Isospin-forbidden analogue resonances in33Cl I.—The lowerT=3/2 analogue resonance

Details are reported on a search for an isospin-forbidden resonance in33Cl, reached by means of (p, p) elastic scattering on32S. The corresponding level, which is one of theT=3/2,A=33 quartet, has been already singled out via an isospin-allowed reaction and localized at an excitation energy of 5.55 MeV in33Cl. The accurate examination of the excitation curve over the energy interval of the incoming proton,Ep=(3200÷3385) keV, revealed the existence of an anomaly at a proton bombarding energy ofEp=(3370±1) keV in the laboratory system. AnR-matrix analysis of the anomaly allows one to state that it represents the required resonance.