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Simple calculation on the energy loss impact on the pointing position

Updated on Fri, 2014-05-16 14:45. Originally created by dongx on 2014-05-16 13:25.

 The pointing position change due to the energy loss in the detector material can be calculated as:

delta_d = 0.15 * B * R^2 / pT^2 * delta_pT

B: magnetic field
R: the radius where the energy loss happens (distance from the pointing position you are looking to)
delta_pT:  pT change due to energy loss

Full evaluation is attached. With this, I can estimate the pointing position change for different silicon material at different radii.

The estimate is for pT = 1 GeV/c track, assuming MIP energy loss. The unit for the postion change is micron-meter.

r (cm) 2.7 8 14 22
0.5%X0 0.01 0.09 0.27 0.65
1.0%X0 0.02 0.17 0.53 1.3
2.0%X0 0.04 0.35 1.06 2.6

Note that the change goes with 1/pT^2! And furthermore, the low momentum particle energy loss goes with 1/beta^2!



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