Problem 2344

Summary:	Angular correlation is ignored in some specific cascades
Product:	Geant4	Reporter:	Luciano Pandola <luciano.pandola>
Component:	processes/hadronic/models/de_excitation/photon_evaporation	Assignee:	Vladimir.Ivantchenko
Status:	RESOLVED FIXED
Severity:	normal	CC:	jasondet
Priority:	P4
Version:	10.7
Hardware:	All
OS:	All

Description Luciano Pandola 2021-03-04 18:50:08 CET

Opening a bug report to keep track of a problem spotted by Oliviero Cremonesi (cremonesi@mib.infn.it) and already diagnosed/fixed by Jason Detwiler (jasondet@uw.edu).

Even if correlated gamma cascades are switched on, e.g. via the flag
 /process/had/deex/correlatedGamma true
the de-excitation takes place isotropically for a subset of cases in which correlation is expected. 

The problematic cases are those in which the starting level is J=0 and the final level is J>0. The current implementation of G4PolarizationTransition.cc produces an isotropic distribution is either the initial or the final level have J=0.

Comment 1 jasondet 2021-03-05 05:10:59 CET

pull request 21 fixes this problem:

https://github.com/Geant4/geant4/pull/21

Comment 2 Vladimir.Ivantchenko 2021-03-08 14:59:09 CET

hello Jason,

your fix is merged to the master  of the development repository and also added to the branch with patches to 10.7.

Vladimir