Low-mass dileptons at the CERN-SpS: evidence for chiral restoration?

An excitation function of the 27Al(p,gamma)^28 Si reaction has been measured over the proton beam energy range Ep=800-2000 keV using a 4(pi) NaI segmented crystal. In the above energy range 47 narrow resonances were measured and their strengths have been deduced. The absolute efficiency of the detection system has been determined for each one of the resonances via Monte-Carlo simulation, taking into account the decay scheme of each resonance. The results of the present work are compared with literature.