European Muon Collaboration

These experiments were motivated by the interest in determining the quark structure of the nucleon following the discovery of high levels of deep inelastic scattering at SLAC.

The two teams came together to design a high intensity muon beam of energy up to 280 GeV to do the experiments.

For this experiment a second magnet containing a streamer chamber was added upstream of the NA2 apparatus to detect and measure the products of the deep inelastic scattering reactions at wider angles.

During the NA9 phase, a state of the art (at the time) processor was installed by the University of Uppsala group to trigger on scattered muons at very small angles to the beam (this was the NA28 experiment).

The first results of the NA2 phase of the experiment showed that charm production was mediated by the photon-gluon fusion process.

The final phase of the experiment with the polarized target produced the most dramatic result from the experiment with the discovery only a small part of the proton spin is carried by quarks, and that the strange quark sea is probably polarized.