Measurement of energy spectra of charged particles emitted after the absorption of stopped negative pions in carbon

Energy spectra of charged particles (protons, deuterons, tritons, ³He, ⁴He and lithium nuclei) emitted after the absorption of stopped negative pions in a thin polyethylene target of 20 mg/cm² have been measured with high accuracy from the experimental threshold energy (of about 0.5 MeV) up to the kinematical limit of about 100 MeV.     

9.38 GeV/c deuteron stripping on photoemulsion nuclei

The interaction of relativistic deuterons with photoemulsion nuclei has been investigated. The photoemulsion method makes it possible to precisely measure small angles between relativistic particles in reactions and to select unambiguously the events of inelastic deuteron absorption. Proton stripping in the interaction of 9.38 GeV/c deuterons has been investigated.     

Angular distributions of light charged particles from 252Cf fission in the ranges 0–46° and 134–180°

Alpha particles, tritons, deuterons and protons accompanying ²⁵²Cf fission were registered in coincidence with both fission fragments by means of a system containing two-dimensional position-sensitive silicon detectors. Angular distributions, kinetic energy spectra of light charged particles as well as mass distributions of fission fragments in coincidence with light charged particles were measured. The experimental results are compared with some theoretical models.     

Optical potential for composite particles

Optical potentials for the elastic scattering of deuterons, ³He and tritons are calculated in terms of the optical potentials of neutrons and protons forming the projectile. The angular distributions for the elastic scattering of these particles from various targets are calculated and compared with experimental results.     

Correlations of neutral and charged particles in 40Ar- 58Ni reaction at 77 MeV/u

The measurement of the two-particle correlation function for different particle species allows to obtain information about the development of the particle emission process: the space-time properties of emitting sources and the emission time sequence of different particles. The single-particle characteristics and two-particle correlation functions for neutral and charged particles registered in forward direction are used to determine that the heavy fragments (deuterons and tritons) are emitted in the first stage of the reaction (pre-equilibrium source) while the majority of neutrons and protons originates from the long-lived quasi-projectile. The emission time sequence of protons, neutrons and deuterons has been obtained from the analysis of non-identical particle correlation functions.     

Investigation of polar emission in 252Cf and 235U + nth fission

The energy distributions and relative intensities of protons, deuterons, tritons and α-particles emitted along the fission axis during spontaneous fission of ²⁵²Cf were measured simultaneously with both fission fragment energies. The absolute intensity of particles, the mass distribution of fragments, the total kinetic energy and total excitation energy of both fragments were subsequently deduced from the experimental data. Statistical model calculations based on a hypothesis that the polar particles are evaporated from fission fragments have been performed for ²⁵²Cf and ²³⁶U fission. Although some experimental results agree remarkably well with the evaporation hypothesis, the considered model cannot describe many features of the polar emission phenomenon.     

Measurements of the secondary particle energy spectra in the Space Shuttle

Measurements of the energy spectra of secondary particles produced by galactic cosmic rays and trapped protons due to the nuclear interactions of these particles with the Shuttle shielding provide a powerful tool for validating radiation transport codes. A code validated in this way can be used to better estimate the dose and dose equivalent to body organs, measurements that cannot be made directly. The principal cause of single event upsets in electronic devices in the region of the South Atlantic Anomaly is secondary particles, and even in the region of galactic cosmic radiation a significant fraction is produced by secondary particles. In this paper, we describe the first direct measurements of the energy spectra of secondary protons, deuterons, tritons, 3He and 4He produced by galactic cosmic rays inside the Space Shuttle using a charged particle spectrometer. A comparison of these spectra with radiation transport code HZETRN showed reasonably good agreement for secondary protons. However, the code seriously underestimated the flux of all other light ions. The code has been modified to include pick-up and knock-on processes. The modified code leads to good agreement for deuterons and 3He but not for other light ions. This revised code leads to about 10% higher dose equivalent than the original code under moderate shielding, if we assume that higher charge ion fluxes are correctly predicted by the model.     

Method for determining the tritium concentration using the effects of dissociation of molecular beams of hydrogen isotopes on thin carbon films

Physical foundations of a new method for mass-spectrometric determination of tritium concentration in hydrogen-containing media, which is based on the effect of dissociation of molecular ions of hydrogen isotopes passing through thin carbon films, are formulated. The effects accompanying the interaction of particles with a solid (angular scattering, change in the charge state, energy losses in protons, deuterons, and tritons) are analyzed. The corresponding theoretical and experimental data indicate that the proposed technology can be implemented in practice for a comparatively low particle energy of ∼10 keV/nucleus.     

Spectra and multiplicities of n, p, d, t, K, π from antiproton annihilation in Cu and U

Inclusive energy spectra of neutrons, protons, deuterons, tritons, charged kaons and pions following antiproton annihilation at rest in copper and uranium have been measured. The determined multiplicity charged kaons is compared to recent measurements and indicates an enhancement of strangeness production. Ratios of directly emitted neutrons and protons have been determined for copper and uranium to 3.0±0.6 and 3.2±0.5, respectively.     

Neutron induced light-ion production from iron and bismuth at 175 MeV

We have measured light-ion (p, d, t, ³He and α) production in the interaction of 175 MeV neutrons with iron and bismuth with low-energy thresholds and for a wide angular range (from 20° to 160°, in steps of 20°). Measurements have been performed with the Medley setup, semi-permanently installed at the The Svedberg Laboratory, Uppsala (Sweden), where a quasi-monoenergetic neutron beam is available and well characterized. Medley is a conventional spectrometer system and consists of eight telescopes, each of them composed of two silicon surface barrier detectors, to perform particle identification, and a CsI(Tl) scintillator to fully measure the kinetic energy of the produced light-ions. We report preliminary double-differential cross sections for production of protons, deuterons and tritons in comparison with model calculations using TALYS-1.0 code. These show better agreement for the production of protons, while the theoretical calculations seem to overestimate the experimental production of deuterons and tritons.     

Fast helium nuclei in interactions induced by very heavy nuclei

Fast helium nuclei emitted in interactions between heavy cosmic ray nuclei (12≦Z≦26) and photoemulsion nuclei at energies >1 GeV/nucleon have been studied. Comparisons with interactions where the incident particles are protons, pions or light nuclei reveal some characteristic features of nucleus-nucleus interactions. The frequency of fast target helium nuclei is much larger and the high energy tail of the energy spectrum of these helium nuclei is more pronounced in nucleus-nucleus interactions than in proton-nucleus and pion-nucleus interactions. The number of helium nuclei emitted depends on the size and disintegration of the interacting nuclei. In order to explain our experimental data several possible production mechanisms have to be considered. Some characteristics of the emission of multiply-charged projectile fragments have-also been studied.     

Scaling Behavior of Spectra of Protons,Deuterons, and Tritons Produced with High Transverse Momenta in pA and 12CA Collisions

JETP Letters - The first data on the yield of the lightest nuclear fragments (protons p, deuterons d, and tritons t) with high transverse momenta pT at an angle of 40° in the laboratory...     

Neutron-induced production of protons, deuterons and tritons on copper and bismuth

Inclusive cross sections for production of protons, deuterons and tritons by neutrons in the energy range of 300–580 MeV on copper and bismuth have been measured at five angles between 54° and 164°. The systematic dependence of the invariant cross sections on incident energy and emission angle are evaluated. For the study of the mass-number dependence earlier data on carbon are included. The results are discussed on the basis of different models, like quasi-two-body sealing or moving-source model.     

Quasi-free inclusive processes in the two-particle splitting of tritons by deuterons with an energy of 37 MeV

The d + t → d + d + n reaction was experimentally and theoretically investigated at an incident deuteron energy of 36.9 MeV. The experiment was performed on the U-240 isochronous cyclotron at the Institute for Nuclear Research, National Academy of Sciences of Ukraine. Inclusive spectra of deuterons and their angular distributions in the range of 15° ≤ θ_d ≤ 52° were measured. Experimental spectra and angular distributions of the final deuterons from the d + t → d + d + n reaction are satisfactorily described in a diffraction approximation that considers interaction in the final state and the correct asymptotic of the wave function of colliding nuclei. The scattered deuterons are the main contributors to the cross section (up to 70–90%), while the deuterons from tritons can be seen well only at low and high energies, at the edges of the spectra.     

Study of the preequilibrium mechanism for individual channels of the 159Tb, 209Bi(α, charged particle xnγ) reactions with particle-γ coincidences

The mechanism of preequilibrium emission of protons, deuterons and tritons has been studied for α-induced reactions on ¹⁵⁹Tb and ²⁰⁹Bi using particle-γ coincidence techniques. The experiments were carried out for α energies of 45, 75 and 110 MeV and the charged ejectiles were detected at angles of 45°, 90° and 135° with respect to the beam direction. The experimental technique allowed to identify individual reaction channels and to determine their differential cross sections as a function of the ejectile energy. The most important finding is that the cross sections of the individual reaction channels show pronounced peaks and additionally low-energy tails for higher beam energies. The peaks are related to the emission of a charged particle in the preequilibrium phase followed by neutron evaporation indicating a breakup-fusion mechanism. For the tails at least two fast particles are emitted resulting from a breakup-fusion mechanism with three or more particles in the continuum. The data furthermore contain information about the depopulation mechanism and it was found that the entry point for compound nucleus decay moves away from the yrast line with increasing beam energy.     

Energy dependence of fusion and reaction cross sections in the 9Be + 12C system

Angular distributions of protons, deuterons. tritons and α-particles were measured for the system ⁹Be + ¹²C at lab energies between 12 and 27 MeV. The compound nucleus model with level densities calculated according to the Gilbert-Cameron formula describes satisfactorily the measured proton, deuteron and triton data. In the α-particle spectra contributions from other processes seem to be present. In the analysis the fusion cut-off angular momentum was adjusted at each energy in order to reproduce correctly the proton, deuteron and triton channels. From this analysis the fusion cross section was determined as a function of the energy. The results were compared with fusion and total reaction cross section values calculated from a potential model with the real part of the interaction potential obtained from the double folding procedure of Satchler.     

Emission of deuterons in the interactions of 9 GeV protons with lead nuclei

The emission of deuterons with energies ranging from 17 to 104 MeV in interactions of 9 GeV protons with lead nuclei has been studied using nuclear emulsion. These deuterons constitute about $\text{1}\text{6}$ of the secondary heavily ionising particles (β < 0.7). Observed features of the emission of the deuterons with energies above 28 MeV can be interpreted in terms of the mechanism proposed by Butler and Pearson.     

Pion and proton emission in interactions induced by relativistic heavy nuclei withZ≧12

The emission of pions and protons in interactions between heavy nuclei from the cosmic radiation (12≦Z≦26) and photoemulsion nuclei has been studied. The angular and energy distributions of target protons are similar to corresponding distributions in proton-nucleus interactions for emission angles >30°. In heavy ion interactions a forward peak of high energy target protons (E>200 MeV)is observed. The energy spectrum of target protons for angles <30° is remarkably flat for heavy ion interactions. For increasing disintegration of the target nucleus the number of produced pions per emitted recoil target proton is almost constant in heavy ion interactions, while it decreases rapidly in proton-nucleus interactions. The logtgΘ distributions of pions have small standard deviations even in interactions with a large target disintegration.     

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.     

Multiparameter studies of polar emission in 236U fission

The energy distributions and relative intensities of protons, deutrons, tritons and α-particles emitted along the fission axis during thermal neutron fission of ²³⁵U were measured simultaneously with both fission fragment energies. The mass distributions of fragments, the total kinetic energy (TKE), the dependence of the mean TKE on the fragment mass, as well as the mean kinetic energy dependence of polar particles on the fragment mass and energy were subsequently deduced from these data. Although some experimental results agree remarkably well with the hypothesis that polar particles are evaporated in flight from fission fragments, the general conclusion is that these particles are emitted according to some other mechanism.