120483275
Role of high ℓ values in the onset of incomplete fusion
A particle-$\ensuremath{\gamma}$-coincidence experiment is performed to investigate the role of high $\ensuremath{\ell}$ values in the production of direct-$\ensuremath{\alpha}$-emitting channels (associated with incomplete fusion) in $^{12}\mathrm{C}+^{169}\mathrm{Tm}$ system. Spin distributions of various $\mathit{xn}/\mathit{pxn}/\ensuremath{\alpha}\mathit{xn}/2\ensuremath{\alpha}\mathit{xn}$ channels are measured at ${E}_{\mathrm{lab}}=5.6A$ and $6.5A$ MeV. Entirely different de-excitation patterns are observed in direct-$\ensuremath{\alpha}$-emitting channels and fusion-evaporation channels. The fusion-evaporation channels are found to be strongly fed over a broad spin range. While narrow range feeding for only high-spin states was observed in the case of direct-$\ensuremath{\alpha}$-emitting channels, in the present work, incomplete fusion is shown to be a promising tool to populate high-spin states in final reaction products. To have better insight into the associated $\ensuremath{\ell}$ values in different reaction channels, the present data are compared with similar data obtained in $^{16}\mathrm{O}({E}_{\mathrm{lab}}\ensuremath{\approx}5.6A \mathrm{MeV}) + ^{169}\mathrm{Tm}$ system. The mean driving angular momenta involved in the production of direct-$\ensuremath{\alpha}$-emitting channels are found to be higher than those involved in the production of fusion-evaporation channels. Direct-$\ensuremath{\alpha}$ multiplicity in the forward cone increases with driving angular momenta, which indicates the origin of direct-$\ensuremath{\alpha}$-emitting channels at high $\ensuremath{\ell}$ values in noncentral interactions.
40508283
Equilibrium and preequilibrium emission in some alpha -induced reactions on enriched isotopes 128,130Te at moderate excitation energies.
Excitaion functions for the reactions [sup 128]Te([alpha],[ital np])[sup 130]I, [sup 130]Te([alpha],[ital np])[sup 132]I, and [sup 130]Te([alpha],[ital np])[sup 132[ital m]]I have been measured using the stacked foil technique and have also been calculated using a statistical model with and without the inclusion of preequilibrium emission. As expected, the inclusion of preequilibrium emission in compound nucleus calculations agrees well with the experimental excitation functions. The preequilibrum fraction has been found to be energy and target mass number dependent.
121070748
Integral frequency distribution of projectile alpha fragments in nuclear multifragmentations at intermediate and high energies
The integral frequency distributions of the numbers of projectile alpha fragments produced in nuclear multifragmentations at intermediate and high energies are studied by a simple two-source model. The calculated results are approximately in agreement with the experimental data of 16 O, 40 Ar, 56 Fe, 84 Kr, 139 La, and 197 Au multifragmentations in nuclear emulsions at 2.00 A , 1.80 A , 1.80 A , 0.08–1.70 A , 0.60–0.99 A , and 0.60–0.99 A GeV, respectively. The initial energy of nuclear limiting fragmentation is expected to be at or lower than 0.08 A GeV. Two correlations between the mean multiplicity of projectile alpha fragments ( 〈 n α 〉 ) and the projectile mass number, as well as 〈 n α 〉 and the maximum multiplicity of projectile alpha fragments are observed.
120591625
Target black fragment flows in magnesium-emulsion collisions at 4.5A GeV/c
The experimental results of polar, azimuthal, and projected angular distributions of target black fragments produced in magnesium-emulsion collisions at 4.5A GeV/c (the Dubna synchrophasotron momentum) are reported. The flow characteristics are obtained. The azimuthal and projected angular distributions as well as some relationships between flows and angles depend on the size of target in the case of considering both light and heavy targets, and do not depend on the multiplicity in the case of considering heavy target.
122504553
Some general characteristics of 28Si-emulsion interactions at 4.5 GeV/c per nucleon
Abstract We present our observations on the salient features of the interactions produced by 28 Si nuclei of 4.5 GeV/ c per nucleon in photographic emulsions. The results on the inelastic mean-free path and interaction cross section are presented and compared with the predictions of a geometrical model. Measurements on the multiplicity distribution, mean multiplicities, multiplicity correlations and multiplicity scaling of charged secondary particles are studied. A comparison with other available data at same/nearby incident momentum per nucleon from proton-nucleus and carbon-nucleus collisions is presented in order to examine the dependence on the projectile mass.
118675467
Inclusive cross section and single transverse spin asymmetry for very forward neutron production in polarized p+p collisions at √s=200 GeV
The energy dependence of the single-transverse-spin asymmetry, A(N), and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at the Relativistic Heavy Ion Collider for polarized p + p collisions at root s = 200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with a momentum fraction of x(F) = 0.45 to 1.0. The energy dependence of the measured cross sections were consistent with x(F) scaling, compared to measurements by an experiment at the Intersecting Storage Ring, which measured neutron production in unpolarized p + p collisions at root s = 30.6-62.7 GeV. The cross sections for large x(F) neutron production for p + p collisions, as well as those in e + p collisions measured at the Hadron-Electron Ring Accelerator, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching A(N) = -0.08 +/- 0.02 for x(F) = 0.8; the measured backward asymmetries, for negative x(F), were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.