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Coulomb Dissociation of $^{15}$C and Radiative Neutron Capture on $^{14}$C  [PDF]
H. Esbensen
Physics , 2009, DOI: 10.1103/PhysRevC.80.059904
Abstract: The semiclassical, dynamical description of diffraction dissociation of weakly bound nuclei is applied to analyze the decay-energy spectra of $^{15}$C that have been measured at 68 MeV/nucleon on a Pb target. The optical potentials that are used to describe the nuclear interaction of $^{15}$C with the target nucleus are realistic because the fits to the two measured spectra, one with a small and one with a very large acceptance angle, are consistent and of similar quality. The cross section for the radiative neutron capture on $^{14}$C to the 1/2$^+$ ground state of $^{15}$C is deduced from the analysis. When combined with an estimated contribution from the capture to the 5/2$^+$ excited state of $^{15}$C, an excellent agreement with a recent direct capture measurement is achieved.
Cross Sections for the Astrophysical Neutron Radiative Capture on 12C and 13C Nuclei  [PDF]
S. B. Dubovichenko,N. A. Burkova,A. V. Dzhazairov-Kakhramanov
Physics , 2012,
Abstract: Within the potential cluster model with Pauli forbidden states the possibility of description of the experimental data on the total radiative n12C- and n13C-capture cross sections in the astrophysical energy range from 25 meV to 1.0 MeV is presented. The E1-transition covers the capture data from the scattering states to the ground one of 13C and 14C nuclei. Capture on the three low laying excited states 1/2+, 3/2- and 5/2+ of 13C was calculated.
The 14C(n,g) cross section between 10 keV and 1 MeV  [PDF]
R. Reifarth,M. Heil,C. Forssen,U. Besserer,A. Couture,S. Dababneh,L. Doerr,J. Goerres,R. C. Haight,F. Kaeppeler,A. Mengoni,S. O'Brien,N. Patronis,R. Plag,R. S. Rundberg,M. Wiescher,J. B. Wilhelmy
Physics , 2009, DOI: 10.1103/PhysRevC.77.015804
Abstract: The neutron capture cross section of 14C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The 14C(n,g) reaction is also important for the validation of the Coulomb dissociation method, where the (n,g) cross section can be indirectly obtained via the time-reversed process. So far, the example of 14C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the 14C(n,g) reaction with neutron energies ranging from 20 to 800 keV.
Exotic Properties of Light Nuclei and their Neutron Capture Cross Sections  [PDF]
A. Mengoni,T. Otsuka,T. Nakamura,M. Ishihara
Physics , 1996, DOI: 10.1016/S0375-9474(97)00264-9
Abstract: We have investigated the implications of the neutron halo configuration, observed in the ground-state of some neutron-rich light nuclei, on neutron radiative transition processes. In particular, we have studied the influence of the neutron halo on the direct radiative capture (DRC) process. The energy dependence as well as the strength of E1 emission due to incident p-wave neutrons is strongly influenced by the halo configuration of the residual nucleus capturing state. We have compared the calculated 10Be(n,gamma)11Be DRC cross section with that derived from the experiment in the inverse kinematics (Coulomb dissociation of 11Be). We show from the comparison that some important information on the structure of the halo nucleus 11Be can be derived.
Differential Cross Sections for Electromagnetic Dissociation  [PDF]
John W. Norbury,Anne Adamczyk
Physics , 2006, DOI: 10.1016/j.nimb.2006.11.060
Abstract: Differential cross sections for electromagnetic dissociation in nucleus-nucleus collisions are calculated. The kinetic energy distribution is parameterized with a Boltzmann distribution and the angular distribution is assumed isotropic in the projectile frame. In order to be useful for three-dimensional transport codes, these cross sections are available in both the projectile and lab frames. Comparison between theory and experiment is good. The formalism applies to single and multiple nucleon removal, alpha particle removal, and fission in electromagnetic reactions of nuclei.
Structure effects in the $^{15}$N($n,γ$)$^{16}$N radiative capture reaction from the Coulomb dissociation of $^{16}$N  [PDF]
Neelam,Shubhchintak,R. Chatterjee
Physics , 2015,
Abstract: Purpose : The aim of this paper is to calculate the $^{15}$N($n, \gamma$)$^{16}$N radiative capture cross section and its subsequent reaction rate by an indirect method and in that process investigate the effects of spectroscopic factors of different levels of $^{16}$N to the cross section. Method : A fully quantum mechanical Coulomb breakup theory under the aegis of post-form distorted wave Born approximation is used to calculate the Coulomb breakup of $^{16}$N on Pb at 100 MeV/u. This is then related to the photodisintegration cross section of $^{16}$N($\gamma, n$)$^{15}$N and subsequently invoking the principle of detailed balance, the $^{15}$N($n, \gamma$)$^{16}$N capture cross section is calculated. Results : The non-resonant capture cross section is calculated with spectroscopic factors from the shell model and those extracted (including uncertainties) from two recent experiments. The data seems to favor a more single particle nature for the low-lying states of $^{16}$N. The total neutron capture rate is also calculated by summing up non-resonant and resonant (significant only at temperatures greater than 1 GK) contributions and comparison is made with other charged particle capture rates. In the typical temperature range of $0.1-1.2$ GK, almost all the contribution to the reaction rate comes from capture cross sections below 0.25 MeV. Conclusion : We have attempted to resolve the discrepancy in the spectroscopic factors of low-lying $^{16}$N levels and conclude that it would certainly be useful to perform a Coulomb dissociation experiment to find the low energy capture cross section for the reaction, especially below 0.25 MeV.
Early Aptian δ13C and manganese anomalies from the historical Cassis-La Bédoule stratotype sections (S.E. France): relationship with a methane hydrate dissociation event and stratigraphic implications  [cached]
Renard Maurice,Rafélis Marc de,Emmanuel Laurent,Moullade Michel
Carnets de Géologie , 2005,
Abstract: Comparison of oxygen and carbon isotope and manganese evolution curves in bulk carbonate from the historical Bedoulian stratotype (Cassis-La Bédoule area, Provence, France) reveals an important geochemical event (negative δ13C and high Mn content) located within the D. deshayesi ammonite Zone and at the base of the R. hambrowi ammonite Subzone. This worldwide event, which can be observed in environments ranging from the fluvial to the pelagic realm (Selli/Goguel level), seems to be related to methane hydrate destabilization. Scenarios for manganese, carbon and oxygen evolutions are proposed for early Bedoulian oxic conditions and for dysoxic/anoxic conditions related to methane hydrate destabilization at the early/late Bedoulian transition. The impacts of this global event on the biosphere (nannoconid crisis) and its stratigraphic implications are considered. Comparison of geochemical and biostratigraphical data from the Cassis-La Bédoule stratotype with that of the Cismon-Apticore reference borehole shows that the La Bedoule sequence records geochemical evolution during the Goguel/Selli Event in more detail than that of any other previously published section.
Structure Effects on Coulomb Dissociation of $^8$B  [PDF]
F. M. Nunes,R. Shyam,I. J. Thompson
Physics , 1998, DOI: 10.1088/0954-3899/24/8/036
Abstract: Coulomb Dissociation provides an alternative method for determining the radiative capture cross sections at astrophysically relevant low relative energies. For the breakup of $^8$B on $^{58}$Ni, we calculate the total Coulomb Dissociation cross section and the angular distribution for E1, E2 and M1. Our calculations are performed first within the standard first order semiclassical theory of Coulomb Excitation, including the correct three body kinematics, and later including the projectile-target nuclear interactions.
Neutron capture cross sections: from theory to experiments and back  [PDF]
Alberto Mengoni
Physics , 2005, DOI: 10.1063/1.1945224
Abstract: The method for an experimental determination of the stellar enhancement factor for the cross section of the $^{151}$Sm$(n,\gamma)$ reaction process is proposed. This study offered the pretext for an excursus on the interconnections between capture and dissociation reactions and the interplay between theory and experiments in the determination of neutron capture cross sections.
Comment on Esbensen, Bertsch and Snover Concerning Reconciling Coulomb Dissociation and Radiative Capture Measurements  [PDF]
Moshe Gai
Physics , 2005, DOI: 10.1103/PhysRevLett.96.159201
Abstract: The RIKEN data on the Coulomb Dissociation (CD) of 8B were shown to be in good agreement with the Direct Capture (DC) data on the 7Be(p,g)8B reaction (that were known at that time) of Filippone {\em et al.} Yet recently it was claimed that the RIKEN2 CD data must be corrected in order to be reconciled with the slope of DC data. Considering the (correct) so called scale independent b-slope parameter of the RIKEN2 CD data, the resultant corrected b-slope parameter suggested by Esbensen, Bertsch and Snover is shown to be considerably smaller than the so called average b-slope parameter of DC data. The suggested corrections of the b-slope parameter lead to a large disagreement with DC data, in sharp contrast to the claim. The slope corrections are only significant for the RIKEN2 CD data. For the GSI kinematics, where in fact one may observe slope different than for DC (at least for the GSI1 data), they find a fortuitous cancellation that leads to a vanishingly small slope correction. Hence the validity of these correction based on the observed slopes can not be substantiated.
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