Angular Distributions Of Protons Research Articles

The 51V(t, p) 53V reaction

Proton angular distributions and energy levels of 53V have been measured at E t = 12.09 MeV. The spin and parity of the ground state of 53V was deduced to be 7 − and its mass excess measured to be −51.863 ± 0.025 MeV.

Angular Distributions and Total Cross Sections of Charged Particles fromLi6+Li6as a Function of Energy

The ${\mathrm{Li}}^{6}$+${\mathrm{Li}}^{6}$ reaction has been studied at 13 incident energies between 2.4 and 9.0 MeV, using a $\frac{\mathrm{dE}}{\mathrm{dx}}\ensuremath{-}E$ particle identification system and an on-line computer. Total cross sections and angular distributions were obtained for protons from the first 12 levels of ${\mathrm{B}}^{11}$, deuterons from the first 5 $T=0$ levels in ${\mathrm{B}}^{10}$, and tritons from the ${\mathrm{B}}^{9}$ ground state. Noticeable variations in the proton angular distributions as a function of bombarding energy and indications of a ($2J+1$) dependence of the proton cross sections as the bombarding energy was increased are indicative of compound nucleus effects. On the other hand, in the deuteron results, the dominant reaction mechanism is the transfer of an alpha particle. This process is favored for the residual states which are formed by ${l}_{\ensuremath{\alpha}}=0$ transfer. There is no evidence for strong structure in the yield curves for the deuteron groups from one energy to the next. Simple considerations of the transfer as a tunneling process, possibly modified by the presence of a long-range effective interaction, adequately describe the deuteron cross sections. Measurements were made on the ground-state deuteron group at a bombarding energy corresponding to measurements on the inverse reaction, ${\mathrm{B}}^{10}(d, {\mathrm{Li}}^{6}){\mathrm{Li}}^{6}$, and the angular distribution and total cross section are in good agreement. The differential cross-section ratio of the 16.62- to 16.92-MeV levels in the ${\mathrm{Li}}^{6}({\mathrm{Li}}^{6}, \ensuremath{\alpha}){\mathrm{Be}}^{8}$ reaction was also measured and found to be 1.20\ifmmode\pm\else\textpm\fi{}0.10 and constant as a function of ${\mathrm{Li}}^{6}$ energy.

Solar proton activation of the lunar surface

The nuclear activation on the surface of the moon due to solar protons has been estimated. Proton and neutron fluxes and the production rate of radionuclides have been calculated as a function of depth, and comparisons have been made between several models of the lunar crust. The purpose of the calculations has been to evaluate the effectiveness of lunar material as a radiation shield and also to predict the particle flux reflected from the surface. The build-up of Mn54, Na22, C14, and Be7 are given in compositions representing both the volcanic and meteoritic-impact hypotheses for the lunar surface. The effect of the angular distribution of the protons on the radionuclide production rate and particle fluxes has also been investigated. Examples involving a monoenergetic beam of 400-Mev protons as well as a solar proton spectrum are included, permitting direct comparisons with experimental irradiations of similar targets. The results show that the activation is strongly dependent on the spectrum and angular distribution of incident protons but relatively insensitive to the composition.

The (t, p) reaction with the even isotopes of Sm

The (t, p) reactions on the even isotopes of Sm have been investigated at a bombarding energy of 12 MeV with the purpose of exploring the transition from spherical to deformed nuclei. The reaction protons were detected in the Aldermaston multi-angle spectrograph, the overall energy resolution being about 20 keV FWHM. Levels in 146, 150, 152, 154, 156Sm were established below 2–3 MeV excitation energy. A number of 0 + and 2 + states were identified from the proton angular distribution data. The 0 + energies (±10 keV) and maximum differential cross sections in mb/sr (±25%) were: 146Sm g.s. (0.29), 2.611 MeV (0.09); 150Sm g.s. (0.57), 0.745 MeV (0.14); 152Sm g.s. (0.19), 0.685 MeV (0.14), 1.091 MeV (0.13); 154Sm g.s. (0.30), 1.117 MeV (0.03), 1.218 MeV (0.10); 156Sm g.s. (0.30), 1.068 MeV (0.02).

Angular distributions and total cross sections of the 27Al( 3He,p) 29Si reaction from 5.4 to 6.1 MeV

The angular distributions of protons from the 27Al( 3He,p) 29Si reactions corresponding to the first seven levels of 29Si are given for five bombarding energies between 5.4 and 6.1 MeV. The angle-integrated cross sections show a 2 J+1 dependence. The 2 J+1 dependence is found to be more reliable for the angular range between 82° and 142° than between 10° and 142°. The angle-integrated cross-section yield curves show pronounced structure. The apparent characteristic width is on the order of several hundreds of keV.

Neutron-induced reactions on silicon: Proton and α-particle energy and angular distributions

Energy and angular distributions of protons and alpha particles emitted in the reactions 28Si(n, p) 28Al and 28Si(n, α) 25Mg were measured at neutron energies of 13.95 and 14.6 MeV by irradiating two Si detectors facing each other and accepting only pulses from charged particles leaving one detector and hitting the other. Particle identification and discrimination between forward and backward angles were achieved by a time-of-flight method.

12C(d, pγ) 13C angular distributions and correlations near threshold

Proton-gamma angular correlations from the 12C(d, pγ) 13C on through the 3.68 and 3.85 MeV states of 13C have been measured at bombarding energies from 2 to 3 MeV and at a strong E d = 2.50 MeV resonance. Yield curves and proton angular distributions for these groups and for protons leaving 13C in the 3.09 MeV state have also been measured. These reactions satisfy the condition E d ≃ −2 Q for which distortions of plane wave stripping theory might be expected to be small. The correlation anisotropies are maximum and the symmetry axis shifts and azimuthal anisotropies are almost zero both at the minimum bombarding energy and at the 2.50 MeV resonance. Highly distorted correlations and distributions are seen at only 2.62 MeV. The 12C(d, p) 13C 3.85 angular correlation at E d = 2.50 MeV involves single-particle resonances both in 14N and in 13C and is an interesting example of a resonant direct reaction. The reduced widths derived from plane wave stripping theory are too low by factors of 3 to 10 and are energy dependent. Thus, while distortions clearly affect reduced widths, the detailed angular properties of the reactions are very closed to the predictions of plane wave theory.

Measurement of the Spins of Some States inFe55

The $p\ensuremath{-}\ensuremath{\gamma}$ angular correlations in the reaction ${\mathrm{Fe}}^{54}(d, p\ensuremath{\gamma}){\mathrm{Fe}}^{55*}$ have been measured for several proton groups. The groups chosen correspond to states for which the proton angular distribution shows formation by $l=1$ neutron capture. These states must therefore have spins ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$ or ${\frac{3}{2}}^{\ensuremath{-}}$. A state with spin ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$ must exhibit an isotropic angular correlation while a state of spin ${\frac{3}{2}}^{\ensuremath{-}}$ will ordinarily show some anisotropy. The results indicate spin ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$ for the first excited state of ${\mathrm{Fe}}^{55}$ at 413 keV, and spin ${\frac{3}{2}}^{\ensuremath{-}}$ for states at 2.490-, 3.556-, and 3.800-MeV excitation. The conclusions are compared with previous results and with theoretical predictions.

Study of the Ne(n, p)F reaction

The Ne(n, p)F reaction is studied at (14.1 ± 0.1) MeV neutron energy using natural neon gas as target and nuclear emulsion as detector. Hydrogen gas is used as standard and the cross-section for the Ne(n, p)F reaction is determined by comparison as (142 ± 28) mb. The angular distributions of protons from hydrogen as well as neon gas targets are given. The angular distribution in the case of hydrogen agrees with known results; in the case of neon, the angular distribution is symmetric around 90° c.m. The neon angular distribution fits well with a 2nd-order Legendre polynomial, 1 +a2P2(cos ϑ) witha2=1.35 ± 0.2. Assuming the energy distribution to be Maxwellian, the temperature of the residual nucleus is determined asT=(1.48 ± 0.20) MeV and the level density parametera=(3.96 ± 0.50) MeV−1 from the observed proton energy distribution in the case of neon; from these, it is concluded that the Ne(n, p)F reaction is essentially a compound-nucleus reaction at this energy. Usinga2=1.35 ± 0.2, the spin cut-off parameterσ=1.10 and moment od inertia ℐ=0.3ℐrigid are obtained.

Stripping Analysis of theTi46(d,p)Ti47Reactions

The ($d,p$) reactions from a target of isotopically separated ${\mathrm{Ti}}^{46}$ have been studied with the MIT multiplegap magnetic spectrograph and the MIT-ONR Van de Graaff accelerator using a 7.0-MeV deuteron beam. Forty-seven excited states in ${\mathrm{Ti}}^{47}$ were observed up to an excitation energy of 4.0 MeV, of which seventeen showed angular-distribution characteristics of a stripping process. Sixty additional energy levels were observed between 4.0 and 6.0 MeV, and angular distributions were obtained for eleven of the most intense of these levels. The ground-state $Q$ value was measured to be 6.665\ifmmode\pm\else\textpm\fi{}0.010 MeV, and the proton angular distribution for this state did not show a characteristic stripping curve. Transition strengths and values of the orbital angular momenta of the transferred neutrons were derived from the experimental measurements and from calculations using a zero-range distorted-wave Born-approximation analysis.

Angular distribution of the photoprotons from carbon

The 34.2 MeV proton angular distribution resulting from the photodisintegration of carbon is measured employing the 55 MeV electron beam of the Orsay linear accelerator. The results are compared with the theoretical values based on the quasi-deuteron, the quasi-alpha particle and the independent particle models.

Rocket measurements of energetic particles: 1. Description of the experiment

Two rockets have been fired along the magnetic field line L = 5.6 to altitudes above 400 km to measure the fluxes, energy spectrums, and angular distributions of protons and electrons with energies above 150 kev. The objectives of the experiment are stated and the payload operation is described in this paper. In following papers, the electron and proton results are presented and interpreted.

Investigation of the (d, p) reaction on 31P in the deuteron energy range 1.3–2.5 MeV

Excitation functions of several proton groups (p 0, p 1, p 2, p 3, p 4, p 6, p 7, p 8, p 9, 10) resulting from the reaction 31P(d, p) 32P were measured at angles of 30° and 150°. The total and differential cross-sections are given. The excitation functions for all groups indicate a number of resonances which exhibit fluctuations in the range of 25 to 100 keV. Many of the observed resonances are uncorrelated at 30° and 150°. There is also no correlation between groups leading to different states of a residual nucleus. Proton angular distributions were measured for six energies of incident deuterons. Some of the angular distributions typical for the direct interaction are compared with those from the stripping formula with regard to nuclear deformation. The value of the deformation calculated from the angular distributions gives a nuclear magnetic moment close to the experimental value.

Measurements of d, pγ directional correlations in 20F

The reaction 19F(d, pγ) 20F was used to measure the directional correlations of the proton groups in coincidence with subsequent gamma radiations produced in de-excitation of the 2.05, 1.31, 1.06, 0.99 and 0.65 MeV levels of 20F. The effective deutron energy was 0.448 Mev. For the 2.05 MeV level, the 1–2 correlation between the protons and the 1.40 MeV gamma transition to the first excited state was measured simultaneously with the 1–3 correlation between the same proton energy group and the 0.65 MeV gamma transition, with the intermediate 1.40 MeV gamma radiation unobserved. These correlations were measured in two configurations: one with the protons being detected at an average angle of 170° with the beam passing through a centre hole in an annular-shaped detector, and the other with a disc-shaped detector at 135° and the gamma detector moving in the plane of the reaction. A plane-wave analysis of these data gave essentially identical correlation coefficients for these two configurations. Directional correlations were also measured in the 170° configuration between the proton energy groups and the subsequent ground-state gamma transitions from the 1.31, 1.06, 0.99 and 0.65 and 0.65 MeV levels. A plane-wave analysis of these data is compared with a distorted-wave analysis of related data from a previous experiment. A thorough computational comparison between all of these data and the predicted correlations, based on a plane-wave analysis using postulated spin values which are consistent with the proton angular distribution data, did not yield a unique spin value for any of these levels. It was possible in some cases, however, to put rather stringent conditions on the ratios of the angular-momentum matrix elements associated with the incoming and outgoing radiations which are compatible with the postulated spins.

The reaction Ni 58(n, p)Co 58 at different neutron energies

The energy and angular distributions of the protons from the reaction Ni 58(n, p)Co 58 at incident neutron energies E n = 8.4, 14.1 and 22.0 MeV have been studied The measurements at E n = 8.4 MeV yield an isotropic angular distribution, while especially at E n = 22 MeV the angular distribution of the high-energy protons is strongly peaked forward. Parts of the energy spectra have been used to evaluate level density parameters for the residual nucleus Co 58. At E n = 22 MeV deuteron spectra have also been recorded.

Study of the (t, p) reaction on O 16, O 17 and O 18 using 5.55 MeV tritons

The (t, p) reaction on O 16, O 17 and O 18 was studied at a triton bombarding energy of 5.55 MeV, with special attention to the reaction O 17(t, p)O 19. The position of several energy levels in O 19 was established. Good agreement was obtained in some cases between the measured proton angular distributions and the predictions of the plane wave double stripping theory. In other cases the contribution of other reaction modes seems to be appreciable. The spin and parity of the ground and 3.153 MeV levels in O 19 obtained by the O 17(t, p) reaction were determined unambiguously to be 5 2 + arising from the d 3 5 2 and d 5 2 s 2 1 2 configurations respectively. The 0.093 and 2.775 MeV levels could be identified with the 3 2 + and 9 2 + levels respectively of the d 3 5 2 configuration. The results for the O 16(t, p)O 18 reaction agreed with those of Jaffe et al. who used tritons of 5.50 MeV. In the O 18(t, p)O 20 reaction the spin and parity assignements for the ground and first three excited levels of O 20 were in essential agreement with those of Middleton et al. who bombarded with tritons of 10 MeV.

An isospin [formula omitted] level of Be 9

A state of Be 9 has been found at an excitation energy of 14.392±0.005 MeV, with a width less than 5 keV. The state is formed in the reaction Li 7(He 3, p)Be 9 and corresponds closely in energy to the expected analogue of the ground state of Li 9. These facts, together with the small width, suggest an assignment of T = 3 2 . The angular distribution of protons corresponding to the 14.39 MeV state is nearly symmetric about 90° in the centre-of-mass with maxima at 40° and 150°. The 90° differential cross sections are approximately the same for 6.5 and 10 MeV He 3, with a minimum value between these energies. The total cross sections are 10 −2 +5 mb for 10 MeV He 3 and 7.5 −2 +4 mb for 7.5 MeV.

The proton yield due to the disintegration of 26 and 23 MeV deuterons in the coulomb field of nuclei

This article describes a measurement of the proton production resulting from bombardment of Au and Cu nuclei with 26 and 23 MeV deuterons. A comparison of proton angular distributions with the results of a simple calculation based on the electric disintegration of the incident deuterons is given. This analysis supports the hypothesis that electric break-up of the deuteron outside the nucleus is mainly responsible for the observed proton continua.

Die winkelverteilungen der protonen aus den reaktionen Be 9(d, p)Be 10, C 12(d, p)C 13, O 16(d, p)O 17 und Ca 40(d, p)Ca 41 bei 11.8 MeV

To determine the absolute total cross sections of (d, p) reactions, the angular distributions of protons from 10° to 165° have been measured for the following reactions: Be 9(d, p)Be 10, C 12(d, p)C 13, O 16(d, p)O 17 and Ca 40(d, p)Ca 41. The deuteron energy was 11.8 MeV. The angular momenta of the captured neutrons were estimated by comparison of the experimental angular distributions with those calculated in the plane wave Born approximation. It is found that the neutron captured into the 7.37 MeV level of Be 10 contributes l = 2 and that, therefore, this level has negative parity. For all levels studied the reduced widths were calculated. A comparison with measurements at other energies showed that a systematic dependence of the reduced widths with energy is rarely noticeable. The reduced width of the 6.28 MeV level of Be 10 is θ 2 = 0.032, which is considerably less than the value reported by Macfarlane. Our reduced widths of Ca 40(d, p)Ca 41 are in better agreement with the values of Nemets et al. than with those of Macfarlane. The reduced width of the 2.47 MeV level of Ca 41 is relatively small which is an indication that the Ca 40 core is excited during the (d, p) process.

Proton angular distributions from the Be 9(t, p)Be 11 reaction measured at 14 MeV triton energy

Proton angular distributions from the Be 9(t, p)Be 11 reaction measured at 14 MeV triton energy