Universal pion freeze-out in heavy-ion collisions.
Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.
Adamová
D
D
Nuclear Physics Institute ASCR, 25068 Rez, Czech Republic.
Agakichiev
G
G
Appelshäuser
H
H
Belaga
V
V
Braun-Munzinger
P
P
Castillo
A
A
Cherlin
A
A
Damjanović
S
S
Dietel
T
T
Dietrich
L
L
Drees
A
A
Esumi
S I
SI
Filimonov
K
K
Fomenko
K
K
Fraenkel
Z
Z
Garabatos
C
C
Glässel
P
P
Hering
G
G
Holeczek
J
J
Kushpil
V
V
Lenkeit
B
B
Ludolphs
W
W
Maas
A
A
Marín
A
A
Milosević
J
J
Milov
A
A
Miśkowiec
D
D
Panebrattsev
Yu
Y
Petchenova
O
O
Petrácek
V
V
Pfeiffer
A
A
Rak
J
J
Ravinovich
I
I
Rehak
P
P
Sako
H
H
Schmitz
W
W
Schukraft
J
J
Sedykh
S
S
Shimansky
S
S
Slívová
J
J
Specht
H J
HJ
Stachel
J
J
Sumbera
M
M
Tilsner
H
H
Tserruya
I
I
Wessels
J P
JP
Wienold
T
T
Windelband
B
B
Wurm
J P
JP
Xie
W
W
Yurevich
S
S
Yurevich
V
V