Production of nuclei and antinuclei in pp and Pb-Pb collisions with ALICE at the LHC

Abstract

We present first results on the production of nuclei and antinuclei such as (anti)deuterons, (anti)tritons, (anti)3He and (anti)4He in pp collisions at $\s$ = 7 TeV and Pb-Pb collisions at $\sNN$ = 2.76 TeV. These particles are identified using their energy loss (dE/dx) information in the Time Projection Chamber of the ALICE experiment. The Inner Tracking System gives a precise determination of the event vertex, by which primary and secondary particles are separated. The high statistics of over 360 million events for pp and 16 million events for Pb-Pb collisions give a significant number of light nuclei and antinuclei (Pb-Pb collisions: \sim30,000 anti-deuterons($\bar{d}$) and \sim4 anti-alpha($\overline{{}^{4}He}$)). The predictions of various particle ratios from the THERMUS model is also discussed.

4 pages, 5 figures, parallel talk at Quark Matter 2011, May 23rd-28th 2011, Annecy, France