Search for photons from the decay of the delta resonance in heavy-ion collisions.

Abstract

Results are presented from a search for high-energy gamma rays (${\mathit{E}}_{\ensuremath{\gamma}}$g140 MeV) resulting from the decay of the delta resonance produced in heavy-ion collisions. The energy spectrum of gamma rays in the energy range 15${\mathit{E}}_{\ensuremath{\gamma}}$180 MeV was measured at a laboratory angle of 90\ifmmode^\circ\else\textdegree\fi{} for the reaction $^{14}\mathrm{N}$+Zn. The incident beam energy was E/A=75 MeV. The energy spectrum in the region 50${\mathit{E}}_{\ensuremath{\gamma}}$180 MeV is exponential with an inverse slope parameter of 26 MeV. There is no indication of an enhancement in the spectrum above 140 MeV due to the decay of the delta resonance.