Dear Friends,
I would like us to mention the change in Eta_RMS
so I made a first stab at some text. After saving the odd word
here and there to save lines the new text fits on 4 pages.
Note that we are currently comparing to pp but not
referencing it. We may also want to reference to SPS distributions.
I have attached the latex file to this message.
For the most peripheral collisions analyzed here (40-50\%)
the multiplicities at $\eta=0$ reach $dN/d\eta=110\pm 10$ while the
corresponding value scaled to the number of participating pairs is
2.9$\pm 0.3$. For comparison, the similar number for proton-proton
collisions at this energy is 2.5, also a 14\% increase as compared to
the lower energy, \cite{ppmult}.
Indeed, the of the most central distributions
is $\eta_{RMS} = 2.33 \pm 0.03$ for $\sqrt{s_{NN}}$=200~GeV, as
compared to $\eta_{RMS} = 2.21 \pm 0.01$ at 130~GeV.
This is large smaller than the corresponding pp result.
In contrast
to lower energy data \cite{SPSmult} $\eta_{RMS}$ is larger
, $2.41 \pm .01$ at (40-50\%) centrality, for more
for more peripheral collisions. This presumably reflects
the increasing importance of hard collisions near $\eta=0$.
For the title how about
title{Charged particle pseudorapidity distributions from AuAu
collisions at \protect{$\sqrt{s_{NN}}$}=200GeV}
which fits on 1 line.
Reaction centrality %if %MJM
is obtained, for example, by assuming that
the 5\% of events with the highest total multiplicity in either the
MA or BBC arrays corresponds to the 5\% most central events.
In analyzing particle
The ZDC detectors are located $\pm$18m from the nominal
interaction vertex and measure neutrons that are emitted at small
angles with respect to the beam direction ~\cite{adler00}.
Reaction centrality %if %MJM
is obtained, for example, by assuming that
the 5\% of events with the highest total multiplicity in either the
MA or BBC arrays corresponds to the 5\% most central events.
Indeed, the FWHM of the most central distributions
is $\Delta \eta = 7.5 \pm 0.5$ for $\sqrt{s_{NN}}$=200~GeV, as
compared to $\Delta \eta = 7.2 \pm 0.8$ for $\sqrt{s_{NN}}$=130~GeV
collisions. For the most peripheral collisions analyzed here (40-50\%)
the multiplicities at $\eta=0$ reach $dN/d\eta=110\pm 10$ while the
corresponding value scaled to the number of participating pairs is
2.9$\pm 0.3$. For comparison, the similar number for proton-proton
collisions at this energy is 2.5, also a 14\% increase as compared to
the lower energy.
Replaced by
%In general, statistical error on
In general, statistical errors on
the measurements are less than 1\%, while we estimate that the
systematic errors are 8\% and 10\% for the SiMA and BBC arrays,
respectively.
Quoting Michael Murray <murray@cyclotronmail.tamu.edu>:
> Dear Trine and Dieter,
> I think it is worth discussing the
> change of shape with centrality even if it only reflects the
> growth of hard collisions at central rapidity. What is |eta| RMS for pp
> and and
> what is the reference?
> Yours Michael
> > and on Thu, 22 Nov 2001, Dieter Rohrich wrote:
> >
> > > At SPS, the h- rapidity distribution is narrower in central
> > > nucleus-nucleus collisions than in nucleon-nucleon. It is not a big
> > > effect, but it is significant. I would like to support Chellis'
> > > proposal to add a sentence and/or to include the RMS/FWHM in the
> table
> >
> > > - if a quantitative analysis (RMS from the histogram, 2-Gaussian
> fit,
> > > etc.) confirms Chellis' observation.
> >
> > I calculated the RMS values for the dN/dEta distributions
> > of various centrality classes for 200 and 130 GeV, from the
> > data in the files dndeta_sym_200.dat and dndeta_sym_130.dat
> > found at "the usual place at the kansas account".
> > The results are plotted as a function of centrality class
> > (1 = 0-5%, 6 = 40-50%) in the figures:
> >
> > http://lynx.uio.no/~trine/brahms/mult/RMS_fullerrors.gif
> > (using the full errors taken from the .dat files)
> >
> > http://lynx.uio.no/~trine/brahms/mult/RMS_smallerrors.gif
> > (using the 3% point-to-point errors like in the alpha,beta fits)
> >
> > Upper panels: Red points 200 GeV data, blue points 130 GeV data.
> > Lower panels: RMS 200 GeV / RMS 130 GeV.
> >
> > The trend pointed out by Chellis looks significant. Also there
> > are indications that the width increase from 130 to 200 GeV
> > is stronger for the more central collisions (as also seen from
> > our figure 4.) What do you think - does this merit a sentence
> > in the paper?
> >
> > The numbers are given below for reference.
> >
> > Best wishes,
> > Trine
> > _____________________________________________________________
> >
> > Full errors:
> > 0-5%:
> > RMS200: 2.32861+-0.0253931 RMS130: 2.21047+-0.024398
> > Ratio: 1.05345+-0.0163451
> > 5-10%:
> > RMS200: 2.3554+-0.0252404 RMS130: 2.23798+-0.0244402
> > Ratio: 1.05247+-0.0161029
> > 10-20%:
> > RMS200: 2.37433+-0.0252682 RMS130: 2.25484+-0.02383
> > Ratio: 1.05299+-0.0157931
> > 20-30%:
> > RMS200: 2.38742+-0.0255841 RMS130: 2.27923+-0.024796
> > Ratio: 1.04747+-0.0159955
> > 30-40%:
> > RMS200: 2.39571+-0.0255872 RMS130: 2.30663+-0.0247556
> > Ratio: 1.03862+-0.0157259
> > 40-50%:
> > RMS200: 2.40582+-0.025714 RMS130: 2.32596+-0.0251689
> > Ratio: 1.03433+-0.0157317
> >
> > Point-to-point errors of 3% on dN/dEta:
> > 0-5%:
> > RMS200: 2.32861+-0.00792104 RMS130: 2.21047+-0.00761942
> > Ratio: 1.05345+-0.00510162
> > 5-10%:
> > RMS200: 2.3554+-0.00793332 RMS130: 2.23798+-0.00766753
> > Ratio: 1.05247+-0.00505651
> > 10-20%:
> > RMS200: 2.37433+-0.00796683 RMS130: 2.25484+-0.00771144
> > Ratio: 1.05299+-0.00504501
> > 20-30%:
> > RMS200: 2.38742+-0.00795419 RMS130: 2.27923+-0.00776257
> > Ratio: 1.04747+-0.00499057
> > 30-40%:
> > RMS200: 2.39571+-0.00795148 RMS130: 2.30663+-0.00779476
> > Ratio: 1.03862+-0.00491955
> > 40-50%:
> > RMS200: 2.40582+-0.00793511 RMS130: 2.32596+-0.00777788
> > Ratio: 1.03433+-0.00485815
> >
>
>
>
> Michael Murray, Cyclotron TAMU, 979 845 1411 x 273, Fax 1899
>
Michael Murray, Cyclotron TAMU, 979 845 1411 x 273, Fax 1899
This archive was generated by hypermail 2b30 : Mon Nov 26 2001 - 06:10:02 EST
