[Olympus] Monday slides

[Becky Russell]

Hi,

The efficiencies I presented are using electron tracks only, so the 
statistics in the front bars are much much better than the statistics in 
the back bars. The very back bars are additionally cut out somewhat by 
the wire chamber acceptance, since I require a good hit coming from the 
center of the target.

The top part of bar 18 is experiencing very high rates in the 3/4 
trigger due to some background that I don't understand yet. This hotspot 
is not seen in the main trigger. I will do more investigation into 
whether it might cause an inefficiency in elastic events.

In the MC digitization, ToF efficiencies due to the effective light 
attenuation in each bar, threshold for each PMT, and ADC ringing in each 
PMT are taken into account, with values extracted from data. These 
mostly produce inefficiencies along the edges of the ToF bars and >98% 
efficiencies in the middle of the bars. I can produce an efficiency plot 
for MC radiative ep events that Jan digitized, but it won't be 
completely comparable to the 3/4 efficiency plots since the event sample 
is significantly different.

One thing I would like to look at that I suspect would be more 
informative than the 3/4 trigger is the elastic yield plots as a 
function of bar number and ToF y position. If the hotspot in bar 18 
causes an inefficiency in elastic triggering, we should be able to see 
it in this plot.

- Becky

On 10/06/2015 07:34 AM, Michael Kohl wrote:
> Hi,
>
> I was unable to attend the meeting on Monday but here I have some
> questions:
>
> On Jan's slides:
> Is there a comparison of data/MC for the two form factor possibilities
> yet, and does it agree qualitatively with the 'should-be's'??
>
>
> On Axel's slides:
> is the spread of the pile-up luminosity data points all statistical, or
> are there drifts within runs or fills (e.g. the red and blue vertical
> bands on slides 3/4?
>
> Do we have any idea what causes the wiggles in phi, and are the same
> phi wiggles also responsible for the structures versus polar angle?
>
>
> On Becky's slides:
>
> Bar 0 seems to have much more yield than bar 17
> Bar 18 seems to be inefficient near top end
>
> slide 4 last bullet: If digitization 'should' account for TOF
> inefficiencies then how big are they in MC and how do they compare with
> the data?
>
>
> Best regards
>     Michael
>
>
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