[Halld-pid] Minutes, GlueX Start Counter Meeting, November 17, 2011

[Eugene Chudakov]

On the sensors for the Start Counter:

One may consider the surface mounted Hamamatsu MPPC S10931-05P: 3x3
mm^2, pixels 50x50um^2.  The shorter side is 3.85mm wide. The packing
factor will be 3.0/3.90=0.77 - not too bad.  120 such sensors can be
arranged in a 30-side polygon (4 sensors per side), for 15.6mm wide
light guides. The radius of such a structure is about 75mm.

Eugene

------------------------------------------------------
Eugene Chudakov
phone (757) 269 6959  fax (757) 269 6331
Thomas Jefferson National Accelerator Facility
12000 Jefferson Ave,
Newport News, VA 23606 USA

On Thu, 17 Nov 2011, Mark M. Ito wrote:

> Folks,
>
> Find the minutes at
> https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_17,_2011
> and below as text.
>
> -- Mark
> ______
>
> GlueX Start Counter Meeting, November 17, 2011
>
> Minutes
>
> Present:
> * FIU: Lei Guo, Puneet Khetarpal
> * JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair), Tim
> Whitlatch
>
> Prototype Report
>
> Lei reports that they got the scintillators back from Plastic Craft
> after re-polishing. Three of them came back badly crazed. One was OK.
> He says they made two mistakes:
> 1. They ignored the recommendation to only use isopropyl alcohol to
> clean the surfaces. Instead they used a solution of isopropyl
> alcohol and naphtha. The naphtha is petroleum based and attacked
> the scintillator surface.
> 2. They processed the counters in the following order: bend, machine,
> then polish. Preferred is: machine, polish, then bend.
>
> Plastic Craft has agreed to replace the scintillator and will try again
> with the new pieces. They will place an order with Eljen.
>
> FIU will test the undamaged piece. Its surface quality seems to have
> improved after re-polishing.
>
> SiPM configuration
>
> Puneet reported that Werner has given it some thought and is
> considering a 1x4 or 1x5 array of 3 mm×3 mm devices. He is thinking of
> using these in a 30-paddle arrangement.
>
> We need to find out what is available from Hamamatsu. It is looking
> like the geometry will be driven by how we arrange the SiPM's, with a
> scintillator/light-guide geometry constrained by that arrangement. It
> would be preferable to have flat light guides with no bend.
>
> Simulation Status
>
> Puneet showed further progress understanding the output of the start
> counter hits in the Monte Carlo. See [29]his slides for details. He
> generated γp to nπ^+π^+π^− events, and from those showed single
> particle energy and direction distributions and hit location
> distributions. The latter revealed an overlap of the scattering chamber
> with the nose section of the start counter in the default geometry. He
> has also looked a deposited energy and detection time. The start
> counter geometry used has 24 paddles.
>
> The drawings and Monte Carlo need to be updated. Sashca Somov may be
> able to help with the Monte Carlo.
>
> There seems to be some feature in the hit location distribution in the
> barrel section. Puneet will run more statistics to see what is going on
> there.
>
> Puneet and Werner are also working on rate and radiation dose studies
> using GEANT4
>
> Action Items
>
> 1. Test re-polished counter. -> Eric Pooser
> 2. Research different SiPM arrangements from Hamamatsu. -> Mark,
> Werner
> 3. Update drawings of target/start-counter region. -> Tim, Chuck
> 4. Update Monte Carlo geometry. -> Puneet, Sascha
>
> Retrieved from
> "https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_17,_2011"
>
> References
>
> 29.
> https://halldweb1.jlab.org/talks/2011-4Q/start_counter/khetarpal_sc_hdgeant2.pdf
>
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