Derivation of capture and reaction cross sections from experimental quasi-elastic and elastic backscattering probabilities

V.V Sargsyan,G.G Adamian,N.V Antonenko,P.R.S Gomes,B.V Carlson,A Deppman

doi:10.1051/epjconf/20136900004

V.V Sargsyan, G.G Adamian + Show 4 more

Open Access

https://doi.org/10.1051/epjconf/20136900004

Copy DOI

Abstract

The direct measurement of the reaction or capture (fusion) cross section is a difficult task since it would require the measurement of individual cross sections of many reaction channels, and most of them could be reached only by specific experiments. This would require different experimental set-ups not always available at the same laboratory and, consequently, such direct measurements would demand a large amount of beam time and would take probably some years to be reached. Because of that, the measurements of elastic scattering angular distributions that cover full angular ranges and optical model analysis have been used for the determination of reaction cross sections. This traditional method consists in deriving the parameters of the complex optical potentials which fit the experimental elastic scattering angular distributions and then of deriving the reaction cross sections predicted by these potentials. Even so, both the experimental part and the analysis of this latter method are not so simple. In the present work we present a much simpler methods to determine reaction and capture (fusion) cross sections. They consist of measuring only elastic or quasi-elastic scattering at one backward angle, and from that, the extraction of the reaction or capture cross sections can easily be performed.

Highlights

The direct measurement of the reaction or capture cross section is a difficult task since it would require the measurement of individual cross sections of many reaction channels, and most of them could be reached only by specific experiments
Quasi-elastic, and breakup data were not taken at 180 degrees, but rather at backward angles in the range from 150 to 170 degrees, the corresponding center of mass energies were corrected by the centrifugal potential at the experimental angle [5]
We propose a new and very simple way to determine reaction and capture cross sections, through the relation (12) between the elastic backscattering excitation function and reaction cross section and through the relation (13) between the quasi-elastic scattering excitation function at the backward angle and capture cross section

Summary

Introduction

The direct measurement of the reaction or capture (fusion) cross section is a difficult task since it would require the measurement of individual cross sections of many reaction channels, and most of them could be reached only by specific experiments. The measurements of elastic scattering angular distributions that cover full angular ranges and optical model analysis have been used for the determination of reaction cross sections This traditional method consists in deriving the parameters of the complex optical potentials which fit the experimental elastic scattering angular distributions and of deriving the reaction cross sections predicted by these potentials. In the present work we present a much simpler method to determine reaction and capture (fusion) cross sections It consists of measuring only elastic or quasi-elastic scattering at one backward angle, and from that, the extraction of the reaction or capture cross sections can be performed. To calculate the critical angular momentum Jcr and the position Rb of the Coulomb barrier, we use the nucleus-nucleus interaction potential V(R, J) of Ref. ). The formula (12) [(13)] relates the reaction [capture] cross section with the elastic [quasi-elastic] scattering excitation function at a backward angle. Of the captured system [1]

Results of calculations

Capture cross sections

Summary