Peak-to-total ratios and efficiencies for A 5 in. DIA. by 5 in. NaI crystal

The peak-to-total ratio and absolute efficiency of a 5″ dia. × 5″ NaI crystal for gamma-ray energies from 0.4 to 9.2 MeV have been measured by using a magnetic spectrometer to isolate nuclear states which decay by only one gamma transition. Particle-gamma-ray coincidence measurements provide the pulse-height spectrum for a single gamma-ray energy. The detector efficiency is determined by detecting only those particles leading to the nuclear state which provides the desired gamma ray. The efficiency is given by the ratio of the coincidence counts in the gamma-ray spectrum to the particle counts in the spectrometer. The peak-to-total ratio data were supplemented by singles measurements from some gamma-ray sources and (p,γ) and (p,αγ) reactions.