Emission pattern of high-energy pions: A new probe for the early phase of heavy-ion collisions

Citation
A. Wagner et al., Emission pattern of high-energy pions: A new probe for the early phase of heavy-ion collisions, PHYS REV L, 85(1), 2000, pp. 18-21
Citations number
15
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
0031-9007 → ACNP
Volume
85
Issue
1
Year of publication
2000
Pages
18 - 21
Database
ISI
SICI code
0031-9007(20000703)85:1<18:EPOHPA>2.0.ZU;2-A
Abstract
The emission pattern of charged pions has been measured in Au + Au collisio ns at 1 GeV/nucleon incident energy. in peripheral collisions and at target rapidities, high-energy pions are emitted preferentially towards the targe t spectator matter. in contrast, low-energy pions are emitted predominantly In the opposite direction. The corresponding azimuthal anisotropy is expla ined by the interaction of pions with projectile and target spectator matte r. This interaction with the spectator matter causes an effective shadowing which varies with time during the reaction. Our observations show that hig h-energy pjons stem from the early stage of the collision whereas low-energ y pions freeze out later.