Isotopically resolved neutron total cross sections at intermediate energies

TL;DR

This study measures neutron total cross sections for various isotopes at intermediate energies using advanced digitizer technology, providing data to improve optical models and understand nuclear structure.

Contribution

It introduces a new digitizer-based measurement method for neutron cross sections and applies dispersive optical model analyses to validate their effectiveness.

Findings

Measured neutron total cross sections for multiple isotopes from 3 to 450 MeV.

Validated the dispersive optical model for different nuclear systems.

Reaffirmed the use of high-energy proton reactions to study nuclear structure.

Abstract

The neutron total cross sections $\sigma_{tot}$ of $^{16,18}$O, $^{58,64}$Ni, $^{103}$Rh, and $^{112,124}$Sn have been measured at the Los Alamos Neutron Science Center (LANSCE) from low to intermediate energies (3 $\leq E_{lab} \leq$ 450 MeV) by leveraging waveform-digitizer technology. The $\sigma_{tot}$ relative differences between isotopes are presented, revealing additional information about the isovector components needed for an accurate optical-model description away from stability. Digitizer-enabled $\sigma_{tot}$-measurement techniques are discussed and a series of uncertainty-quantified dispersive optical model (DOM) analyses using these new data is presented, validating the use of the DOM for modeling light systems ($^{16,18}$O) and systems with open neutron shells ($^{58,64}$Ni and $^{112,124}$Sn). The valence-nucleon spectroscopic factors extracted for each isotope reaffirm the usefulness of high-energy proton reaction cross sections for characterizing depletion from the mean-field expectation.