7 TABLE OF CONTENTS TEXT i I. ; II. ‘ i CALIBRATION OF NEW 4" 3 x 4" NaI(T1) DETECTORS......... Photopeak Area Method... ... cece cee ee eee eee ewes 3 Energy Band Method........ cece cece eee eee eee ete e eae 5 ‘ i INTRODUCTION, 2... ccc we ee eer ee eee ee teem ete te tte tees III. i Total Spectrum "Energy" Method... .... ccc eee ee ee eee 6 MAJOR FIELD INVESTIGATIONS-1965......... 200 cc eee ecene 8 Resurvey of 1962 and 1963 SiteS...... cc eee eee ees 9 Preface... ccc ee ee we eee ee ee eee eee ees 8 Studies of Cosmic Ray Ionization... 1... cc eee eee wenn 10 Spectrometric Determination of 137¢s Concentrations : : in SOULS... cc ee ee ee ee ee tee eee eens 12 Measurements over Solid Rock... .... cece eee ee ee eee 14 Measurements of Low Level Radiation............0-e-0008. 15 ; Study of B-ray Ionization Intensity...............00- 16 , Special Studie€S..... ccc eee ee eee ee ee ee eee 16 ; Correlation with Neonatal Death Rate “and Birth j Weight... . ccc cee ee eee et ee ees 16 i : Comparison with Continuous Monitoring Experiment...17 Measurement in High Uranium Area......... eee eee eee 17 : Correlation with Aerial Survey Data.............64. 17 Intercalibration of Detectors... .. cc ewe eee ees 17 : IV. CONTINUING ENVIRONMENTAL RADIATION STUDIES........... 18 Beta Radiation... . ccc ee we te ee eee eet eee 18 Variation of Natural Dose Rates with Time............ 20 i ‘ High Pressure Ionization Chambers..........0.eeeeeeee 23 Theoretical Investigation of Gamma Ray Transport..... 26 ACKNOWLEDGEMENTS... ... cc ee eee eee ee ee ee ees vee ee ewe 28 : | REFERENCES. .....000 00000 cece cece eee eeeeeteneeeeeenenees 29 ' ; APPENDIX APPENDIX 1. CALCULATION OF IONIZATION CHAMBER RESPONSE... .33 =- t V-