共查询到20条相似文献,搜索用时 31 毫秒
1.
G. Vourvopoulos M.B. Greenfield J.B. Ball S. Raman W.K. Dagenhart 《Physics letters. [Part B]》1974,52(2):187-188
The forward-angle differential cross sections have been measured for the 22Ne(p,t) reaction leading to the 4.97 MeV, 2? state in 20Ne. Comparison of the data with the results of calculations shows that the two-step mechanism responsible for exciting this state is (p-p′-t) rather than (p-d-t). 相似文献
2.
Y. Nagame H. Nakahara K. Sueki H. Kudo I. Kohno M. Yanokura 《Zeitschrift für Physik A Hadrons and Nuclei》1984,317(1):31-44
Strongly damped components have been studied in relatively light heavy ion reaction systems;20Ne(E lab=93, 120 and 146MeV)+50Cr,20Ne(E lab=146MeV)+54Cr and20Ne(E lab=146MeV)+92Mo,100Mo. The kinetic energy, angular and charge distributions have been observed for those products. The yields of symmetric-mass-splitting products for20Ne+50Cr were found about three times larger than those for20Ne+54Cr. There was also observed a similar difference in the cross sections of the symmetric-mass-splitting products between20Ne+92Mo and20Ne+100Mo reactions. In order to explain the bombarding energy dependence of the cross sections of symmetric-mass-splitting products by the transport theory, it was found necessary to assume that the mean life of the composite nucleus was dependent on the bombarding energy. However, the target isotope dependence of the cross sections could not be explained by such an assumption. They could be partly explained by fission calculations. 相似文献
3.
The 12C(12C, α)20Ne reaction is studied near Ec.m. = 15 MeV. Angular distributions for three energies and excitation functions at θlab = 30° over an energy range Ec.m. = 14.5?15.4 MeV for about 20 levels in 20Ne (Eex = 0–13 MeV) are examined. The statistical analysis yields the results that a correlated resonance is present at Ec.m. = 14.75 MeV. A nonstatistical contribution to the reaction is also apparent when energy-averaged cross sections are compared with the Hauser-Feshbach model predictions. Strong population of the 0+3 band in 20Ne is observed. 相似文献
4.
C. Volant M. Conjeaud S. Harar S.M. Lee A. Lépine E.F. Da Silveira 《Nuclear Physics A》1975,238(1):120-140
States in 20Ne have been studied through the 12C(14N, 6Li)20Ne reaction. Excitation functions have been measured from 20 MeV to 60 MeV in steps of 5 MeV at different angles for 20Ne states up to 10 MeV excitation energy. States of 24Mg have been also populated using the 12C(14N, d)24Mg reaction; excitation functions of 24Mg states up to 9 MeV excitation energies as well as angular distributions at 35 MeV bombarding energy have been obtained. Comparisons of data with Hauser-Feshbach calculations show clearly that the compound nucleus mechanism is the main process for both 12C(14N, 6Li)20Ne and 12C(14N, d)24Mg reactions. Strong evidence has been provided for inhibition of the 26Al compound nucleus formation for angular momenta higher than critical values. The location of the yrast line in the 26Al nucleus is discussed. 相似文献
5.
W. Buck F. Hoyler A. Stäbler G. Staudt H.V. Klapdor H. Oeschler 《Nuclear Physics A》1983,398(2):189-202
The differential cross sections for the 11B(p, α)8Be and 23Na(p, α)20Ne reactions were measured at bombarding energies between 6 and 24 MeV. The observed angular distributions can be divided into two domains: at low energies the shapes vary rapidly with incident energy indicating a compound nucleus reaction ; at higher energies rather stable diffraction patterns are seen exhibiting a direct reaction mechanism and DWBA calculations are able to describe the shapes. The change from one region to the other is rather abrupt and this behaviour seems typical for reactions having an α-like compound nucleus. The energy at which this change occurs corresponds to an excitation energy in the compound nucleus of about 20 MeV above the α-threshold. 相似文献
6.
H.-P. Rother W. Henning H.-J. Körner R. Müller K.E. Rehm M. Richter H. Spieler 《Nuclear Physics A》1976,269(2):511-519
The (18O, 20Ne) reaction on the even Ni isotopes has been studied at 63.0 MeV with ΔE-E time-of-flight telescopes. From the measured ground-state Q-value for the 64Ni(18O, 20Ne)62Fe reaction, ?1.97±0.20 MeV, a mass excess ?58.87±0.20 MeV is obtained for the 62Fe nucleus. This result is in good agreement with a recent measurement of the β-endpoint energy. Angular distributions for the transitions to the Fe ground states, leaving 20Ne in its ground and 1.63 MeV 2+ excited state, yield relative spectroscopic strengths in fair agreement with DWBA calculations based on simple shell-model estimates. 相似文献
7.
We have examined the role of inelastic processes in the 19F(3He, d)20Ne reaction. By coupling three levels in both the entrance and exit channels it was found that the inelastic processes were able to account for both the magnitude and rather flat shape of the angular distribution for the 4.25 MeV 4+ level observed in the 19F(3He, d)20Ne reaction at 16 MeV bombarding energy. In contrast the DWBA could not account for the data. The magnitude of the inelastic processes was found to be quite sensitive to some of the optical model parameters involved. The DWBA predictions for the 0+ and 2+ cross sections were modified by the inelastic processes requiring some adjustment of the spectroscopic amplitudes to account for the data. 相似文献
8.
The reaction channels of the system 16O + 16O with outgoing heavy particles from lithium to magnesium have been measured using a ΔE-E telescope. Excitation functions from 49 to 65 MeV at θLab = 30° and angular distributions from θLab = 10° (20°) to 50° at ELab = 51.5 MeV are presented for the strong transitions. The excitation function of the 12C-20Ne (4.25 MeV) channel shows a pronounced regular cross structure with peaks at 52 and 60 MeV. A selective excitation of certain states in the inelastic scattering and the 12C-20Ne channel is observed; the yields of the other heavy-ion channels being weaker by at least one order of magnitude. An explanation of this phenomenon is given by considering the angular momentum matching between entrance and exit channels. Furthermore it is shown that no strong dependence of the cross sections on the transferred angular momentum or on the nuclear structure of the final states is observed. Possible implications of these results on the reaction mechanism are discussed. 相似文献
9.
Analyzing powers and cross sections have been measured for elastic and inelastic scattering of 24.5 MeV protons from 20Ne and 22Ne, and for 16O, 28Si and 32S at 30.3 MeV. The experimental results were analyzed in terms of the coupled-channels formalism using the rotational model and (for 32S and 16O) the vibrational model. The results for 20Ne, 22Ne and 28Si show a systematic trend of the hexadecapole deformation. Prolate shapes for 20Ne and 22Ne and an oblate shape for 28Si are confirmed. The results for 32S are almost equally well-reproduced by the vibrational or rotational model, and there is a slight preference for the prolate shape for this nucleus. The best fits for the analyzing power for all the nuclei were obtained by using the full Thomas form for the spin-orbit potential 相似文献
10.
Differential cross sections of the reactions24Mg(n,α)21Ne,25Mg(n,α)22Ne, and26Mg(n,α)23Ne have been measured at neutron energies of 13.19,13.93 and 14.33 MeV, at 13.93 and 14.33 MeV, and at 13.47 and 13.93 MeV, respectively. In forward direction, differential excitation functions of those reactions have been measured at energies between 12.67 and 16.05 MeV. The results are analysed in terms of direct-reaction and compound-nucleus theories. 相似文献
11.
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
12.
Absolute cross sections have been measured for the reactions 10B(16O, 6Li)20Ne and 12C(14N, 6Li)20Ne at several energies in the range Ec.m. = 7.5–16.2 MeV, and 13.8–16.6 MeV, respectively. The predictions of Hauser-Feshbach calculations show generally good agreement with the experimental data without parameter variation. The consequences of an angular momentum cutoff in the entrance channel and in the compound nucleus are discussed. 相似文献
13.
D. J. Morrissey W. Loveland G. T. Seaborg 《Zeitschrift für Physik A Hadrons and Nuclei》1978,289(1):123-124
Target residue mass and charge distributions have been measured radioanalytically for the reaction of 8.0 GeV20Ne ions with Ta. These distributions are very similar to those distributions observed in the reaction of Ta with protons of equivalent total energy rather than equivalent velocity. Detailed comparisons of the production cross sections for near target residues with abrasion-ablation model calculations show these products to have an excitation energy of ~75 MeV. 相似文献
14.
Mass distributions of evaporation-residue-like fragments have been measured using a time-of-flight system for the reaction 20Ne + 26Mg in the energy range of 51 to 400 MeV bombarding energy for 20Ne. A good mass resolution allowed for the separation of the evaporation residues and fragments from two-body reactions like e.g. damped processes. The residue distributions were compared with evaporation calculations. The analysis of velocity spectra measured at bombarding energies of 85–395 MeV showed incomplete momentum transfer for evaporation-residue-like fragments at higher energies. Statistical-model calculations and Monte Carlo methods applied to the calculation of the velocity spectra have been used to extract the complete-fusion cross section. 相似文献
15.
H. Tricoire C. Gerschel N. Perrin H. Sergolle L. Valentin D. Bachelier H. Doubre J. Gizon 《Zeitschrift für Physik A Hadrons and Nuclei》1982,306(2):127-137
Direct α particles cross sections and angular distributions have been measured when bombarding a124Sn target with various projectiles:16O (90, 105, 125 MeV)19F (104 MeV)20Ne (112, 156 MeV). Results have been found independant of the projectile structure. In the same reactions, gamma multiplicity measurements have shown that direct α particles are emitted in collisions with intermediate impact parameters. The angular momentum is found to be about half of the valuel cr for complete fusion. 相似文献
16.
J.F. Petersen 《Nuclear Physics A》1975,255(2):307-314
The two-proton transfer reaction (3He, n) has been measured on four gas targets, 16O, 18O, 20Ne, and 22Ne, with an incident 3He energy of 18.3 MeV. The data were taken with a neutron time-of-flight spectrometer in the angular range 0° to 40° c.m. The results for selected transitions are compared to DWBA predictions using shell-model spectroscopic amplitudes. In addition, the data for the 18O(3He, n)20Ne reaction are compared to predictions of the SU(3) strong coupling model. 相似文献
17.
C. Bauer H. Richter P. Gippner R. Mann W. Rudolph B. Eckhardt K. O. Groeneveld 《Zeitschrift für Physik A Hadrons and Nuclei》1981,303(1):13-22
Absolute Ag, Ta and AuL-shell X-ray cross sections were measured using protons,4He,14N as well as20Ne ions in the energy range of 0.125–4 MeV/amu. By means of single-hole fluorescence yields experimental ionization cross sections were deduced and compared with calculations according to the corrected PWBA model — PWBA(BPCR). With decreasing asymmetry of the collision system the experimental cross sections exceed the predictions of the direct ionization theory. This is caused by an increasing contribution of a competing KL charge exchange mechanism which was investigated in detail for Ne+Ag. The Lapicki and Losonsky capture model was found to fail at energiesE<1 MeV/amu because adiabatic relaxation effects in the projectileK-shell become important. An estimation by means of the Nikitin model led to more physically comprehensible results at the lowest ion velocities investigated. 相似文献
18.
A. d'Onofrio B. Delaunay J. Delaunay H. Dumont J. Gomez del Campo A. Brondi R. Moro M. Romano F. Terrasi J. F. Bruandet 《Zeitschrift für Physik A Hadrons and Nuclei》1987,326(3):335-336
The production cross sections of7Li in its ground and first excited states have been measured at 14°, 120°, 150°, for the 742 MeV20Ne+60Ni reaction. Hauser-Feshbach calculations show that the backward angle data are consistent with an emission temperature greater than 6 MeV. This is in agreement with the values extracted from the slope of the energy spectra and indicates that the emitting source is equilibrated. 相似文献
19.
《Nuclear Physics A》1998,635(3):292-304
Total reaction cross sections, σR, on Si were measured near 40 A MeV for the proton-halo candidate 12N and the two-proton-halo candidate 17Ne, and were compared with σR for other light proton-rich nuclei. The A-dependence shows enhanced σR's for 12N and 17Ne, relative to their neighbors, but the effect is smaller than for 8B which has been argued to have a proton halo. In general, nuclei with loosely bound last protons (Sp ⩽ 1.5 MeV) have significantly larger σR's than their neighbors. Cross sections for charge-removal from 12N and 17Ne also were obtained. 相似文献
20.
V. A. Khryachkov I. P. Bondarenko B. D. Kuzminov N. N. Semenova A. I. Sergachev 《Physics of Atomic Nuclei》2012,75(4):404-410
The cross section for the reaction 20Ne(n, α)17O was measured in the neutron-energy range 4–7 MeV. An ionization chamber equipped with a Frisch grid combined with a pulse-shape
digitizer was used as a detector. Gaseous neon that served as a target on which the reaction being studied proceeded was added
to the gas filling the ionization chamber. The partial cross sections for the α
0, α
1, α
2, and α
3 channels of the reaction 20Ne(n, α)17O were obtained for the first time. 相似文献