Re: [Brahms-l] qm04- first drafts

Hi,
Keep in mind that both the TOFW slats used has changes and the Trigger
counter at the front of TPM1.

dana

----- Original Message ----- 
From: "Claus O. E. Jorgensen" <ekman@nbi.dk>
To: <yin.zhongbao@fi.uib.no>
Cc: "brahms-l" <brahms-l@lists.bnl.gov>
Sent: Monday, December 29, 2003 7:53 AM
Subject: Re: [Brahms-l] qm04- first drafts


>
> Hi Zhongbao,
>
> > For scaledown correction, it is clear that the inel trigger scaledown
> > factor is vertex position and centrality dependent from a
two-dimensional
> > histogram. I think it is quite understandable since the inel trigger
> > efficiency has weak centrality and vertex position dependence. Certainly
> > if ignoring this weak dependence, the yield for central collisions will
be
> > lowered, but I think that not the right thing to do. I would appreciate
> > if you could show your experience in how to deal with the scale down
> > factor correctly or reasonablly.
>
> As I understand it the inel trigger is equally efficient in the vertex
> range were normally looking at, so I don't think we should worry about
> this. It's correct that the inel trigger is less efficient for the more
> peripheral events (<60% for d+Au I think), but it doesn't matter as
> long as you only look at centrality ranges below 60% or MB.
>
> For the inel trigger efficieny for p+p collisions I use 90%. In d+Au it's
> 91% so I think that 90% for p+p is a bit high, I would expect it to be
> lower that for d+Au. Any comments on this?
>
> In your analysis you count the number of tracks and the number of events.
> If you want to correct for the scaledown you should select events only
> with the event trigger and multiply with the scaledown factor (for the
> event count) and select tracks in events with the track trigger and
> multiply with the corresponding scale down factor. It's quite simple.
>
> > I still doubt the acceptance map. The map generated from BRAG is very
much
> > different from map generated from Claus' pure geometrical method (the
> > same cut on slats of tofw is applied). And the map from BRAG for B1000
is
> > also very much different from that for B1050. The map generated from
BRAG
> > doesn't match data at all. Then I would think it the current is wrong, I
> > mean much lower than 1050 actally, then the acceptance correction might
> > be larger, then the yield will be lower.
>
> Did you check if the TOFW panels and slat numbering in BRAG changed with
> the new setup? My guess is that this is the problem (since this is what
> have been changed from last run). You say that the B1000 and B1050 maps
> are different. Did you make both of them using the current BRAG setup or
> are you comparing the new B1050 with the old B1000?
>
> > I would use constructed spectra from PHENIX pi^0 spectra for pp
> > collisions+Pythia  simulation as reference spectrum for R_AA of pi at
both
> > mid-rapidity and forward rapidity.
> >
> > By the way I have re-studied the RICH efficiency via simulation for
12A427
> > with a fiducial cut applied on track intersetion with RICH mid-plane.
The RICH
> > efficiecy for pion at pt>3GeV/c is ~97% constantly.
>
> That sounds reasonalbe.
>
> Thanks for the update,
>
> Claus
>
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