[Halld-physics] Solenoid Current Studies

[Volker Crede]

Curtis,

I had a brief discussion with Paul Eugenio about the "Track Efficiency" this morning. We assumed that the photon reconstruction efficiency is different from the track efficiency, counted the number of tracks and photons for the two reactions (3 tracks, 2 photons for the 'eta' case; 5 tracks and 2 photons for the 'omega' case), and computed numbers which are overall somewhat lower than what you have in the table. This of course depends on the assumption for the photon reconstruction efficiency but I think about 60-70% for a pair of photons is probably realistic. However, the numbers we derived are even more consistent.

I think we can conclude at least that adding tracks (when going from the eta to the omega reaction) does not significantly reduce the tracking efficiency. Unfortunately, Aristeidis confirms the decreasing overall acceptance with increasing solenoid current.

- Volker


On Aug 13, 2014, at 8:52 AM, Curtis A. Meyer <cmeyer at cmu.edu> wrote:

> I have taken numbers from both Michael’s and Aristeidis’ studies and combined them in
> an Excel spread sheet that can be obtained from:
> 
> https://www.dropbox.com/s/0p1iuhpnc4ialzu/GlueXCurrentStudies.xlsx
> 
> In this spreadsheet, I accounted for the omega-> pi+ pi- pi 0 (89%)  and the eta->gam gam (39.1%)
> in obtaining the efficiencies. I also used Aristeidis’ (100,4) numbers, that may have been the wrong
> choice???
> 
> I then computed a “Track Efficiency” from the number of candidates to the BDT versus the number of 
> correct events thrown. In this I just counted the number of tracks and photons, so for the eta pi pi case, this is 5, while for the omega pi pi case, it is 7. The number is clearly a bit lower for the omega case, but not by a huge factor.
> 
>   Curtis
> ---------
> Curtis A. Meyer			MCS Associate Dean for Faculty and Graduate Affairs
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