Re: [Brahms-l] 63 AGeV results

   Hi Flemming, Peter,

  Thank you for your prompt reply. I'm trying now to find what could be
wrong in my analysis. The problem at mid-rapidity seems to be the biggest
one since I get pion ratios significantly different than 1.
  First I want to point out the rough results that come out from the
analysis. At 0-10% centrality, around mid-rapidity, the yields are:
  165 for pions,
  ~24 for kaons,
  ~17 for protons,
  ~8 for anti-protons.
 The ratios are
  ~1 for pions,
  0.9-0.95 for kaons,
  ~0.5 for pbar/p.
 The net proton yield at mid-rapidity is aprox. 9 (at 200GeV was 7).
 At least for mesons the numbers seems to be right, following the Landau
formula, as Peter said.
   The corrections that I used are: acceptance, tracking efficiency (only
for FS because it seems that in the dst version that I used the MRS hits
was not available and I could not use Truls's curves), pid efficiency,
decay, multiple scattering and absorption for anti-protons. The acceptance
maps are maked with the 'generateMaps' script. I think is basicly Peter's
work.
   As Trine suggested, for the MRS, I tryied to use only data from one
polarity at a time, e.g. \pi^{+} only from A polarity settings, and
compare the results. Doing this I observed a correlation between
the setting that I used and the resulting yield. The spectra is very well
fitted at mid-rapidity, so maybe this can come from the acceptance maps?

              Ionut

P.S. Please reply at this address, since my address from the brahms-l
seems not to be available at the moment


On Fri, 18 Mar 2005, Peter H.L. Christiansen wrote:

> Hi Ionut,
>
> A few comments:
> If it is possible I would make a 0-5% sample, becuase it is well known
> that theorists (ok, most people) only remember values for this centrality
> class.
>
> I think that for a fixed centrality class dN/dy \propto s^(0.25) (Landau)
> so that you would expect the yields to be sqrt(63.0/200.0)~0.56 times the
> 200 GeV yields. We published ca. dN/dy(y=0)=290 pions and dN/dy(y=0)=180
> kaons, so I would expect your yields to be roughly 160 and 100. The fit to
> the dN/dy curves should be done with Gaussians with fixed mean (0) or at
> least be symmetrical in y (K+ looks strange). There you could compare the
> width to the Landau estimate: sigma^2 = ln (gamma_beam).
>
> If I were you I would focus on 1 specie e.g. pions where statistic is not
> a problem. Then I would cut down on centrality classes and do maybe 0-5%
> and 30-40%.
>
> About pions:  As Flemming writes more details are needed, but what is a
> great idea (and not so difficults) is to make a plot of the yield in the
> acceptance range which should be damn close for pi+ and pi- (if you use
> the same range) and then the extrapolated yield from the fit, so that you
> can see the acceptance coverage. It is fx. clear that your fits don't have
> the same shape for pion spectra which is usually the case (both as a
> function of rapidity and centrality).
>
> I think there is a really good story with the pion yields alone.....
>
> Cheers,
>    Peter
>
> P.s: I'm really looking forward to the final net-proton spectra!!!!!
>
> On Fri, 18 Mar 2005, Ionut Christian Arsene wrote:
>
> >
> >      Hi all,
> >
> >    I obtained some results from the Au+Au 63 AGeV data run. A part of the
> > graphs are posted at the following address:
> >   http://www4.rcf.bnl.gov/~aic/.
> > In the next days I will update the page with new plots.
> >    I would like to present these results at the workshop that will take
> > place in Bergen at the end of this month, so I will appreciate your
> > comments and sugestions about these results.
> >
> >              Regards,
> >                 Ionut
> >
> >
> > _______________________________________________
> > Brahms-l mailing list
> > Brahms-l@lists.bnl.gov
> > http://lists.bnl.gov/mailman/listinfo/brahms-l
> >
>
> --
> :-) --------------------------- )-:
>  Peter H L Christiansen
>  pchristi@nbi.dk / (+41)764870425
> :-D --------------------------- \-:
>
>
>

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