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The electron detector

  • The electron detector is placed 5 mm above the primary electron beam. To check that, I forced the energy of the scattered electrons to be the one of the primary beam (E=1.165 GeV). The figure below demonstrates that the electron detector is effectively located above the primary beam (ignore the photon detector and scattered photons).

Electron beam position.gif

  • Then after restoring the scattered electron energy formula, 100 events are generated in the following figures:

Scattered beam 3.gif ----- Scattered beam 1.gif

  • A close-up on the electron detector

Scattered beam 4.gif ----- Scattered beam 2.gif

  • Now looking at some distributions and numbers. The simulation was run with the following inputs:
   Beam energy = 1.165 GeV
   Beam polarization = 80%
   Dipole length and height: 125cm x 4.125"
   Laser: 532nm, 1kW and alpha_c=35.28 mrad
   Nevt generated: 20000

no cut 19909
require trigger the e detector 16457
and cut on k'/kmax min 9612
and cut on 4 hits in the e detector 9612*

(* spaces between strips might have not been taken into account yet.)


The analyzing power distribution is shown on the bottom plot. The cut on k'/kmax is adjusted to separate the negative and positive parts of the analyzing power (which will be required in the accumulated mode since the integral of the analyzing power will be used). The middle and top plots show the k'/kmax and Egamma distributions respectively for analyzing power >0 (red) and <0 (green).

Egamma edet.gif

Looking now at the electron detector efficiency, the top plot shows the Egamma distributions for no cut (black), e-detector trigger required (blue), k'/kmax cut (red) and number of hits in the e-detector equals 4 (green). Nhits=4 means that each electron detector planes fired. The bottom plot shows the total electron energy deposited for no cut (black), e-detector trigger required (blue) and k'/kmax cut (red).