共查询到20条相似文献,搜索用时 31 毫秒
1.
A new TOF facility has been built for measurements of differential (γ, n) cross sections to discrete final states of light nuclei in the photon energy range between giant resonance and pion threshold. The observed neutron angle θn can continuously be varied between 0° and 150°, and additionally measurements at 175° and 180° are possible. Differential cross sections for the reaction 16O(γ, n0)15O are presented for Eγ = 60 MeV (40° ? θn ? 149°) and for θn = 90° (60 MeV ? Eγ ? 160 MeV). The results, combined with the corresponding (γ, p0) cross sections, indicate an absorption mechanism of high energy photons by neutron-proton pairs. 相似文献
2.
The differential cross section of the elastic scattering 3He(4He, 4He)3He has been measured at center of mass energies Ec.m. between 28 and 44 MeV and in the c.m. angular range of 20° to 160°. The 3He polarization P at Ec.m. = 42 MeV and θc.m. = 132° was determined in a double scattering experiment. The analysis of the cross section data with the optical and the cluster model has been described previously. The phase shifts obtained in the cluster model calculations were used as starting values in a phase shift analysis. The resulting final real phase shifts and elasticity parameters give good fits to the cross section data. At 44 MeV the elasticity parameters show a pronounced odd-even dependence on angular momentum which had been found already in the case of the real phase shifts. The result of the polarization experiment |P| < 0.22 is consistent with cluster model predictions. 相似文献
3.
D. Bisello S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori J.E. Augustin G. Busetto G. Cosme F. Couchot B. Dudelzak P. Eschstruth F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne G. Capon 《Nuclear Physics B》1983,224(3):379-395
The cross section has been measured in the energy interval (1975 ? 2E ? 2250) MeV for |cosθ| < 0.7. The measurement is based on ~ 100 events, thus improving by a factor 3 on the previous existing statistics in this energy interval. The form factor |G|2 is given as a function of energy under the assumption |GE| = |GM|. We also give the first measurement of the differential cross section, averaged over the energy interval, and estimate the ratio GM|/|GE| from it. 相似文献
4.
Total cross sections and angular distributions in the 6Li(p,3He)4He reaction have been measured over the energy range Ep = 100?700 keV. The extrapolation of the cross section to the energy region which is of interest in controlled thermonuclear reactors is given. The values of the “astrophysical S-function” are deduced from the cross sections. 相似文献
5.
The differential cross section of the 2H(n, np) reaction was measured at θn = 0°. Because of the applied special geometry the experimental data extend over a large fraction of the phase space, including several final state interaction regions as well as regions far from the dominance of quasi-two-body processes. The experiment was analysed with an exact three-body calculation using s-wave separable potentials (CEE). The analysis of the n-n and n-p final state interaction peaks gave ann = ?16.3 ± 1.6 fm for the n-n 1S0 scattering length and rnn = 3.15 ± 0.7 fm for the effective range. Remarkable deviations from the calculated cross sections-were found in regions where no strong final state interaction was present. 相似文献
6.
The elastic differential scattering cross section from 55Mn has been measured at θ = 140° with Eγ = 5.5–11.4 MeV photons. Evidence for destructive interference between nuclear resonance (NR) scattering and nuclear Thomson (NT) scattering has been obtained. 相似文献
7.
The differential cross sections at 90° for the 51V(e, p0)50Ti and 52Cr(e, p0 + p1)51V reactions have been measured over the giant dipole resonance region. These cross sections were used to obtain the differential cross sections of the 51V(γ, p0)50Ti and 52Cr(γ, p0 + p1)51V reactions. The results show two peaks that appear at the same energies as the main peaks of the (γ, n) and (γ, p) cross section for both nuclei. The angular distributions of protons from the (e, p) reaction have also been measured at several points of the incident electron energy. The coefficients A2 obtained by fitting with a series of Legendre polynomials, W(θ) = 1 + A1P1(cos θ)+A2P2(cos θ), varies with excitation energy. These results are discussed in terms of the direct-semidirect process considering isospin effects in the giant dipole resonance. 相似文献
8.
H. Klein H. Elchner H.J. Helten H. Kretzer K. Prescher H. Stehle W.W. Wohlfarth 《Nuclear Physics A》1973,199(1):169-185
The break-up reaction p0 + d → p1 + p2 + n has been studied at E0 = 16 MeV in kinematically complete p1-p2 coincidence experiments with special regard to n-p final-state interactions (f.s.i.) and p1-p2 quasifree scattering (q.f.s.). The absolute differential cross section has been measured for n-p f.s.i. c.m. production angles from 60° to 140° and for four pairs of angles with strong contributions due to q.f.s. Calculations with separable nucleon-nucleon potentials based on the Faddeev equations are in good agreement with the data obtained. In general, the shape of the experimental differential cross section is well reproduced. Discrepancies of up to 30 % in the worst cases arise between the absolute values of the theoretical predictions and the experimental data. 相似文献
9.
C.K. Gelbke R. Bock P. Braun-Munzinger D. Fick K.D. Hildenbrand W. Weiss S. Wenneis G. Baur 《Physics letters. [Part B]》1973,43(4):284-286
The elastic scattering of 16O on 17O has been measured at Elab = 24, 28 and 32 MeV and θc.m. = 90° ?150°. At large energy the cross section exhibits a structureless rise at backward angles which can be described consistently with the DWBA approach for the elastic transfer. 相似文献
10.
W. Trombik W. Trautmann F. Krug W. Dünnweber D. Konnerth W. Hering R. Singh D. Zeppenfeld 《Physics letters. [Part B]》1984,135(4):271-274
Using the out-of-plane γ-ray particle coincidence method we have measured the spin alignment Pzz of excited 12C(2+) nuclei from 12C+12C inelastic scattering in the energy range 16 MeV ? Ecm ? 33 MeV.Pzz varies strongly as a function of energy and angle. The correlation of resonant structures in the cross section with maxima of the alignment is particularly clear in mutual inelastic scattering and in θcm = 90° single inelastic scattering. 相似文献
11.
J.M. Cameron P. Kitching W.J. Mcdonald J. Pasos J. Soukup J. Thekkumthala H.S. Wilson R. Abegg D.A. Hutcheon C.A. Miller A.W. Stetz I.J. Van Heerden 《Nuclear Physics A》1984,424(3):549-562
We report the results of measurements of the differential cross section and analyzing power for the reaction pd → γ3He at six energies in the range 200 < Ep < 500 MeV. The cross-section data are in good agreement with the most recent results for the inverse process assuming detailed balance; thus no evidence for time-reversal violation is inferred. In addition, the shapes of the measured angular distributions are in general overall accord with those measured in the photodisintegration reaction. The data are compared with several theoretical calculations showing inclusion of meson-exchange current contributions to be important in reproducing the measured cross section. The analyzing powers measured at Ep = 500 MeV are not yet explained by microscopic models. 相似文献
12.
A.S. Demyanova S.A. Fayans Yu.A. Glukhov A.A. Ogloblin S.B. Sakuta S.N. Ershov F.A. Gareev N.I. Pyatov 《Nuclear Physics A》1985,444(3):519-540
The energy spectra of 6He nuclei from the 90Zr(6Li, 6He) reaction at E6Li = 93 MeV have been measured over the angular range of 7 ° ? θlab ? 20 °. The theoretical DWBA analysis of these spectra and angular distributions was performed employing transition densities of bound and resonance states obtained on the basis of the theory of finite Fermi systems. It is shown that up to excitation energies of Ex ≈ 10 MeV in 90Nb a direct charge-exchange mechanism dominates in this reaction, while at higher Ex the contribution made by multistep processes increases significantly. It is also shown that the quasi-elastic cross section is determined by a sum of partial contributions of spin-isospin-flip transitions with multipolarities L=0 through L=6. 相似文献
13.
We have measured the differential cross section of the reaction π−p→π−p in the range 0.92 ? cos θc.m. ? 0.99 at 15 momenta between 0.875 and 1.580 GeV/c. The results we report complete the available data; previous measurements of this reaction do not extend beyond cos θc.m.=0.90. We compare our experimental results with dispersion relation predictions. A comparison of our results for B, the slope of the differential cross section, with earlier results shows many discrepancies. 相似文献
14.
《Nuclear Physics A》1988,483(2):406-428
The 13C+13C total fusion cross section has been determined in the range 3.26⩽Ec.m.⩽8.0 MeV using Ge(Li) detector measurements of low-lying transitions in the residual nuclei and a statistical model calculation of excited state populations. The six most abundantly produced residual nuclei have been observed and their yields are given. To constrain the parameters in fusion models for these reactions, we have also taken elastic scattering data at θc.m.=60°, 70°, 80°, and 90° for 4.5⩽Ec.m.⩽8.5 MeV, as well as angular distributions at Ec.m.=7.0 and 8.0 MeV. The IWBC model and an optical model with a “shallow” potential have been used for parametrizing the nucleus-nucleus interaction. 相似文献
15.
Alpha particles have been measured in coincidence with heavy recoil nuclei from the 28Si + 12C reaction. At Elab = 87 MeV angular correlations for alphas between 15° and 55° and heavy ions at angles ?9°, ?12° and ?15° have been taken. An excitation function of coincidence events with θα = 30° and θHI = ?12° has been measured for 84 MeV < Elab < 91.5 MeV. The results are well described by a statistical-model calculation for compound nucleus decay. No evidence is found for additional processes. 相似文献
16.
G.A. Anzelon I. Šlaus S.Y. Tin W.T.H. Van Oers R.M. Eisberg M. Makino C.N. Waddell M.B. Epstein 《Nuclear Physics A》1975,255(2):250-266
Proton-α bremsstrahlung cross sections have been measured at 45 MeV for θp = 91°, θα = 30° and θp = 70°, θα = 39°; at 40 MeV for θp = 92°, θα = 29°; and at 22 MeV for θp = 70°, θα = 30°. Calculations for these cross sections have been made using the Feshbach-Yennie model following the methods of Green and Prodon including p-α partial waves up to L = 4. These potential-independent calculations have only the proton-α elastic-scattering phase shifts as input. Good agreement with the experimental cross sectios has been obtained. 相似文献
17.
W.A. Sterrenburg S. Brandenburg J.H. van Dijk A.G. Drentje M.B. Greenfield M.N. Harakeh H. Riezebos H. Sakai W. Segeth S.Y. van der Werf A. van der Woude 《Nuclear Physics A》1984,420(2):257-284
The nucleus 16F was studied via the 16O(3He, t) reaction at 81 MeV. Differential cross sections for many states were obtained and interpreted with DWBA calculations, using microscopic wave functions and an effective projectile-nucleon interaction. Proton decay to several states in 15O was observed and angular correlations for protons in coincidence with tritons detected at θ = 0° were measured. Several spin-parity assignments have been made. The distribution of isovector ΔL = 1 strength could be deduced. The analog of the giant dipole resonance ( is strongly excited. The magnetic quadrupole strength has two strong components, one low, at Ex = 0.424 MeV, and one high, at . Evidence is given for a proportionality between cross section and M2 strength for transitions to Jπ = 2? states, which possibly make the (3He, t) reaction a suitable tool for determining quantitatively isovector M2 (or Bij) strengths. 相似文献
18.
《Physics letters. [Part B]》1986,179(3):212-216
The tagged photon technique has been used to measure the 12C photoproton cross section over the angular range θp = 30°–135° for Eγ = 60 and 80 MeV. Comparison of the results with quasifree knockout and quasideuteron calculations shows that photon interaction with two-nucleon pairs is dominant at least for high excitation energies in the residual nucleus. 相似文献
19.
R. Frascaria I. Brissaud N. Marty M. Morlet F. Reide A. Willis R. Beurtey A. Boudard M. Garcon G.A. Moss Y. Terrien W.T.H. Van Oers 《Physics letters. [Part B]》1977,66(4):329-332
Large-angle p-3He elastic scattering differential cross section have been measured at Ep = 415 and 600 MeV where they look very similar, and at 800 MeV where the cross section is 10% of the value at 600 MeV. A one-meson-plus-2N exchange mechanism could explain this feature. 相似文献
20.
J.A. Edgington V.J. Howard I.M. Blair B.E. Bonner F.P. Brady M.W. McNaughton 《Nuclear Physics A》1974,218(1):151-168
We have measured the double differential cross section for bremsstrahlung production in neutron-proton collisions near 130 MeV. Outgoing nucleons were detected at eight pairs of angles simultaneously. The cross sections agree with several theoretical predictions for those four angle pairs in which the proton emerged at 20° (θ = 20°), but are larger than expected in the four cases that θp = 32°. The method of data reduction, and the sources of uncertainty, are discussed in detail. 相似文献