424
R. Stock
Fig. 7.70 Allowed regions of
freeze-out temperature vs.
radial expansion velocity for
central Pb+Pb collisions at
√
s = 17.3 GeV and
mid-rapidity, combining
negative hadron and
deuterium spectral data
analysis with BE π −
correlation results on K T
dependence of R ⊥ ≈ R s [90]
200
180
160
140
120
100
80 0
0.2
0.4
0.6
0.8
1.0
T
d
h -
T ]
V e
M [
2 - BE
Fig. 7.71 The surface
velocity (here denoted as ρ 0 )
of radial expansion at
decoupling in central Au+Au
and Pb+Pb collisions vs.
√
s.
From combined analysis of
hadron p T spectra and π − pair
correlation [291, 297]
10
10
2
0
s [GeV]
1.2
1.0
0.8
0.6
0.4
0.2
0
AGS (E895)
SPS (NA49)
PHENIX ( = 130 GeV)
STAR ( = 200 GeV)
s
s
orthogonal constraint on β 2
T /T f results from a blast wave model fit of the HBT K T
dependence of R T ≈ R side [298], employed here. We see that the three independent
1σ fit domains pin down T f and β T rather sharply, to [115 MeV, 0.55]. A relativistic
correction [297] leads to T f = 105 MeV, β T = 0.60. The
√
s dependence of β T at
the freeze-out surface, from such an analysis [291, 297] is shown in Fig. 7.71. The
data again exhibit a plateau at SPS energies, which remains to be understood [299].