[Color_transp] [EXTERNAL] HGC

[Dave Gaskell]

Hi Sebouh -

In principle, 0.65 atm should not be a problem - I think one would 
expect about 15 photoelectrons at that pressure.  However, there's a 
pretty big hole in the center of the acceptance that will need to be cut 
out.

I'm cc-ing Bill Henry here as he takes care of the Cherenkov 
configuration for the Hall C experiments.  Bill - do you see any issue 
with running at 0.65 atm?

Cheers,
Dave

On 10/31/25 12:35 PM, Sebouh Paul wrote:
> Hi Dave,
> We seek your advice regarding the HGC.  In the Pion CT experiment at
> Hall C, we will want to detect pi+ and filter out kaons in the SHMS
> using the HGC.  We calculated that in order to ensure that the index
> of refraction is less than 1/β for the highest momentum kaons within
> the acceptance in the SHMS at our highest momentum setting (the
> central momentum would be approx 9 GeV, exact value TBD), we'd need to
> have around 0.65 atm.  Would this be feasible?  Are there standard
> procedures we would need to follow, or anything else we would need to
> know, in order to set up the HGC for this experiment?
> Thanks,
> Sebouh