charged hadron results from 19.6 gev au+au

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Charged Hadron Results from 19.6 GeV Au+Au. Daniel Cebra University of California, Davis (for the STAR Collaboration). Triggering for the 19.6 GeV dataset. ZDC Trigger (147953). Counts. CTB Trigger (27513). Nch. - PowerPoint PPT Presentation

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STAR Low Root S RunningDaniel Cebra
*
The STAR trigger was not optimized for 19.6 GeV Collisions. The correlation between
ZDC and CTB that had been observed in the 130 and 200 GeV data sets was not seen in the lower energy collisions. To approximate a minimum bias trigger, events were selected if they satisfied either a minimum ZDC threshold or a minimum CTB threshold.
Triggering will be a resolvable issue for the future beam energy scan.
ZDC Trigger
*
10% centrality events = 5106
*
The mid-y (|h|<0.5) charged particle multiplicity is shown on the left for the four RHIC collision energies. The cut lines correspond to percentages of the total minimum bias cross section.
Note the 20 GeV trigger had inefficiencies for collisions in the impact parameter range corresponding to 10-30% and 70-100%
Using a Glauber Model, we estimate that our 0-10% data selection had an average number of participant sof 337.
2nd method (Dan) to get centrality at 20 GeV
See
One observes good consistency in the scaling from au200 and au130.
The results shown in the above figures seem consistent with the method used earlier at 20 GeV suggested by Zhangbu. Updated results of this method, including 20, 130 and 200 GeV are presented here
This Fig. shows the good agreement observed at 20, 130 and 200 GeV. The points at 0% cross section were obtained using Zhangbu's method. All the points above 0% for 130 and 200 GeV were determined previously at STAR. The points above 0% cross section for 20 GeV were obtained using the 2nd method discussed here.
Here are details of what was done on the 2nd method suggested by Dan Cebra:
0) Files :
au200: /auto/stardata/starspec2/flow_pDST_production/reco/MinBiasVertex/ReversedFullField/P01gk/2001/
------------------------------------------------------------------
mUncorrNegMult and mUncorrPosMult are copied from StEventUtilities function uncorrectedNumberOfNegativePrimaries(const StEvent&) and uncorrectedNumberOfPositivePrimaries(cont StEvent&). It is number of tracks that are: number of Fit points >=10 |eta|<=0.5 DCA < 3.0 cm For detail, please look at $STAR/StRoot/StEventUtilities/StuRefMult.hh. mMultEta seems to be defined as number of tracks of which |eta|<0.75. It is counted by a variable goodTracksEta in StFlowMaker.cxx in SL02e. I used SL02e to produced 20GeV Au+Au flow pico DSTs, because it is P02ge production.
Best regards,
Masashi Kaneta
------------------------------------------------------------------------
2) Histograms were made for Nch= mUncorrNegMult+mUncorrPosMult, as defined in the code. x-bin= 800. Printed out the x and y values.
3) In a spread sheet program (Kaleid) the x-axis for au130 was multiplied by a factor x130 such that the spectra along the x-axis matches (by eye) the one for au20. Also the y-axis of the au130 spectra was scaled to match (by eye) the spectra at au20.
Similarly, the x-axis for au200 was multiplied by a factor x200 such that the spectra along the x-axis matches (by eye) the one for au20. Also the y-axis of the au200 spectra was scaled to match (by eye) the spectra at au20.
The present factors x130 and x200 extracted are listed in the figures and here:
au130: x130=0.652
au200: x200=0.562
4) Finally, the centrality values for au20 derived from those determined for au130, as quoted by Manuel, are listed next. The last column was obtained by multiplying the au130 values by x130 = 0.652, as determined above.
cent au130 au20
chN 0 50 100 150 200 250 300 350 400
Ev en ts
1
10
210
310
Au+Au 19.6 GeV Au+Au 62.4 GeV (scaled) Au+Au 130 GeV (scaled) Au+Au 200 GeV (scaled)
0-10%10-30%30-50% 50-7
STAR PRELIMINARY
Identified Hadron spectra at mid-rapidity are displayed for several centrality selctions.
200 GeV AuAu and pp data
STAR PRL92, 112301 (2003)
STAR PRELIMINARY
NA49 PRC66, 054902 (2002) - pim, kam, and kap
NA49 PRC69, 024902 (2004) - protons
NA49 nucl-ex/0512033 - protons and anti-protons
WA98 PRL83, 926 (1999) - pi-zero
WA98 NPA698, 647 (2002) - pim
WA98 PRC67, 014906 (2003) - pim and kam
*
d y
T d
m T
-K STAR
Correcting the Comparisons
Centrality (Np) Effect
Studied the rapidity densities, then determine the effect of the rapidity slice for each particle
Energy Dependence
Comparisons of Pion Yields
Fit all experimental data with exponential over the range 200-800 MeV/c2
Fix temperature to 185 and corre t for difernces in centrality, rapidity, and beam eanergy
STAR PRELIMINARY
Daniel Cebra
Kaon Yields
Fit all experimental data with exponential over the range 100-600 MeV/C2
Fix temperature to 250 and corre t for difernces in centrality, rapidity, and beam eanergy
STAR PRELIMINARY
Proton Yields – Corrected for Feed-down
Fit all experimental data with exponential over the range 200-800 MeV/c2
Fix temperature to 300 and corre t for difernces in centrality, rapidity, and beam eanergy
* STAR Data are corrected using NA49 Lambda and anti-Lambda results
STAR PRELIMINARY
STAR PRELIMINARY
In order to estimate the integrated yield, the spectral shapes are modeled and extrapolated
17.pdf
0.2 0.4 0.6 0.8
)2 (GeV/c0-mTm 0.2 0.4 0.6 0.8
-! -K p
*
> Tβ<
0.2
0.4
0.6
0.8
STAR PRELIMINARY
STAR PRELIMINARY
STAR PRELIMINARY
The yields are studied as a function of rapidity and centrality
NA44 PRC66, 044907 (2002) - all
NA49 PRC66, 054902 (2002) - pim, kam, and kap
NA49 PRC69, 024902 (2004) - protons
NA49 nucl-ex/0512033 - protons and anti-protons
WA98 PRL83, 926 (1999) - pi-zero
WA98 NPA698, 647 (2002) - pim
WA98 PRC67, 014906 (2003) - pim and kam
QM2008, Jaipur, 09-February-2008
+ /K-
K
0
0.2
0.4
0.6
0.8
1 E866/E917 E802 NA49 NA44 STAR 19.6 STAR PHENIX PHOBOS BRAHMS
21.pdf
+!/+K E866/E917 NA44 NA49 STAR 19.6 STAR PHENIX
-!/-K E866/E917+E895 E802 WA98 NA44 NA49 STAR 19.6 STAR PHENIX
QM2008, Jaipur, 09-February-2008
STAR PRL92, 112301 (2003)
*
„Standard” HBT analysis
impressive agreement: STAR Au+Au @19.6GeV with CERES/NA49 Pb+Pb @17.3 GeV
weak s dependence of HBT cancels weak Abeam dependence --> ~apples:apples
Scale and p-dep. of homogeneity regions
follow already-established trends
Slide courtesy of Z. Chajecki and M. Lisa
*
Summary
We have measured the pion, kaon, and proton spectra in 19.6 GeV Au+Au collisions
These spectra have been measured as a function of rapidity and centrality
Detailed comparisons of these spectra to the published SPS results have been made, in most cases the results are compatible.
The RHIC Beam Energy Scan will be able to reduce the statistical and systematic errors.
QM2008, Jaipur, 09-February-2008
0.4 mb-1 integrated luminosity
IBS and aperture dominated beam and luminosity lifetime
Another run at this energy may improve this by factor of 2-5
1.0+x109/bunch
Raise * to improve lifetime
*
Daniel Cebra
Studied the production trends as a function of Np and root S
Flat as a function of Np for central collisions
Parameterized the energy
Proton Yields before correction
Fit all experimental data with exponential over the range 200-800 MeV/c2
Fix temperature to 300 and corre t for difernces in centrality, rapidity, and beam eanergy
* Corrected for hyperon feeddown

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