Realistic calculations of parity distributions and densities of exciton states at high excitation energy

Effects of the density-dependence of theα-particle-bound nucleon effective interaction on single-folding models of inelasticα-particle scattering are studied, in particular in view of corrections of the isoscalar transitions rates extracted by implicit folding procedures. Thel-dependent corrections factorsC _l are calculated and tubulated for applications.     

The excitation of collective nuclear states by high energy particles

The excitation of collective nuclear states by high energy particles is considered within the framework of the Glauber theory. The approach is based on the adiabatic approximation and expansion of the scattering amplitude in powers of the nonsphericity parameter. The formulae for the excitation cross sections of the rotational and one- and two-phonon vibrational states, as well as the elastic scattering cross section with the collective motion included, are obtained. The effect of nucleon correlations in both elastic and inelastic cross sections is also studied. The theoretical predictions are compared to new data on 1 GeV proton scattering by ⁵⁸Ni, ²⁰⁸Pb, ¹²C, ⁴⁰Ca and ³⁹K. A comparison with electron scattering data is simultaneously carried out. The agreement with the experimental data is generally good.     

Observation of two-hole states at high excitation energy in (p,t) reactions

Bumps of two-hole states at high excitation energies were observed systematically in the triton spectra from (p, t) reactions with 52 MeV protons on nuclei in a broad range of masses. The cross sections of the bumps are almost equal for various targets with the same deep major shells. These cross sections vary discontinuously with variation of the corresponding deep major shell. About 20 to 50 % of the total expected strength is observed experimentally, if the bumps are assumed to arise from two-neutron pickup from the deep major shells. The centres of gravity of the bumps are located at excitation energies of about 7 to 9 MeV in all cases. On the other hand, the widths of the bumps change from about 3 MeV for ⁶⁶Zn to about 9 MeV for ²³⁰Th.     

Behaviour of single-particle states and their eigenvalues near zero energy

For a state in a single-particle potential we derive simple expressions that the eigenvalue behavior and normalization integral properties near threshold. For the square-well, the various parameters in these expressions can be derived analytically. For the more realistic Saxon-Woods well-shape, we have made numerical calculations for s- and p-states and obtained values of these parameters and give rules for their evaluation. We show that those parameters determining the negative energy eigenvalues are also involved in determining the positive energy behavior, and the normalization properties. These studies have direct relevance to recent theories of some types of (d, p) and (n, γ) reactions which critically involve threshold behavior.     

On the energy spectra of single-particle states in nuclei

The single-particle spectra of ¹⁶O, ⁴⁰Ca, ⁴⁸Ca and ⁵⁶Ni have been studied using self- consistent field methods and a quadratically velocity-dependent two-nucleon effective (reaction- matrix) interaction. The self-consistent field equations are derived in some detail for the spin- independent interaction which is used. A one-body spin-orbit interaction of the Thomas form is added.     

A new possibility of identifying high-spin states at high excitation energies

A new method of identifying high-spin states at high excitation energies is presented.     

On the production of hidden-flavored hadronic states at high energy

I discuss the production mechanism of hidden-flavored hadrons at high energy. Using e+e-collisions and light-meson pair production in high energy exclusive processes, I demonstrate that hidden quark pairs do not necessarily participate in short-distance hard scattering. Implications are then explored in a few examples. Finally, I discuss the production mechanism of X(3872) in hadron collisions, where some misunderstandings have arisen in the literature.     

Hole states in single-particle knock-out reactions

The hole states created in single-particle knock-out reactions are physical states but have finite lifetime. The hole is moving in a complex potential, the imaginary part of which is related to the width of the state, and the hole energy and wave functions are complex. The influence of these features on the momentum distributions of the hole is studied for the knock-out of the 1s and 1p protons from ¹²C and is found to be rather insignificant. However it is interesting to note that the overlap integral in momentum space shows a significant change.     

Proton-antiproton states in high energy photoproduction

Exclusive and inclusive $\text{p}\text{p}$ photoproduction (with ? 2 accompanying charged particles) have been measured in the photon energy range 44–70 GeV. The exclusive process shows no prominent features; the inclusive process shows evidence for S(1936) production as a resonant-like structure with mass 1930 ± 2 MeV and width 12 ± 7 MeV.     

Coupling of core excitation and single-particle motion in odd-a-nuclei

A physical fractional parentage expansion is presented which can be used to treat the coupling of single-particle and core motion in terms of the physical eigenstates of the core. The antisymmetry requirement is formulated in a subsidiary condition which allows diagonalization of the coupling Hamiltonian in the product space of the core and the extra-core particle. Restriction to a subset of core excitations leads to only approximate fulfillment of the subsidiary condition. The usefulness of the method is tested in the quasi-spin model.     

Collective octupole vibration and proton single-particle levels in zirconium nuclei

Self-energy correction to the shell model single-particle motion, arising from the excitation of octupole vibration in the intermediate state, accounts quite well for the energy shifts of the 2p _1/2 and 1g _9/2 proton orbits in zirconium nuclei.     

Soft-gluon resummation for single-particle inclusive hadroproduction at high transverse momentum

We consider the cross section for one-particle inclusive production at high transverse momentum in hadronic collisions. We present the all-order resummation formula that controls the logarithmically-enhanced perturbative QCD contributions to the partonic cross section in the threshold region, at fixed rapidity of the observed parton (hadron). The explicit resummation up to next-to-leading logarithmic accuracy is supplemented with the computation of the general structure of the near-threshold contributions to the next-to-leading order cross section. This next-to-leading order computation allows us to extract the one-loop hard-virtual amplitude that enters into the resummation formula. This is a necessary ingredient to explicitly extend the soft-gluon resummation beyond the next-to-leading logarithmic accuracy. These results equally apply to both spin-unpolarized and spin-polarized scattering processes.     

Behavior of the giant-dipole resonance in 120Sn and 208Pb at high excitation energy

The properties of the giant-dipole resonance (GDR) are calculated as a function of excitation energy, angular momentum, and the compound nucleus particle decay width in the nuclei ¹²⁰Sn and ²⁰⁸Pb, and are compared with recent experimental data. Differences observed in the behavior of the full-width-at-half-maximum of the GDR for ¹²⁰Sn and ²⁰⁸Pb are attributed to the fact that shell corrections in ²⁰⁸Pb are stronger than in ¹²⁰Sn, and favor the spherical shape at low temperatures. The effects shell corrections have on both the free energy and the moments of inertia are discussed in detail. At high temperature, the FWHM in ¹²⁰Sn exhibits effects due to the evaporation width of the compound nucleus, while these effects are predicted for ²⁰⁸Pb.     

Collective excitation modes in the intermediate and superconducting states of doped and undoped indium and lead

Ultrasonic attenuation was studied in pure In, In + 0.003 at.% Pb, pure Pb and Pb + 0.003 at.% In in the intermediate states (for the magnetic fields 0.7H _c and 0.9H _c ) and superconducting states, for frequencies varying from 9.9 to 29.7 MHz, in the temperature range 4.2 to 1.4K. Collective excitation modes were observed in both the states for all the samples. There exist two distinct phases in the intermediate state but only one phase in the superconducting state in all the samples. The first phase was dependent on the magnetic field and independent of the concentration and nature of the dopant. The second phase was independent of the magnetic field and dependent essentially on the concentration of vacancies and marginally on the concentration of the dopant. The origin of the two phases has been discussed.     

Nuclear structure at high excitation energies

The present paper deals with the investigation of hot GDR and quadrupole shapes of ^106,120Sn isotopes as a function of temperature and spin utilizing cranked quadrupole-quadrupole model interaction hamlitonian in the linear response theory and static path approximation to the grand canonical partition function.     

Particle-to-fission competition at high excitation energies

For application in statistical model evaporation codes, a model is presented which describes the experimental observation of multifold particle emission prior to fission, even from very fissile highly excited composite nuclei. This model is based upon the assumption that collective motion of many nucleons towards the scission point is slow compared to evaporation times for single nucleons. The relative times required for particle evaporation and collective motion towards the scission point are estimated, using as a first-order approximation, the frequencies of the lowest modes of particle vibration and low-frequency β-quadrupole vibration, respectively. Comparisons with data for the systems¹²C+¹⁸²W,⁴⁰Ar+¹⁵⁴Sm,¹⁹F+¹⁸¹Ta, and²⁰Ne+¹⁶⁵Ho show good agreement with the model calculations.     

The continuum strength of single-particle states in nuclei

Methods are devised to calculate the continuum strength of neutron valence orbits starting with an empirical optical-model potential. Allowance is made for the fact that the bound-state and real optical-model potentials have a common nonlocal origin. Direct calculations are made for the $\text{2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{, 1}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{,}\text{and}\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ orbits of the contribution from the elastic-scattering chann also of the total continuum strength using a spectral representation. As predicted by McKellar and also by an improved perturbation model given here, most of the continuum strength lies in inelastic and rearrangement channels. When combined with 5% missing strength from the NN potential core, the estimated total continuum strength is ?12–15% of the single-particle sum rule, which is compatible with other deductions from experimental data.