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Panda target and vertex cuts [message #18584] Tue, 27 October 2015 15:50 Go to previous message
Elisabetta Prencipe (2) is currently offline  Elisabetta Prencipe (2)
Messages: 214
Registered: February 2013
first-grade participant
From: *ikp.kfa-juelich.de
Dear all,

following a discussion started at the open-charm meeting, and today at the computing meeting, I would like to point you on a non-trial problem.
I am trying to reduce the DPM bkg in the simulation ppbar to Ds- Ds2317+. It turns out that a cut around the vertex position can be effective. However, I am currently using the /rho package, and I did not find a way to compute how effectively the target smearing can affect such a cut. It should be done at level of sim- macro.
Based on MC signal simulations, the vtx resolution ix x,y is in between 50 and 80 micrometer (it depends also on which vtx fitter one makes use of), and it is roughly double value for the z vtx position. However, to apply even a 5 sigma cuts around those distributions, it is not a clever idea, due to the fact that the we cannot assume IP(0,0,0): it is simply non realistic, due to the target smearing, which is still not taken in consideration.

Here is a phD thesis performed in 2011, from T. Randriamalala: http://www-brs.ub.ruhr-uni-bochum.de/netahtml/HSS/Diss/RandriamalalaTsit ohainaH/diss.pdf

At pag.58-61 studies are reported in this sense, for the pellet target. I point you at pag. 60, fig. 4.34.
If I understand it correctly, a cut at <= 2mm would be safe. Do you agree?

I do not find such a study related to the cluster-jet target, and/or related simulation for a physics channel. Anybody has some any clue?

Looking forward to hear from you,

Elisabetta
 
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