|Message: pi+ decay to mu+||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
Hello, I've encountered a problem with pion decay. Initially, I had written an application to look at transport of GCR protons through slab geometries. When looking at the flux at various depths within the slab, I noticed the mu+ flux had a strange jump discontinuity near 4 MeV. I eventually back-tracked the problem to low eneryg pi+ decay (< 20 MeV) and was able to reproduce the issue with the example application Hadr01. Using Hadr01, I added a line to StackingAction.cc to print out the energy of any mu+ produced through pi+ decay. For some targets (G4_Galactic, G4_He), the energies of the produced mu+ seem reasonable, but for other targets (G4_WATER, G4_Al, G4_Si), almost all mu+ get generated with 4.11981 MeV. This problem only seems to be obvious when the pion energy is small ( < 20 MeV) The case of mu- production from pi- decay seems to work fine in general. I've attached a copy of the macro file I used with Hadr01 to reproduce the problem. I'm using Geant4.9.4 (default build - no patches installed) on a Linux machine. I also downloaded and ran a pre-built version of Geant4.9.5 with Hadr01 and got the same issue to come up - although I was less confident about the installation/build/compilation process since an issue with the EXPAT library had to be worked out. Thanks, Tony ***************************** /run/verbose 0 /event/verbose 0 /tracking/verbose 0 /testhadr/TargetMat G4_Li /testhadr/TargetRadius 1 km /testhadr/TargetLength 4 mm /testhadr/NumberDivZ 1 /run/initialize /gun/particle pi+ /gun/energy 7.5 MeV /testhadr/PrintModulo 1000 /run/beamOn 1000 *****************************
|Inline Depth:||Outline Depth:||Add message:|