On the measurement of B(E2, 0+ -> 2+) using intermediate-energy Coulomb excitation

TL;DR

This paper evaluates the accuracy of semi-classical Coulomb excitation analysis for B(E2) measurements, demonstrating that quantum coupled-channel calculations provide more precise results with reduced theoretical uncertainties.

Contribution

It introduces fully-quantal coupled-channel calculations to assess multi-step, nuclear, and feeding effects in Coulomb excitation, improving the accuracy of B(E2) extraction.

Findings

Nuclear effects can contribute over 10% to excitation strengths.

Feeding contributions can exceed 15%.

Quantum analysis reduces theoretical error to below 7%.

Abstract

Coulomb excitation is a standard method used to extract quadrupole excitation strengths of even-even nuclei. In typical analyses the reaction is assumed to be one-step, Coulomb only, and is treated within a semi-classical model. In this work, fully-quantal coupled-channel calculations are performed for three test cases in order to determine the importance of multi-step effects, nuclear contributions, feeding from other states and corrections to the semi-classical approximation. We study the excitation of 30S, 58Ni and 78Kr on 197Au at ~ 50 AMeV. We find that nuclear effects may contribute more than 10% and that feeding contributions can be larger than 15%. These corrections do not alter significantly the published B(E2) values, however an additional theoretical error of up to 13% should be added to the experimental uncertainty if the semi-classical model is used. This theoretical error is reduced to less than 7% when performing a quantal coupled-channel analysis.