Antihelium-3 production in lead-lead collisions at 158AGeV/c

The NA52 experiment measured particle and antiparticle yields at 0° production angle over a wide range in rapidity in lead-lead (Pb-Pb) collisions at 158 A GeV/ c with a minimum bias trigger. Besides (10 6 ) antiprotons ( ) and (10 3 ) antideuterons ( ) a total of five antihelium-3 ( ) were found. The resulting invariant differential production cross sections at p t ≃0 GeV/ c turn out to be E (d 3 σ)/(d p 3 ) = (2.5 ± 1.8) × 10 -7 b c 3 GeV -2 at a rapidity of y = 3.4 in the laboratory system and (5.9 ± 3.4) × 10 -8 b c 3 GeV -2 at y = 4.0. The results are discussed in the framework of a simple coalescence model.