H. Appelshauser et al., Eur. Phys. J. C2:661 (1998)

Hadronic expansion dynamics in central Pb+Pb collisions at 158 GeV per nucleon

Data

• Pb+Pb at 158 GeV/c
• 2h-, Y (2.9:5.5), and Kt (0.1:0.6)
• 80k tpc events
• 300k events from MTPC and TOF
• Momentum resolution determined to be 5 +/- 1.5 MeV/c

Analysis

• Fits to Generalized Yano-Koonin
• Coulomb correction from h+h-
• Systematic errors at 15%, mostly from resolution, pid contamination

Results

• Rt mt parameters for mid-Y: Rg=6.5 +/- 0.5 fm, bb/T=3.7 +/- 1.6 GeV-1
• Note above value for bb/T encompases b=0.86/T=200 to b=0.61/T=100
• These flow values are higher than single particle, b=0.55
• Note from Ref. x that res. contribution to bb/T is 0.75 GeV-1
• Use only Rg to constrain single particle fit to get beta/T contours from one- and two-particles separately
• They compare the 6.5 to the transverse rms of di-neuclear cylinder of 2.7 fm for an expansion factor of 2.4.
• Rl mT scaling gives Tau_0=8fm/c at mid-Y
• R0 durations in range 3-4 fm/c

Figures

1. Na49 layout
2. Qinv for 2h-, and h+h-
3. C2 for GYK
4. Rl, Rt, R0 vs. Y and Kt
5. Beta_src vs. Ypr
6. Rt vs. Kt for four bins Ypr

References

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Additional References

• E.Shuryak, Phys. Rep. 61:72 (1980)
• J.D. Bjorken, Phys. Rev. D27:140 (1983)