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1.
R. Ballini N. Cindro J.P. Fouan C. Kalbach M. Lepareux N. Saunier 《Nuclear Physics A》1974,234(1):33-52
We have measured excitation functions for the 20Ne(α, α′)20Ne and 23Na(p, α)20Ne reactions in the energy ranges corresponding to, respectively, 17.85-21.67 and 19.35-20.65 MeV of excitation in 24Mg, that is in the region of the sub-Coulomb resonances in 24Mg observed in the reactions. By using statistical analysis techniques we have determined the energies of possible quasibound states in 24Mg responsible for the deviations from the average trends in the above excitation functions and compared them to the energies of known sub-Coulomb resonances in 24Mg. The comparison speaks in favour of interpreting the simple structures associated with the resonances as alpha-like configurations in the 24Mg continuum. 相似文献
2.
Proton energies and strengths of (p,γ) and (p, p1) resonances of the 35Cl + p reaction were determined for Ep = 0.4?3.0 MeV and 1.9?3.0 MeV, respectively. The γ-decay of 84 resonances was studied with a 40 cm3 Ge(Li) detector. The branching ratios and excitation energies of 38 bound levels were determined. A new bound level was observed at Ex = 8472.0 ± 1.0 keV. Doppler-shift attenuation experiments yielded lifetimes of 20 bound levels. Spins and/or parities for bound levels and resonances were derived on the basis of observed transition strengths. 相似文献
3.
Resonance energies and strengths are reported for forty-five 33S(p, γ)34Cl resonances in the range Ep = 1.0–2.0 MeV. Analysis of the γ-ray spectra by means of two Ge(Li) detectors leads to precise excitation energies of bound states and branching ratios of resonant levels and bound states. New bound levels are found. The reaction Q-value is 5140.3 ± 1.5 keV. Mean lives (or limits) of twelve bound states of 34Cl have been obtained from DSA measurements at seven of the studied 33S(p, γ)34Cl resonances. 相似文献
4.
Angular distributions for 6Li-α scattering at six α-particle energies between 1.39 and 2.98 MeV (lab) along with the excitation functions for two narrow resonances have been measured. A phaseshift analysis of the off-resonance angular distributions was made for l ≦ 3 with the higher phases fixed at values calculated for d-exchange. The l ≦ 3 phase-shifts are compared with those calculated for d-exchange and known wide resonances. 相似文献
5.
Energy levels of 93Mo have been investigated by means of the 93Nb(p, nγ)93Mo reaction. The excitation functions of the level de-excitation γ-rays were measured with a Ge(Li) detector under proton bombardment in the energy range 3.0 to 5.0 Me V. A detailed γ-ray decay scheme which includes 69 levels and 123 γ-ray lines was constructed from the threshold energies for 64 γ-rays and the γ-ray excitation functions around five isobaric analogue resonances in the 93Nb(p, nγ) reaction. Spin-parity values for 59 levels and favourable values for 8 levels were assigned from the analysis of relative neutron yields via the isobaric analogue resonances of the parent odd-odd nucleus 94Nb. The results of the present experiment are compared with shell-model calculations. 相似文献
6.
Tanimura Osamu 《Nuclear Physics A》1980,334(1):177-188
The intermediate resonances observed in the inelastic 12C + 12C cross sections to the single and mutual 21+(4.43 MeV) excitations and the single 31? (9.64 MeV) excitation are studied by the coupled-channel method with the use of the coupling interaction derived by the folding procedure between 12C and 12C. It is shown that the model is successful in reproducing the gross structures of the inelastic cross sections and especially the correlated resonance energies of the inelastic channels. The inelastic resonances are shown to be due to the molecular resonances in an adiabatic potential between two 12C, which reproduces correctly the coupled channel resonances. 相似文献
7.
A.E. Schilling N.F. Mangelson K.K. Nielson D.R. Dixon M.W. Hill G.L. Jensen V.C. Rogers 《Nuclear Physics A》1976,263(3):389-396
The excitation function for the 7Li(d, p)8Li reaction was determined at incident deuteron energies ranging from 0.613 to 1.948 MeV by measuring delayed α-particles. This excitation function revealed resonances at 0.773 ± 0.010 MeV and 1.025 ± 0.010 MeV with cross sections of 181 ± 8 mb and 168 ± 7 mb, respectively. No resonance was observed in the region of 1.4 MeV. 相似文献
8.
W.A. Schier B.K. Barnes G.P. Couchell J.J. Egan P. Harihar S.C. Mathur A. Mittler E. Sheldon 《Nuclear Physics A》1975,254(1):80-92
35Cl states at excitation energies between 9.9 and 11.8 MeV have been identified through sharp resonances in the 31P(α, po)34S excitation functions at 25°, 105° and 155° for Eα = 3.25–5.50 MeV. Forty-eight on-resonance angular distributions, normalized to an absolute cross section scale, have been subjected to single-level and two-level analyses resulting in spin and parity assignments for each resonance. Approximately half the resonances were of the pure single-state type, having unique angular distribution shapes. Data from 12 resonances of an earlier experiment 1) were analyzed with the same theory, extending the diagnostics down to a 35Cl excitation energy of 9.1 MeV. A set of optical potentials consistent in all four reactions that this experimental program encompasses has been incorporated in the present analysis. Validity of the optical potential is demonstrated for α-particles elastically scattered by 31P. 相似文献
9.
《Nuclear Physics A》1988,481(3):458-476
Giant resonances and spectroscopic factors of 16O are studied in the framework of the shell model with (0 + 2)ħω model space. It is found that the Hartree-Fock condition is crucial in order to obtain reasonable excitation energies of giant resonances in 16O. The calculated spectroscopic factors in 15N are quenched only by 10% due to the coupling to 1p-2h states. The spectroscopic factor of the s-state in 11B is also discussed. 相似文献
10.
Marco Fernández Ghiraldo Murillo Jesús Ramírez Olga Avila S.E. Darden M.C. Rozak J.L. Foster B.P. Hichwa P.L. Jolivette 《Nuclear Physics A》1981,369(3):425-452
Cross-section and analyzing power angular distributions have been measured for 20Ne(p, p)20Ne and 20Ne(p, p1)20Ne1(1.63 MeV) for proton energies between 3.7 and 7.9 MeV. The measurements were made in 25 keV intervals between 3.7 and 4.4 MeV, and in 10 keV intervals over most of the region between 4.4 and 7.9 MeV. A phase-shift analysis of the elastic-scattering data has yielded resonance parameters for thirty-three levels in 21Na in the excitation energy region 6.0–9.9 MeV. Some of the strong even-parity resonances can be understood within the framework of the Nilsson model or the shell model. These resonances are also predicted by a macroscopic coupled-channels calculation involving rotational excitation of the 2+ and 4+ states of 20Ne. 相似文献
11.
The excitation of nuclear molecules, formed in the scattering of 12C on 12C, is treated by the collective two-center model (CTCM). The model is referred to a rotating coordinate system and describes the continuous transition from the collective states of the separated nuclei to the states of the compound system. The diagonalization of the interaction between the nuclei leads to a splitting of the excitation energies as function of parity and angular momentum projection. The theory is applied for the explanation of the molecular resonances observed in the 12C-12C scattering. 相似文献
12.
A.A. Cowley J.C. Van Staden S.J. Mills P.M. Cronje G. Heymann G.F. Burdzik 《Nuclear Physics A》1978,301(3):429-440
Resonances observed in the 177° (lab) excitation function of α-particles scattered elastically from 20Ne are investigated in terms of a single Regge pole. The position of the pole in the complex angular momentum plane is determined from angular distributions measured at incident α-particle energies of 25.8 and 27.0 MeV, at which energy values prominent maxima were observed in the excitation function and the pole contribution to these angular distributions is therefore expected to be a maximum. The complete trajectory of the pole over the energy region investigated (24.6 to 31.7 MeV) is obtained by means of extrapolation. The pole trajectory across the surface absorption region of the target nucleus clearly shows the reason for the occurrence of only three large resonances in this energy region, the remaining resonances being attenuated considerably. An angular distribution obtained for 22Ne(α, α)22Ne at an incident energy of 27.0 MeV also indicates the presence of the Regge pole found for 20Ne at the same energy, even though its strength is severely reduced due to the isotopic dependence effect. 相似文献
13.
N. Aissaoui F. Haas R. M. Freeman C. Beck A. Morsad B. Djerroud R. Čaplar G. A. Monnehan A. Hachem 《Zeitschrift für Physik A Hadrons and Nuclei》1997,359(3):271-276
The search and study of quasi-molecular resonances in the 31P composite system populated via two entrance channels are performed with two different experimental techniques. The 16O + 15N reaction products have been studied by the γ-ray detection method at cm. energies ranging from 15.5 MeV to 36.1 MeV. Binary channels of the 16O + 15N and 12C + 19F collisions have been studied by using the kinematical coincidence method at 26 incident energies ranging from Ec.m. = 20.6MeV to 33.5MeV for the first system, and at energies corresponding to the same excitation energies of the composite system for the second system. The 16O + 15N reaction exhibits two prominent gross structures in the large angle elastic scattering excitation function correlated with the resonant structures observed in inelastic channel γ-ray yield measurements. Spin assignments were tentatively made for the two resonances. On the contrary, no such structures can be clearly established in the 12C + 19F system where only indications of non-correlated structures in various channels have been observed. 相似文献
14.
Ph Chomaz Y. Blumenfeld N. Frascaria J. P. Garron J. C. Jacmart J. C. Roynette W. Bohne A. Gamp W. Von Oertzen Nguyen Van Giai D. Vautherin 《Zeitschrift für Physik A Hadrons and Nuclei》1984,319(2):167-176
Energy spectra of fragments from the36Ar+208Pb reaction at 11 MeV/n exhibit structures at high excitation energies. These structures are interpreted in terms of target multi-phonon excitations built from giant resonances. The importance of such processes for the kinetic energy dissipation in heavy ion collisions is emphasized. 相似文献
15.
J. Van Der Plicht M.N. Harakeh A. Van Der Woude P. David J. Debrus H. Janszen J. Schulze 《Nuclear Physics A》1981,369(1):51-76
The fission probabilities and angular distributions of the fission fragments for the (α, α'f) reaction on 232Th and 238U at a bombarding energy of 120 MeV have been measured from about 4 to 14 MeV excitation energy. Evidence for sub-barrier resonances has been found, the negativeparity ones occurring at the same excitation energy where photofission resonances have been observed. The data are analyzed with the two-humped barrier model. For 238U the data are reasonably well fitted with barriers similar to those known from the literature. For 232Th though, the outer barrier parameters are quite different: the height EB = 6.6 MeV and the width (khω)B = 1.2 MeV. Also for 232Th, introducing an additional mass symmetric and axially asymmetric outer barrier, as was previously found necessary for 238U, does not result in a good fit to the data at higher excitation energies. 相似文献
16.
U. Goerlach D. Habs M. Just V. Metag P. Paul H. J. Specht H. J. Maier 《Zeitschrift für Physik A Hadrons and Nuclei》1978,287(2):171-181
The prompt and isomeric fission probabilities of240Pu have been studied using the239Pu(d,p) reaction. A number of resonances are observed in the subbarrier population of the 4 ns fission isomer for excitation energies between 4.0 and 6.2 MeV. Apart from a structure at 4.3 MeV, they do not coincide with transmission resonances found in prompt fission. Calculations with an extended doorway state model which simultaneously reproduce the measured delayed and prompt fission probabilities yield revised fission barrier parameters as well as spectroscopic information on fission and gamma widths of highly excited states in the second minimum. 相似文献
17.
D. Lebrun G. Perrin P. Martin P. De Saintignon J. Arvieux M. Buenerd H.V. Geramb K.A. Amos 《Nuclear Physics A》1976,265(2):291-300
Differential cross sections and analyzing powers for the inelastic scattering of polarized protons from 16O leading to the 2? state at 8.88 MeV excitation have been measured at incident energies of 31.7, 33.8, 35.8, 36.8 and 39.9 MeV. These data have been analyzed using a distorted wave theory in which the effects of virtual excitation of E1, E2 and E3 giant resonances as doorway states are included explicitly. This analysis shows that the strong energy variation in the data between 30 and 40 MeV may be predominantly due to a new isoscalar E3 resonance with the contributions from the E1 and E2 resonances corroborating earlier findings. 相似文献
18.
Theβ ?, (n→p) and (p→n), transition strengths and excitation energies for first forbidden resonances with λπ=0? and 2? in spherical nuclei are calculated in the framework of the linear response theory. The results show that the intensities associated with these modes are strongly fragmented, particularly, for the λπ=2? states. 相似文献
19.
We review the experimental evidence for alpha chain states in 4N-nuclei. Bloch-Brink cranked cluster model calculations suggest that such states should exist in all light A=4N nuclei. Recently a strong resonance has been observed in the12C(12C,12C(O 2 + ))12C(O 2 + ) reaction at 33 MeV which has been taken as evidence of a 6-α chain state in24Mg. The angular distributions show strong peaks at 90° due to the simultaneous excitation of several nearly degenerate resonances with a range of L-values. We review our analysis of these data and present the results of calculations for the widths of resonances in hyperdeformed nuclei. We demonstrate that such resonances may have relatively narrow widths despite their high excitation energies. We surmise that the 33 MeV resonance in12C+12C scattering has a chain state structure. 相似文献
20.
The structure of levels of the 46Ti nucleus is studied by means of the nonselective reaction 45Sc(p, γ) at proton energies ranging between 1.2 and 3.1 MeV. Spin-parity assignments for 46Ti states of excitation energies up to 5.5 MeV are obtained by using the method of averaged resonances. Radiative strength functions for E1 transitions populating these states are determined. The resulting data are compared with predictions of various models. 相似文献