Hi Brad,<br><br>I have put together some kinematic plots for H2 elastic run 1258:<br><br>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.<br>
<br>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. <br>
<br>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:<br>
<br>**************************************************************************************************<br> Cut Events %diff from cut to cut<br>**************************************************************************************************<br>
- no cut 4009380 -<br>- triggers+beam 216022 -<br>- triggers+beam+track 214883 0.5 0.50<br>
- triggers+beam+track+tg_y 142087 34.2 33.88<br>-triggers+beam+track+tg_y+tg_ph 112676 47.84 20.69<br>-triggers+beam+track+tg_y+tg_ph+tg_th 65533 69.66 41.84<br>
-above +ex_tg_p 65309 69.77 0.30<br>-above +ex_tg_p+energy 53235 75.36 18.49 <br>-above +ex_tg_p+energy+cer 50852 76.46 04.47<br>
-above +ex_tg_p+energy+cer+vdc 47832 77.85 0.594<br>-above +ex_tg_p+energy+cer+vdc+prl 11339 **Don't think this one is correct. It requires prl1 and prl2 to fire.***<br>
<br>-without acceptance cuts 152197<br> <br><br>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.<br>
<br>-Matt<br><br><div class="gmail_quote">On Tue, Apr 27, 2010 at 10:12 AM, Brad Sawatzky <<a href="mailto:brads@jlab.org">brads@jlab.org</a>> wrote:<br><blockquote class="gmail_quote">
Looks like good progress Matt. A few comments:<br>
<br>
p. 11: (copy-paste error) 'BCM scalers' isn't right -- trigger<br>
scalers maybe?<br>
<br>
p. 14: You should use the acceptance defined by the cuts you've<br>
applied to theta, phi, p, etc earlier. Those will be smaller<br>
than the "wide open" parameters listed on the Hall A page.<br>
<br>
p. 17: I'm a little puzzled that there are 216k coincidence events in the<br>
LHRS, but only 11k protons. What is cutting out 95% of the<br>
data? Are we really 20:1 proton to pi+ in elastic kinematics?<br>
<br>
It would be very good to see a missing mass plot that shows the elastic<br>
proton peak.<br>
<br>
I can believe the 93% number for electron tracks in BB in these<br>
kinematics. That's lower than I would have hoped, but it isn't<br>
terrible.<br>
<font color="#888888"><br>
-- Brad<br>
</font><div class="im"><br>
On Fri, 23 Apr 2010, <a href="mailto:posik@jlab.org">posik@jlab.org</a> wrote:<br>
<br>
> I have just put together a few slides that go over what I have done with<br>
> computing the H2 cross section. You can find the link here:<br>
><br>
> <a href="https://hallaweb.jlab.org/wiki/index.php/Analysis_resources_for_d2n#23_April_2010_Meeting">https://hallaweb.jlab.org/wiki/index.php/Analysis_resources_for_d2n#23_April_2010_Meeting</a>:<br>
><br>
> I put it under April 23 Meeting.<br>
><br>
> Currently I am waiting on the H2 GMA ref cell target density. Once I have<br>
> this I should be able to pull a rough cross section. Also looking at the<br>
> proton tracks that show up in the LHRS, the BB has ~93% coin electron<br>
> tracks, which I don't think is too bad.<br>
><br>
> Let me know if you have any questions or suggestions.<br>
><br>
> Thanks<br>
> Matt Posik<br>
><br>
><br>
><br>
><br>
><br>
</div><div class="im">--<br>
Brad Sawatzky, PhD <<a href="mailto:brads@jlab.org">brads@jlab.org</a>> -<>- Jefferson Lab / Hall C / C111<br>
Ph: 757-269-5947 -<>- Fax: 757-269-5235 -<>- Pager: <a href="mailto:brads-page@jlab.org">brads-page@jlab.org</a><br>
The most exciting phrase to hear in science, the one that heralds new<br>
discoveries, is not "Eureka!" but "That's funny..." -- Isaac Asimov<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Matthew Posik<br>Email: <a href="mailto:posik@temple.edu">posik@temple.edu</a><br>Temple University Physics Dept.<br>Office: BA-319<br>Office #: 215-204-1331 <br>
WebSites:<br>Temple:<br><a href="http://quarks.temple.edu/">http://quarks.temple.edu/</a><br>d2n:<br><a href="http://hallaweb.jlab.org/experiment/E06-014/">http://hallaweb.jlab.org/experiment/E06-014/</a><br><br>