[Hps] Electrons tracks

[Garcon Michel]

Hi all,

                In addition/complement  to Maurik's plot which demonstrate the point, here are 2 more graphs: for electrons tracks in the horizontal plane, E vs position on ECal front face, with angle of incidence color coded. Angle of incidence is track angle on ECal - crystal angle (which explains the vertical structures since the crystal angles are discretized). Generated with wide angle range at target. Negative x is to the right of ECal (electron side).

First graph is with the condition that the track does not hit the vacuum chamber at any point between target and magnet exit. At 2.2 GeV, there are no tracks above x = 200 mm ! (see Note)
Second graph is with the additional condition that at least 4 SVT planes are hit.

                Note that for 2.2 GeV (top of graph) the incident angles are nearly symmetrical, so that the shower develops at +/- 6 degrees wrt to the crystal. That would be my explanation for Luca's yellow crystals, because the seed hit is a lesser fraction of the total. To be absolutely sure (and to distinguish with Maurik's hypothesis), one would have to plot the total cluster energy (complete cluster with JLab algorithm). In Maurik's hypothesis, it degrades in the yellow crystals, in mine not.

                                                                              Michel.

Note:    This is from my own simulation; there might be (in fact there are) small differences with SLIC geometry, of the order of a few mm to 1 cm on various distances.

_______________
Michel Garçon
Irfu/SPhN
CEA-Saclay, bât. 703
91191 Gif-sur-Yvette cedex
France
Tél.: +33 1 69 08 86 23

Until October 31st, on leave at
Jefferson Lab
Office in CC-B129
Phone : +1 757 269 7636

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/hps/attachments/20140723/ae7ab31f/attachment-0001.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: alpha_x_e_el.png
Type: image/png
Size: 25697 bytes
Desc: alpha_x_e_el.png
Url : https://mailman.jlab.org/pipermail/hps/attachments/20140723/ae7ab31f/attachment-0002.png 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: alpha_x_e_el_svt.png
Type: image/png
Size: 23419 bytes
Desc: alpha_x_e_el_svt.png
Url : https://mailman.jlab.org/pipermail/hps/attachments/20140723/ae7ab31f/attachment-0003.png