| Dipole and transcient B field effect [message #8597] |
Tue, 19 May 2009 17:50  |
Tsitohaina Randriamalala
Messages: 14
Registered: October 2007
Location: FZ Jülich
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occasional visitor |
From: *ikp.kfa-juelich.de
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Dear all,
I have performed simulations just to check if the B fields (especially for the dipole and the transition region ) are as well implemented in pandaroot as how they are described in the Magnet Technical Design Report (MTDR).
5000 events with single antiproton propagated from the IP at different momenta (1.5 , 4.06 , 8.9 , 11.91 , 15 GeV/c) were run. At z=10m is placed an active plane. No subdetector, including the beam pipe was used.
The projection on x-axis of the hit positions are plotted (see attached files) for these values of momenta.
According to the MTDR, at z=10m, the distance that separates the two extreme antiproton beams trajectories is 0.4mm. Here I got about 1 cm wide. Too wide!!!
I think the field maps need to be treated with more accuracy!
Otherwise the scattered particles by the beam pipe will create a high level of background for some forward subdetectors ( for the luminosity monitor, for instance).
Thank you.
Cheers,
Tsito
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| Re: Dipole and transcient B field effect [message #8609 is a reply to message #8604] |
Wed, 20 May 2009 16:24  |
Tsitohaina Randriamalala
Messages: 14
Registered: October 2007
Location: FZ Jülich
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occasional visitor |
From: *ikp.kfa-juelich.de
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I plotted here the field components variation along z-axis.
The shifts at the low values of x, at the momenta 4.6 GeV/c and 11.91GeV/c of the antiproton beam in the histogram (in the first mail), may be related to the existing cut at z ~ 600 cm of the y component of B.
And similarly the presence of a jump on By at z~600cm may be the cause of the shift at the high values of x for the case of 8.9 GeV/c beam momentum.
Tsito
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