[d2n-analysis-talk] LHRS Trigger Efficiency Study

[David Flay]

On Mon, Jul 12, 2010 at 1:28 PM, Brad Sawatzky <brads at jlab.org> wrote:

> The idea is that T4 should catch the good triggers that T3 misses, thus
> measuring the inefficiency of T3.  So, what you do is this:
>  - Get a sample of good electrons by applying cuts similar to when you
>    did the cerenkov efficiency analysis (but allow the trigger type to
>    be T3 .or. T4.
> For the case where we have a prescale of 1 for T3, then each T4 (after
> 'good electron' cuts) means that we have something that looks like an
> electron, but it only fired one paddle plane when both should have
> fired.  So, this expression:
>
> eff_3 = bit3/(bit3 + bit4)
>
>  bitN = trigger N latch bit, after prescaling.  This is set
>          if and only if:
>          - a TN trigger is seen at the TS within 10ns of whatever
>            generated the L1A, .AND.
>          - it passes the prescale condition for trigger N
>
> will give you the effieciency of the T3 trigger.  That is, it will
> answer the question: for good electrons, what fraction of the time will
> T3 fire?  As defined above, it should be independent of other triggers,
> prescaling, etc.
>

Using this equation, I have (for run 20676):

efficiencies:
Trigger 3: 99.9280 +/- 0.0228%
Trigger 4: 0.0720 +/- 0.0228%

with the statistical error given as:

de = sqrt((bit4)/(bit3)*1.0/((bit3)+(bit4)));  (for trigger 3)

for trigger 4, let bit3 <-> bit4 in the above equation.

The cuts used:

    //one track from the target
    cut0 = Form("(L.tr.n==1)");
    //cut out the pulser, T8 trigger
    cut0 += Form("&&(DL.edtpl==0)&&(((DL.evtypebits&(1<<8))!=(1<<8)))");

    cut1 = cut0;
    //VDC cuts -- requirement of one track reconstruction
    cut1 += Form("&&(L.vdc.u1.nclust==1)&&(L.vdc.v1.nclust==1)");
    cut1 += Form("&&(L.vdc.u2.nclust==1)&&(L.vdc.v2.nclust==1)");

    cut2 = cut1;
    //PID cuts
    cut2 += Form("&&(L.cer.asum_c>300)&&(prl_E_P>0.54)&&(L.prl1.e>200)");

I wanted to show you these numbers before I do this for all the kinematics.

-- 
-----------------------------------------------------------
David Flay
Physics Department
Temple University
Philadelphia, PA 19122

office: Barton Hall, BA319
phone: (215) 204-1331

e-mail: flay at jlab.org
            flay at temple.edu

website: http://www.jlab.org/~flay
              http://quarks.temple.edu
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