Browsing by Author "Eriksen, T. K."

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    Galactic production of 138La : Impact of 138,139La statistical properties
    (Elsevier, 2015) Kheswa, B. V.; Wiedeking, M.; Giacoppo, F.; Goriely, S.; Guttormsen, M.; Larsen, A. C.; Bello Garrote, F. L.; Eriksen, T. K.; Gorgen, A.; Hagen, T. W.; Koehler, P. E.; Klintefjord, M.; Nyhus, H. T.; Papka, P.; Renstrom, T.; Rose, S.; Sahin, E.; Siem, S.; Tornyi, T.
    The γ-ray strength functions and nuclear level densities of 138La and 139La have been measured below the neutron separation energies. These new data were used to calculate astrophysical Maxwellian-averaged (n, γ) cross-sections to investigate the production and destruction of the p-nucleus 138La in the photodisintegration process. The results confirm the underproduction of 138La in the p-process with respect to the observed abundances and strongly support the ν-process through νecapture on 138Ba as the main contributor to the synthesis of 138La in Type II supernovae.
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    ¹³⁷,¹³⁸,¹³⁹La(n,γ) cross sections constrained with statistical decay properties of ¹³⁸,¹³⁹,¹⁴⁰La nuclei
    (American Physical Society, 2017) Kheswa, B. V.; Wiedeking, M.; Brown, J. A.; Larsen, A. C.; Goriely, S.; Guttormsen, M.; Garrote, F. L. Bello; Bernstein, L. A.; Bleuel, D. L.; Eriksen, T. K.; Giacoppo, F.; Gorgen, A.; Goldblum, B. L.; Hagen, T. W.; Koehler, P. E.; Klintefjord, M.; Malatji, K. L.; Midtbo, J. E.; Nyhus, H. T.; Papka, P.; Renstrm, T.; Rose, S. J.; Sahin, E.; Siem, S.; Tornyi, T. G.
    The nuclear level densities and γ-ray strength functions of ¹³⁸,¹³⁹,¹⁴⁰La were measured using the ¹³⁹La(³He,α), ¹³⁹La(³He,'³He), and ¹³⁹La(d,p) reactions. The particle-γ coincidences were recorded with the silicon particle telescope (SiRi) and NaI(Tl) (CACTUS) arrays. In the context of these experimental results, the low-energy enhancement in the A∼140 region is discussed. The ¹³⁷,¹³⁸,¹³⁹La(n,γ) cross sections were calculated at s- and p-process temperatures using the experimentally measured nuclear level densities and γ-ray strength functions. Good agreement is found between ¹³⁹La(n,γ) calculated cross sections and previous measurements.