[Eic-exclusive] [EXTERNAL] Re: Exclusive Meeting Monday 1/27/20 11am

[Hyde, Charles E.]

Hello,
Here are some parameters of the forward acceptance design from slides of Alexander Jentsch
https://urldefense.proofpoint.com/v2/url?u=https-3A__indico.bnl.gov_event_6799_timetable_&d=DwIFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=AuqPVKnsEOgeRWAaMMLgHpZcS5k6fPv4Bx7HgTTr4WE&m=tqYD_n9m9gblUJQtI7VENkpm6hgqLhHzz_59X6p7RcY&s=ISkU4FlRgsmzZjINaAGRvWJxjqQyStbj3LvOxnYhpZc&e= 

RP:  Theta < 4mrad . (minimum angle is not clearly defined, but about 1.4 mr at 275 GeV and 2 mrad at 100 GeV . 
B0 Magnet aperture:  7 mrad to ~ 25 mrad
Endcap theta > 35 mrad (2deg)

At 100 GeV proton energies, the gap between 4 and 7 mrad is a gap of p_T between 400 and 700 MeV/c
This is a gap in t' between 0.16 and 0.49 GeV^2

Small angle acceptance is achieved only at 275 GeV by  increasing  the beta*  by a factor of 2 (lowers luminosity by a factor of 2)
This allows the roman pot detectors to move closer to the beam, to 0.65 mrad, or p_T > 0.18 GeV/c

It should also be noted that the forward acceptance seems to be strongly quadrupolar:  Different in x and y

Sincerely,
Dr. Charles E. Hyde
Chair, Department of Physics
Eminent Scholar and University Professor
Old Dominion University
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