Measurement of the elliptic flux of Z ⩾ 2 charged particles in collisions of relativistic nuclei with photoemulsion nuclei

• Published in: Physics of atomic nuclei 2007-02, Vol.70 (2), p.319-325
• Main Authors: Dubinina, V. V., Egorenkova, N. P., Krotkova, V. I., Pozharova, E. A., Smirnitsky, V. A.
• Format: Article
• Language: English
• Subjects: ANISOTROPY; ASYMMETRY; CHARGED PARTICLES; Collisions; EMISSION; GEV RANGE; GOLD 197; IMPACT PARAMETER; INTERACTIONS; IRON 56; Iron isotopes; LEAD 207; Lead isotopes; MAGNESIUM 24; NEON 22; NUCLEAR MATTER; NUCLEAR PHYSICS AND RADIATION PHYSICS; Nuclei; Nucleons; Projectiles; PROTONS; Relativistic particles; RELATIVISTIC RANGE
• ISSN: 1063-7788; 1562-692X
• DOI: 10.1134/S1063778807020135

The azimuthal asymmetry is measured for the emission of Z ≥ 2 particles from the interaction of 22Ne, 24Mg, 32S, 56Fe, 197Au, and 207Pb nuclei with photoemulsion nuclei that is induced by semicentral collisions characterized by projectile energies in the range Epr = 1.88–200 GeV per nucleon and by impact-parameter (b) values in the range 0.12 ≤ b/bmax ≤ 0.70. The results of these measurements are compared with the results of similar measurements for protons. It is found that, at a low energy of Epr ≈ 2 GeV per nucleon, the ratio of the azimuthal-anisotropy coefficients v2 for Z ≥ 2 particles and protons is 6 ± 2, but that, for energies in the region Epr ≥ 4 GeV per nucleon, the coefficients in question agree with each other. This may suggest that, at low energies, Z ≥ 2 particles are predominantly formed at an early stage of the development of a collective flow. For Epr ≥ 4 GeV per nucleon, these particles are presumably formed at the stage of nuclear-matter expansion. Other possible explanations for the results of the observation of an elliptic flux of Z ≥ 2 particles are discussed.