Message: Re: =?UTF-8?B?QnVnPz8=?= A question of G4EqEMFieldWithSpin.cc Not Logged In (login)

## Re: =?UTF-8?B?QnVnPz8=?= A question of G4EqEMFieldWithSpin.cc

Forum: Fields: Magnetic and Otherwise
Re: =?UTF-8?B?QnVnPz8=?= A question of G4EqEMFieldWithSpin.cc (Hiromi Iinuma)
Re: Re: =?UTF-8?B?QnVnPz8=?= A question of G4EqEMFieldWithSpin.cc (Kevin Lynch)
Date: 05 Nov, 2009
From: Hiromi Iinuma <Hiromi Iinuma>

 Dear Kevin, Hello. Thank you for a reply. Let me explain what I have done: 1) I checked so-called "spin-frozen" condition. There is a good example article hep-ph/0012087v1. This article discusses about how to cancel the muon g-2 precession by applying an electric field. Here, I am going to use these parameters: 1) beta is muon velocity, 2) B is an uniform magnetic field and \vec{beta}.\vec{B}=0, "." means scalar product, 3) Radial electric field (E) in the lab frame and \vec{beta}.\vec{E}=0, 4) a=(g-2)/2 is muon anomalous magnetic moment. The required electric field to cancel the g-2 precession is, E=a*B*light_c*gamma^2*beta. In case of gamma=5 and B=0.24 Tesla, the required electric field is E=2 MV/m. "Spin-frozen" happens when spin rotation cycle and muon rotation cycle are same. In this case, both cycles should be 149.5 nsec. This is my expectation from the article hep-ph/0012087v1 and Jackson, 3rd edition. (Actually, my Jackson is Japanese version.) Then I tried to apply proper electromagnetic field and muon momentum in GEANT4 simulation. Although I got correct muon rotation cycle,I did not get correct spin rotation cycle. Therefore I modified "G4EqEMFieldWithSpin.cc" as I wrote in the previous e-mail, and finally I got expected results. I can show you more detail analysis note as needed. Best regards, Hiromi ----- Original Message ----- > > *** Discussion title: Fields: Magnetic and Otherwise > > It's possible ... I asked the Geant collaboration to add this code, so > I'm responsible for any bug is this piece of code. Before 4.9.2.p02, the > whole beta x E terms was missing. I could have screwed it up. It's been > a while since I wrote this, so let me trace back through what I did and > see how the argument went.... > > When you say the "simulated spin rotation frequency do not agree with > the correct frequency from Thomas-BMT equation", did you check that? Are > you sure the C is not hiding somewhere else? Are you sure you're using > the Maxwell equations in the right units? I cribbed most of the > equations from Jackson, 2nd edition, and matched them onto the existing > code to try and get the units right. > > I'm not sure I got it all right, but it would be nice to do so before I > need to start relying on my own simulation results :-) > > ------------------------------------------------------------- > Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or unsubscribe) at: > http://hypernews.slac.stanford.edu/HyperNews/geant4/get/emfields/161/1. html > 

 Inline Depth: Outline Depth: Add message:

1 Re: =?UTF-8?B?QnVnPz8=?= A question of G4EqEMFieldWithSpin.cc   (Kevin Lynch - 06 Nov, 2009)
 to: "Re: =?UTF-8?B?QnVnPz8=?= A question of G4EqEMFieldWithSpin.cc"
This site runs SLAC HyperNews version 1.11-slac-98, derived from the original HyperNews

[ Geant 4 Home | Geant 4 HyperNews | Search | Request New Forum | Feedback ]