[Hps] HPS is taking data

[Graham, Mathew Thomas]

Also, as we were discussing in the counting room, the sampling fraction of the calorimeter is ~0.8 - 0.85% which the plot shown doesn’t account for…so this is a big chunk of the discrepency.


On Dec 13, 2014, at 7:40 PM, Valery Kubarovsky <vpk at jlab.org<mailto:vpk at jlab.org>> wrote:

Hi Volker,
As Ben pointed me out the clusters on the perimeter (and near the beam pipe) effectively have 6 crystals in the window instead of 3x3=9.
Clusters on the corners have 4 crystals in their window. The majority of the clusters are near the beam pipe..
So the leakage may be upto 50% of the total energy.
Valery


On Sat, Dec 13, 2014 at 2:14 PM, burkert <burkert at jlab.org<mailto:burkert at jlab.org>> wrote:
Hi all,
  Congratulations to starting the real data taking!

I have a question on the single cluster energy spectrum. I would expect
that single clusters at forward angles should have a peak at nearly the
full beam energy from quasi-elastic ep scattering minus the platinum
binding energy, and at very-very forward angles from e-PT -> e-PT
elastic scattering. The peak sits however at much lower energy , which
may indicate incorrect energy calibration, or the energy in the cluster
is not completely summed up.
My question is, how many crystals are summed up to define an energy
"cluster"?

Volker



On 12/13/14, 11:05 AM, Maurik Holtrop wrote:
> Hello Takashi, Stepan and all of you on shift,
>
> This is really great!
>
> I went through the logbook entries and don't see the entry that explains what the source of background was and how it was eliminated. If you have a moment, could you please point me to the right entry? Was it beam-gas interactions?
>
> Best,
>       Maurik
>
>
> On Dec 12, 2014, at 8:39 PM, Maruyama, Takashi <tvm at slac.stanford.edu<mailto:tvm at slac.stanford.edu>> wrote:
>
>> With heroic effort by Stepan, the anomalous source of background was identified and eliminated completely. 1.5 micron-thick Pt target was inserted. Attached is a ECal single rate map at 10 nA. This is very similar to what you see in Monte Carlo.
>>
>> Ben has setup a very loose two cluster trigger and Sergey's DAQ system is taking data at 4.5 kHz at 10 nA. This data will be used to find optimum cuts for pair trigger.
>>
>> Takashi
>> RC <fadc_firsttarget.png>_______________________________________________
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>
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