Neutron total cross sections on nuclei at Fermilab energies

We have measured total cross sections for neutrons on protons, deuteriom, beryllium, carbon, aluminium, iron, copper, cadmium, tungsten, lead, and uranium for momenta between 30 and 300 GeV/c. The measurements were carried out in a small-angle neutral beam at Fermilab. Typical accuracy of the data is 0.5 to 1%. The cross sections are consistent with an A^0.77±0.01 dependence over the entire momentum range. The cross sections are compared with theoretical predictions. Agreement is found only if inelastic screening is included. Nuclear radii obtained from our data are in good agreement with previous determinations.     

Total cross sections scattering at of positron-sodium low energies

A new calculation for the total cross section of positron-sodium scattering is performed in an energy range down to a few tenths of one electron volt using the coupled-channel optical method.The ionization continuum and the positronium formation channels are included via an equivalent-local complex potential.The role played by the break-up and rearrangement processes in the low energy positron-sodium scattering is also investigated.The total scattering cross section is reported and compared with the available theoretical and experimental data.     

A barrier-penetration model for heavy-ion fusion,valid at all energies

We present a barrier-penetration model for heavy-ion fusion valid from the lowest energies available up to the largest energies for which the critical-radius picture is realistic. The parameters of the model are a critical radius and the parameters of a nucleus-nucleus interaction, whose form factor can be chosen freely. Fusion cross sections for a large number of systems, for which low-energy data exist, are fitted with a Woods-Saxon potential. Realistic parameters are obtained for the Coulomb barrier. Different applications and some limitations of the model are discussed.     

Total cross sections of positronben sodium scattering at low energies

A new calculation for the total cross section of positron-sodium scattering is performed in an energy range down to a few tenths of one electron volt using the coupled-channel optical method. The ionization continuum and the positronium formation channels are included via an equivalent-local complex potential. The role played by the break-up and rearrangement processes in the low energy positron-sodium scattering is also investigated. The total scattering cross section is reported and compared with the available theoretical and experimental data.     

Topological cross sections in hadron-nucleon and hadron-nucleus collisions at very high energies

We apply our microscopic model for the topological cross section σ_n to produce n charged particles in hadron-proton interactions to hadron-nucleus scattering. The model is based on a stochastic branching process for hadronization. We calculate multiplicity distributions of hadron-nucleus collisions for 50 GeV ? E_L ? 400 GeV based on a multiple collision model. The production of “grey” $\text{(0.3 <}\text{ν}\text{c}\text{< 0.7)}$ particles is considered together with the shower $\text{(}\text{ν}\text{c}\text{> 0.7)}$ particles in order to test the model for higher number of collisions. The joint probability distribution of numbers of shower and grey particles F(n_s, n_g) is calculated. Finally, we critically compare the results to experimental data.     

Maximal electromagnetic contribution to pp inelastic cross sections at ISR energies

The maximal electromagnetix contribution to the pp inelastic cross section is estimated. Although this contribution is insufficient in itself to explain all of the recently observed rise at ISR energies if the purely strong cross section is asymptotically constant, it could amount to as much as approximately 3 mb at √s ≈ 53 GeV if the purely strong cross section rises with energy through the range of present accelerator energies like (ln s)² or slower.     

Unexpected behavior of heavy-ion fusion cross sections at extreme sub-barrier energies

The excitation function for fusion evaporation in the (60)Ni+ (89)Y system was measured over a range in cross section covering 6 orders of magnitude. The cross section exhibits an abrupt decrease at extreme sub-barrier energies. This behavior, which is also present in a few other systems found in the literature, cannot be reproduced with present models, including those based on a coupled-channels approach. Possible causes are discussed, including a dependence on the intrinsic structure of the participants.     

Differential cross sections for Higgs boson production at tevatron collider energies

The transverse momentum Q(T) distribution is computed for inclusive Higgs boson production at sqrt[S]=1.96 TeV. We include all-orders resummation of large logarithms associated with emission of soft gluons at small Q(T). We provide results for Higgs boson and Z* masses from M(Z) to 200 GeV. The relatively hard transverse momentum distribution for Higgs boson production suggests possibilities for improvement of the signal to background ratio.     

Coulomb polarization corrections to the cross sections of nucleosynthesis at low energies

The effects of electric polarizability of particles are shown to play an insignificant role in nucleosynthesis reactions at astrophysical low energies. The polarization corrections to S-factors of the reactions under consideration are defined by the value of the polarization potential at the boundary of the nuclear force range and do not exceed the quantity of the order of 0.1%.     

Angular and energy dependences of cross sections for deuteron electrodisintegration at subbarrier energies

A method is proposed for analyzing a large set of spectra calculated for the Coulomb breakup of deuterons. The regularities in the behavior of the respective cross section as a function of the emission angles and energies of particles constituting the deuteron are studied on the basis of this method. The deuteron-breakup reaction on lead nuclei at an energy of E _d = 8 MeV is considered by way of example. It is shown that the approximate Landau-Lifshitz formulas for this process are unable to predict some of its features. An experiment is proposed for studying the physical nature of the Nemets effect.     

Total electron scattering cross sections for carbon dioxide at low electron energies

Absolute total electron scattering cross sections for carbon dioxide have been measured at low electron energies using a photoelectron source. The measurements have been carried out at 27 electron energies varying from 0.91–9.14 eV with an accuracy of ±3%. The cross sections obtained in the present experiment have been compared with other measurements and theoretical computations.     

Fusion cross sections for 10,11B+12C at sub-Coulomb energies

Total fusion cross sections for the ¹⁰B + ¹²C and ¹¹B + ¹²C reactions have been determined over a 5 MeV (c.m.) energy range extending to ≈ 3 MeV below the Coulomb barrier. Absolute γ-ray yields for specific transitions in the de-excitation of the heavy products following compound nucleus decay were measured using a Ge(Li) detector. Statistical model calculations of the decay modes of the compound nucleus have been used to deduce, from the γ-ray data, cross sections for single proton, neutron and α-particle emission, and to determine total cross sections for compound nucleus formation. No evidence has been found for sub-Coulomb resonances in either reaction. The total reaction cross sections are compared with optical model calculations using different parameter sets and the observed trend in the very low energy cross sections is discussed relative to other reactions in the same mass region.     

Test of the universal rise of hadronic total cross sections at super-high energies

The increase of the total cross sections at very high energies described by log²(s/s₀) appears to be confirmed. In the analysis of the COMPETE collaboration in the Particle Data Group (2006), the Blog²(s/s₀) was assumed to extend the universal rise of all the total hadronic cross sections to reduce the number of adjustable parameters. We test if the assumption on the universality of B is justified, through investigation of the values of B for π^±p(K^±p) and p̄p,pp scatterings. We search for the simultaneous best fit to the σ_tot and ρ ratios, using a constraint from the FESR of the P^′ type for π^∓p scatterings and constraints that are free from the unphysical regions for the p̄p,pp and K^±p scatterings. By including rich information of the low-energy scattering data owing to the use of FESR, the errors of the B parameters decrease especially for πp. The resulting value of B_pp is consistent with B_πp within two standard deviations, which appears to support the universality hypothesis. PACS 11.55.Hx; 13.85.Lg     

The validity of the factorization hypothesis for nucleus-nucleus cross sections at high energies

We have calculated nucleus-nucleus cross sections for a variety of projectile and target nuclei and a wide range of energy. Total, reaction and elastic cross sections, as well as the slopes of the elastic diffraction peak, exhibit an approximate factorization property when the nuclei differ by less than 50% in r.m.s. radii. A simple geometrical interpretation is provided for the failure of factorization which occurs when target and projectile differ greatly in size.     

Elastic differential cross sections of electron scattering by CF_4 at intermediate energies

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