Study of the spectra of fast deuterons produced in the interaction of 670 MeV protons with nuclei

The spectra of deuterons emitted at angles of 6.5°, 9.5°, 13.5° and 16° (lab system) in the interaction of protons with the nuclei ¹H, ²H, ⁶Li, ⁷Li, C, Al, Cu, Rh and Pb have been measured in the momentum range 700–1700 MeV/c. The secondary particles were analyzed with the help of magnetic and time-of-flight spectrometers. The differential cross sections for deuteron production in the reactions p + 〈2N〉 → N + d and p + 〈N〉 → d + π have been measured for selected nuclei and angles. The effective numbers of nucleons and of two-nucleon clusters for the investigated nuclei were determined. The results obtained are discussed in terms of the dispersion theory of direct nuclear reactions.     

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.     

Target fragments in collisions of 1.8 GeV/nucleon Fe nuclei with photoemulsion nuclei, and the cascade-evaporation model

Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM).     

Interactions of 9.4 GeV/c deuterons in an emulsion: Multiplicity and angular distributions

An analysis of 1650 stars induced by 9.4 GeV/c deuterons in a nuclear emulsion is presented. Multiplicity and angular distributions of secondaries are discussed.     

Production of fast fragments by bombarding light nuclei with intermediate-energy protons

The high-energy parts of the spectra of ³H, ³He and ⁴He nuclei obtained in bombarding Li, Be and C targets with 665 MeV protons as well as the spectra of fast deuterons as a function of the proton energy (from 380 to 665 MeV) at a lab angle of 5.5° have been measured. The mechanisms of the interactions of intermediate-energy protons with light nuclei are discussed. It is found that the production of fast nuclear fragments at a small angle can be explained to a large extent by direct nuclear reactions of two types, i.e. quasielastic scattering and pion production processes on clusters.     

Triton emission in the interactions of fast neutrons with nuclei

Cross sections have been measured for the formation of tritium in the interactions with Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, Ca, V, Co, As, Y, La, Pr, Tb, Ho and Tl of fast neutrons produced via break-up of 53 MeV deuterons on a Be target (E_n = 11.5–43.5 MeV; I_max at 22.5 MeV; FWHM = 15.8 MeV). The activation technique in combination with vacuum extraction and low-level gas phase β^? counting of tritium was employed. Furthermore, cross sections were measured for isotopes of the elements Ne, Mg, Ar, Ca, Ti, Cr, Fe, Ni, Zn, Ge, Se, Zr, Mo, Pd, Te, Ba, Pr, Dy, W, Tl and Pb by γ-ray spectroscopic analysis of the radioactive reaction products. A comparison of the two sets of cross sections shows that for nuclei with A > 40 the emission of three single particles (lp2n) is much more probable than the emission of a bound tri-nucleon (³H). The cross-section data obtained via tritium counting show that the (n, t) cross sections for the lightest nuclei are exceptionally large, probably due to direct interactions, and the process competes with other modes of de-excitation; for elements with Z > 20, on the other hand, the cross section is low (< 0.25 % ofσ_n.e.) and practically constant, showing thereby that in the medium and heavy mass regions the probability of emission of a triton is relatively independent of the target nucleus. A comparison of the cross-section systematics at E_n = 14.6 MeV and for the neutron spectrum described above is presented; the trends are somewhat similar.     

Production of Tb from gold by 0.2 to 0.5 GeV protons

The production of ¹⁴⁹Tb from gold by 200–450 MeV protons has been observed with cross sections (α-branch only) as follows: 0.0028 ± 0.0011 μb at 218 ± 14 MeV, 0.23 ± 0.09 μb at 384 ± 21 MeV, and 0.84 ± 0.34 μb at 434 ± 24 MeV.     

α-particle break-up in the interaction with protons at 8.6 GeV/c 4He momentum

Helium break-up reactions have been studied in ⁴He-proton interactions at 8.6 GeV/c⁴He momentum in the hydrogen bubble chamber. Total and differential cross sections for different reaction channels without pion production have been measured. The results have been compared with multiple scattering model predictions.     

On the angular dependence of photoprotons from nuclei irradiated with γ-quanta with maximum energy 4.5 GeV

The angular dependences of proton photoproduction from the nuclei ¹²C, ⁶³Cu and ²⁰⁸Pb irradiated by bremsstrahlung γ-quanta with maximum energy 4.5 GeV, both in the cumulative region (i.e. in the kinematical region in which the production of protons in the collision of γ-quanta of the given energy with the quasi-free nuclear nucleon is forbidden) and in the non-cumulative region, are investigated. The experimental data obtained are compared with the results of theoretical calculations of cumulative proton photoproduction according to the following models: the “quasi-two-body” scaling model, the low-nucleon correlation model, the fluctuon model and the cluster model.     

Total cross-section measurements for the production of nuclear gamma rays from light nuclei by low-energy deuterons

The thick target yields of the reactions ⁶Li, ⁹Be, ¹⁰B(d, nγ) for specific final nucleus γ-rays have been measured between deuteron bombarding energies of 48 and 170 keV. The measured thick target yields are used, together with recently published values of the stopping power of low-energy deuterons in matter, to infer the total reaction cross sections for the production of the specific γ-rays between deuteron energies of 65 and 160 keV. The cross sections are compared to appropriate Coulomb barrier penetration probabilities and the astrophysical functions S(E) are deduced.     

Interactions of relativistic nitrogen nuclei in an emulsion at 2.1 GeV/nucleon

An analysis of multiple production induced by 2.1 GeV/n ¹⁴N ions in nuclear emulsions is presented. Multiplicity and angular distributions of charged secondaries and correlations among them are discussed. The presented data are compared with relevant values from proton-nucleus interactions. The possible appearence of collective phenomena in nucleus-nucleus interactions is discussed.     

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.     

Relativistic α-particles emitted in Fe-emulsion interactions at 1.7A GeV

Relativistic α-particles have been studied in 423 interactions of Fe in emulsion at 1.7A GeV. Comparisons of the observed angular distribution with that from ¹⁶O-emulsion reactions at 2.1A GeV reveal that more α-particles are observed at large angles in the Fe-emulsion reactions. The α-particles at large angles cannot be explained by fragmentation from a clean-cut spectator. Comparison of the experimental data with moving relativistic Boltzmann distributions shows that a single Boltzmann distribution cannot fit the fragmentation peak and the tail simultaneously. A thermal source (fireball) explaining the tail part of the distribution needs to be formed by a mechanism other than a simple clean-cut participant-spectator process. A large transverse momentum transfer to the spectator before fragmentation may explain the tail.     

Spallation of copper by 9 GeV/c protons and deuterons

The spallation of copper by 9 GeV/c protons and deuterons has been studied. Cross sections for the production of radionuclides with 24 A 60 were determined from direct gamma-ray counting of irradiated targets with a Ge(Li) — spectrometer. The results were parametrized in terms of a 6-parameter formula which reproduces the measured charge-dispersion and mass-yield distributions. The proton results are compared with previous investigations.We wish to acknowledge with thanks the cooperation of Yu. A. Panebratsev, A. N. Khrenov, V. G. Perevozchikov and the members of the Dubna synchrophasotron staff. Without their assistance the present work would not have been possible.     

Multiparticle production in pTa interactions at 8 GeV/c

pTa interactions have been studied. The total inelastic cross section, multiplicities, net charge distributions and inclusive momentum and rapidity spectra for produced particles are reported. The correlations between fast and slow particles are presented and the reaction mechanisms for multiparticle production in pTa interactions are discussed.     

Fast neutron production with 54 MeV deuterons

The yield of neutrons above 10 MeV produced by irradiating 14 elements with 54 MeV deuterons were determined. Energy spectra in the forward direction were measured with a time- of-flight technique. The angular distributions were measured with threshold detectors. The observed neutron spectra were compared with theoretical results for nuclear and Coulomb break-up of deuterons.     

Investigation of inelastic interactions of 400 GeV protons with emulsion nuclei

The basic experimental characteristics of incoherent interactions of 400 GeV protons on emulsion nuclei, such as the multiplicity of charged secondaries, one-particle distributions and two-particle correlations, are reported and discussed in details. They are compared with the results of other experiments on hadron-nucleus interactions at lower energies. We have shown from both the quantitative and qualitative comparison of the data presented with predictions of various model approaches to nuclear production, that most of them cannot explain the complete set of experimental observations.An analysis of the experimental data presented gives strong support to the idea that the production mechanism in high-energy hadron-nucleus interactions has two or multi-component character.     

A study of the elastic scattering of polarized deuterons from 60Ni and 90Zr nuclei

Five quantities, σ₀, iT₁₁, T₂₀, T₂₁ and T₂₂, have been measured for the elastic ($\text{d}$, d) scattering from ⁶⁰Ni at 9 and 12 MeV and from ⁹⁰Zr at 10, 11 and 12 MeV over a wide angular range. Excitation functions for σ₀ and T₂₀ have been also measured at an angle of 175°(lab) in the approximate energy range of 6–13 MeV for both target isotopes. The experimental results, together with similar data published earlier for 15 MeV have now been analysed using the optical model with the complex central, spin-orbit and tensor T_R potentials. Excellent fits are obtained for the angular distributions for all five measured quantities. The main features of the excitation functions are also well reproduced. Five of the optical-model parameters can be fixed. Three other parameters can be constrained by simple mass dependence functions. Further evidence for the presence of an imaginary component of the spin-orbit potential is supplied by the analysis of the present data.