共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Szerypo M. Kicińska-Habior T. Matulewicz 《Zeitschrift für Physik A Hadrons and Nuclei》1986,324(4):439-442
The experimental excitation function of the232Th(p, γ)233Pa reaction in the proton energy range 7–20 MeV was analysed within the direct-semidirect model. It was found that the confinement of the direct transition matrix element integral to the surface of the nucleus improves the fit of the theoretical curve to the experimental data. This conclusion was strengthened by the calculations carried out for the176Yb(p, γ)177Lu experimental reaction cross sections, available from the literature. 相似文献
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W. Kurcewicz J. Szerypo P. Hornshøj N. Rud Z. Zelazny W. Reisdorf 《Zeitschrift für Physik A Hadrons and Nuclei》1982,306(2):99-103
The excitation function for the232Th(p,f) reaction has been determined in the energy range from 4 to 11 MeV. A discrepancy existing in the literature is resolved. The mass yield distribution has been studied at 8 MeV proton energy and the peak-to-valley ratio has been determined to be 9.2. The fission data, together with evaporation residue data from an earlier experiment, are understood rather well within the framework of a statistical decay model which derives its parameters from independent data. The absorption cross sections for protons in the vicinity of and below the Coulomb barrier are also discussed and confronted with optical model predictions using published global proton potentials. 相似文献
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The cross sections for the formation of monopole proton bound states are calculated in the dipole approximation and found to be of the order of the proton Compton wavelength squared, weakly dependent on the relative velocity and on the binding energy of the system. Cross sections for the inverse (photodetachment) process are also given. 相似文献
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T. J. Kennett W. V. Prestwich J. S. Tsai 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(1):121-127
A high precision study of the gamma ray spectrum following neutron capture by a target of natural sulfur is reported. The energy precision obtained has permitted construction of decay schemes for33S and35S. In the case of the former isotope a total of 22 levels have been identified while for the latter and much weaker reaction 7 states have been observed. While some transitions attributable to capture by33S are observed, their weakness prohibited detailed analysis. The neutron separation energies, based upon the14N(n, γ)15N standard are found to be 8,641.60 (3) keV and 6,985.84 (5) keV for33S and35S respectively. 相似文献
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We have analyzed the process of electron capture to the continuum with photon emission, which is referred to as radiative electron capture (RECC). We have considered different projectiles on He targets, observing the behavior of the differential cross section in the first Born approximation, for asymptotic high velocities. These results have been compared with Dettmann's mechanic electron capture to the continuum (MECC) theory. For He targets we find that the RECC process prevails over MECC when the projectile velocity is greater than 20 au. Furthermore we observed that RECC requires larger velocities to prevail when the target is heavy. 相似文献
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R. Samanta M. Purkait 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):311-315
Four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation have been applied to calculate the single-electron capture cross sections by fast protons through some helium-like ions in a large energy range from 30–1000 keV. In this model, distortion has been taken into account in the entrance channel. In the final channel, the passive electron plays the role of screening of the target ion. However, continuum states of the projectile and the electron in the field of the residual target ion are included. The comparison of the results is made with those of other theoretical investigations and experimental findings. The present calculated results are found to be in good agreement with the available experimental findings. 相似文献
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High-energy photon spectra were obtained with moderate resolution for a number of neighboring nuclei: 56Fe, 59Co, 58Ni, 60Ni, 61Ni, 63Cu and 64Zn in bombardments with protons (8 to 22 MeV). The shapes, magnitudes and energy dependence of the observed spectra are found to be consistent in most of their essential features with the implications of the semidirect model for fast nucleon capture. 相似文献
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Fully reproducible nuclear reactions have been observed by high density protons in host metals leading to a large number of
nuclides spread over the whole periodical system of elements [G.H. Miley et al.: inProgress in New Hydrogen Energy (Ed. by M. Okamoto), Inst. of Applied Energy, Tokyo, 1997, p. 629]. We present here an explanation based on a sequence of
nuclear reactions including virtual states (compound nuclei) in an endothermic branch with final exothermic sums of reaction
energy. 相似文献
13.
A search for axions at a 500 MW light water power reactor was performed. From the measured upper limit on the n + p → d + a cross section the “standard” axion is ruled out. 相似文献
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《Physics letters. [Part B]》1970,31(9):609-612
Negative pion radiative capture differential cross-sections at forward c.m. gamma angles (around 30°) have been measured at nine different incident energies between 110 MeV and 270 MeV. Experimental results are compared with the theoretical predictions based on dispersion relations for the photoproduction process, and show excellent agreement with the preliminary data. 相似文献
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The transition rate for radiative capture of negative pions in deuterium is calculated with the Hamiltonian deduced from pion photoproduction data and with the transition amplitude obtained on the basis of the soft-pion theory. A large contribution to the physical amplitude from the intermediate states with the ρ-meson and nucleon-antinucleon pairs in the soft-pion approach brings both results into agreement within 5 %. 相似文献
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Absolute electrofission cross sections for238U and232Th in the energy regionE e =7 ?65 MeV and fission fragment angular distributions forE e =7–30 MeV have been measured. The angular distributions show strong anisotropies for low energies. The relative dipole and quadrupole contributions as a function of excitation energy are discussed in terms of the low lying fission transition states above the fission barriers. The cross sections show significant deviations from the results of some earlier measurements, in particular in the energy region above the giant dipole resonance. From the difficulties of absolute electrofission cross section measurements and the ambiguities in their interpretation it is concluded that by this time the quantitative analysis of electrofission cross sections with respect to the contributions of the giant quadrupole resonances to the fission decay channel should be regarded as rather tentative. 相似文献
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Olmo González-Magaña Remigio Cabrera-Trujillo Cristian Gleason Martin Salazar 《辐射效应与固体损伤》2013,168(12):738-747
Double electron capture (DEC) by protons from He was studied in collisions at energies in the keV regime, theoretically and experimentally. Theoretical cross-sections were calculated using the electron nuclear dynamic approach and a binomial distribution method in the energy range 1–100 keV. Experimental cross-sections were measured by means of the grow-rate method in the energy range of 4–10 keV. The cross-sections measured are consistent with those of the previous data at the high energies of the measured interval and show a different trend for the low energy. This behavior is consistent with those of other DEC cross-sections measured by protons from He-like targets. With the two collision models, it is proven that the reference data for this system are consistent only with the assumption of uncorrelated electrons and with independent target-projectile nuclei dynamics. 相似文献
19.
W. Korten P. Bröcking H. Hübel W. Pohler U. J. van Severen P. Willsau T. Haertlein C. Ender P. Reiter D. Schwalm J. Gerl T. Happ T. Kröll M. Kaspar I. Peter S. Schremmer K. Vetter 《Zeitschrift für Physik A Hadrons and Nuclei》1995,351(2):143-147
We report on a measurement of the lifetime of the 1414 keV state in232Th by the Doppler-shift recoil-distance method. This 4+ state shows all characteristics of a nearly-harmonic two-phonon-vibrational excitation. The result for the B(E2) value obtained from the lifetime,=3.2 ± 0.7 ps, is in agreement with an earlier estimate of the collectivity from Coulomb-excitation yields and supports the interpretation of the 1414 keV state as a two-phonon-vibrational excitation.We would like to thank the accelerator crew of the Max-Planck-Institut für Kernphysik for the excellent running conditions they maintain. We are also indebted to Dr. H.J. Maier, University Munich for supplying us with the232Th targets. This work was supported by the Bundesminister für Forschung und Technologie under contract numbers 06BN601 and 06HD5251. 相似文献
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We have investigated the isotope effect for electron capture into the 2S-state of hydrogen in close collisions for the processes H+ in H2 and H+ in D2. The differential cross sections and transition probabilities P2S obtained for capture into H(2S) as a function of energy at a fixed angle of θ = 1° exhibit distinctive features, but no apparent isotope effects are detected. 相似文献