To find out you need to count events or extract yields from our data.
I assume many of you know. Take two sets of runs are analyzed (charge
and lrn): runs #100-200 have gas, and runs #300-400 have no gas
1)
root count_charge.C #100-200
root count_charge.C #300-400
will tell you much total charge you have for the two data sets
2)
root lr.C 100-200 -d 300-400
chain[0]->Draw("zwl","abs(zwl)<50") will plot to z-left distribution for
runs 100-200
chain[1]->Draw("zwl","abs(zwl)<50") will plot to z-left distribution for
runs 300-400
You can use chain[1]->Draw("zwl","abs(zwl)<50","same") to plot on top
of existing picture. You can use ohter cuts, such as Helastic_L or
Helastic_R for e- on L/R.
3)
To properly normalized the spectra you have to divide by the charge
obtained in step 1. One way to do it is to first fill two histograms
TH1F *gas = new TH1f("gas","gas",200,-50.,50.) (200 bins, +- 50 range, hname = "gas")
TH1F *empty = new TH1f("empty","empty",200,-50.,50.)
chain[0]->Draw("zwl>>gas","abs(zwl)<50")
chain[1]->Draw("zwl>>empty","abs(zwl)<50")
fill the histogram. gas->Draw() will draw histogram gas, empty->Set (tab)
will show many option (line, fill color) for histogram empty..... (RootManual)
Then
gas->Scale(1/.23423)
empty->Scale(1/.43234) will scale histos to x 1/charge determined in 1)
gas->Draw()
empty->Draw("same")
will compare the two. There are root experts around ask them.
Bottom line is that for nominal gas runs taken *after* the collimator was
installed we have the same normalized yield as for empty target runs,
although the pressure in the scattering chamber increased.
> rumor spread through email about no gas in target when operating
> gas feed system.
> calls to counting bay from Manoucher and Ernie etc.
> decision was made to warm cell and open up in the morning.
> no info about the background of this rumor was found!
> no note in logbook, no data or plots in counting bay and no information
> passed on to shift crew.
> when operating gas feed system found pressure increase in TC ok,
> leaves internal problem, if any.
>
> warmed up target cell so that we can open chmaber in the morning.
> several vacuum bumps into the 1e-6 range during warmup.
> temp at 250 by 00:30h.
>
> continued bump study.
> 2 hours of tuning the beam.
> horizontal 0mm, vertical +1mm.
> started taking data on this at 00:15h.
>
>
>
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