Re: [Brahms-l] INEL trigger efficiency in pp

I do not think gray protons are defined in PP. This is used in pA
collisions.
dana

----- Original Message ----- 
From: "Murray, Michael J" <mjmurray@ku.edu>
To: <jhlee@bnl.gov>; "Claus O. E. Jorgensen" <ekman@nbi.dk>; "brahms-l"
<brahms-l@lists.bnl.gov>
Sent: Thursday, February 12, 2004 10:36 AM
Subject: RE: [Brahms-l] INEL trigger efficiency in pp


  Dear Claus,
           JH is right. The fluctations of b vs multiplicity are large
enough in AA let alone d-Au. The only really accurate way to get B in pp is
to measure "gray" protons from the Au like the emulsion gusy or NA49, WA98.
Michael

-----Original Message-----
From: J.H. Lee [mailto:jhlee@rcf.rhic.bnl.gov]
Sent: Thu 2/12/2004 9:21 AM
To: 'Claus O. E. Jorgensen'; 'brahms-l'
Cc:
Subject: RE: [Brahms-l] INEL trigger efficiency in pp

Hi, Claus,

In pp collisions, multiplicity is relatively small and
spread in "multiplicity vs impact parameter" is rather
large. That means that events with a BB vertex are not
exclusively more "central" compared to INEL events.
If you look at HIJING events selected by BB, they are
sampled in all impact parameters as INEL events, but just
with poor efficiency since the phase space coverage of BB
is smaller than coverages of INEL.
There is some tendency sampling events with
a smaller impact parameter (more "central") in BB, but for
the trigger test I did described earlier, I think it's quite
valid (and probably only way).

JH

> -----Original Message-----
> From: brahms-l-bounces@lists.bnl.gov
> [mailto:brahms-l-bounces@lists.bnl.gov] On Behalf Of Claus O.
> E. Jorgensen
> Sent: Thursday, February 12, 2004 3:08 AM
> To: 'brahms-l'
> Subject: RE: [Brahms-l] INEL trigger efficiency in pp
>
>
>
> Hi JH,
>
> Thanks for the quick reply. You say that you compare the BB
> vertex distributions - but by doing this I guess you bias the
> data sample towards more "central" events, or? I mean, the
> p+p events that give BB vertex are probably not missed by the
> INEL trigger to begin with.
>
> Claus
>
>
> On Wed, 11 Feb 2004, J.H. Lee wrote:
>
> > Hi, Claus,
> >
> > > these (28%) missing events? How do we evaluate the Ntr in
> the missed
> > > events. If we just calculate the yields by dividing Nev by the
> > > trigger efficiency (i.e. multiply the spectrum by
> > > 0.72) we somehow assume that the missing events don't have any
> > > tracks. Is that fair?
> >
> > Yes, it's fair.
> > This shouldn't be an issue since the spec. triggers include
> > inelastic trigger(trigger5).   If you are interested in trigger
> > bias from including INEL in spec triggers, see the attached message.
> >
> > JH
> >
> > -----------------------------------------------------
> >  ----- Original Message -----
> > From: "J.H. Lee" <jhlee@bnl.gov>
> > To: "Flemming Videbaek" <videbaek@bnl.gov>
> > Cc: "Chellis Chasman" <chasman@bnl.gov>; <beavis@bnl.gov>;
> > <debbe@bnl.gov>
> > Sent: Friday, May 02, 2003 5:41 PM
> > Subject: Trigger3 with and without INEL
> >
> >
> > > Hi, Flemming,
> > >
> > > I've looked at the special run you took today, run 8767, with
> > > trigger3 = Hodo+R.C.  I compared the BB vertex distribution for
> > > trigger3 in the run with the one from run 8768 taken
> right after the
> > > run with the normal spec trigger condition (trigger3 =
> Hodo + INEL).
> > > I normalized the two distributions with the number of accumulated
> > > ZDC(Y+B) counts in the scaler.  I assumed dead time is
> similar for
> > > the two runs.  It looks like there seems to be no obvious
> bias from
> > > INEL in Trigger3 by looking at the distributions.  The
> INEL in the spec trigger
> > > simply cut out tracks outside of the range.   Looks
> pretty good to me.
> > >
> > > JH
> > >
> >
> >
>
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> Brahms-l@lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-l
>


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