Total Interaction Cross Sections Research Articles

Microscopic study of interaction cross sections measured at relativistic energies for stable and unstable nuclei

Fully quantal calculation of the total reaction cross sections and interaction cross sections, induced by stable and unstable He, Li, C and O isotopes on 12C target at E 1ab≈0.8 and 1 GeV/nucleon has been performed using the microscopic (complex) optical potential given by the folding model. Realistic nuclear densities for the projectiles and 12C target as well as the complex t-matrix parameterization of free nucleon-nucleon interaction by Franey and Love were used as inputs for the folding calculation. Given the interaction cross sections measured with high accuracy, the presented folding approach was shown to be very efficient in testing the nuclear ground state densities and is thus a reliable (microscopic) alternative to the Glauber model in deducing the nuclear radius from the measured nucleus-nucleus interaction cross section.

Do we really understand nuclear reactions within thick targets using GeV-hadrons?

Three experimental evidences are presented to show that, using classical concepts of physics, we are unable to understand the interaction of 72 GeV 40 Ar (and 44 GeV 12 C ) and their relativistic secondary fragments in thick Cu-targets. The first observation is connected with fragmentation products of mass A in the range of 10⩽ A⩽40, in particular to the production of more-than-calculated yields of 24 Na . The reason for this unexpected behavior is due to some enhanced interaction properties for relativistic secondary fragments. Moreover, due to the observation of constant classical total interaction cross sections for primary and secondary hadrons, this enforces a reduced production of spallation products being close to the target, as is in fact experimentally observed (the second evidence). The third experimental observation is a more-than-linear increase in the production of secondary neutrons for reactions induced by 44 GeV 12 C in thick Pb- and Cu-targets as compared to 12 GeV 12 C . This can be understood within the context of the first two experimental evidences. These effects are experimentally confirmed above about 40 GeV for hadronic primaries, however, they may even extend down to 1 GeV primary hadron energy. Results are discussed within the context of a new theoretical approach.

Nucleon–nucleus real potential of Woods–Saxon shape between −60 and +60 MeV for the 40 ⩽ A ⩽ 208 nuclei

Nucleon differential elastic scattering cross sections, total proton reaction cross sections and single-particle energies of nucleon bound states for 40Ca, 90Zr and 208Pb nuclei are reanalysed in terms of the dispersive optical model at energy from −75 MeV to 60 MeV. The real effective Woods–Saxon potential, which corresponds to the real part of the dispersive optical model potential, is studied with respect to its dependence on A, Z, E and on projectile nature (proton or neutron). For the first time, a parametrization of the Woods–Saxon real part of the nucleon–nucleus optical potential is proposed for the 40 ⩽ A ⩽ 208 nuclei in an energy range from −60 MeV to +60 MeV, which obviously includes the Fermi energy range. The parametrization reflects the dispersion relation between the real and imaginary parts of the optical model potential through the energy dependence of the radius parameter of the real part of the potential. The method of determining the imaginary part of the optical model potential, which is symmetrical relative to the Fermi energy, is also proposed for the nuclei with 40 ⩽ A ⩽ 208. Differential elastic scattering cross sections, total neutron interaction cross sections, total proton reaction cross sections and single-particle energies of the nucleon bound states are calculated in terms of the proposed nucleon–nucleus potential parametrization for some of the (n + A) and (p + A) (40 ⩽ A ⩽ 208) systems and compared with the available experimental data, yielding a fairly good agreement.

Total cross section for photon-nucleon interaction in the energy range $$\sqrt \mathcal{S} = 40 - 250 GeV$$

Results obtained by directly measuring the total cross section for photon-nucleon interaction through recording photoproduction processes at the Baksan underground scintillation telescope of the Institute for Nuclear Research (Russian Academy of Sciences, Moscow) are presented. The effect of a faster growth of photon-hadron cross sections in relation to hadron-hadron cross sections is confirmed in the energy range \(\sqrt \mathcal{S} = 40 - 130 GeV\). It is shown that an increase in the number of additive quarks in photon-hadronization products may be one of the reasons behind this effect. Experimental data on the cross sections for photon-nucleon and photon-photon interactions are subjected to a comparative analysis, and the status of the results obtained from direct and indirect cross-section measurements in the high-energy region is discussed.

Fading out of J/ ψ color transparency in high energy heavy ion peripheral collisions

We provide predictions for the J/ ψ coherent production in the peripheral heavy ion collisions at LHC and RHIC using the leading twist model of nuclear shadowing based on the QCD factorization theorem for diffraction and the HERA hard diffraction data. We demonstrate that for LHC kinematics this model leads to a bump-shape distribution in rapidity which is suppressed overall as compared to the expectations of the color transparency regime by a factor ∼6. This is a significantly larger suppression than that expected within the impact parameter eikonal model. Thus we show that the interaction of spatially small wave package for which the total cross section of interaction with nucleons is small is still strongly shadowed by nuclear medium in high energy processes.

Contribution ofα2terms to the total interaction cross sections of relativistic elementary atoms with atoms of matter

It is shown that the corrections of ${\ensuremath{\alpha}}^{2}$ order to the total cross sections for the interaction of elementary hydrogenlike atoms with target atoms, reported in a previously published paper [S. Mr\'owczy\ifmmode \acute{n}\else \'{n}\fi{}ski, Phys. Rev. D 36, 1520 (1987)], do not include some terms of the same order of magnitude. This results in a significant contribution of these corrections in particular cases. The full ${\ensuremath{\alpha}}^{2}$ corrections have been derived and it is shown that they are really small and could be omitted for most practical applications.

Molar extinction coefficients in aqueous solutions of some amino acids

Mass attenuation coefficients of amino acids viz. glycine (C2H5NO2), l-Serine (C3H7NO3), l-Theronine (C4H9NO3), l-Proline (C5H9NO2), l-Valine (C5H11NO2) and l-Phenylalanine (C9H11NO2) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by the gamma-ray transmission method in a narrow beam good geometry setup. Precisely measured densities of these solutions were used for the determination of these coefficients which varied systematically with the corresponding changes in the concentrations (g/cm3) of the solutions. Molar extinction coefficients of amino acids were then obtained at these energies and were found to be in good agreement with the theoretical results. In addition, total interaction cross sections of amino acids in aqueous solutions were also calculated.

INVESTIGATION ON THE NEUTRINO INDUCED MUONS FROM ACTIVE GALACTIC NUCLEI

The fluxes of neutrino induced muons at different zenith angles have been calculated using the high energy diffused neutrino spectra emitted from blazars. We have used the standard formulation developed by Gaisser based on charge-current interactions in rock and the QED-based energy loss formulation to estimate the spectra of neutrino induced muons. The energy spectra of neutrino flux generated from blazars has been taken from the model calculations of Protheroe. The latest charge-current and total interaction cross-sections at ultrahigh energies from Kwiecinski et al. have been used to find the probability of muon generation from neutrinos and the loss of neutrinos during propagation through the Earth. We find that our derived horizontal neutrino induced muon energy spectra expected from blazar model of Protheroe is comparable with the upper limits as predicted by SOUDAN 2 experiment.

Determination of atomic cross-sections and effective atomic numbers for some alloys

The transmission of gamma-rays at the energies, 81, 356, 511, 662, 835, 1274 and 1332 keV has been studied on the alloys brass, bronze, steel, aluminum–silicon and lead–antimony. The mass absorption coefficients have been measured. The total interaction cross-sections and effective atomic numbers have been determined on the basis of mixture rule and compared with the results obtained from theory.

Electromagnetic Dissociation of Au Targets by Relativistic Pb Projectiles

Electromagnetic Dissociation (ED) occurs in collisions of relativistic heavy ions involving impact parameters larger than the nuclear interaction radius. In such collisions strong electromagnetic fields acting at the nucleus can produce, for high charges and ultrarelativistic energies, cross sections much larger than the total nuclear interaction cross section. In ED collisions absorption of a virtual photon generally leads to excitation of a nuclear giant resonance. The NA53 experiment studied ED by bombarding Au targets with 158 GeV/nucleon Pb projectiles from the SPS accelerator. Preliminary values of σED for the one- and two-neutron removal processes were determined to be 26.4 ± 4.0 and 4.6 ± 0.7 barns, respectively. Theoretical predictions for σED were calculated including the effects of both the E1 and E2 giant resonances. The calculations are extended to energies planned for heavy ion collisions at the RHIC and LHC colliders.

Electromagnetic dissociation of Au targets by relativistic Pb projectiles

Electromagnetic Dissociation (ED) occurs in collisions of relativistic heavy ions involving impact parameters larger than the nuclear interaction radius. In such collisions strong electromagnetic fields acting at the nucleus can produce, for high charges and ultrarelativistic energies, cross sections much larger than the total nuclear interaction cross section. In ED collisions absorption of a virtual photon generally leads to excitation of a nuclear giant resonance. The NA53 experiment studied ED by bombarding Au targets with 158 GeV/nucleon Pb projectiles from the SPS accelerator. Preliminary values of σ ED for the one- and two-neutron removal processes were determined to be 26.4 ± 4.0 and 4.6 ± 0.7 barns, respectively. Theoretical predictions for σ ED were calculated including the effects of both the E1 and E2 giant resonances. The calculations are extended to energies planned for heavy ion collisions at the RHIC and LHC colliders.

Total interaction cross sections of relativistic +--atoms with ordinary atoms in the eikonal approach

The total interaction cross sections of the relativistic +--atoms with ordinary atoms are obtained in the eikonal approach which takes into consideration all multiphoton exchange processes. The contribution of these processes strongly depends on the atom nucleus charge Z and varies from 1.5% for titanium (Z = 22) to 14% for tantalum (Z = 73). The formulae derived are applicable for an arbitrary initial state of the +--atom.

Detector Calibration by Monte Carlo Simulation Based on the Energy-Range Relationship of Energetic Ions

The experimental measurement of the total interaction cross sections of N, C, B, and Be isotopes on 12C target at medium energies is described. A new formula that gives a good description of the energy-range relationship of energetic ions over a wide energy range is presented. The energy calibration of detectors is made by a Monte Carlo simulation method based on this new formula.

Small x physics at HERA

Recent measurements of the structure function F 2 in e +p scattering at HERA were presented for a wide range of Q 2 and x. The rapid rise of F 2 with decreasing x has been confirmed with high statistical data obtained in 1994. In the measurements, the Q 2 range was extended down to 1.5GeV 2. The rise corresponds to the rapid increase of the total virtual photon-proton cross section at high energies. On the other hand, the total cross section of photon-proton interaction at Q 2 = 0 has no strong energy dependence. H1 and ZEUS performed new F 2 measurements for Q 2 < 1GeV 2 with upgraded detectors in order to study the transition region. The results were shown and compared to predictions of various models.

Total interaction and proton-removal cross-section measurements for the proton-rich isotopes 7Be, 8B, and 9C

In an experiment performed at the FRS of GSI, we measured total interaction cross sections for 7Be, 8B, and 9C, one-proton-removal cross sections for 8B and 9C as well as two-proton-removal cross sections for 9C on targets ranging from carbon to lead at an energy of 285 MeV/nucleon. In addition, we performed measurements at 142 MeV/nucleon for 8B. The experimental results are compared to different calculations. Glauber-type calculations with different model·density distributions show that, down to incident energies of about 50 MeV/nucleon, total interaction cross-section measurements with light targets are not sensitive to an extended proton distribution in 8B. However, at lower incident energies, a tail in the proton density distribution is needed to explain the total interaction cross sections. Total interaction cross-section measurements with high-Z targets in the present experiment show a significant increase of the cross sections due to low-lying electromagnetic strength.

Computer simulation of SiC and B 4C sputtering by Ar + and He + ions bombardment

The detailed research of the B 4C and SiC sputtering differential characteristics under Ar + and He +-ions irradiation with the energies 0.5–20 keV has been carried out using both CASNEW and like-TRIM Monte Carlo codes. The major difference between these codes is the following: the dependence of the total interaction cross-section on energy is considered by CASNEW. In its turn it influences upon the collision probability with species and the free flight path. The partial and total yields as well as the angle and energy spectra, ion and point defect depth distributions have been calculated. As it was noticed both CASNEW and TRIM codes give close results at low energies. Differences grow with energy and are more for SiC than for B 4C. In both cases the preferred sputtering of the heavier component is observed.

Ionization and fragmentation of C60 by highly charged, high-energy xenon ions.

${\mathrm{C}}_{60}$ vapor was bombarded by $^{136}\mathrm{Xe}^{35+}$ and $^{136}\mathrm{Xe}^{18+}$ ions in the energy range 420--625 MeV to study the various ionization and fragmentation processes that occur. Since the center-of-mass energies used in this work exceeded those of previous studies by several orders of magnitude, new excitation and dissociation modes were expected and indeed found. Positive ions were extracted from the interaction region and their times of flight were measured both singly and in coincidence with other ionic fragments. A wide range of stable charge states and cluster sizes from monatomic carbon up to ${\mathrm{C}}_{60}$ was observed. Even-numbered carbon fragments dominated the heavier mass range but both even and odd carbon numbers occurred at lower masses. Evidence was found for three qualitatively different ionization and fragmentation channels suggesting different ranges of collision impact parameters: ionization of the parent ${\mathrm{C}}_{60}$ molecule, loss of even numbers of carbon atoms, and ``multifragmentation'' into many small fragments. This latter mode included the production of singly charged ${\mathrm{C}}_{\mathit{n}}^{+}$ fragments with all values of n being observed from n=1 up to at least n=19. We interpret our results in terms of a theoretical model that indicates that the total interaction cross section contains comparable contributions from (a) excitation of the giant dipole plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. The distribution of fragment cluster masses for n\ensuremath{\lesssim}20 is reproduced by a ``percolation theory'' description analogous to that used to describe multifragmentation of nuclei by high-energy protons. \textcopyright{} 1996 The American Physical Society.

Proton halos in the 1 s0 d shell

The shell-model properties of proton halo states in proton-rich 1 s0 d shell nuclei are investigated. The most interesting cases appear to be those in 26,27P and 27S. The parallel-momentum distributions of core fragments from proton stripping reactions may provide experimental insight into the structure of the halo states and the role played by the reaction mechanism. The “generalized Coulomb shift”, defined as the difference between the neutron and proton separation energies for an analogue pair, is shown to vary smoothly as a function of proton-separation energy and provides a good tool for mass extrapolations. The relation between the total interaction cross section and the matter radius is discussed.

Doubly, singly differential and total ionization cross sections of rare-gas atoms

A variant of the Born approximation is used to calculate doubly, singly differential and total ionization cross sections for the (e, 2e) interaction between an electron and the rare-gas atoms neon, argon and krypton. The calculation is done for the ionization of the valence electron. This work is a continuation of a previous study of the alkali atoms, and the purpose, as it was there, is to elucidate basic features. Comparison to experiment is made where possible.

Lattice dynamics of solid molecular hydrogen for densities 26.18 + 60.78 nm−3, as seen from total neutron interaction cross section measurements

Abstract The total neutron interaction cross sections versus energy measurements have been carried out on solid parahydrogen for almost 100% change of its density. Some integral parameters of hydrogen very anharmonic phonon spectrum have been determined fro. an analysis of these data.