Re: pair spectrometer (fwd from Hrachya)

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Thu, 28 Aug 2008 17:40:21 +0500 (AMST)
From: Hrachya.Hakobyan <hakopian@mail.yerphi.am>
To: Richard Jones <richard.t.jones@uconn.edu>
Cc: Hall D beam working group <halld-tagger@jlab.org>
Subject: Re: pair spectrometer (fwd)

Richard,

I agree with your arguments in the favor of equal  left/right
counter number configuration  in the sense of making more optimal design.

  The discussion of  the questions related to design such as a
required PS granularity,resolution, efficiency and structure of PS
hodoscopes  itself , are  unfortunately delayed since  May when I
presented the first  draft of a quite  symmetric 10x8 PS design.


The last PS design, version 9-1.cor, is made in base of non-symmeric
24x6 left/right configuration, that I've preferred from point of view of
easier mechanical design as compared  for example to equivalent
by granularity option 12x12 as I've already mentioned.

- In non symmetrical 24x6 design the tight pack layer of 24 strips in
FSF arm is easy to adjust and assembly in base of common services' box and
single mechanical holder structure. In WSF arm there are a 6 single
counters.
  The 24x8 configuration contains in total  40 counters, including 24+4 and
6+6 ones in FSF+FSB and WSF+WSB arms respectively.

   An equivalent by granularity,resolution and efficiency  12x12
configuration contains in total  38 counters or 12+2 and  12+12 ones  in
FSF+FSB and WSF+WSB arms. In WSF arm there are 12 single counters
requiring a precise positioning.

I hope we may discuss more details on required PS granularity/
resolution, efficiency and structure of hodoscopes, including possibility
to use an active PS converter.

Hrachya