon and thoron concentrations were measured in 34 houses, and in 2004 a detailed investigation was carried out at six houses with elevated indoor radon concentrations. The paper presents the results of these detailed measurements. The complementary techniques were applied to determine radon and thoron concentrations in indoor air, in soil gas, radon exhalation from soil, soil permeability, and indoor and outdoor gamma doses. Soil and water samples were collected and analysed in the laboratory. Indoor radon and thoron. concentrations were found to be more than 1 kBq m(-3) and 200 Bq m(-3) respectively. Extremely high concentrations of soil-gas radon ( GT 2000 kBq m(-3)) and radon exhalation rates (1.5 mBq m(-2) s(-1)) were observed. These results will be utilised to set up the methodology for a more systematic investigation. (c) 2006 Elsevier Ltd. All rights reserved

Lifetime measurements of low-lying states in 73Ga and 70,72,74Zn isotopes

Lifetimes of low-lying states in 73Ga and 70,72,74Zn were measured using the Recoil Distance Doppler Shift (RDDS) method. These nuclei were produced in deep-inelastic reactions in inverse kinematics with a 208Pb beam impinging on a 76Ge target. Prompt γ rays were detected using the AGATA tracking array coupled to the VAMOS++ spectrometer. Lifetime of the 5/2- state in 73Ga, measured for the first time, provides additional evidence for the existence of a 1/2-, 3/2- ground-state doublet. The lifetimes of the 4+ states in 70,72,74Zn were remeasured in an attempt to understand the discrepancies observed between earlier measurements. Our results are in agreement with those of previous plunger experiments

Improved Value for the Gamow-Teller Strength of the 100^{100}Sn Beta Decay

A record number of Sn100 nuclei was detected and new isotopic species toward the proton dripline were discovered at the RIKEN Nishina Center. Decay spectroscopy was performed with the high-efficiency detector arrays WAS3ABi and EURICA. Both the half-life and the β-decay end point energy of Sn100 were measured more precisely than the literature values. The value and the uncertainty of the resulting strength for the pure 0+→1+ Gamow-Teller decay was improved to BGT=4.4-0.7+0.9. A discrimination between different model calculations was possible for the first time, and the level scheme of In100 is investigated further

Numerical modelling of ship/ice interaction

A parametric study using finite element method is carried out to investigate the ship/ice interaction for ice thickness up to 80cm and ship velocity up to 4 m/sec. In the dynamic analysis the mechanism of load transfer during the ship/ice impact is treated as a contact process taking account of the area of contact. The ice failure is specified by the Tsai-Wu criterion. The effects of frame angle and impact velocity of the ship, and thickness of the ice sheet on the failure loads are critically investigated.NRC publication: Ye

Erratum: Properties of γ\gamma-decaying isomers and isomeric ratios in the 100^{100}Sn region [Phys. Rev. C 96 , 044311 (2017)]

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Properties of gamma-decaying isomers and isomeric ratios in the Sn-100 region

Half-lives and energies of gamma rays emitted in the decay of isomeric states of nuclei in the vicinity of the doubly magic Sn-100 weremeasured in a decay spectroscopy experiment at RikagakuKenkyusho (The Institute of Physical and Chemical Research) of Japan Nishina Center. The measured half-lives, some with improved precision, are consistent with literature values. Three new results include a 55-keV E2 gamma ray from a new (4(+)) isomer with T-1/2 = 0.23(6) mu s in Rh-92, a 44-keV E2 gamma ray from the (15(+)) isomer in Ag-96, and T-1/2(6(+)) = 13(2) ns in Cd-98. Shell-model calculations of electromagnetic transition strengths in the (p(1/2), g(9/2)) model space agree with the experimental results. In addition, experimental isomeric ratios were compared to the theoretical predictions derived with an abrasion-ablation model and the sharp cutoff model. The results agreed within a factor of 2 for most isomers. From the nonobservation of time-delayed gamma rays in Sn-100, new constraints on the T-1/2, gamma-ray energy, and internal conversion coefficients are proposed for the hypothetical isomer in Sn-100