Problem 1914

Summary:	Daughter particle polarization not set in G4PrimaryTransformer
Product:	Geant4	Reporter:	Michal Koval <michal.koval>
Component:	event	Assignee:	asai
Status:	RESOLVED FIXED
Severity:	normal
Priority:	P4
Version:	10.1
Hardware:	All
OS:	All
Attachments:	G4PrimaryTransformer.cc with the fix (source code to be included in version 10.3)

Description Michal Koval 2016-11-17 09:17:51 CET

In our application we use G4PrimaryParticle and SetDaughter method in order to force a specific decay channel.

We noticed that the polarization which is set to the daughter by SetPolarization function is not used in the subsequent decay of the daughter particle (muon decay with spin). After enabling verbose tracking output we found that the polarization is indeed not set for the daughter particle. We found a possible bug in the G4PrimaryTransformer where in the transformation from Primary to Dynamic particle, the polarization is set for the mother particle but not for the decay products in the SetDecayProducts function.

A simple fix would be to assign the polarization of the daughter primary particle to the newly created dynamic particle, like it is done for momentum, charge, etc.

Comment 1 asai 2016-11-29 00:21:16 CET

Thank you for reporting the issue. We will fix it very soon, but the fix won't go with version 10.3 scheduled on this coming Friday. It will go with the next patch release, and we will also make a retroactive patch for 10.2.
Kind regards,
Makoto Asai

Comment 2 asai 2016-12-09 02:46:03 CET

Created attachment 434 [details]
G4PrimaryTransformer.cc with the fix (source code to be included in version 10.3)

Comment 3 asai 2016-12-09 03:12:50 CET

The fix will be included in version 10.3. It may also be included in a retroactive patch for 10.2 as well. For your convenience, the fixed code is attached.
Thank you for reporting this issue.
Makoto