Problem 1910

Summary:	anisotropic distribution of secondary pions from antiproton annihilation at rest
Product:	Geant4	Reporter:	Jongwon Hwang <hjw8707>
Component:	processes/hadronic/models/parton_string/management	Assignee:	Alberto.Ribon
Status:	RESOLVED FIXED
Severity:	normal	CC:	Gunter.Folger
Priority:	P4
Version:	10.2
Hardware:	PC
OS:	Linux

Description Jongwon Hwang 2016-11-14 10:09:57 CET

I wrote the code for antiproton annihilation at rest by using FTFP_BERT_TRV physics, which uses Fritiof model for the annihilation.

Checking the angular distribution of secondary pions from the antiproton annihilation at rest (in any material),
it is not isotropic.

1) cosine(theta): not uniform
2) phi: uniform

where (r, theta, phi) is the momentum direction using the general spherical coordinate with respect to the z-axis.

Comment 1 Alberto.Ribon 2016-12-02 11:13:42 CET

Thanks for problem you have found and reported. We confirm that the problem is present, and we will work on it early next year. I'll keep the ticket open till then.

Comment 2 Alberto.Ribon 2017-12-11 15:27:26 CET

Improvements should be seen with the new version of Geant4 10.4.
Please let me know if you confirm it.