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In this paper, the electron scattering transverse and longitudinal form factors for positive low-lying excited states in the 17O nucleus are calculated. The shell model calculation included zbme model space with the rewile interaction using different potentials (HO, WS, Ska, Bsk9) were adopted for the single-particle radial wave function and compared with experimental data. Calculation results indicated that including core-polarization effects together with polarized charge contribution produced better results. [ABSTRACT FROM AUTHOR]

The study of collisions around the Coulomb barrier induced by halo and/or weakly bound nuclei has been the object of many publications in the last years, since the peculiar structure of such nuclei can strongly affect the reaction dynamics. In this paper we will summarize some results on the above topic obtained by our group at INFN-LNS Catania. Results concerning the study of elastic scattering and different reaction mechanisms in collisions induced by the halo nuclei 11Be and 6He and by the weakly bound stable nuclei 6,7Li on a 64Zn target, at energies around the Coulomb barrier, will be presented. The conclusions of our studies will be compared with the ones of other authors, in order to show if clear systematic conclusions can be drawn from the different papers published in the literature so far. [ABSTRACT FROM AUTHOR]

The elastic scattering process Λp → Λp offers insights on multiple problems in nuclear physics. SU(3)F symmetry implies a close agreement between the Λp and pp scattering cross sections. The Λp elastic scattering cross section can also illuminate the structure of neutron stars. A data-mining project was started using multiple CLAS data sets taken for other purposes with photon beams on a long liquid hydrogen target. A Λ produced in a process such as γp → K+ Λ can interact with a second proton inside the target before either decaying or leaving the target. The good angular acceptance and momentum resolution of CLAS make it well-suited for this type of analysis, even though it was not designed for such a measurement. The scattered Λ can be identified from the π− p invariant mass. The four-vector of the initial Λ is then reconstructed in the process Xp → Λp, which shows a strong peak at the Λ mass with roughly twice the number of events as the existing world data sample. This observation opens up the possibility of other measurements using secondary beams of short-lived particles. This paper will discuss the current status of the analysis, and our plans for future work on this project. [ABSTRACT FROM AUTHOR]

This paper considers the time- and space-dependent linear Boltzmann equation with general boundary conditions in the case of inelastic (granular) collisions. First, in the (angular) cut-off case, mild L1-solutions are constructed as limits of the iterate functions and boundedness of higher velocity moments are discussed in the case of inverse power collisions forces. Then the problem of the weak solutions, as weak limit of a sequence of mild solutions, is studied for a bounded body, in the case of very soft interactions (including the Coulomb case). Furthermore, strong convergence of weak solutions to the equilibrium, when time goes to infinity, is discussed, using a generalized H-theorem, together with a translation continuity property. [ABSTRACT FROM AUTHOR]

The present report gives a detailed analysis of experimental works and a review of alpha-induced reaction cross-section data of five alpha-alpha nuclei, Mg-24, Si-28, S-32, Ar-36 and Ca-40, for incident alpha energy up to 20 MeV. Alpha-induced reactions play an important role in the helium burning stage of stars, novae, and supernovae. These reactions are basic to the CNO and Al-Mg cycles, and also to the production of neutrons producing S and R processes occurring in stars. Thus, the availability of cross-section data for these reactions is a prime need for the study of nuclear interactions taking place in stars. These data have been compiled as part of an international collaboration, funded in part by the Civilian Research & Development Foundation, and are available in the EXFOR databases. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Investigations in the field of quantum optics very often requires a molecular simulation of transport phenomena. This paper presents a discrete kinetic model to deal with the quantum optical problem of hole burning. Based on a full discretization of the velocity space, Boltzmann-like equations are established to govern the temporal evolution of heavily disturbed Maxwell distributions of optically excited particles diffusing in a buffer gas. These model equations involve elastic collisions and the interaction of photons with three-level atoms by taking into account the Doppler effect. Important features of the developed model are the realistic simulation of the relaxation process and the existence of a stable and unique equilibrium solution. [ABSTRACT FROM AUTHOR]

The study of the elastic scattering potential on the heavy-ions at various incident energies is a method to investigate the nuclear structures and radii. The cluster structure of the heavy-ions is proposed in order to investigate its reaction potentials. Reaction potentials of the heavy-ions have been a puzzle for many years. In this paper, the cluster structure of the heavy-ions is proposed in order to solve this puzzle. Based on this structure the elastic scattering cross-sections of p+43Ca reaction at Ep = 21--65 MeV are calculated and the results are in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The discrepancy between the proton charge radius extracted from the muonic hydrogen Lamb shift measurement and the best present value obtained from the elastic scattering experiments, remains unexplained and represents a burning problem of today's nuclear physics: after more than 50 years of research the radius of a basic constituent of matter is still not understood. This paper presents a summary of the best existing proton radius measurements, followed by an overview of the possible explanations for the observed inconsistency between the hydrogen and the muonic-hydrogen data. In the last part the upcoming experiments, dedicated to remeasuring the proton radius, are described. [ABSTRACT FROM AUTHOR]

The discrepancy between the proton charge radius extracted from the muonic hydrogen Lamb shift measurement and the best present value obtained from the elastic scattering experiments, remains unexplained and represents a burning problem of today's nuclear physics: after more than 50 years of research the radius of a basic constituent of matter is still not understood. This paper presents a summary of the best existing proton radius measurements, followed by an overview of the possible explanations for the observed inconsistency between the hydrogen and the muonic-hydrogen data. In the last part the upcoming experiments, dedicated to remeasuring the proton radius, are described. [ABSTRACT FROM AUTHOR]

Small angle scattering (SAS) is the collective name given to the techniques of small angle neutron (SANS) and X-ray (SAXS) scattering. They offer the possibility to analyze particles without disturbing their natural environment. In each of these techniques radiation is elastically scattered by a sample and the resulting scattering pattern is analyzed to provide information about the size, shape and orientation of some component of the sample. Accordingly, a large number of methods and experimental patterns have been developed to ease the investigation of condensed matter by use of these techniques. Some of them are the discussed in this paper. [ABSTRACT FROM AUTHOR]

In this paper we give a brief description of diffractive processes. We focus on ep collisions at HERA and outline key features of exclusive diffraction in hadron-hadron collision. We discuss respectively: diffractive parton distributions of the proton obtained from DGLAP fits to HERA data, including the twist-4 contribution, afterwards diffractive charm production from dipole model and at the end shortly exclusive production of a Higgs boson in pp scattering. [ABSTRACT FROM AUTHOR]

COUPP (Chicagoland Observatory for Underground Particle Physics) is an experiment with bubble chambers able to detect dark matter directly either with Spin-Dependent or with Spin-Independent interactions. The target material is a superheated liquid (usually CF3I) that can be bubble nucleated due to nuclear recoils produced by elastic collisions of dark matter particles. The bubble growth inside the chamber is accompanied with an acoustic signature. The acoustic technique has been successfully used to have a good alpha discrimination (about 99%). In this paper, we present different studies and results related with the characterization of the acoustic properties of the detector and the different phenomena involved in the acoustic measurements of the bubble growth, such as sound generation, sound transmission and optimization of piezoelectric transducers. [ABSTRACT FROM AUTHOR]

This paper summarizes the discussion about the role of two-particle-two-hole (2p2h) excitations in neutrino-nucleus interactions in the few-GeV region, held at NuInt11. [ABSTRACT FROM AUTHOR]

In this paper, I present an overview and preliminary results from three experiments at Jefferson Lab that were recently completed using a 3He gas target with polarization oriented normal to the scattering plane of unpolarized incident electrons. A target single spin asymmetry was formed by periodically flipping the direction of the target spin. In the reaction ↑3He(e,e[acute_underaccent]), the Born contribution is expected to be zero, giving direct sensitivity to two photon exchange. This asymmetry was measured in the quasi-elastic and deep-inelastic regimes with 0.1 < Q2 < 1.0 GeV2. The asymmetry is predicted to decrease by two-orders of magnitude for deep-inelastic versus quasi-elastic scattering. Preliminary results from these experiments will be presented. [ABSTRACT FROM AUTHOR]

In this paper I will discuss some results of experiments concerning the study of reaction mechanisms with halo and loosely bound stable nuclei at energies around the Coulomb barrier. [ABSTRACT FROM AUTHOR]

In this paper, we present the analysis of the 6He+12C elastic scattering at 18.0 MeV within the framework of the double folding model. In order to make a comparative study, we have used four different types of nucleon density distributions for the ground state of the 6He in the microscopic potential calculations. We have observed that all these density distributions provide a consistent description of the elastic scattering angular distributions for this system. [ABSTRACT FROM AUTHOR]

To improve the reliability of statistical model calculations in the region of heavy proton rich isotopes alpha elastic scattering experiments have been performed at ATOMKI, Debrecen, Hungary. The experiments were carried out at several energies above and below the Coulomb barrier with high precision. The measured angular distributions can be used for testing the predictions of the global and regional optical potential parameter sets. Moreover, we derived the variation of the elastic alpha scattering cross section along the Z = 50 (112Sn–124Sn) isotopic and N = 50 (89Y–92Mo) isotonic chains. In this paper we summarize the efforts to provide high precision experimental angular distributions for several A≈100 nuclei to test the global optical potential parameterizations applied to p-process network calculations. [ABSTRACT FROM AUTHOR]

An innovative polarimeter based on proton carbon elastic scattering in the Coulomb Nuclear Interference (CNI) region was first successfully tested in the Brookhaven AGS. CNI Polarimeters were then installed in the AGS and both RHIC rings. The polarimeter consists of ultra-thin carbon targets and silicon strip detectors. The waveform digitizers used for signal readout allow deadtime-less data processing on the fly. Polarimeters are crucial instrumentation for the RHIC spin physics program. This paper summarizes the polarimeter design issues and operation results. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The nuclear Ramsauer model is a semi-classical, analytic approximation to nucleon-nucleus scattering that reproduces total cross-section data at the 1% level for A > 40, En = 5–60 MeV with 7–10 parameters. A quick overview of the model is given, demonstrating the model’s utility in nuclear data evaluation. The Ramsauer model predictions for reaction cross section, elastic cross section, and elastic scattering angular distributions are considered. In a recent paper it has been shown that the nuclear Ramsauer model does not do well in predicting details of the angular distribution of neutron elastic scattering for incident energies of less than 60 MeV for 208Pb. However, in this contribution it is demonstrated that the default angular bin dispersion most widely used in Monte Carlo transport codes is such that the observed differences in angular shapes are on too fine a scale to affect transport calculations. Simple studies indicate that 512–2048 bins are necessary to achieve the dispersion required for calculations to be sensitive to the observed discrepancies in angular distributions. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

A new evaluated nuclear data library has been created. The library consists of two sub-libraries for neutron and proton incident particles. The first version of neutron sub-library has been completed and described in the present paper. The library contains nuclear data for transport, heating, and shielding applications for 242 nuclides ranging in atomic number from 8 to 82 in the energy region of primary neutrons from 10-5 eV to 150 MeV. Data below 20 MeV are taken mainly from ENDF/B-VI (Revision 8) and for some nuclides, from the JENDL-3.3 and JEFF-3.0 libraries. The evaluation of emitted particle energy and angular distributions at the energies above 20 MeV was performed with the help of the ALICE/ASH code and the analysis of available experimental data. The total cross sections, elastic cross sections, and elastic scattering angular distributions were calculated with the help of the coupled channel model. The results of the calculation were adjusted to the data from ENDF/B-VI, JENDL-3.3m or JEFF-3.0 at the neutron energy equal to 20 MeV. The library is written in ENDF/B-VI format using the MF=3/MT=5 and MF=6/MT=5 representations. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this talk we demonstrate the results of application of the perturbative effective theory formaism developed in papers [1]–[6] to the calculation of πN elastic scattering amplitude. Restrictions on the contributing resonance parameters are obtained and the low energy coefficients are calculated. [ABSTRACT FROM AUTHOR]

The paper presents new experimental data on the spin rotation parameter A obtained recently by ITEP-PNPI collaboration at the ITEP accelerator. The set of measurements was performed in carefully chosen critical points with precision sufficient for choosing the correct branches of partial wave analyses. The data for both π+ and π--scattering at 1.0, 1.43 and 1.62 GeV/c is included. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Calculated values of the Sherman function for krypton at 60 and 65eV incident electron energy show large predicted values and a rapid dependence on energy for the sign of the asymmetry. These unexpectedly large asymmetries have prompted an experimental investigation of this target. In this paper the current status of these measurements and further theoretical and experimental results for the Sherman function for elastic scattering of spin polarised electrons from krypton will be discussed. [ABSTRACT FROM AUTHOR]

A new polarimeter based on proton carbon elastic scattering in the CNI (Coulomb Nuclear Interference) region has been proposed for RHIC and one pC CNI polarimeter has been installed in the blue ring of RHIC. This paper summarizes the design and parameters of this new polarimeter. It is a simple, compact, and cost effective polarimeter. [ABSTRACT FROM AUTHOR]

The inverse kinematics thick target scattering method (TTIK) has been used to study the 8Li elastic scattering on 4He in order to investigate 8Li-α cluster configurations in excited states of 12B. A 8Li beam, provided by the radioactive beam facility EXCYT, at Ebeam = 30.6 MeV, passing through helium thick target, continuosly decreases its energy inducing elastic scattering starting from the initial energy down to zero. Four ΔE-E double stage silicon detector telescopes were used to detect the recoil α-particles coming from the scattering. Event by event time measurement between beam particles passing through a MCP detector and α-particles impinging on ΔE stage allows elastic from inelastic events discrimination, thus representing an improvement of the TTIK method. In this paper the used experimental technique and some preliminary results will be briefly described. [ABSTRACT FROM AUTHOR]

The reactions 9,10,11Be+64Zn have been studied at energies around the Coulomb barrier in order to better understand the role played by the halo features on the reaction dynamics. Preliminary results on such studies will be reported in this paper. [ABSTRACT FROM AUTHOR]

It is emphasized that the collective dynamics associated with color confinement is dominating over a point-like mechanism related to a scattering of the proton constituents at the currently available values of the momentum transferred in proton elastic scattering at the LHC. Deep-elastic scattering and its role in the dissimilation of the absorptive and reflective asymptotic scattering mechanisms are discussed with emphasis on the experimental signatures associated with the multiparticle production processes. [ABSTRACT FROM AUTHOR]

We discuss two topical problems of diffraction dissociation at the LHC, namely the role of the background and the elastic contribution. [ABSTRACT FROM AUTHOR]

Reactions induced by Rare Isotope Beams (RIB) at low or intermediate energies represent a major tool to enrich our knowledge about exotic nuclei (along with decay studies and mass measurements). They allowed us, in the last decade or more, to go beyond the beta-stability line with our structure or reaction mechanism studies, and are considered to be the way low energy nuclear physics will go. I will present here a few of the types of reactions currently used: elastic scattering, single-nucleon transfer, breakup at intermediate energies. I will focus on the experimental aspects but, while remaining general, due to my own experience, I will concentrate on reactions that are indirect methods in nuclear astrophysics. The material will, hopefully, prepare you for some of next week's subjects. [ABSTRACT FROM AUTHOR]

We solve the nd scattering in the Faddeev formalism, employing the NN sector of the quark-model baryon-baryon interaction fss2. The energy-dependence of the NN interaction, inherent to the (3q)-(3q) resonating-group formulation, is eliminated by the standard off-shell transformation utilizing the [formula] factor, where N is the normalization kernel for the (3q)-(3q) system. This procedure yields an extra nonlocality, whose effect is very important to reproduce all the scattering observables below En≤65 MeV. The different off-shell properties from the standard meson-exchange potentials, related to the non-locality of the quark-exchange kernel, yields appreciable effects to the differential cross sections and polarization observables of the nd elastic scattering, which are usually attributed to the specific properties of three-body forces. [ABSTRACT FROM AUTHOR]

Systematic cross section measurements of alpha-capture reactions at sub-Coulomb energies relevant to the p process were performed in the Ge-Sn region. At the same time a recent global α-nucleus optical model potential (OMP) based on the double-folding method was updated using all existing data on alpha elastic scattering and alpha-induced reactions. In this paper, we report on our recent measurements of alpha-capture reactions and present calculations using the improved alpha-nucleus OMP. [ABSTRACT FROM AUTHOR]

In this report, we show the calculation for the inclusive spectrum in the region of pion production in electron-nucleon and electron-nucleus scattering in the GeV region. We combine the calculation of quasi-elastic scattering with the spectral function and the pion production using MAID model. The calculated results are in fairly good agreement with experimental data over the whole range of energy transfer, between the quasielastic peak and the first resonance. In the calculation, we show the contributions of quasielastic cross section, the Δ cross section and the pion production at each W or equivalently at each scattered electron energy, separately. [ABSTRACT FROM AUTHOR]

An alternative method is proposed to extract the optical potentials of exotic nuclear systems in the outgoing channels by means of transfer reactions. An example of 208Pb(7Li, 6He)209Bi is demonstrated in details. Compared to the conventional method of which the optical potentials are directly extracted from the elastic scatterings, this indirect method has many benefits. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The RIBRAS (Radioactive Ion Beams Brazil) facility recently installed at the Pelletron Laboratory of the University of São Paulo consists of two superconducting solenoids used to produce and focalize beams of light radioactive nuclei, as 6He, 7Be,8Li etc. The low energy, light, radioactive beams available are used to study reactions close to the Coulomb barrier. The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier. Reaction cross sections were extracted from the optical model fits, using the São Paulo Potential (SPP). The reduced reaction cross sections of 6He on 27Al were compared to reduced reaction cross sections for other projectiles as 6,7Li, 9Be and 16O on 27Al and they are larger than those for stable projectiles by an amount similar to the calculated nuclear break-up cross section for this system. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The MPI/OpenMP/C++ /Fortran package of computer codes has been developed for high-performance numerical analysis of experimental data on elastic nucleus-nucleus scattering within a microscopic model of optical potential. In the package, a modified DWUCK4 Fortran-code for calculating the physical characteristics of elastic scattering based on a numerical solution of the corresponding Schrödinger equation has been incorporated into the C++ framework, which is responsible for the input-output procedure and a comparison of numerical results with experimental data. MPI-based parallelism allows efficient calculations of the observables depending on a wide range of parameters of real and imaginary parts of the microscopic optical potential. The package has been used to analyze experimental data on differential cross sections of nucleus-nucleus elastic scattering of neutron-rich exotic nuclei 12,14Be on the target nucleus 12C at energy about 56 MeV/nucleon. [ABSTRACT FROM AUTHOR]

In order to model and diagnose the low-temperature edge plasmas, a complete database for electron-impact collision processes is required for molecular species containing beryllium and hydrogen. Dominant elementary processes in cold ionized gases are dissociative recombination, elastic collisions, vibrational excitation, vibrational de-excitation and dissociative excitation. In this study, using the stepwise version of the Multichannel Quantum Defect Theory, cross sections and rate coefficients have been obtained for reactions induced on BeT+. A set of vibrational resolved rate coefficients for BeT+ cations' reactive collisions with electrons below to the ion dissociation threshold is provided. The incident electron energy range is 10-3 - 2.7 eV and the electron temperature range is 100 - 5000 K. [ABSTRACT FROM AUTHOR]

A model that allows interpretation of positron annihilation spectra (LT and CDB) in nanodispersed dielectric powders is developed. Model takes into account e+ capture by vacancy-type defects, formation of e+ surface-bound states, as well as the formation of quasi-free positronium (inside crystallites) which may escape into intergranular space where it becomes thermalized during elastic collisions. The process of annihilation of ortho-Ps is narrowed down to its conversion into the para-state as a result of collisions with oxygen molecules (O2) adsorbed on the surface of crystallites. A computer program for lifetime spectra fitting that accounts on the parameters of the above model is developed (with ROOT framework). Combination of the program with our CDB software allows joint processing of the LT and CDB annihilation spectra of nanopowders. [ABSTRACT FROM AUTHOR]

The elastic and inelastic scatterings of α-particles were investigated at an energy of 29 MeV with excitation of lowlying states of the 11B nucleus. As a result of research we obtained new experimental data for the α + 11B inelastic scattering one leading to the 2.12 MeV (1/2−), 4.44 MeV (5/2−) and 6.74 MeV (7/2−) excited states of 11B nucleus. In the framework of Modified diffraction model, the root mean square radii of these excited states are calculated. The theoretical calculations for the concerned excited states were performed using the coupled channel (CC) method. [ABSTRACT FROM AUTHOR]

We describe the implementation of kinetic solvers in 1d2v phase space using adaptive Cartesian mesh. Spherical coordinates in velocity space are used to simplify the Lorentz and Fokker-Planck collisional operators. The key capabilities of the new solvers are illustrated for electron elastic scattering, acceleration, continuous energy loss in collisions, and ionization processes in weakly-ionized plasma. We have also implemented two-stream approach to reduce computational cost for studies of gas breakdown dynamics in the presence of runaway electrons. The benefits and limitations of the nonsplit- phase-space method for kinetic solvers with adaptive mesh in phase space are discussed. [ABSTRACT FROM AUTHOR]

A model of scattering of elastic wave by point-like scatterer on the plane is suggested. Point-like perturbation is constructed for the Lamé operator in the framework of the theory of self-adjoint extensions of symmetric operators. The eigenvalues of the model operator are found. The scattering matrix is obtained. [ABSTRACT FROM AUTHOR]

Boundary integral equations methods are inherently advantageous for infinite medium problems such as elastic wave scattering for ultrasonic Nondestructive Testing. The reduction in dimensionality of the problem (e.g., volume to surface) also leads to computational advantages versus finite element or finite difference methods for homogeneous media. However, numerical integration of the strongly singular (1/r²) kernels of the traditional BIE formalism has been a challenge in implementation; although successful functioning codes have long existed. Still, methods to incrementally minimize this difficulty have been the subject of research for three decades. This new BIE method utilizes an analytical representation for the incident plane wave’s stress field and Betti reciprocity to eliminate the strongly singular kernel integration that is required by scatterers with stress-free boundary conditions (such as voids, open cracks, and any nearby free surfaces). An associated weakly singular (1/r) BIE is readily solved instead. [ABSTRACT FROM AUTHOR]

Elastic scattering reactions have been part of a campaign of studies at the Cyclotron Institute from Texas A&M University for more than 30 years. The studied nuclei ranged from 8Be to 22Ne. In order to study the astrophysically important 26Si (through its mirror 26Mg), it was necessary to perform an upgrade of the focal plane detection system. Several scattering reactions on nuclei heavier than A=22 were measured as tests and the preliminary results are presented here. [ABSTRACT FROM AUTHOR]

The glue-like behavior of valence neutrons has been investigated in the Li isotopes. The 7Li nucleus is well known to be weakly bound system with the α + t cluster structure. By adding the valence neutrons, the reduction of the root-mean-square (RMS) radius of the proton density for the 7Li, 8Li and, 9Li nuclei is also well known from the viewpoint of the experimental data and theoretical approach. Elastic scattering cross sections of the Li isotopes on the 12C and 28Si targets at E/A～50 MeV are calculated. We find the change of the channel coupling (CC) effect on elastic scatterings of such Li isotopes by the glue-like role of the valence neutrons. Finally, we realize that the valence neutrons stabilize the binding of core parts, and the CC effect related the core excitation is indeed reduced. [ABSTRACT FROM AUTHOR]

The proposed theoretical model allows for the perfectly elastic collision of three bodies (three mass points) to calculate: 1) the definite value of the three bodies’ projected velocities after the collision with a straight line, along which the bodies moved before the collision; 2) the definite value of the scattering bodies’ velocities on the plane and the definite value of the angles between the bodies’ momenta (or velocities), which the bodies obtain after the collision when moving on the plane. The proposed calculation model of the velocities of the three collided bodies is consistent with the dynamic model of the same bodies’ interaction during the collision, taking into account that the energy flow is conserved for the entire system before and after the collision. It is shown that under the perfectly elastic interaction during the collision of three bodies the energy flow is conserved in addition to the momentum and energy conservation. [ABSTRACT FROM AUTHOR]

The elastic α-12C scattering at low energies is studied in the cluster effective field theory, in which the ground states of α and 12C are treated as elementary-like fields. We first discuss a construction of an effective field theory for radiative α capture reaction on 12C at the Gamow energy, TG = 0.3 MeV, in the stars and fix some parameters appearing in the theory from the phase shift data of the elastic α-12C scattering. We then discuss the uncertainties of the present approach when interpolating the scattering amplitudes to TG. [ABSTRACT FROM AUTHOR]

We consider dark matter as an analog of hydrogen in a secluded sector and study its astrophysical implications. The self interactions between dark matter particles include elastic scatterings as well as inelastic processes from hyperfine transitions. We show that for a dark hydrogen mass in the 10-100 GeV range and a dark fine-structure constant larger than 0.01, the self-interaction cross section has the right magnitude and velocity dependence to explain the low dark matter density cores seen in small galaxies while being consistent with all constraints from observations of galaxy clusters. Excitations to the hyperfine state and subsequent decays, however, may cause significant cooling losses and affect the evolution of low-mass halos. We also find minimum halo masses in the range of 103.5-107 M..., which are significantly larger than the typical predictions for weakly interacting dark matter models. This pattern of observables in structure formation is unique to this model, making it possible to determine the viability of hidden-sector hydrogen as a dark matter candidate. [ABSTRACT FROM AUTHOR]

We discuss diphoton semi(exclusive) production in ultraperipheral PbPb collisions at energy of ysNN = 5.5 TeV (LHC). The nuclear calculations are based on equivalent photon approximation in the impact parameter space. The cross sections for elementary γγ → yy subprocess are calculated including three different mechanisms: box diagrams with leptons and quarks in the loops, a VDM-Regge contribution with virtual intermediate hadronic excitations of the photons and the two-gluon exchange contribution (formally three-loops). We got relatively high cross sections in PbPb collisions. This opens a possibility to study the γγ → γγ (quasi)elastic scattering at the LHC. We find that the cross section for elastic γγ scattering could be measured in the lead-lead collisions for the diphoton invariant mass up to ψ γγ 15 - 20 GeV. We identify region(s) of phase space where the two-gluon exchange contribution becomes important ingredient compared to box and nonperturbative VDM-Regge mechanisms. We discuss also first results concerning production of two e+e-pairs in UPCs of heavy ions. We considered only double scattering mechanism. [ABSTRACT FROM AUTHOR]

Elastic scattering of relativistic spin 1/2 particle was investigated in the spherically-symmetric case. Based on the phaseshift method, a general solution of the Dirac equation with superposition of N δ-potentials is obtained. The method for approximate solutions of Dirac equation with arbitrary smooth potentials is presented. Scattering cross section dependences on various parameters are investigated. [ABSTRACT FROM AUTHOR]

In the plumes of Hall thrusters and ion thrusters, high energy ions experience elastic collisions with slow neutral atoms. These collisions involve a process of momentum exchange, altering the initial velocity vectors of the collision pair. In addition to the momentum exchange process, ions and atoms can exchange electrons, resulting in slow charge-exchange ions and fast atoms. In these simulations, it is particularly important to accurately perform computations of ion-atom elastic collisions in determining the plume current profile and assessing the integration of spacecraft components. The existing models are currently capable of accurate calculation but are not fast enough such that the calculation can be a bottleneck of plume simulations. This study investigates methods to accelerate an ion-atom elastic collision calculation that includes both momentum- and charge-exchange processes. The scattering angles are pre-computed through a classical approach with ab initio spin-orbit free potential and are stored in a two-dimensional array as functions of impact parameter and energy. When performing a collision calculation for an ion-atom pair, the scattering angle is computed by a table lookup and multiple linear interpolations, given the relative energy and randomly determined impact parameter. In order to further accelerate the calculations, the number of collision calculations is reduced by properly defining two cut-off cross-sections for the elastic scattering. In the MCC method, the target atom needs to be sampled; however, it is confirmed that initial target atom velocity does not play a significant role in typical electric propulsion plume simulations such that the sampling process is unnecessary. With these implementations, the computational runtime to perform a collision calculation is reduced significantly compared to previous methods, while retaining the accuracy of the high fidelity models. [ABSTRACT FROM AUTHOR]