[Halld-pid] Minutes, Time-of-Flight Meeting, February 2, 2012

[Elton Smith]

Hi Sasha,

It would be interesting to determine the threshold (30 mV) in terms of 
ADC counts. This could be done by adding a PMT to the trigger and see 
where the ADC spectra cuts off. It would be useful to see it on the ADC 
plot to see how it cuts into the ADC spectra. This should be consistent 
with the determination of efficiency.

Cheers, Elton.

Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite #16
Newport News, VA 23606
(757) 269-7625
(757) 269-6331 fax


On 2/3/12 2:19 PM, Mark M. Ito wrote:
> Colleagues,
>
> Find the minutes at
> https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_February_2,_2012#Minutes
> and below as text.
>
>     -- Mark
>     _____
>
> GlueX TOF Meeting, February 2, 2012
>
> Minutes
>
>      Present:
>        * FSU: Paul Eugenio, Sasha Ostrovidov
>        * JLab: Chuck Hutton, Mark Ito (chair), Tim Whitlatch, Beni Zihlmann
>
> Minutes from the last meeting
>
>      We reviewed the [22]minutes from the January 19th meeting. Some items
>      received continuing discussion in this meeting. See below.
>
> Contract
>
>      Procurement at JLab and the Office of Sponsored Research at FSU are in
>      touch and are exchanging information about the construction contract.
>
> Mechanical Design
>
>      There have been a couple of conference calls with the design teams on
>      the design of the light guides for the half-width (or split) paddles.
>      We have agreement on a final design in hand.
>
>      Chuck showed the [23]latest drawings, demonstrating the assembly steps
>      we might follow on the floor of the Hall.
>
>      We talked a little about how the thickness of the scintillator wrapping
>      material affects the design. Paul agreed to send us numbers on the
>      thickness.
>
>      Paul showed a jig, produced by his machine shop, for gluing PMT's to
>      the light guides. The light guide is housed in an aluminum frame and
>      there is a clamp for holding the PMT while the glue dries.
>
> Prototype Status
>
>      Sasha showed [24]results from on-going tests of the eight-stage
>      phototubes from Hamamatsu. The gains are a several times lower than for
>      the ten-stage, as expected, but still show good separation from
>      pedestal. Efficiency was reduced to about 80% when using a 30 mV
>      discriminator threshold, for triggers in the middle of the counter (no
>      amplification). Time resolution measurements are in the works.
>
> TDC Choice
>
>      Paul was wondering if there is any data-acquisition-based reason for
>      not using the CAEN VX1290 TDC's. They see better performance with this
>      unit than with the F1 TDC at FSU, both with a pulser and with detector
>      pulses. They are purchasing the unit they have; up until now it has
>      been on loan from CAEN. Paul is willing to loan it out if that helps
>      answer any questions.
>
>      Mark promised to ask the DAQ folks if there is any fundamental reason
>      we cannot use it.
>
> Action Items
>
>       1. Paul agreed to send us numbers on the thickness of the scintillator
>          wrapping.
>       2. Mark will ask about compatibility of the CAEN VX1290 TDC with the
>          GlueX DAQ.
>
>      Retrieved from
>
> "https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_February_2,_2012"
>
> References
>
>     22.
> https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_January_19,_2012#Minutes
>     23. https://halldweb1.jlab.org/talks/2012-1Q/tof%20assy.pptx
>     24.
> https://halldweb1.jlab.org/talks/2012-1Q/First%20results%20from%208-stage%20PMTs.html
>