Elastic and inelastic scattering of 185 MeV protons from 12C

The polarization of 185 MeV protons in elastic scattering and in the excitation of the 2⁺ state at 4.44 MeV and the 0⁺ state at 7.65 MeV in ¹²C has been measured in the angular region 2°–60°. Optical model calculations are performed for the elastic scattering. Angular distributions for the inelastic scattering from the 2⁺ state at 4.44 MeV and the 3^? state at 9.64 MeV are calculated in the distorted-wave impulse approximation (DWIA) as well as in the distorted-wave Born approximation (DWBA).     

Elastic and the 2+ inelastic scattering of high energy protons on12C and the alpha-particle model

The alpha-particle model has been applied to calculate the elastic and the 2⁺ inelastic angular distribution of 1 GeV protons on¹²C within the framework of Glauber multiple scattering theory. The results are compared with the recent experimental data and with some previous calculations. The model gives a fairly good account of the inelastic data and its predictions for the elastic scattering are essentially the same as those of the shell model.     

Elastic and inelastic scattering of 12C ions at intermediate energies

Elastic and inelastic scattering of ¹²C ions on ¹²C and ²⁰⁸Pb targets have been measured at the incident energies per nucleon E / A = 120 MeV/u and E / A = 200 MeV/u. Optical-model analysis is reported and nuclear surface transparency effects are discussed, together with the nuclear potential-energy dependence. The transparency region extends down to a radial internuclear distance of about 3 fm for the ¹²C-¹²C system and 8 fm for the ¹²C-²⁰⁸Pb system. A decrease of the imaginary potential with increasing incident energy is deduced for the two systems. Anomalous collapse of the real potential in the surface region is observed for ¹²C-²⁰⁸Pb system at 200 MeV/u. DWBA analysis of data on the 2⁺, 4.4 MeV state of ¹²C is reported and trends for the energy dependance of mean-field excitations are deduced.     

Elastic scattering of polarized deuterons by protons at intermediate energies

The tensor analyzing power T₂₀(θ) in dp backward scattering has been measured at or near center-of-mass angle θ = 180° in the energy range 0.3–2.3 GeV. A pronounced structure is observed around T_d = 0.5 GeV which is explained by a predominant one-neutron-exchange mechanism. Other structures appear around 1 GeV and higher. They are not explained by calculations which include Δ-excitations in intermediate states. In addition, full angular distributions of vector A_y and tensor A_yy analyzing powers and differential cross sections have been obtained at 1.2 GeV and limited angular ranges explored at 0.5 GeV (back angles) and 1.6 GeV (forward angles).     

Interactions between 4He nuclei and protons at intermediate energies

Since the early 1970s, experiments have been performed to investigate the fragmentation of the lightest nuclei (d, ³H, ³He, and ⁴He) on protons at intermediate energies (～0.2–2 GeV per nucleon). These experiments were set up in ITEP and LHE JINR and realized in an exclusive approach with the help of liquid hydrogen bubble chambers. This investigation is of great interest from two points of view: first, the possibility of detailed theoretical analysis of the data obtained in 4π geometry on the basis of a good understanding of the structure of the wavefunctions of these nuclei and, second, the search for exotic interaction mechanisms. This overview presents the latest, most interesting results of the ITEP experiment on the study of ⁴Hep interactions at ⁴He momenta of 2.7 and 5 GeV/c, on cross sections, elastic scattering, pair correlations of secondary nucleons, cumulative production of nucleons and the lightest nuclei (d, ³H, and ³He), the main features of exclusive reactions, and the search for possible multiquark bag production (dibaryons and tribaryons). The essential results of the independent JINR experiment at 8.6 and 13.6 GeV/c also come under discussion.     

Energy dependence of heavy ion collisions 4He + 12C and 12C + 12C elastic scattering

We have studied the transparency of heavy ion collisions at high energies by using Glauber's multiple scattering theory. The good agreement between our calculation and the existing data available strongly emphasizes the dominance of the nucleon-nucleon interaction in nucleus-nucleus collisions at high energies.     

Elastic and inelastic scattering of 12C by 12C in the energy range between 10 and 37.6 MeV

The elastic and inelastic scattering of ¹²C by ¹²C has been measured over a wide angular range employing a kinematical analysis with the help of position-sensitive detectors. The bombarding energy was varied in 200 keV steps between 10 and 37.6 MeV. The cross sections are analysed in the framework of compound fluctuations and the direct reaction model.     

The elastic and inelastic scattering of intermediate energy protons on deuterium at small momentum transfer

The differential cross sections for the elastic and inelastic scattering of protons on deuterium have been measured for scattering angles less than 14° at 198.5, 297.6 and 456.6 MeV. These quantities were determined relative to dσ / dΩ for pp elastic scattering with a precision of typically 2%. The range of excitation energies for the (p, p') reaction was chosen to emphasize the region near the np threshold dominated by the final-state interaction in the ¹S₀ channel. Particular attention was given to the dependence on excitation energy of the spectra at 198.5 MeV to examine the sensitivity to the ¹S₀ scattering length, a_np In this paper all data are compared with a new, detailed formulation of a simple model of the reaction mechanism based on the impulse approximation. The experimental results differ from the predictions by typically 10% and the differential cross sections exhibit a sensitivity to the intermediate-energy nucleon-nucleon amplitudes. If the impulse approximation is used to estimate a_np from the data at 198.5 MeV a value of − 24.7 ± 0.4 fm is obtained.     

Elastic scattering of high-energy protons from nuclei

The elastic scattering of high-energy protons from zero-spin nuclei is considered within the framework of Glauber theory. The sensitivity of the cross sections to the nuclear structure and to the proton-nucleon amplitude is studied. Results of calculations demonstrating the investigated effects are presented for the case of 1 GeV proton scattering from ⁴He, ¹⁶O and ⁵⁸Ni.     

Elastic scattering at small angles of protons

Differential cross sections and asymmetries are obtained from elastic scattering, between 0° and 7°, of 36.2 MeV polarized protons by C, Al, Fe and Ni natural targets.     

Elastic proton scattering from 4He at 0.58 and 0.72 GeV

The energy spectra of α-particles recoiling from a ⁴He gas target bombarded by 0.58 and 0.72 GeV protons have been measured to obtain the differential cross sections for elastic scattering $\text{d}{}_{\mathrm{\sigma }}\text{d}{}_{\mathrm{t}}$, in the region of four-momentum transfer squared, ?t=0.13 ? 0.55 (GeV/c)². The experiment was designed especially to observe the region between the first and second diffraction maxima.     

Elastic scattering of 1-GeV protons by nuclei

The calculated elastic scattering of 1.04-GeV protons by ²⁰⁸Pb, ⁵⁸Ni, and ⁴⁰Ca is compared with experiment. The effects of the spin-orbit potential, Pauli and short-range correlations, variations in the ratio of the real to the imaginary part of the nucleon-nucleon scattering amplitude at 0° are found to have similar effects. Further experiments are required before these effects can be disentangled. Changes of the neutron density compared to the proton density can be distinguished. The proton polarization by elastic scattering by ²⁰⁸Pb and ⁴⁰Ca is calculated omitting the effects of correlations.     

Elastic scattering of6Li on12C at 20 MeV

The elastic scattering of lithium nuclei from carbon was measured atE _lab=20 MeV. The obtained angular distribution was fitted by an optical model calculation. Parameter sets and the corresponding transmission coefficients are given.     

Elastic scattering of intermediate-energy weakly bound particles on 12C nuclei

The differential cross-section for elastic scattering of deuterons at 700 MeV, ⁶Li and ⁶He at 2.07 GeV nuclei on ¹²C nucleus is calculated under the assumption of two-cluster (for deuterons and ⁶Li) and three-cluster (for ⁶He) structure of incident particle. For ⁶Li-¹²C and ⁶He-¹²C elastic scattering it is shown that there are quantitative distinctions in the behaviour of the observables calculated in the above approaches. Received: 13 October 1999 / Accepted: 3 January 2001     

Charged particle production on 12C by intermediate energy neutrons

Energy spectra of protons, deuterons and tritons produced on ¹²C by 545 MeV neutrons have been measured at 7 angles between 73° and 165°. The slopes of the invariant cross sections and absolute yields are compared to corresponding proton induced reactions at similar energies and angles.     

Monopole excitation of 4He in α-particle scattering from 12C, 13C,and 16O

The excitation of the O⁺ state in ⁴He at 20.1 MeV has been studied in α-scattering from ¹²C, ¹³C, and ¹⁶O at E_α=65MeV by measuring the decay $\text{α}{}^1\text{→}\text{p}\text{+}\text{t}$ with a coincidence method. DWBA calculations of this monopole transition using both microscopic and collective model transition densities are presented.