Angular Distributions Of Protons Research Articles

Nuclear States ofZr98

By means of the reaction $^{96}\mathrm{Zr}(t,p)$, we have achieved the first reported production of excited states of $^{98}\mathrm{Zr}$. Comparison of the experimental proton angular distributions with the predictions of a distorted-wave calculation has yielded spin and parity assignments for many of the states. Possible identification of neutron configurations with some of the states is discussed.

The Angular Distribution of Protons from the 12C(g, p0)11B Reaction in the Giant Resonance Region

Proton spectra from the 12C(y, po)l1B reaction have been obtained at angles of 30�, 50�, 70�, 90�, 110�, 130�, and 150� using semiconductor detector telescopes. From these spectra the angular distribution of the 12C(y, po)l1B reaction has been determined every 250 ke V throughout the excitation energy region between 20 and 27 MeV. The observed energy dependence of the angular distribution is compared with that expected from the collective correlations model description of 12C.

Die energieabhängigkeit der 2H(d, p) 3H reaktion bei niedrigen energien

The proton angular distribution of the 2H(d, p) 3H reaction was measured with polarized and unpolarized deuterons. The results are compared with an improved theory of Rook and Goldfarb. At the energies 80≦ E≦150 keV, the polarization efficiencies and the anisotropy factor are measured. They show a resonance-like behaviour at E≈105 keV.

Pi-Pair Photoproduction Below 850 MeV

Preliminary results of an experiment on double-pion photoproduction with spark chamber and counter techniques below 1 GeV are reported. Proton angular and ($p,{\ensuremath{\pi}}^{+}$) invariant-mass distributions at fixed ${\ensuremath{\pi}}^{\ensuremath{-}}$ momentum are given. Comparison with the expected values computed by the isobaric model are shown.

Distribution angulaire du groupe de protons p 1 et corrélations angulaires p 1− γ dans la réaction 11B(d, p) 12B

Angular distribution of protons p 1 feeding the first excited state of 12B and p 1− γ angular correlations have been measured in the 11B(d, p) 12B reaction at a bombarding energy of 700 keV. These results can be made to agree with a simple Butler theory, but a comparison with the previously measured angular distribution of the 955 keV γ-rays shows that the plane wave description is inadequate.

Protons from Zn64 and Zn66 Bombarded with 14.1 MeV Neutrons

Energy spectra and angular distributions were measured for protons emitted from Zn 64 and Zn 66 bombarded with 141.1 MeV neutrons. Any of level density formulae fits equally well the energy spectrum for backward angles. The constant temperature formula gives 1.22±0.07 MeV and 1.35±0.05 MeV as the nuclear temperatures of Cu 64 and Cu 66 respectively. Using the Lang level density formula, the level density parameters for Cu 64 and Cu 66 are given as 8.26±0.78 MeV -1 and 5.39±0.56 MeV -1 respectively. The proton angular distributions are concave and symmetric around 90°. Anisotropy is greater for higher energy protons. The anisotropy of lower-energy protons emitted through the ( n , p ) reaction is found to be comparable to the anisotropy of those emitted through the ( n , n p ) reaction. The cross sections for the ( n , p ) and ( n , n p ) reactions for Zn 64 through compound process are 127±9 mb and 169±26 mb and those for Zn 66 30.0±1.1 mb and 40.5±8.3 mb respectively. The direct ( n , p ) reaction for Zn...

A study of 52Cr, 54Cr and 56Cr by the (t, p) reaction

The (t, p) reactions leading to 52,54,56Cr have been investigated at a bombarding energy of 12 MeV, using the Aldermaston multi-angle magnetic spectrograph. Levels in the final nuclei were measured for excitation energies below 5–6 MeV. A number of 0 +, 2 +, 3 − and 4 + states were identified from the shapes of the proton angular distributions. The results are compared with previous assignments where possible, and good agreement is obtained. The strongest L = 0 transitions in each of the reactions 50,52,54Cr(t, p) are those to the 2.663 MeV excited state of 52Cr and to the ground states of 54Cr and 56Cr. This is an agreement with the previously observed trend in (t, p) reactions. The level structure of 52Cr and 54Cr is compared with theoretical calculations.

The j-dependence of the vector analyzing power in the 6Li (d, p) 7Li reaction

For the 6Li(d,p) 7Li reaction, where no j-dependence had been seen in the proton angular distribution, one can see a j-dependence in the angular distribution of the vector analyzing power. Compound nucleus effects are discussed.

Final state interactions in (e, e'p) experiments

The angular distribution of protons in (e, e'p) experiments is shown to be quite strongly dependent on the interaction between the ejected proton and the residual nucleus. A simple method of accounting for this interaction is suggested.

T = 2 states in 16N

T = 2 levels have been observed in 16N at excitations of 9.928 and 11.701 MeV in the 14C( 3He, p) 16N reaction. Analysis of the proton angular distributions indicates 0 + for the 9.928 MeV level and 1 − or 2 + for the 11.701 MeV level.

A study of the nuclear structure of 28Si by the 28Si(p, p′) 28Si reaction

Angular distributions to the ground and first five excited states of 28Si have been measured for the 28Si(p, p′) 28Si reaction at a bombarding energy of 21.2 MeV. An analysis has been carried out describing the inelastic proton angular distributions in terms of the collective model. An attempt has also been made to describe the data in terms of simple particle-hole shell-model configurations. Shell model form factors are used in distorted wave calculations, the requirement being that a particular configuration satisfies both 27Al( 3He, d) 28Si and 28Si(p, p′) 28Si data.

A study of the nuclear structure of 60Ni by the [formula omitted] reactions

Angular distributions to the ground and 16 excited states of 60Ni have been measured for the 59Co( 3He, d) 60Ni reaction at a bombarding energy of 37.7 MeV. The 59Co( 3He, 3He) 59Co angular distribution was also obtained at the same energy. Discrete sets of optical potentials are found which give good fits to the elastic scattering data. It is found that DWBA calculations give better fits to the 59Co( 3He, d) 60Ni data with a depth of the real part of the optical potential of U ≈ 170 MeV and r u ≈ 1.15 fm, than with shallower potentials. It is also found that changes in optical model parameters obtained by fitting the elastic scattering data out to 90° or 150° have very little effect on DWBA fits to the 56Co( 3He, d) 60Ni angular distributions. The angular distribution to the ground state of 60Ni is characteristic of a proton transfer of l p = 3 expected from the closing of the 1 f 7 2 proton shell. The next higher excited states show angular distributions with more than one l p value contributing, indicating that the (1 f 7 2 ) −1 ( 2 p 3 2 , 2 p 1 2 or 1 f 5 2 ) proton particle-hole configurations are mixed. An analysis of 60Ni(p, p′) 60Ni data taken at 17.9 MeV at Berkeley by Jarvis et al. has been carried out in an attempt to describe some of the inelastic proton angular distributions in terms of simple shell-model configurations. Shell-model form factors are used in distorted wave calculations, the requirement being that a particular particle-hole configuration satisfies both ( 3 He, d) and ( p, p′) data. It is noted that these configurations are still not without ambiguity.

ROCKET MEASUREMENTS IN PROTON AURORA

Proton and electron intensities, energy spectra, and angular distributions derived from a recent rocket flight launched into a 40-rayleigh Hβ aurora are reported. High-intensity proton precipitation (~0.45 erg cm−2 s−1 for protons with energies above 30 keV) was detected throughout the flight above 100 km, whereas the electron intensity was above the limit of detectability for only a short time. The proton and electron spectra and angular distributions in the 20–60 keV energy range were found to be remarkably similar, with angular distributions being isotropic over the pitch-angle range 0–90°, and with e-folding energies of about 12 keV and 18 keV for protons and electrons respectively. The results are interpreted in terms of current magnetospheric models, and are shown to place certain restrictions on the source mechanisms.

Structure ofPb208Determined by the (d, p) Reaction

The structure of the doubly magic nucleus ${\mathrm{Pb}}^{208}$ has been investigated using the reaction ${\mathrm{Pb}}^{207}(d, p){\mathrm{Pb}}^{208}$ with a deuteron bombarding energy of 21.6 MeV. Proton angular distributions in the interval 10\ifmmode^\circ\else\textdegree\fi{} to 80\ifmmode^\circ\else\textdegree\fi{} have been measured for more than twenty levels up to 6 MeV excitation in ${\mathrm{Pb}}^{208}$. The experimental results have been analyzed to extract the factors $(2J+1){S}_{\mathrm{lj}}$, an important link between experiment and theory. An interesting feature of the data analysis is the use of ${\mathrm{Pb}}^{208}(d, p){\mathrm{Pb}}^{209}$ angular distributions to obtain the necessary reduced cross sections rather than obtaining them from a distorted-wave Born analysis calculation as is usually the case.

Study of theCr52(d,p)Cr53Reaction in the Coulomb Stripping Energy Region

The ${\mathrm{Cr}}^{52}(d,p){\mathrm{Cr}}^{53}$ stripping reaction has been studied at incident deuteron energies below the Coulomb barrier. The differential cross sections of proton groups corresponding to the ground and excited states of ${\mathrm{Cr}}^{53}$ up to approximately 4.7-MeV excitation have been measured at ${E}_{d}=3.01$ MeV between 7.5 and 172.5 deg, and excitation functions for selected proton groups were measured between ${E}_{d}=2.5 \mathrm{and} 3.25$ MeV. As the proton energy goes below the Coulomb barrier, the proton angular distributions shift from forward to backward peaked distributions charactristic of Coulomb stripping. Distorted-wave Born-approximation analysis of the data indicates that in the Coulomb stripping region the absolute cross sections and angular distributions are very insensitive to the exact form of the optical-model potential parameters used to calculate the deuteron- and proton-scattering wave functions, as well as to the use of radial cutoffs in the numerical integration procedures. Reduced width factors have been calculated.

Angular distribution of protons from the (d, p) reaction in56Fe

Angular distribution of protons from the (d, p) reaction in56Fe

Nuclear Structure Studies ofSr88andY89Using 19-MeV Proton Scattering and theSr88(He3, d)Reaction

Elastic and inelastic angular distributions were obtained for 19-MeV protons scattered from ${\mathrm{Sr}}^{88}$ and ${\mathrm{Y}}^{89}$. Deuteron angular distributions were also obtained from the ${\mathrm{Sr}}^{88}({\mathrm{He}}^{3}, d)$ reaction and used to study the single-particle nature of the excited states of ${\mathrm{Y}}^{89}$. Spectroscopic information was obtained by comparing the inelastic proton distributions with predictions of the distorted-wave theory using a real collective-model form factor. Proton angular distributions of the low-lying states of ${\mathrm{Y}}^{89}$ and ${\mathrm{Sr}}^{88}$ were compared to determine if the states of ${\mathrm{Y}}^{89}$ could be explained as the weak coupling of the $2{p}_{\frac{1}{2}}$ proton to the core-excited states of ${\mathrm{Sr}}^{88}$. The states at 1.49 and 1.74 MeV in ${\mathrm{Y}}^{89}$ do not appear to be described adequately as core-excited states, while the states at 2.22 (or 2.87) and 2.52 MeV do. The proton angular distributions for those states which could be described in terms of simple shell-model configurations were also analyzed with the distorted-wave theory using shell-model form factors.

Improved Monte-Carlo calculation of the nucleon-meson cascade in shielding material: II. Comparison of the results for incident proton beams with momenta of 10 and 20 GeV/ c with experimental data

The Monte-Carlo method for the calculation of the nucleon meson cascade, which was described in a first paper (p. 133 of this volume), is applied to incident proton beams with momenta of 10 and 20 GeV/ c. The shielding material is steel. The calculated three dimensional star and track densities are discussed and compared with corresponding experimental results. The calculated and measured star and track densities agree very well. We present further the calculated momentum spectra and angular distributions of protons, neutrons and pions as function of the depth inside the shielding material. The results of cascade calculations for incident proton beams with momenta between 30 and 300 GeV/ c are described by some parameters like build-up factor and attenuation length.

A 50V(d, p) experiment

The reaction 50V(d, p) 51V has been investigated at 7.50 MeV bombarding energy, using the MIT multi-angle spectrograph. A total of 71 transitions were recorded below 6.65 MeV of excitation in 51V. l n-values and spectroscopic strengths were determined from the measured proton angular distributions by means of a distorted wave analysis. The spectroscopic strengths are analysed in terms of the multipole sum roles for orders λ = 0, 1 and 2. It is concluded that the 50V(g.s) wave function does not have good seniority. The possibility of observing “intermediate structure” in the (d, p) strength function is discussed.

Improved Monte-Carlo calculation of the nucleon-meson cascade in shielding material

Abstract The nucleon-meson cascade in shielding material is calculated by a Monte-Carlo method. The principle of the method and the physical data used in the calculation are described. For primary proton beams in the GeV region we calculate the three dimensional densities of proton, neutron and pion stars inside the shielding materials as well as the total star density (sum of proton, pion and neutron star densities) and the total track density (sum of proton, pion and muon track densities). We calculate further the momentum spectra and the angular distributions of protons, pions and neutrons as function of the depth inside the shielding material. The results, which will be described in a second paper (p. 261 of this volume), are in good agreement with the available experimental data.