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Author |
n_TOF Collaboration (Torres-Sanchez, P. et al); Babiano-Suarez, V.; Caballero, L.; Domingo-Pardo, C.; Ladarescu, I.; Tain, J.L. |
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Title |
Measurement of the 14N(n, p) 14C cross section at the CERN n_TOF facility from subthermal energy to 800 keV |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
107 |
Issue |
6 |
Pages |
064617 - 15pp |
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Keywords |
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Abstract  |
Background: The 14N(n, p) 14C reaction is of interest in neutron capture therapy, where nitrogen-related dose is the main component due to low-energy neutrons, and in astrophysics, where 14N acts as a neutron poison in the s process. Several discrepancies remain between the existing data obtained in partial energy ranges: thermal energy, keV region, and resonance region. Purpose: We aim to measure the 14N(n, p) 14C cross section from thermal to the resonance region in a single measurement for the first time, including characterization of the first resonances, and provide calculations of Maxwellian averaged cross sections (MACS). Method: We apply the time-of-flight technique at Experimental Area 2 (EAR-2) of the neutron time-of-flight (n_TOF) facility at CERN. 10B(n, & alpha;) 7Li and 235U(n, f ) reactions are used as references. Two detection systems are run simultaneously, one on beam and another off beam. Resonances are described with the R-matrix code SAMMY. Results: The cross section was measured from subthermal energy to 800 keV, resolving the first two resonances (at 492.7 and 644 keV). A thermal cross section was obtained (1.809 & PLUSMN; 0.045 b) that is lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 and JEFF-3.3 evaluations. A 1/v energy dependence of the cross section was confirmed up to tens of keV neutron energy. The low energy tail of the first resonance at 492.7 keV is lower than suggested by evaluated values, while the overall resonance strength agrees with evaluations. Conclusions: Our measurement has allowed determination of the 14N(n, p) cross section over a wide energy range for the first time. We have obtained cross sections with high accuracy (2.5%) from subthermal energy to 800 keV and used these data to calculate the MACS for kT = 5 to kT = 100 keV. |
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Address |
[Torres-Sanchez, Pablo; Praena, Javier; Porras, Ignacio; Ogallar, Francisco] Univ Granada, Granada, Spain, Email: pablotorres@ugr.es |
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Amer Physical Soc |
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English |
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Series Volume |
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ISSN |
2469-9985 |
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Conference |
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Notes |
WOS:001063209900001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5701 |
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Author |
n_TOF Collaboration (Mendoza, E. et al); Domingo-Pardo, C.; Tain, J.L. |
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Title |
Measurement and analysis of the Am-243 neutron capture cross section at the n_TOF facility at CERN |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
90 |
Issue |
3 |
Pages |
034608 - 16pp |
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Keywords |
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Abstract |
Background: The design of new nuclear reactors and transmutation devices requires to reduce the present neutron cross section uncertainties of minor actinides. Purpose: Improvement of the Am-243(n, gamma) cross section uncertainty. Method: The Am-243(n, gamma) cross section has been measured at the n_TOF facility at CERN with a BaF2 total absorption calorimeter, in the energy range between 0.7 eV and 2.5 keV. Results: The Am-243(n, gamma) cross section has been successfully measured in the mentioned energy range. The resolved resonance region has been extended from 250 eV up to 400 eV. In the unresolved resonance region our results are compatible with one of the two incompatible capture data sets available below 2.5 keV. The data available in EXFOR and in the literature have been used to perform a simple analysis above 2.5 keV. Conclusions: The results of this measurement contribute to reduce the Am-243(n, gamma) cross section uncertainty and suggest that this cross section is underestimated up to 25% in the neutron energy range between 50 eV and a few keV in the present evaluated data libraries. |
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Address |
[Mendoza, E.; Cano-Ott, D.; Guerrero, C.; Alvarez-Velarde, F.; Balibrea, J.; Gonzalez-Romero, E.; Martinez, T.; Villamarin, D.; Vicente, M. C.] CIEMAT, E-28040 Madrid, Spain |
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Amer Physical Soc |
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English |
Summary Language |
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Series Volume |
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Series Issue |
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ISSN |
0556-2813 |
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Conference |
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Notes |
WOS:000341912100005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1935 |
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Author |
Escrig, S. et al; Morales, A.I. |
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Title |
Persistence of the Z=28 shell gap in A=75 isobars: Identification of a possible (1/2(-)) μs isomer in Co-75 and beta decay to Ni-75 |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
103 |
Issue |
6 |
Pages |
064328 - 12pp |
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Keywords |
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Abstract |
Background: The evolution of shell structure around doubly magic exotic nuclei is of great interest in nuclear physics and astrophysics. In the 'southwest' region of Ni-78, the development of deformation might trigger a major shift in our understanding of explosive nucleosynthesis. To this end, new spectroscopic information on key close-lying nuclei is very valuable. Purpose: We intend to measure the isomeric and beta decay of Co-75, with one-proton and two-neutron holes relative to Ni-78, to access new nuclear structure information in Co-75 and its beta-decay daughters Ni-75 and Ni-74. Methods: The nucleus Co-75 is produced in relativistic in-flight fission reactions of U-238 at the Radioactive Ion Beam Factory in the RIKEN Nishina Center. Its isomeric and f decay are studied exploiting the BigRIPS and EURICA setups. Results: We obtain partial beta-decay spectra for Ni-75 and Ni-74, and report a new isomeric transition in Co-75. The energy [E-gamma = 1914(2) keV] and half-life [t(1/2) = 13(6) μs] of the delayed gamma ray lend support for the existence of aJ(pi) = (1/2(-)) isomeric state at 1914(2) keV. A comparison with PFSDG-U shell-model calculations provides a good account for the observed states in Ni-75, but the first calculated 1/2(-) level in Co-75, a prolate K = 1/2 state, is predicted about 1 MeV below the observed (1/2(-)) level. Conclusions: The spherical-like structure of the lowest-lying excited states in Ni-75 is proved. In the case of Co-75, the results suggest that the dominance of the spherical configurations over the deformed ones might be stronger than expected below Ni-78. Further experimental efforts to discern the nature of the J(pi) = (1/2(-)) isomer are necessary. |
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Address |
[Escrig, S.; Morales, A., I] Univ Valencia, Inst Fis Corpuscular, CSIC, E-46071 Valencia, Spain, Email: Samuel.Escrig@csic.es; |
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Amer Physical Soc |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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ISSN |
2469-9985 |
ISBN |
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Conference |
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Notes |
WOS:000669040500001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4887 |
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Author |
Karakoc, M. et al; Molina, F. |
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Title |
Gamow-Teller transitions in the A=40 isoquintet of relevance for neutrino captures in Ar-40 |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
89 |
Issue |
6 |
Pages |
064313 - 7pp |
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Keywords |
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Abstract |
Background: The Gamow-Teller response of Ar-40 is important for the use of liquid argon as a medium for neutrino detection. An ambiguity about the Gamow-Teller strength for the excitation of 1(+) states at 2290 and 2730 keV in K-40 results in a significant uncertainty for neutrino capture rates. This ambiguity is caused by the large discrepancy observed between strengths extracted from Ar-40(p, n) charge-exchange data and the transition strengths for the analog transitions studied in the beta decay of Ti-40. Purpose: This study was aimed at resolving the ambiguity between the results from the Ar-40(p, n) charge-exchange and Ti-40 beta-decay data. Method: Shell-model calculations in the sd-pf shell with a new interaction (WBMB-C) were used to study differences between the structure of the transitions from Ar-40 and Ti-40. Distorted-wave Born approximation reaction calculations were used to investigate uncertainties in the extraction of Gamow-Teller strength from the Ar-40(p, n) data. New high-resolution data for the Ar-40(He-3,t) reaction were used to gain further insight into the charge-exchange reaction mechanism and to provide more information to test the validity of the shell-model calculations. Results: The shell-model calculations showed that interference between amplitudes associated with pf and sd components to the low-lying Gamow-Teller transitions, in combination with a difference in Coulomb energy shifts for Ar-40 and Ti-40, can produce the differences on the scale of those observed between the Ar-40 charge-exchange and Ti-40 beta-decay data. In combination with the difference in nuclear penetrability of the (p, n) and (He-3,t) probes, the different contributions from amplitudes associated with transitions in the pf and sd shells are likely also responsible for the observed discrepancy between the ratio of the cross sections for the low-lying 1(+) states in the Ar-40(p, n) and Ar-40(He-3,t) data. Conclusions: On the basis of this study, it is recommended to use Gamow-Teller strengths extracted from the Ar-40(p, n) data, not the Ti-40 beta-decay data, for the calculation of neutrino capture rates. Further theoretical studies are required to achieve a consistent quantitative description for the energy differences between low-lying 1(+) states in K-40 and Sc-40 and the experimentally observed Gamow-Teller strengths. |
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Address |
[Karakoc, M.; Boztosun, I.] Akdeniz Univ, Dept Phys, TR-07058 Antalya, Turkey, Email: zegers@nscl.msu.edu |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0556-2813 |
ISBN |
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Area |
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Conference |
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Notes |
WOS:000338641500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1851 |
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Author |
Siciliano, M. et al; Gadea, A.; Perez-Vidal, R.M. |
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Title |
Lifetime measurements in the even-even Cd102-108 isotopes |
Type |
Journal Article |
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Year |
2021 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
104 |
Issue |
3 |
Pages |
034320 - 16pp |
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Keywords |
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Abstract |
Background: The heaviest T-z = 0 doubly-magic nucleus, Sn-100, and the neighboring nuclei offer unique opportunities to investigate the properties of nuclear interaction. For instance, the structure of light-Sn nuclei has been shown to be affected by the delicate balance between nuclear-interaction components, such as pairing and quadrupole correlations. From Cd to Te, many common features and phenomena have been observed experimentally along the isotopic chains, leading to theoretical studies devoted to a more general and comprehensive study of the region. In this context, having only two proton holes in the Z = 50 shell, the Cd isotopes are expected to present properties similar to those found in the Sn isotopic chain. Purpose: The aim of this work was to measure lifetimes of excited states in neutron-deficient nuclei in the vicinity of Sn-100. Methods: The neutron-deficient nuclei in the N approximate to Z approximate to 50 region were populated using a multinucleon transfer reaction with a Cd-106 beam and a Mo-92 target. The beamlike products were identified by the VAMOS++ spectrometer, while the gamma rays were detected using the AGATA array. Lifetimes of excited states were determined using the recoil distance Doppler-shift method, employing the Cologne differential plunger. Results: Lifetimes of low-lying states were measured in the even-mass Cd-102-(108) isotopes. In particular, multiple states with excitation energy up to MeV, belonging to various bands, were populated in approximate to 3 Cd-106 via inelastic scattering. The transition strengths corresponding to the measured lifetimes were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach. Conclusions: Despite the similarities in the electromagnetic properties of the low-lying states, there is a fundamental structural difference between the ground-state bands in the Z = 48 and Z = 50 isotopes. The comparison between experimental and theoretical results revealed a rotational character of the Cd nuclei, which have prolate-deformed ground states with beta(2) approximate to 0.2. At this deformation Z = 48 becomes a closed-shell configuration, which is favored with respect to the spherical one. |
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Address |
[Siciliano, M.] Univ Paris Saclay, Irfu CEA, Gif Sur Yvette, France |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000704568900001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4998 |
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