Proton-nucleus Cross Sections Research Articles

Proton–nucleus scattering and cross section fluctuations at RHIC and LHC

We consider high-energy proton–heavy nucleus scattering within the framework of the Glauber–Gribov approximation and taking into account cross section fluctuations. Fixing parameters of the model for cross section fluctuations by the available data, we make predictions for the total, elastic and coherent diffractive dissociation proton–nucleus cross sections for the RHIC and LHC energy range. We predict a strong change of the A-dependence of diffraction dissociation from A0.42 at RHIC energies to A0.27 at LHC energies. Based on the obtained results, we discuss the approach of the interactions to the black body (unitarity) limit. We estimate the electromagnetic contribution to coherent pA diffraction and find that it dominates the coherent diffractive cross section on heavy nuclear targets in the LHC kinematics.

Limiting fragmentation from the color glass condensate

We show how the limiting fragmentation phenomenon can arise from the Color Glass Condensate model of high energy QCD. We consider the very forward rapidity region in relativistic heavy ion collisions and argue that in this region, nucleus-nucleus collisions are similar to proton-nucleus collisions (up to shadowing corrections). We then use the known results for proton-nucleus cross sections to show that it leads to the phenomenon of limiting fragmentation in the very forward region of heavy ion collisions as observed at RHIC.

Parameterization and optical model analyses of proton-nucleus cross sections for space shielding

For space system shielding analysis, proton-nucleus nonelastic cross sections of /sup 12/C, /sup 14/N, /sup 16/O, /sup 27/Al, /sup 28/Si, /sup 40/Ca, /sup 56/Fe, /sup 90/Zr and /sup 208/Pb below 400 MeV, were evaluated by optical model analysis and parameterized utilizing accumulated experimental data.

Proton-nucleus cross section at high energies

Cross sections for proton inelastic collisions with different nuclei are described within the Glauber and multiple scattering approximations. A significant difference between the approximate `Glauber' formula and exact calculation with a geometrical scaling assumption for very high-energy cross section is shown. Experimental values of proton-proton cross sections obtained using extensive air shower data are based on the relationship of proton-proton and respective proton-air absorption cross sections. According to obtained results values reported by the Akeno and Fly's Eye experimental groups are about 10% overestimated. The proper energy dependence of absorption cross section for collisions with air nuclei is of a great importance for studies of high-energy cosmic rays using the Monte Carlo technique.

Partial Cross Sections of Nucleus‐Nucleus Reactions

Spallation cross sections of nucleus-nucleus reactions are calculated by scaling up the proton-nucleus cross sections (with additional fitting factors) using the weak factorization property of fragment production and, with adjusted energy dependence, using the concept of nuclear participants and spectators in nuclear interactions. Special fittings are provided for charge-pickup cross sections. Separate calculations are presented for electromagnetic dissociation cross sections. Elemental and isotopic resolution is comparable to that of the proton-nucleus interactions. Also a brief discussion is presented of the total inelastic cross sections and their energy dependence.

Single diffractive hadron-nucleus interactions within the dual parton model

Single diffractive hadron-nucleus interactions are studied within the framework of the dual parton model. Introducing a diffractive component into the Monte-Carlo event generator DTUNUC we investigate particle production and the dependence of the diffractive cross section on the atomic number of the target nucleus. A comparison of the numerical results with recent experimental data is presented. We furthermore introduce hadronic cross section fluctuations and discuss their influence on diffractive proton-nucleus cross sections.

K+ mesons as a probe of the nuclear interior.

The sensitivity of intermediate energy K/sup +/ meson-induced elastic and inelastic differential cross section predictions to nuclear structure effects in the nuclear interior is examined for /sup 40/Ca and /sup 208/Pb targets. The observed sensitivity for K/sup +/ mesons is compared to that obtained with intermediate energy protons. In general, the K/sup +/ meson+nucleus elastic and inelastic scattering differential cross sections are an order of magnitude more sensitive to details of nucleon density distributions in the nuclear interior than corresponding proton-nucleus cross sections at comparable incident momentum. It is found that theoretical analyses of high quality K/sup +/ meson+nucleus data which extend to 3 fm/sup -1/ momentum transfer could, in principle, provide new information regarding neutron ground state and transition density distributions in the interiors of large nuclei.

Analyzing Power in Inclusive Proton-Nucleus Cross Sections

This paper reports measurements of the analyzing power, A/sub y/, in the production of both ''backward'' protons and forward (quasifree scattering) protons in the reaction p + A ..-->.. p + X, using 800-MeV polarized protons. For the backward protons the measurements show large negative A-dependent values of A/sub y/ at low momenta, changing to large positive values at high momenta; in the quasielastic region, A/sub y/ is large and positive, is smaller than A/sub y/ measured in hydrogen, and decreases with increasing A.

Analytic representation of the proton-proton and proton-nucleus cross-sections and its application to the sea-level spectrum and charge ratio of muons

We have calculated the sea-level differential muon momentum spectrum and their charge ratio from 1 GeV/c to 5000 GeV/c, using all of the available accelerator data. We find an excellent agreement between our calculation and the existing experimental data. We see no need, at present, to invoke any change either in the cosmic-ray chemical composition or in the nature of the hadron-nucleus interaction at hadron energies above 1500 GeV.

A search for precursors to extensive air showers

No evidence for precursors to cosmic ray air showers was found ( “ flux”≲10 −8 cm −2 sr −1 s −1 ) in a sample 2.8 times that of Clay and Crouch and a system noise level several times lower. A simple model leads to a cross leation for production ≲60 times the total proton-nucleus cross section.

Proton-nucleus cross sections and the peripheral component of elastic scattering

A model of proton-proton scattering is presented in which ${\ensuremath{\sigma}}_{\mathrm{pp}}$ rises with energy due to large-impact-parameter effects which are associated with the two-pion-exchange cut. The model is applied to the question of determining ${\ensuremath{\sigma}}_{\mathrm{pp}}$ from proton-nucleus interactions of cosmic rays.

Total proton-nucleus cross-section and coherent processes in the TeV region from cosmic-ray data

Total proton-nucleus cross-section and coherent processes in the TeV region from cosmic-ray data