Energy Distribution Of Protons Research Articles

Extension of the isobar model for intranuclear cascades to 1 GeV

An intranuclear cascade model is proposed for studying pion and nucleon induced reactions in the region of single pion production. The model explicitly considers the production and subsequent interactions of (3,3) isobars. The predictions of the model are compared with experimental data from proton induced reactions such as pion production yields, pion and proton energy and angular distributions, and spallation yields. The model gives a fair to excellent representation of all these data.

Neutron, proton, and α-particle emission from 3He induced reactions

A study of the three most important outgoing reaction channels has been undertaken in order to see if pre-equilibrium models can simultaneously explain spectra of different particles emitted in the same reaction. Measurements of energy and angular distributions of neutrons, protons and α-particles emitted from 3He induced reactions on 57Fe, 61Ni, 62Ni and 63Cu at an incident energy of 25.6 MeV were performed. The hybrid model succeeds in giving an overall description of particle spectra, when initial configurations of four excitons are involved in the case of nucleon emission. Besides the evaporative and pre-equilibrium processes, a contribution due to the break-up of the incident particle has also to be taken into account in the case of proton spectra.

Use of position sensitive detectors at energies below 1 MeV: Application to a fast determination of the pitch angle distribution of protons inside the magnetosphere

Experimental data which were obtained in the laboratory are presented, concerning the possible use of a position sensitive detector (P.S.D.) to determine the pitch angle and energy distribution of protons inside the magnetosphere. The pitch angle α is determined by putting a slit in front of the P.S.D. Each value of α is therefore associated with a value x of the abscissa of the particle impact on the P.S.D. A division of the two impulses (one being proportional to the particle energy E, and the other to the product of x by E) gives the value of x, hence of α. It is shown that the measurement of x is improved if one takes into account the correlated noise between the two impulses, E and xE. Experimental evidence is given that with such a system, one can achieve an angular resolution of 15° for E ≈ 0.1 MeV and 2.5° for E ≈ 1 MeV. Practical application to spin stabilized satellites is also considered.

Electrodisintegration of the deuteron

The energy and angular distribution of the electrodisintegration protons from deuterium have been measured. A theoretical comparison with the data is also presented.

Energy distribution of protons with primary energy of 15 keV backscattered from a Ni single crystal

Abstract A nickel single crystal was bombarded with 15 keV protons incident in the vicinity of the and directions. The backscattered protons were energy-analysed with a spherical electrostatic analyser which could be moved around the target. The energy resolution was E/ΔE=140. The surface peak and a very low scattering intensity from the bulk was observed in a channelling experiment. The latter intensity is zero within the experimental error in double alignment. In this case it can be deduced from the width of the surface peak that less than two atomic layers contribute to it. When the angle between a close-packed direction and the incident beam is increased, at fist only the scattering intensity from the bulk increases. When a critical angle is exceeded, the surface peak increases as well. At the same time it broadens and shifts to lower energies. In addition, at energies below the surface peak new peaks in the backscattering spectra appear, Computer simulations indicate that backscattering i...

Proton Irradiation of Beagle Eyes. I. Si(Li) and Thermoluminescent Dosimetry of 20, 35, and 45 MeV Protons

A Si(Li) solid state detector, CsI, LiF thermoluminescence dosimeters (TLD), and fast film were used to measure proton fluence, energy distribution, and depth dose in a cubical Lucite phantom exposed to beams of 20, 35, and 45 MeV protons. The recoiled deuterons and scattered protons from a deuteron gas chamber were used as a beam monitor during irradiation of the animals. The depth-dose measurements illustrate that thermoluminescence dosimeters can be used to estimate proton exposures in a Lucite phantom for 20-45 MeV protons. It also appears that TLD is relatively energy independent over this energy interval. Young Beagle dogs' eyes (100 days old) were exposed to 70, 125, 240, and 480 surface rads. The average dose to iris, lens and retina was calculated from the surface dose and the depth-dose curves. The maximum dose to the lens and retina was about 4.5 times the surface dose, respectively, for 35 MeV and 45 MeV protons. The maximum dose to the iris for the 20 MeV protons was about 2.6 times the surfa...

Proton energy and angular distributions from (n, p) and (n, np) reactions

Abstract The proton energy and angular distributions from (n, p) and (n, np) reactions on 27Al, 32S, 59Co and 58Ni have been measured for 14.1 MeV neutrons. The proton detection threshold was approximately 2 MeV and the reaction angles from 0° to 120° were used in 20° increments. Thin isotopically pure targets and particle discrimination were used. The level-density parameters, nuclear temperatures and total (n, p) and (n, np) cross sections are reported. Direct contributions are estimated.

Nuclear Disintegrations Produced by Multiply Charged Particles

Nucleus-nucleus collisions produced in nuclear emulsions by heavy cosmic ray primaries have been analysed. The kinetic energy of the incident nuclei are larger than 100 MeV/nucleon. The angular and energy distributions of protons with energies <10 MeV and alpha-particles with energies <200 MeV have been studied. Low energy protons and alpha-particles are emitted isotropically in a system moving with a mean velocity component in the forward direction of 0.02 c. It is found that there is an excess of low energy protons which cannot be explained without using extremely low values of the Coulomb barrier. It is also found that evaporation theory cannot account for all the alpha-particles. In high energy nucleus-nucleus interactions alpha-particles are produced partly by emission from disintegrating fragments and partly by a knock-on process in which quasi-elastic collisions between nucleons and alpha-clusters take place. This last statement is supported by the fact that alpha-particles are emitted with high momentum components in the forward as well as in the transverse direction.

Messung und Poldiagramm-analyse des 2H(n, p)2n Reaktionswirkungsquerschnitts bei 14.5 MeV

The deuteron break-up reaction was investigated by means of the two-dimensional measurement of proton and neutron energy distributions at neutron emission angles of 10°, 20°, 30° and 40°. The pole diagram approximation was applied to analyse the mesaured cross sections for a bombarding neutron energy of 14.5 MeV. Reasonable agreement between the observed and calculated cross sections was obtained.

Very-Low-Frequency and Particle Rocket Experiment at Kerguelen Islands: 2. Particle measurements

The mean particle distribution functions observed between 100 and 400 km at L∼3.7 are in agreement with other measurements made in the same energy range and at the same L value; our measurements extend the results toward lower energies and lower altitudes. The proton energy distribution is fitted by two experimental curves with e-folding energies E0∼50 kev up to energies of the order of 400 kev and E0∼1 Mev above. The same is generally true for the electron distribution, although the break in the spectrum is less marked, the e-folding energies being E0∼20 kev up to 100 kev and E0∼100 kev above. The ratio J⊥/J∥ is usually smaller for protons than for electrons, especially for one flight during which it was smaller than 1. Some characteristics of the particle fluxes have been observed in relation to VLF emissions: a flux increase of the newly injected electrons, both trapped and precipitated, is observed during dawn chorus events. A highly characteristic fluctuation (T∼80 sec) of the trapped electron intensities has been detected in coincidence with a VLF periodic hiss emission and a hydromagnetic wave of the same periodicity. This phenomenon is interpreted in the frame of reference of the quasi-linear theory as a pitch-angle scattering associated with VLF emission.

Angular distribution of protons from the reaction Co59(n, p) Fe59 forE n ∼6·3 MeV

The energy and angular distributions of protons in the reaction Co59 (n, p) Fe59 have been measured forEp=6·3 MeV. The results show the presence of other mechanism than compound nucleus.

Nuclear structure studies by the 62–64Ni(d, p) reaction

Levels of 63Ni and 65Ni below 5 MeV have been studied by observation of the energy and angular distribution of protons emitted in the 62–64Ni(d,p) reactions. For many levels, l-values of the captured neutrons have been assigned by comparison of the angular distribution with calculations based on the DWBA. These comparisons yield the spectroscopic factors. A sum rule analysis is made and the results are compared with the predictions of the strong-pairing and shell models. The positions of the single quasiparticle states determined have been used as input for an IGE calculation to obtain the force parameters.

Models for High-Energy Processes

Recent developments in the concepts and models used to describe high-energy collisions of fundamental particles are reviewed. The areas of appreciable activity in research in high-energy physics are surveyed briefly and the general framework for the description of processes at high energies is outlined. There follows a sampling of recent experimental data designed to show the extent and detail of present-day experimental results. Recent applications of Regge pole models are reviewed with emphasis on the difficulties as well as the successes of models employing only Regge poles. The various multiple-scattering models are then discussed and correlated by means of the methods of Glauber. The connection of these models with amplitudes having branch cuts in the angular-momentum plane (Regge cuts) is described, as well as some comparisons with experiment. Finite energy sum rules as a means of relating the low-energy and high-energy domains are discussed in some detail. Next, the far-reaching concept of duality whereby the direct-channel resonances are (in some sense) the crossed-channel Regge exchanges is described, along with the related ideas of exchange degeneracy, the special role of the Pomeranchon Regge pole, and duality diagrams. An explicit realization of duality is achieved in the Veneziano model. This model is discussed in some detail for the relatively simple and interesting example of pion-pion scattering. Brief mention is also made of the extensions of the Veneziano model to the $n$-particle amplitude, attempts at unitarization, and various applications. The topic of multiparticle final states is covered relatively briefly with emphasis on the applications of double Regge pole exchange to three-body final states, the calculation of proton and pion energy and angular distributions in proton-proton collisions by means of the multi-Regge exchange model, and the generation of self-consistent Regge singularities with the multi-Regge exchange model and unitarity. The final section of the review concerns recent results on pion-pion scattering phase shifts and also $K\ensuremath{-}\ensuremath{\pi}$ phase shifts, and some remarks on theorems connecting decay correlations of resonances with the mechanism of production. The literature survey ended, with a few exceptions, in May 1969.

Energy spectra of blocking patterns

The effect of multiple electronic scattering on the angular and energy distribution of protons scattered in the vicinity of a blocking direction in a Si single crystal is investigated experimentally. A fairly good agreement has been found with the theory.

Back-scattering of keV hydrogen ions in solids

By assuming that incident ions are scattered in a single wide-angle collision and that the energy loss in the solid is due only to interaction with electrons, an expression for the number of ions back-scattered from a surface is derived. Measurements have been made of the energy distribution of protons and deuterons back-scattered from titanium and niobium. Good agreement is obtained between the measured and calculated energy distributions both in general shape and in the absolute values of the number of particles back-scattered from titanium. In the case of niobium there is evidence that multiple scattering is taking place.

OGO-V Ion Spectrometer

The ion spectrometer aboard OGO-V is a most versatile instrument for topside ionospheric and magnetospheric investigations. The concentration profiles of O+, He+ and H+ ions are obtained in the topside ionosphere with excellent spatial resolution and with a sensitivity sufficient to measure less than 1 ion/cm3. The dynamic range of the instrument is better than 8 orders of magnitude. These functions are accomplished with an absolute minimum of telemetry bandwidth. The instrument also functions as an energetic particle analyzer and is capable of measuring energy distributions of protons from 0 to 600 eV. The bow shock crossings of the OGO-V vehicle are easily detected with the ion spectrometer and temperature measurements within the magnetosheath are obtained.

Energy spectrum of protons produced in collisional dissociation of fast H2+ ions

Energy distributions of protons produced in dissociative collisions of H2+ with H2, Ar and Xe have been measured in the forward direction at 10 keV. An experimental method giving the corresponding excess kinetic energy spectrum in the centre-of-mass system of H2+ is briefly discussed. The measured spectra are explained in terms of electronic and vibrational transitions to dissociative states of the H2+ molecular ion. The dissociation cross section by vibrational transitions in the 1sσg state is estimated to be, respectively, σv = 1.4 × 10-18 cm2, σv = 4.3 × 10-18 cm2 and σv = 5 × 10-18 cm2 for hydrogen, argon and xenon targets. The dependence upon the target density is interpreted as a double collision dissociation process of the type H2+ -> H20* -> H+. The influence of ion source parameters is also studied. Comparison is made with theory and the agreement is found to be good if one makes allowance for the dependence of dissociation upon the internuclear axis orientation.

Proton channeling in ionic and semiconducting single crystals

Measurements have been made of the energy distributions of protons passing through NaCl, KCl, Si, and Ge single crystals at various angles with respect to the {100} and {110} planes. The fraction of protons passing through lattice channels has been evaluated, and its dependences on the angle of incidence, the chemical composition of the sample, and the proton energy have been found.

Nuclear-Structure Studies with (d, p) Reactions onPd106andPd108

Energy distributions of protons emitted at various angles from 12-MeV-deuteron-induced ($d, p$) reactions on ${\mathrm{Pd}}^{106}$ and ${\mathrm{Pd}}^{108}$ were measured with 7-keV energy resolution using an Enge split-pole spectrograph. The results for the two isotopes are very similar except that summed spectroscopic factors are a little smaller in ${\mathrm{Pd}}^{108}$, as expected from the fact that it has more neutrons. The level densities were found to be about 25 levels per MeV, and the single-particle levels are fragmented over a wide range of energies, although a large fraction of the strength of single-particle levels in the 50-82 shell is always in the lowest-lying nuclear level. The $l=4$ strengths seem to be too large, and the $\frac{(d, p)}{(d, t)}$ cross-section ratio of one of these states in each isotope indicates that it may be ${g}_{\frac{9}{2}}$ rather than ${g}_{\frac{7}{2}}$; the ${h}_{\frac{11}{2}}$ strengths are too small. Possible explanations for this are discussed, including the possibility that these nuclei are strongly deformed. The $s$ and $d$ states are somewhat more full in ${\mathrm{Pd}}^{108}$ than in its isotone ${\mathrm{Sn}}^{112}$.

Fast Neutron Spectroscopy by Proton-Recoil Proportional Counting

Small proportional counters containing hydrogen and without collimation have measured reactor neutron spectra with resolution adequate for comparison with existing energy-group methods of calculation over the energy range from 1 keV to 1 MeV. The counters are efficient and operate satisfactorily at low (105/cm2 sec) flux levels. Experimental methods currently in use for in-core measurements using proportional counters vary; the one described here makes use of an electronic pulse-shape discrimination to eliminate the background of gamma radiation. The nature of the numerical procedure required to extract neutron spectra from measured energy distributions of recoil protons bears upon the resolution and statistical precision of the result. Examples of measured neutron spectra are given where they illustrate the various points of experimental technique.