peony He PORE ARIA oe ; dee he neh | ABSTRACT The spectrometric techniques developed by the authors for measuring total and individual component gamma dose rates from naturally-occurring and fallout emitters are elaborated upon and extended to new applications. The calibration of high resolution 4" x 4" NaI(Tl) detectors for such measurements is described. Field studies utilizing these techniques during 1965, including measurements of gamma dose rates at approximately 50 ground sites scattered around the United States as well as on high altitude lakes and in deep mines, are summarized and the data presented in full. These results provide useful information relevant to continuing studies of the application of field spectrometry to the rapid assessment of fallout deposition, particularly 137’7cs, the variations of AeA APape natural gamma dose rate with time, and the contributions of soil beta activity and cosmic radiation to free air ionization near the air-ground interface. A detailed description of the argon-filled high pressure ionization chamber used for total dose rate measurements is presented. - 1ii -