Problem 2344 - Angular correlation is ignored in some specific cascades
Summary: Angular correlation is ignored in some specific cascades
Status: RESOLVED FIXED
Alias: None
Product: Geant4
Classification: Unclassified
Component: processes/hadronic/models/de_excitation/photon_evaporation (show other problems)
Version: 10.7
Hardware: All All
: P4 normal
Assignee: Vladimir.Ivantchenko
URL:
Depends on:
Blocks:
 
Reported: 2021-03-04 18:50 CET by Luciano Pandola
Modified: 2021-03-08 14:59 CET (History)
1 user (show)

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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