Charged Hadron Results from 19.6 GeV Au+Au

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QM2008, Jaipur, 09-February-2008 1 Daniel Cebra Charged Hadron Results from 19.6 GeV Au+Au Daniel Cebra University of California, Davis (for the STAR Collaboration)

description

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

Transcript of Charged Hadron Results from 19.6 GeV Au+Au

Page 1: Charged Hadron Results from 19.6 GeV Au+Au

QM2008, Jaipur, 09-February-2008 1Daniel Cebra

Charged Hadron Results from 19.6 GeV Au+Au

Daniel CebraUniversity of California, Davis(for the STAR Collaboration)

Page 2: Charged Hadron Results from 19.6 GeV Au+Au

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Triggering for the 19.6 GeV dataset

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ZDC Trigger(147953)

CTB Trigger(27513)

Nch

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The STAR trigger was not optimized for 19.6 GeV Collisions. The correlation betweenZDC 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.

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The STAR 19.6 GeV Au+Au Data Set

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• One day of running

• 12 data runs

• Total recorded events = 175466

• Events with good vertex = 42412

• 10% centrality events = 5106

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Centrality Determination

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The mid-y (||<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.

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Spectra as a Function of Centrality

STAR PRELIMINARY

Identified Hadron spectra at mid-rapidity are displayed for several centrality selctions.

200 GeV AuAu and pp dataSTAR PRL92, 112301 (2003)

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Charged Particle Spectra Compared SPS

STAR PRELIMINARY

NA44 PRC66, 044907 (2002) - all NA49 PRC66, 054902 (2002) - pim, kam, and kapNA49 PRC69, 024902 (2004) - protonsNA49 nucl-ex/0512033 - protons and anti-protonsWA98 PRL83, 926 (1999) - pi-zeroWA98 NPA698, 647 (2002) - pimWA98 PRC67, 014906 (2003) - pim and kam

The central mid-rapidity spectra are displayed against the most comparable SPS spectra

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Correcting the ComparisonsCentrality (Np) Effect

Studied the rapidity densities, then determine the effect of the rapidity slice for each particle

Collaboration System trig/inel <Npart> Ratio

STAR Au+Au 0-10% 337 1.000

NA49 Pb+Pb 0-5% 357 1.059

NA44 Pb+Pb 0-3.7% 340 1.009

WA98 Pb+Pb 0-10% 330 0.979

Particle A B Ratio

-0.132 0.236 0.946

-0.168 0.207 0.942

K- -0.048 0.034 0.919

K+ -0.038 0.039 0.938

p-bar -0.050 0.021 0.781

p +0.300 -1.221 1.019

Energy Dependence

Particle dN/dy (y=0)

180+/-5 1.40+/-0.03

164+/-4 1.44+/-0.04

K- 17.4+/-1.6 1.14+/-0.10

K+ 31.2+/-2.1 1.25+/-0.13

p-bar 3.5+/-0.6 1.10+/-0.26

p 33.9+/-1.7 2.50+/-0.35

Particle Experiment <y> Ratio NA49 -0.1 0.997 NA44 0.4 0.96 WA98 -0.55 0.926 NA44 0.4 0.9260 WA98 -0.3 0.978K- NA49 0 1K- NA44 0.15 0.991K- WA98 -0.8 0.782K+ NA49 0 1K+ NA44 0.15 0.993

p-bar NA49 -0.3 0.963p-bar NA44 -0.45 0.92

p NA49 -0.3 0.993p NA44 -0.45 0.984

NA49 rapidity density dataN(A661, 45c (1999)

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Comparisons of Pion Yields

Exp dN/dy T(MeV) dN/dy

- STAR 148.2 182+/-1 147.4+/-0.6

WA98 111.1 195+/-5 136.1+/-2.8

NA44 113.9 201+/-8 132.9+/-1.3

NA49 146.0 182+/-3 144.6+/-1.6

+ STAR 143.2 186+/-1 143.7+/-0.6

0 WA98 90.7 179+/-8 95.6+/-7.4

+ NA44 111.5 203+/-3 130.0+/-1.5

Fit all experimental data with exponential over the range 200-800 MeV/c2

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STAR PRELIMINARY

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Kaon Yields

Exp dN/dy T(MeV) dN/dy

- STAR 18.2 269+/-10 17.7+/-0.3

WA98 10.6 222+/-11 14.5+/-0.4

NA44 15.4 229+/-2 16.3+/-0.1

NA44 14.9 225+/-6 17.2+/-0.1

NA49 16.9 233+/-3 17.5+/-0.1

+ STAR 29.5 277+/-9 28.5+/-0.4

NA44 24.0 225+/-9 27.6+/-0.4

NA44 27.5 245+/-3 29.2+/-0.2

NA49 29.0 238+/-4 29.1+/-0.3

Fit all experimental data with exponential over the range 100-600 MeV/C2

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STAR PRELIMINARY

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Proton Yields – Corrected for Feed-down

Exp dN/dy T (MeV) dN/dy

p-bar STAR 2.09* 339+/-30 2.06+/-0.20

NA44 1.84 323+/-26 2.53+/-0.06

NA49 1.65 305+/-11 2.08+/-0.05

Proton STAR 27.8* 292+/-6 27.6+/-1.24

NA44 27.1 299+/-4 27.7+/-0.16

NA49 25.6 322+/-17 23.9+/-0.75

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* STAR Data are corrected using NA49 Lambda and anti-Lambda results

STAR PRELIMINARY

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Fitting the Shape of the Spectra

STAR PRELIMINARY

In order to estimate the integrated yield, the spectral shapes are modeled and extrapolated

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Radial Flow Analysis

STAR PRELIMINARY

Statistical Model:Tch = 164.7 +/- 0.5 B = 205.5 +/- 0.6 S = 27.2 +/- 0.9

FoPi NPA612, 493 (1997)FoPi NPA610, 49c (1996)EOS PRL75, 2662 (1995)E866 APPB29, 3253 (1998)NA44 PRL78, 2080 (1997)NA49 PRL82, 2471 (1999)PHENIX NPA715, 498 (2003)BRAHMS nucl-ex/0404011STAR PRL92, 112301 (2003)

200 GeV data STAR PRL92, 112301 (2003)

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Rapidity Density Distributions

STAR PRELIMINARY STAR PRELIMINARYSTAR PRELIMINARY

The yields are studied as a function of rapidity and centrality

NA44 PRC66, 044907 (2002) - all NA49 PRC66, 054902 (2002) - pim, kam, and kapNA49 PRC69, 024902 (2004) - protonsNA49 nucl-ex/0512033 - protons and anti-protonsWA98 PRL83, 926 (1999) - pi-zeroWA98 NPA698, 647 (2002) - pimWA98 PRC67, 014906 (2003) - pim and kam

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Particle Ratios

STAR PRELIMINARY

E802 NPA610, 139c (1996)E802 PRL81, 2650 (1998)E866 PLB476, 1 (2000)E917 PLB490, 53 (2000)NA49 PRC66, 054902 (2002)NA44 PRC66, 044907 (2002)PHENIX PRC69, 034909 (2004)STAR PRL92, 112301 (2003)STAR PLB595, 143 (2004)STAR PRL86, 4778 (2001)STAR PLB567, 167 (2003)

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K/ Ratios

STAR PRELIMINARYE802 PRL81, 2650 (1998)E866 PLB476, 1 (2000)E917 PLB490, 53 (2000)NA44 PLB471, 6 (1999)WA98 PRC67, 104906 (2003)NA49 PRC66, 054902 (2002)NA49 EPJC33, S621 (2004)NA49 arXiv:0710.0118v2PHENIX PRC69, 034909 (2004)PHENIX PRL88, 242301 (2002)STAR PRL92, 112301 (2003)STAR PLB595, 143 (2004)

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Pion Ratios

STAR PRELIMINARY

KaoS PLB420, 20 (1998)E866 NPA610, 139c (1996)NA44 PLB372, 339 (1996)WA98 nucl-ex/0607018STAR PRL92, 112301 (2003)

The pion ratios are fit with a coulomb model. The extracted potential of the source is 8.5 MeV

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„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 • disfavor signals of increased lifetimes at

intermediate collision energiesSlide courtesy of Z. Chajecki and M. Lisa

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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.

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Backup Slides

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STAR PRELIMINARYSTAR PRELIMINARY

STAR PRELIMINARY

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2001 19.6 GeV Au+Au collisions• 2 days of 9.8 GeV beams

– 0.4 b-1 integrated luminosity

– *=3m by necessity– 60-90 minute stores– 56 Au bunches,

0.6x109/bunch– 10-30 Hz ZDC rates– 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

• RHIC is best used as a storage ring collider below beam energies of ~12 GeV

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Figure from T. Satogata

STARPHENIX

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Added62.5

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Studied the production trends as a function of Np and root S

Flat as a function of Np for central collisions

Parameterized the energydependence

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STAR PRELIMINARY

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-

STARNA49WA98NA44

STAR PRELIMINARY

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+

STARWA98NA44

STAR PRELIMINARY

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K-

STARNA49WA98NA44

STAR PRELIMINARY

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K+

STARNA49NA44

STAR PRELIMINARY

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p-

STARNA49NA44

STAR PRELIMINARY

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p+

STARNA49NA44

STAR PRELIMINARY

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Proton Yields before correction

Exp dN/dy T(MeV) dN/dy

p-bar STAR 3.42 339+/-30 3.38+/-0.12

NA44 2.66 299+/-16 3.66+/-0.08

NA49 1.65* 305+/-11 3.00+/-0.07

Proton STAR 36.7 292+/-6 36.5+/-0.39

NA44 36.1 279+/-3 36.3+/-0.20

NA49 25.6* 322+/-17 31.8+/-0.98

Fit all experimental data with exponential over the range 200-800 MeV/c2

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* Corrected for hyperon feeddown

STAR PRELIMINARY

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STAR62.5 2.72 +/- 0.24200 3.94 +/- 0.28

PHENIX19.6 1.86 +/- 0.15130 3.46 +/- 0.18200 3.89 +/- 0.23

NA4917.2 1.86 +/- 0.0812.4 1.54 +/- 0.078.7 1.24 +/- 0.06

NA45 17.2 1.87 +/- 0.19 8.7 1.35 +/- 0.08NA50 17.2 1.98 +/- 0.16 8.7 0.95 +/- 0.10

PRC 71, 0344908 (2005)

STAR PRELIMINARY

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NA44

NA49

STAR PRELIMINARY