the s, 24Na, 7 counts to peak comparison r using These these isotopes and the response data given in Tables I, counts/ (ur/hr - 238U) and 1300 counts/ (ur/hr - 232Th). similar correction of 350 counts/(ur/hr - 232Th) must be A | made to the 0.51 MeV peak before estimating the 106Rh dose the rate. Energy Band Method le. is £ the imate of slightly chemes RF Le aA IT esponse In determining natural emitter dose rates, the total "energy" (counts per channel multiplied by mean y-ray energy corresponding to that channel) in the spectrum between energy values that bracket significant peaks is related to the total dose rate contribution from the emitter or series of emitters characterized by these peaks. The three bands used are centered about the 1.46 MeV peak (49K), the 1.76 MeV peak (214pi-238u series), /T) 3 II qd of Ss, are for the areas continuum, (Np/T) higher. nproved c and II, and III these correction factors were determined to be 3000 two ber ral the 0.61 Mev the area of the entire smeared-out peak and subtract a contribution based on the ?38y and 232Th dose rates determined from higher energy peaks. From the decay scheme data for smaller. Yr source es and overlaps the 137cs dose rate, therefore, it is necessary to estimate ntegration for these stribution angular energies rate, 1s often much larger than peak, and we cannot separately determine the areas of these two peaks or the 0.58 MeV 2087) peak. In order to estimate 1 Mev thus The new detectors are able to resolve the 0.66 Mev 13/’cs At present however, the 0.66 MeV and 0.61 Mev 214Bi peaks. an tion, the 1.76 MeV je 1.46 and the 2.62 MeV peak (20871-232tmseries). As in the 5" x 3" detector calibration, three simultaneous equations relating the "energy" in the bands EF), 1.32 - 1.60 MeV; E>, 1.62 - 1.90 MeV; and E3, 2.48 - 2.75 MeV to natural emitter open field dose rates were derived by applying a multiple regression analysis to the peak area estimate of the dose rates and Ej, E92, and E3 for a large number of field locations. The cosmic ray contribution to each energy band was first subtracted out using crystal response data from Spectra taken over large lakes at different altitudes. Section III and Figure 3) (See The resulting equations for the 4" x 4" detectors with bakelite shields are K U= .O78E]' .337E9' T = .297E3' - .055E9' .179E3' - .022E3'