Three-body Coulomb interaction effects in the final state of thePb208(B8,

Abstract

The photodissociation reaction 8 B + γ → 7 Be + p is used to provide information on the astrophysical S 17 factor of the inverse radiative capture reaction, knowledge of which is crucial for an estimation of the high-energy neutrino flux from the sun. Since, at present, the Coulomb field of a fully stripped nucleus serves as the source of the photons, an adequate analysis requires a genuine three-body treatment of this reaction. Among the uncertainties still affecting present analyses, the possible modification of the dissociation cross section by the post-decay acceleration of the fragments 7 Be and p in the target field plays a major role. Working with the prior form of the dissociation amplitude, we first discuss why the standard approximation for the final-state wave function is not appropriate for a proper investigation of this problem; instead, use of a genuine three-particle wave function for the final state proves to be mandatory. Such is provided by a recently proposed wave function for three charged particles in the continuum [A. M. Mukhamedzhanov and M. Lieber, Phys. Rev. A 54, 3078 (1996)] which possesses all the essential features required. It is an exact solution of the three-body Schrödinger equation, but only asymptotically, i.e., for large distances. Therefore, only qualitative predictions can be made currently, such as predicting the kinematic configurations in which post-decay acceleration effects play a negligible role. Explicit calculations are presented for the single and the double differential cross sections for the 208 Pb( 8 B, 7 Be p) 208 Pb Coulomb breakup reaction. We also investigate the influence of the E2 multipole and find its contribution to be small for small scattering angles, but comparable to the one from the E1 dipole for large scattering angles.

Rapidity and energy dependence of the electric charge correlations inA+Acollisions from20Ato158A

“…a narrowing of the BF [1]. Indeed, results on the BF obtained for Au+Au collisions at RHIC [5] and Pb+Pb interactions at the top SPS energy [4] observed this narrowing for central collisions in the mid-rapidity domain. In this paper, the study of the BF is extended to the forward rapidity region.…”

“…In order to further investigate this effect, the Ultra-relativistic Quantum Molecular Dynamics model (UrQMD) [10], which is a microscopic model of (ultra)relativistic heavy ion collisions in the energy range from Bevalac and SIS up to AGS, SPS and RHIC, was used. The results from the study of this conventional hadronic model as well as the widths obtained from shuffled 1 data [5,4] are also plotted in fig. 2.…”

“…As in previous publications from the NA49 experiment on the BF [4], the analysis is performed for all charged particles (predominantly pions) in order to avoid the additional complications from the identification procedure. Consequently the pseudo-rapidity (η) of charged particles is examined and the BF is defined as [1]:…”

Narrowing of the charge balance function and hadronization time in relativistic heavy-ion collisions

“…It is argued that if the system produced in heavy-ion collisions has undergone a quark-parton phase, the hadronization will occur at a later time and, therefore, the temperature will be lower and the diffusive interaction with other particles will be lesser than those in the direct hadronization without going through a quark-parton phase. These will result in a narrower charge balance function for a system with quark-parton phase than that without such a phase.Two heavy-ion experiments [6,7] have measured the balance function at various centralities and for different colliding nuclei. A narrowing of the balance function is indeed observed with increasing centrality of the collision and with increasing size of the colliding nuclei.…”

“…Then the hadronization time in AMPT model is described, and its connection with the width of balance function is presented. A summary and discussion then follow.The balance function is defined as [7] B(δy|Y w ) = 1 2where n +− (δy), n ++ (δy) and n −− (δy) are the numbers of pairs of opposite-and like-charged particles satisfying the criteria that all of them fall into the rapidity window Y w and that their relative rapidity equals δy; n + and n − are the numbers of positively and negatively charged particles in the interval Y w , respectively. The balance function B(δy|Y w ) represents the probability that the balancing charges are separated by δy [5].…”