Report from the Geant4 Radioactive Decay Mini-workshop on 3-4 March 2015

1. Report from the Geant4 Radioactive Decay Mini-workshop on 3-4 March 2015 Dennis Wright 25 March 2015

2. Objectives • Address open bug reports, problems, multithreading concerns • Discuss new design for RDM package • Plan the update and reconciliation of data in the various files now used • Plan new features

3. Reproducibility • Data divergence • multiple files with slightly different data, as well as hard-coded arrays • at least one cause of non-reproducibility • Remedies • G4NuclideTable: will read nuclide data (masses, level energies, etc.) from file instead of using hard-coded data • unify database files, provide sufficient precision for level energies • examine cases where truncation of strings occurs in translating data from one form to another • Put photon evaporation and RDM databases in same file structure/directory

4. New Features • Correlation of gamma angular distributions • will install Jason Detweiler’s code • photon evaporation code to be modified to use this • also contains some useful utility classes (Legendre, general polynomial sampling, etc. • Decay by proton, neutron emission • Luis will implement • Beta-delayed neutrons and spontaneous fission • Luis will implement • Local energy deposit proposed by RDM process • Dennis

5. Energy Conservation • Current levels • alpha decay : << 1 eV • beta-/+ decay: << 1 eV • IT: < 10 keV • EC: < 10 keV • IT, EC can be improved by including local energy deposit in RDM process (Dennis will implement) • Current levels attained using Q values from database • not nuclear masses • investigate use of nuclear masses for fully stripped ions, atomic masses otherwise – requires modification of particle category

6. New Design Adopted • Following critique of Hauf and Kuster: • RDM decay processes now much simpler, more modularized • Accomplished by removing one level of inheritance • easy to add new decays • New design to be extended to biased operation • current biased code is old, and interwoven with unbiased code • will begin separating biased from unbiased code • finally, will look into using generic biasing when it is ready for use in at-rest processes

7. Testing • System tests • rdecay01 – physics comparison reference (Michel) • rdecay02 – Michel has cleaned up • had06, testEm1 in good shape • Unit tests • clean up existing, but old, unit tests in radioactivedecay/test/ directory (Dennis) • develop a common set (5 decays) of simple tests – Michel, Dennis • 60Co, 133Ba, 234Th, beta+/EC, alpha, IC, etc. • good gamma spectrum, lifetime, are all expected species produced?, relaxed KS cuts

8. Validation • Begin collecting data for comparison and posting on hadronic validation web pages • database validation nuclide (Z,A) plots – Laurent • particle spectra (beta+, beta-, alpha, etc. - Dennis, Laurent

9. Backup Slides

10. Bug fixes • Re-enable atomic relaxation as default • Dennis (done) • No atomic relaxation is occurring after IC : fix this • Dennis (done by Michel) • 131XE, 60Ni, 212Po: lifetime = 0 for some intermediate states • Dennis • Do not normalize sum of branching ratios to 1 if the strength of some branches are missing – stop and kill if parent at rest • (what about in-flight?) – Laurent, Dennis, Luciano • energy non-conservation after atomic relaxation • Random generator problems – Alex, Laurent, Andrea