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1.
π ±-Nucleus scattering cross sections are calculated applying the Watanabe superposition model with a phenomenological Woods-Saxon potential. The phenomenological potential parameters are searched for π ± scattering from 6Li and 12C to reproduce not only differential elastic cross sections but also inelastic and total and reaction cross sections at pion kinetic energies from 50 to 672 MeV. The optical potentials of 6Li and 12C are calculated in terms of the alpha particle and deuteron optical potentials. Inelastic scattering has been analyzed using the distorted waves from elastic-scattering data. The values of deformation lengths thus obtained compare very well with the ones reported earlier.  相似文献   

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3.
Measurements of absolute elastic-scattering differential cross sections for π±He at Tlabπ = 30.2 MeV, 45.1 MeV and 65.0 MeV and for π±-4?4He at Tlabπ = 25.1 MeV and 51.1 MeV have been made in the angular range 40° to 145°. An overall accuracy of about ±5% was achieved. The results are compared with available theoretical calculations.  相似文献   

4.
π+-nucleus scattering cross section are calculated by solving a Schrödinger equation reduced from the Klein-Gordon equation. Local potentials are assumed, and phenomenological potential parameters are searched energy dependently for π+ scattering from 12C, 40Ca, and 208Pb to reproduce not only differential elastic cross sections but also inelastic and total and reaction cross sections at 800 MeV/c pion laboratory momentum. The collective model is used to calculate the angular distributions of differential inelastic cross sections for pions leading to the lowest 2+ and 3? states of 12C. The deformation parameters and lengths are extracted and compared to the corresponding ones from other works. Local potentials well describe the scattering of pions from nuclei.  相似文献   

5.
《Nuclear Physics A》1987,475(4):761-773
Double differential cross sections of the reaction 14N(e, π+) have been measured at E0 = 173.5 MeV for pion production angles of Θπ = 25° and 100° which correspond to momentum transfer values of q2 = 0.22 and 1.14 fm2. Using the virtual photon theory single differential cross sections of the reaction 14n(γ, π+)14Cg.s. are extracted from the measured data. The data are compared with recent DWIA calculations and indicate a larger nuclear spin-flip transition matrix element between 14N and 14C than that obtained from β-decay. Mixing parameters for shell model wave functions of 14N and 14C ground states are derived from the data.  相似文献   

6.
Differential cross sections for elastic scattering of pions by deuterons have been measured for centre-of-mass angles between 130° and 175°, and at laboratory energies 141, 177, and 260 MeV for π+, and at 151, 185, and 189 MeV for π?. At 177 and 260 MeV the cross sections are a factor of 2 lower than the predictions of three-body theories.  相似文献   

7.
The cross sections for the reactions π±π±, π0 on 12C with excitation of the T = 1 states are calculated for the N331 energy region. The Chew-Low amplitude for pion-nucleon scattering is used in the framework of impulse approximation which has been supported by recent calculation of pion scattering with excitation of definite nuclear states.  相似文献   

8.
Angular distributions from the (p, π±) reactions have been measured at 200 MeV on 12C and 13C leading to discrete final states in the residual nuclei. A comparison of the cross sections is made between transitions to isobaric analog and non analog final states. Differences between the (p, π+) and (p, π?) reactions are found in the shape and magnitude of the differential cross section as well as in the energy variation.  相似文献   

9.
Low-energy pion scattering (up to 50 MeV) on 12C and 16O is described quantitatively in the framework of the UST approach. It is shown that at Tπ ∼ 50 MeV the differential cross sections arise as a result of a strong interference between the pure potential and absorption channels. The importance of nuclear structure effects in the pion-nucleus dynamics at low energies is discussed.  相似文献   

10.
Reaction cross sections for 12C(π+, πN)11C at 134, 161, 177, and 200 MeV and for 19F(π+,πN) at 161, 177, and 200 MeV were measured by activation methods.  相似文献   

11.
12C+4He fusion reaction at E cm  = 0.3 MeV is one of the main reaction in 4He-burning in stars, and is very important in nuclear synthesis. However the fusion cross section has not been determined yet in spite of 40 years efforts in the world. Recently we succeeded in the measurement at 1.5 MeV. We have a plan to make direct measurement of the total fusion cross section down to 0.7 MeV at Kyushu University Tandem accelerator Laboratory (KUTL), and to determine the cross section at 0.3 MeV by extrapolation.  相似文献   

12.
The π+ total nuclear cross sections for 9Be, 12C, 16O, and 27Al have been measured in the energy range 114 to 210 MeV, while π? data have been taken at 153 MeV. In the center-of-mass coordinate system the π-nucleus total cross sections reach their maximum value near the π-nucleon (32, 32) resonance (TπC.M.= 1.52 MeV) where they scale as A23. The measured total cross sections exhibit considerable broadening with respect to the π-nucleon resonance.  相似文献   

13.
In order to obtain data on the photon absorption process between the giant resonance and the meson threshold the cross sections of the reactions12C(γ,n)11C,12C(γ, 2n)10C,39K(γ,n)38Kg, and40Ca(γ,np)38Kg have been determined by the analysis of yield curves at the 140 MeV electron synchrotron of the PTB. Though the (γ,n) cross sections grow small with increasing photon energy they are different from zero up to energies of 60 MeV and above. The cross section of the reaction12C(γ, 2n) is extremely small; its highest value amounts to 0.15% of the highest value of the12C(γ,n) reaction. The measured40Ca(γ,np) cross section is of the order predicted by the naive quasi-deuteron model. The integrated cross sections of the above reactions up to 140MeV are 85±7,0.90±0.10, 139±16, and 76±7MeVmb respectively.  相似文献   

14.
From a measurement of the cross section for 12C(α, γ)16O at the Eα = 4.253±0.014 MeV(E = 10.352±0.011 MeV) resonance, the radiative width for the 10.35 MeV (Jπ = 4+) to 6.92 MeV (Jπ = 2+) transition was determined to be Γγ = 58±7 meV. This is somewhat higher than the value predicted by large j-j shell-model calculations, but agrees well with predictions based on the rotational and the SU(3) models for a 4p-4h band, and the deformed- basis calculation of Green and Brown.  相似文献   

15.
Within the Glauber diffraction theory of multiple scattering, the differential cross sections for the elastic and inelastic scattering of π± mesons are calculated for energies in the range between 130 and 260 MeV. This is the region where the broad Δ33 resonance in the π±N system occurs, the maximum corresponding to this resonance being at approximately 165 MeV. The wave function for the 9Be nucleus was chosen on the basis of the 2αN multicluster model. The sensitivity of the resulting differential cross sections to the target-nucleus wave functions computed with various intercluster-interaction potentials, to the contributions of wave-function components, and to various scattering multiplicities in the Glauber operator Ω is analyzed. A comparison with experimental data and with the results of other calculations is performed, and conclusions concerning the quality of the wave functions used and advantages of the present approach are drawn.  相似文献   

16.
New data are presented for the reaction K?p → Λπ+π? at 11 energies between 1775 and 1957 MeV in the centre-of-mass. New values for the masses and widths of the Σ±(1385) are given. The differential cross sections and the complete spin density matrices for the reactions K?p → π±Σ? (1385) were extracted from these data using also the information from the Λ decay. An energy-dependent partial-wave analysis has been carried out over the c.m. range 1775–2170 MeV also using data from an earlier experiment. Comparisons between the observed resonant amplitudes and SU(3) and SU(6)W ? O(3) predictions have been made.  相似文献   

17.
The cross section for the reaction π?n→π?π?p has been measured in a deuterium bubble chamber. The cross section at Eπ,lab = 226, 250 and 312 MeV was found to be equal to 9.4 ± 2.3, 25.0 ± 5.3 and 57 ± 10 μb, respectively.  相似文献   

18.
The 16O(d, α)14N, 14N(d, α)12C and 12C(d, α)10B reactions at Ed = 40MeV and the 12C(α d)114N at Eα = 55 MeV were investigated. A total of seventeen transitions are analysed in terms of one-step, zero-range DWBA calculations, using the two-particle coefficients of fractional parentage obtained from the Cohen-Kurath Op shell wave functions. For most transitions, fair agreement is obtained between experiment and calculation, possible exceptions being the transition to the Ex = 4.43 MeV, Jπ = 2+ state in 12C and to the Ex = 2.15 MeV, Jπ = 1+ state in 10B, for which the calculations predict too much L = 0 strength. Where possible, a comparison with previous (p, 3He) results is made. In 14N a state at Ex = 11.04 MeV was observed for which the values (Jπ; T) = (3+; 0) are suggested. In 12C we found, in addition to the well known T = 0 states, two relatively sharp T = 0 states at Ex = 19.50 ± 0.10 and 20.55 ± 0.10 MeV. The shape and strength of the angular distribution for the transitions to these states can be approximately accounted for by the calculations, although no one-to-one correspondence between observed and predicted levels could be established.  相似文献   

19.
Energy distributions of neutrons from the (d, n) reactions on 12–14C leading to unbound states of 13–15N have been measured at 6.3 or 6.5 MeV deuteron energy. Angular distributions have been extracted for 13, 14C(d, n) transitions and analysed with DWBA using the extra-polation technique to give l-values and transition strengths for ten unbound states in 14N and six in 15N. For the 15N level at 10.541 MeV it is concluded that Jπ is 32?. A new 15N level is observed at 11.44 MeV. The 0° (d, n) cross sections have been set in proportion to (p, p0) resonance cross sections, and a pronounced l-dependence of the ratio is obtained.  相似文献   

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