[Halld-pid] Minutes, GlueX TOF Meeting, July 7, 2011

[Mark M. Ito]

Folks,

Find the minutes below as wiki-text. I will post them to the wiki when 
it becomes available, of course.

   -- Mark

   ==

=Minutes=

Present:
* '''FSU''': Paul Eugenio, Sasha Ostrovidov
* '''JLab''': Chuck Hutton, Mark Ito (chair), Beni Zihlmann

==Drawings==

* Paul sent the 3-D drawing of the light guides in step format to the 
email list. Chuck has looked at both versions and both look good.
* Chuck asked for 3-D drawings of Ian's support scheme and any other 
drawings that Ian is working with.
* Ian is currently working on the design for the light guides for the 
split counters (3-cm-wide counters).
* Paul sent out the drawings of the Hamamatsu phototubes to the list.

==Contract==

Paul will send out a draft of the statement of work soon.

==Prototype News==

* Paul received the UVT plastic from Polymer Plastics Corporation. It 
looks good. They can produce casts like it at the rate of four per week, 
which should be adequate. The price is comparable (or better) than 
commonly available UV-inhibing material.
* We talked about Elton's arguments for going with UVT material. Given 
the price, the choice is clear (clear...get it? ;-) ). Chuck reminded us 
that the BCAL folks are using UVT for their light guides.
* Paul has had his machine shop make a couple lightguides with the new 
design.
** One has been polished.
** Another will be sent for vapor polishing.
** The plan is to test both and compare performance.
** Beni also suggested looking at them with a laser pointer to get a 
qualitative feeling for the effect of polishing.
* Paul raise a concern: there is a short section of the light guide 
that, because of the bending, the cross-sectional area gets a bit larger 
before returning to the nominal size. He wonders whether this is 
something to worry about or not.

==Time-Walk Corrections==

Sasha has been working on applying Elton's time-walk correction 
prescription to data from the prototype set-up.
* He re-arranged the trigger paddles so that their long axes are at 
right angles to that of the test paddle.
* 400 k events have been collected with varying pulse height.
* Time walk is evident for the low ADC values.
* He is currently having some problems with the fit.