Deep Inelastic Reactions Research Articles

Angular constraints and the collinearity breaking of SU(6) w symmetry

We show from Lorentz invariance that the Melosh transformation, as well as its generalization (à la Carlitz and Tung) to interacting quark theories, cannot be invariant under the Lorentz transformation along the z axis. This non-invariance introduces exotic terms (transforming as the representation 35 × 35) in the structure of the physical currents, otherwise transforming as the adjoint representation of SU(6) W currents. It is shown, within the free quark model, that the contribution from these exotic terms is small for resonance decays but non-negligibly large in deep inelastic reactions, thus underscoring the need for a reexamination of the latter processes within the Melosh framework.

Polarization of 12B in deep-inelastic heavy-ion reaction 100Mo( 14N, 12B)

Spin polarization of 12B was measured for 100Mo( 14N, 12B) at E i ( 14 N) ≅ 200 MeV as a function of Q value down to Q ⋍ −150 MeV , and was found anti-parallel to k f × k i in the deep-inelastic region. The data together with those at lower incident energies show a systematic trend in Q -value dependence of the polarization.

Role of Particle Transfer and Excitation of Collective Surface Vibrations in the Damping Processes Leading to Deep Inelastic Reactions

Deep inelastic reactions are studied including both particle transfer and excitations of collective surface modes. Detailed results are given for three examples.Received 29 March 1978DOI:https://doi.org/10.1103/PhysRevLett.41.25©1978 American Physical Society

Triple differential cross section for angle, atomic number and energy (or angular momentum transfer) calculated for the 280MeV40Ar+58Ni (or 365MeV63Cu+197Au) system in a simple model

We apply a dynamical model which includes both dissipation and statistical fluctuations to the computation of triple differential cross sections for deep inelastic reactions. It is seen that for different Z values the overall pattern of the cross sectiond 3 σ/dθdEdZ (calculated, for the 280 MeV40Ar +58Ni system) as a function ofE andθ is fairly well reproduced—the mean angular momentum transfer for the 365 MeV63Cu+197Au system is calculated and compared withγ-multiplicity measurements. In both applications, possible implications of the remaining discrepancies are discussed.

Fission induced by heavy-ion collisions

Fission fragment angular distributions from sequential fission induced in heavy-ion reactions will depend on the angular momentum exchange occuring in such reactions in considerable detail. Theoretical expressions for the angular distributions of fission products from totally and partly polarized nuclei are presented. They are compared with recent measurements and discussed in relation to the deep inelastic reaction mechanism.

Influence functionals in deep inelastic reactions

It is suggested that the concept of influence functionals introduced by Feynman and Vernon could be applied to the study of deep inelastic reactions among heavy ions if the coupling between the relative motion and the internal degrees of freedom has a separable form as suggested by Hofmann and Siemens.

Calculation of nuclide distributions in deep inelastic scattering and the production of neutron rich nuclei

Nuclide distributions for deep inelastic fragments are calculated considering the diffusion of the intermediate dinuclear system in a two-dimensional liquid drop potential energy surface. Particle decay from the fragments is taken into account by statistical model calculations. The concept of charge equilibration is investigated. Calculations are compared to previously measured nuclide distributions. Predictions are made for the production cross sections of neutron-rich nuclei in deep inelastic reactions.

Nuclide distributions in deep inelastic reactions

The mass and charge of fragments produced in deep inelastic reactions induced by 236 MeV 40Ar on targets of 42, 48Ca, 50Ti. 50Cr, 56Fe and 60Ni were identified by using a time-of-flight ΔE- E detector telescope. The measured nuclide distributions are very broad along the mass asymmetry coordinate, but narrow along the charge asymmetry coordinate. A detailed description of the variations of the mass and charge distributions as a function of target neutron excess is obtained by calculating primary distributions assuming a diffusion-like mass transfer in a two-dimensional potential energy surface determined by liquid drop energies of two touching spheres and folding this primary distribution with the secondary particle decay pattern calculated in the statistical model. Exotic nuclei are produced with comparatively large cross sections.

Influence of Coulomb and nuclear forces on the pattern of the double differential cross sectiond2σdθdEfor deep inelastic reactions

The tremendous change in the pattern of the Wilczynski curves for deep inelastic reactions with the product ${\mathrm{Z}}_{1}$${\mathrm{Z}}_{2}$ is interpreted within a model including both dissipation and statistical fluctuations. The competition between Coulomb and nuclear forces seems to account for this effect.NUCLEAR REACTIONS Calculation of double differential cross sections $\frac{{d}^{2}\ensuremath{\sigma}}{d\ensuremath{\theta}\mathrm{dE}}$ for deep inelastic reactions.

Primary-Fragment Angular Momenta in Deep-Inelastic Reactions

Primary-Fragment Angular Momenta in Deep-Inelastic Reactions

Theoretical Correlation between Energy Dissipation, Angular Momentum Transfer, and Charge Diffusion in Deep Inelastic Reactions

The $Z$ dependence of the orbital angular momentum transferred into the intrinsic spins of deep-inelastic collision partners is studied. The correlation between energy loss and nucleon transfer calculated by the present method is compared with that derived by previously proposed empirical methods. The currently used empirical approaches appear to be subject to serious systematic errors.

Recoil range distributions of heavy mass products in deep inelastic reactions with gold and uranium targets

Recoil range distributions have been measured for the elements between lutetium ($Z=71$) and astatine ($Z=85$) produced in heavy ion reactions of 420, 491, and 581 MeV$^{86}\mathrm{Kr}$ with $^{197}\mathrm{Au}$, 686 MeV $^{86}\mathrm{Kr}$ with $^{238}\mathrm{U}$, and 868 MeV $^{136}\mathrm{Xe}$ with $^{197}\mathrm{Au}$; the relative yields were established by use of x-ray spectrometry. These elements have been identified in radioanalytical mass distribution studies and kinematic studies as deep inelastic and quasielastic transfer reaction products. For the uranium target reactions they form the mass distribution colloquially referred to as the "gold finger." The measured recoil range distributions for the gold target reactions are correlated with energy and angular distribution measurements made on the projectile - like fragments formed in deep inelastic reactions.NUCLEAR REACTIONS $^{197}\mathrm{Au}(\mathrm{Kr},X)Y$, ${E}_{\mathrm{lab}}=420, 491, 581$ MeV; $^{197}\mathrm{Au}(^{136}\mathrm{Xe},X)Y$, ${E}_{\mathrm{lab}}=868$ MeV; $^{238}\mathrm{U}(^{86}\mathrm{Kr},X)Y$, ${E}_{\mathrm{lab}}=686$ MeV. Measured recoil range distributions for $72<~{Z}_{y}<~84$.

Trimuons from charm

We have calculated charm pair production in νμN collisions using quantum chromodynamics (QCD). The resulting trimuon rate turns out to be small at present energies: σ(3μ)σ(1μ)≲10−6 at Eν = 200 GeV for αs = 0.2. (However, this process may be measurable at the high energies attainable with colliding beam ep machines.) We emphasize the general importance of looking for inclusive JΨ or the bound states of heavier flavors in deep inelastic reactions, as a signal for the pair production of heavy quarks.

Space-time evolution and transverse- momentum structure of jets

We discuss models in which the temporal evolution of hadronic jets and the rapidity ordering of particles within jets are correlated. Observable effects on the particle average transverse momentum (energy and longitudinal momentum dependence) characteristic of such models are pointed out. In particular, models in which, within jets, slow particles are produced first and fast particles come out last should exhibit the well-known seagull effect, with 〈 p T〉 rising, for fixed x, proportionately to the square root of the mean particle multiplicity. If, by analogy, the transverse-momentum distributions of partons also exhibit such features, then we have a source of scaling violation in deep inelastic reactions that shows up at high energies rather than at low energies, and a source for an energy and Q 2 dependent 〈 q T〉 in lepton pair production.

Statistical fluctuations and the double differential cross section for energy and angle in deep inelastic reactions

We use a model which accounts for dissipation and statistical fluctuations to compute the double differential cross sectiond2σ/dθdE. The calculation is performed for the 388 MeV Ar + Th system. The typical experimental pattern of the cross section versus angle and energy is reproduced.

Large contribution of deep inelastic processes to reactions of40Ar and48Ca with238U

Differential recoil range distributions have been measured for heavy-reaction products ranging from Te(Z=52) to quasielastic transfer products near the charge and mass of the targets for the reactions of 276 MeV48Ca+238U, 237MeV and 250 MeV40Ar+238U, and 259 MeV40Ar+197Au. The measured recoil range distributions for the40Ar+197Au reaction agree with range distributions calculated from the known projectile-like fragment angular distributions for this reaction. The angular distributions of recoil products formed in the uranium target reactions are deduced and show that the products in the75Re to83Bi region have backward peaked angular distributions characteristic of deep inelastic reactions. The heavy product angular distributions smoothly vary from a (1/sinθ) shape to an exponential shaped backward peak as the atomic number of the product increases from 52 to 83. The trend in the deduced angular distributions for those elements for which recoil range distributions were determined in the40Ar+197Au reaction and the 250 MeV40Ar+238U reaction is similar, suggesting that just as for the Ar+Au system the composite system for the uranium target reaction is also not fully equilibrated along the mass asymmetry coordinate. These conclusions show that the fraction of the total reaction cross section resulting in complete fusion must be re-evaluated for the40Ar+238U reaction and similar heavy-target reactions.

On the validity of a model for deep inelastic reactions

The inclusive inelastic proton cross section on 208Pb in the energy-loss range of 10–20 MeV cannot be reasonably accounted for by one-step reactions, contrary to a claim of a recent article. We make a sum rule analysis to expose the problem as clearly as possible.

Deep inelastic pion-induced nuclear reactions in the isobar model

Deep inelastic pion-induced nuclear reactions are calculated in the isobar model, which assumes that an interacting resonant pion and nucleon form an unstable particle, the $\ensuremath{\Delta}$, which can propagate through the nucleus and either decay or be absorbed by interacting with other nucleons in the nucleus. The propagation of the particles is treated classically and the interactions are assumed to be incoherent. The lifetime of the $\ensuremath{\Delta}$ is taken to be energy dependent as prescribed by measured pion-nucleon scattering and the cross section of the $\ensuremath{\Delta}$ absorption is determined by measured pion production in two nucleon collisions. The formation of the $\ensuremath{\Delta}$ by a pion and nucleon and the subsequent absorption of the $\ensuremath{\Delta}$ provide a two-step mechanism for pion absorption. These calculations indicate that the pion is absorbed mostly on the inside forward edge of the nuclear surface where the nuclear density has almost reached central density. The calculations are compared with measured pion absorption cross sections, proton spectra, and spallation products in pion-induced reactions. All of these data indicate that pion absorption is underestimated in this model by perhaps as much as 35%, particularly for low energy (\ensuremath{\sim} 100 MeV) pions. Possible explanations for these discrepancies are discussed.[NUCLEAR REACTIONS Calculated absorption cross section, proton spectra, and spallation products for pion-induced reactions on various nuclei.]

Deep inelastic reactions with heavy ions. A probe for nuclear macrophysics studies

Deep inelastic reactions with heavy ions. A probe for nuclear macrophysics studies

Neutron-multiplicity in deep inelastic collisions: 365 MeV Cu+Au system

Neutrons have been detected in coincidence with the two outgoing fragments in deep inelastic reactions of63Cu on197Au at 365 MeV. Most of these neutrons are evapored from the fully accelerated fragments. An additionnal low energy contribution appears.