4th Consultant's Meeting on
R-matrix Codes for Charged-particle Reactions in the Resolved-Resonance Region
Motivation
Two exercises were adopted at the previous meetings held in 2016 and 2017: an inter-comparison of R-matrix algorithms used to calculate cross sections using the same resonance parameters, boundary conditions and spin-parity groups as input parameters (Test1a) and an inter-comparison of fitting capabilities starting from the same resonance parameters and boundary conditions using the same experimental data and normalizations (Test1b).
The results of Test1a have shown that the excitation functions and angular distributions for the α- and proton-induced channels leading to the compound system 7Be obtained from the participating R-matrix codes (AZURE, AMUR, RAC, SFRESCO, SAMMY) agree within 1-2%.
The purpose of the forthcoming meeting is to present and discuss the results of Test1b and draw final conclusions on the fitting and evaluation capabilities of the codes includign treatment of uncertainties. The meeting will also discuss the finalization of a joint evaluation and preparation of the final publication of the work performed by the group of participants during the course of all the four meetings held since 2015.
Some of the technical topics to be discussed in detail are:
- Experimental data covariances
- Preservation of data norms with evaluations
- Angular distributions of decay gammas: including in the fit
- Changes with parameter transformations (e.g. Brune or Barker or formal-rwa)
- Pointwise reconstructions: methods and codes for charged particles
as well as more general issues such as:
- Plans for new fits of nuclear reaction: Data assessments, data error checking, use of previous fits, etc.
- Going above dissociation thresholds
- R-matrix theory extended to higher energies: URR, statistical model regime
Agenda
The Agenda is available here.
Report
The summary report is published as INDC(NDS)-0767.