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Re: back-propagation with GEANE [message #10737 is a reply to message #10732] Tue, 25 May 2010 14:57 Go to previous messageGo to previous message
Anastasia Karavdina is currently offline  Anastasia Karavdina
Messages: 76
Registered: May 2010
Location: Mainz, Germany
continuous participant

From: *kph.uni-mainz.de
Hi Lia and Alberto,
I'm simulating antiprotons from the IP (0, 0, 0) with beam momentum 8.9 GeV/c in angles range (2,9) mrad for theta and (0,2*Pi) for phi angle.
The luminosity monitor is placed at 11 m downstream in z direction and z axis of the luminosity monitor is rotated for 2.33 degrees at 4.76 m. So it should be placed close to beam pipe.
But in my simulation I switched off beam pipe and I don't have any material before first plane of the luminosity detector.
You are right, in absence of magnetic field differences in my plots are very small. But as I don't have any material I can explain these differences only in two ways:
a) It's accuracy of calculation methods used in GEANE.
b) I did something wrong.
Differences in absence of magnetic field are not important I've asked you just to be sure that I used GEANE correct Rolling Eyes

In magnetic field situation become worse: I have difference 2*10^-3 rad for phi angle an 7*10^-6 rad for theta angle. From multiple scattering I expect uncertainties about 6*10^-5 rad for this beam momentum and for phi angle I obtained much more difference. Also I worried about two spots in plot of momentum magnitude (Delta P(P_MC) in file uncer.eps from my first post). Here Delta P is a difference between true simulation value P_MC and magnitude of momentum obtained after back-propagation. Do you know any reason why I obtained two different value for momentum magnitude after back-propagation?

Cheers,
Anastasia.
 
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