Title:
"Quarkonia production with the HERA-B experiment"
Speaker: A. Spengler
         MPI Heidelberg - Germany (e-mail: Joachim.Spengler@desy.de)



Abstract:
"HERA-B is a fixed target experiment at the 920 GeV HERA proton beam at
DESY which uses a variety nuclear targets.  A di-lepton trigger can
select events containing leptonic $J/\psi$ decays.  During the last
data taking period Nov.02-Feb.03, 150 million di-lepton triggers and
200 million minimum bias triggers were recorded.

About 300.000 leptonic $J/\psi$ decays ($\sim 170.000 J/\psi
\rightarrow \mu^+\mu^-$ and $\sim 130.000 J/\psi \rightarrow e^+e^-$)
were acquired with the di-lepton trigger.  These samples allow for the
first time the study of charmonium production (such as $J/\psi$ and
$\chi_c$ states) in the negative Feynman x region ($x_F$), and will
provide important input for testing charmonium production
mechanisms. Results are being prepared on the A-dependence of
charmonium production, $J/\psi$ polarization, $\chi_c$ production and
the determination of the $b \bar b$ cross section in proton-nucleus
collisions.

A summary of the first results obtained on these items  
are presented as well as an overview of the topics
currently under investigation."