1530 – error in the magnetic field for Bx to control the track along y

Problem 1530 - error in the magnetic field for Bx to control the track along y

Summary: error in the magnetic field for Bx to control the track along y

Status:	RESOLVED WORKSFORME

Alias:	None

Product:	Geant4
Classification:	Unclassified
Component:	geometry/magneticfield (show other problems)
Version:	9.6
Hardware:	All All

Importance:	P5 critical
Assignee:	John Apostolakis

URL:

Depends on:
Blocks:

Reported:	2013-10-25 21:41 CEST by Fada Guan
Modified:	2014-01-24 18:02 CET (History)
CC List:	0 users

See Also:

Attachments
spot (107 bytes, text/plain) 2013-10-25 21:49 CEST, Fada Guan	Details
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Description Fada Guan 2013-10-25 21:41:21 CEST

I used two uniform magnetic fields to bend proton beam in x and y directions for proton spot scanning.

For example, I want to deliver a spot on (-10 cm, -10 cm) on one plane.

In Geant4.9.5.p01, the proton spot position is correct as specified.
However, in Geant4.9.6.p02, for the same problem with the same source code, the spot position is away from the specified position in y direction. It was delivered to (-10 cm, -14 cm).

Please see the attached two pictures.

Who can help check the source code of G4UniformMagField.

Thanks a lot!

Fada Guan

Comment 1 Fada Guan 2013-10-25 21:49:14 CEST

Created attachment 241 [details]
spot

      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/10/25/12.47-7864-_guanfada_Desktop_9.5.png
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/10/25/12.47-80530-_guanfada_Desktop_9.6.png

Comment 2 Fada Guan 2013-12-25 00:36:42 CET

I tested the same problem using Geant4.10.0, and the result was correct.
Hence, I believe it is only the Geant4.9.6 specific problem.

Comment 3 Fada Guan 2014-01-24 18:02:05 CET

I guess it is due to the MSC algorithm in magnetic field.