[d2n-analysis-talk] H2 update report
MATTHEW R POSIK
tua88437 at temple.edu
Tue Apr 27 17:07:30 EDT 2010
Hi Brad,
I have put together some kinematic plots for H2 elastic run 1258:
H2_L_BB.png shows the invariant mass sqrt(w2) (left), scattering angle in
degrees, and momentum in GeV . The red Hist is the HRS and the blue histo is
the BB. All plots here have T5 coin cut.
I then selected events in a tight cut on the BB elastic peak
"PriKineBB.W2>0.86&&PriKineBB.W2<0.96 && T5_coin_trigger" and plotted the
LHRS theta L.tr.tg_th this is plot lables el_th.png. As you can see there
are now 3 resolved peaks in the theta variable.
I also looked into the cuts that I was using for selecting good protons in
the LHRS. It seems that a lot of events are lost when I make the LHRS
acceptence cuts. Here is a run down of how the cuts affect the events, the
%diff is how many events are lost compared to the trigger+beam cut, and the
cut to cut % is how many events are lost from the previous cut. The tg_xx
are the acceptence cuts:
**************************************************************************************************
Cut
Events %diff from cut to cut
**************************************************************************************************
- no cut
4009380 -
- triggers+beam 216022
-
- triggers+beam+track 214883
0.5 0.50
- triggers+beam+track+tg_y 142087
34.2 33.88
-triggers+beam+track+tg_y+tg_ph 112676
47.84 20.69
-triggers+beam+track+tg_y+tg_ph+tg_th 65533 69.66
41.84
-above +ex_tg_p 65309
69.77 0.30
-above +ex_tg_p+energy 53235
75.36 18.49
-above +ex_tg_p+energy+cer 50852
76.46 04.47
-above +ex_tg_p+energy+cer+vdc 47832
77.85 0.594
-above +ex_tg_p+energy+cer+vdc+prl
11339 **Don't think this one is correct.
It requires prl1 and prl2 to fire.***
-without acceptance cuts 152197
I also realized my prl cut is probaly not good, I required both prl1 and
prl2 to fire. But if the proton deposits all it's energy in prl1 than it
will not count. So I am going to take that cut out.
-Matt
On Tue, Apr 27, 2010 at 10:12 AM, Brad Sawatzky <brads at jlab.org> wrote:
> Looks like good progress Matt. A few comments:
>
> p. 11: (copy-paste error) 'BCM scalers' isn't right -- trigger
> scalers maybe?
>
> p. 14: You should use the acceptance defined by the cuts you've
> applied to theta, phi, p, etc earlier. Those will be smaller
> than the "wide open" parameters listed on the Hall A page.
>
> p. 17: I'm a little puzzled that there are 216k coincidence events in the
> LHRS, but only 11k protons. What is cutting out 95% of the
> data? Are we really 20:1 proton to pi+ in elastic kinematics?
>
> It would be very good to see a missing mass plot that shows the elastic
> proton peak.
>
> I can believe the 93% number for electron tracks in BB in these
> kinematics. That's lower than I would have hoped, but it isn't
> terrible.
>
> -- Brad
>
> On Fri, 23 Apr 2010, posik at jlab.org wrote:
>
> > I have just put together a few slides that go over what I have done
> with
> > computing the H2 cross section. You can find the link here:
> >
> >
> https://hallaweb.jlab.org/wiki/index.php/Analysis_resources_for_d2n#23_April_2010_Meeting
> :
> >
> > I put it under April 23 Meeting.
> >
> > Currently I am waiting on the H2 GMA ref cell target density. Once I
> have
> > this I should be able to pull a rough cross section. Also looking at the
> > proton tracks that show up in the LHRS, the BB has ~93% coin electron
> > tracks, which I don't think is too bad.
> >
> > Let me know if you have any questions or suggestions.
> >
> > Thanks
> > Matt Posik
> >
> >
> >
> >
> >
> --
> Brad Sawatzky, PhD <brads at jlab.org> -<>- Jefferson Lab / Hall C / C111
> Ph: 757-269-5947 -<>- Fax: 757-269-5235 -<>- Pager: brads-page at jlab.org
> The most exciting phrase to hear in science, the one that heralds new
> discoveries, is not "Eureka!" but "That's funny..." -- Isaac Asimov
> _______________________________________________
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>
--
Matthew Posik
Email: posik at temple.edu
Temple University Physics Dept.
Office: BA-319
Office #: 215-204-1331
WebSites:
Temple:
http://quarks.temple.edu/
d2n:
http://hallaweb.jlab.org/experiment/E06-014/
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