HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Corey, J. C. Articles by Wakat, M. A. Search for Related Content PubMed Articles by Corey, J. C. Articles by Wakat, M. A. Agricola Articles by Corey, J. C. Articles by Wakat, M. A.

Measurement of Attenuation of ¹³⁷Cs and ²⁴¹Am Gamma Rays for Soil Density and Water Content Determinations¹

ABSTRACT

Soil density and water content can be determined concurrently by measuring the attenuation of two different gamma energies. A dual source containing ²⁴¹Am and ¹³⁷Cs was shown to be suitable for these measurements. Multichannel pulse-height analyzers were evaluated to determine their accuracy under experimental conditions for simultaneous measurements of soil density and water content. NaI(Tl) and Ge(Li) detectors were also evaluated. The measurements were made with a collimated beam, 1 cm in diameter, of 662-keV gamma rays and 59.6-keV gamma rays from a source containing 70 mCi of ¹³⁷Cs and 29 mCi of ²⁴¹Am. Measured mass attenuation coefficients were 0.08565, 0.07803, and 0.07887 cm²/g for cesium gamma rays and 0.20493, 0.27100, and 0.33480 cm²/g for americium gamma rays with water, Cecil, and Houston Black soil, respectively. The higher resolution of the Ge(Li) detector and a 4096-channel pulse-height analyzer had no significant advantage with peaks as widely separated as 662 keV and 59.6 keV. A NaI(Tl) detector and a 400-channel pulse-height analyzer were satisfactory. With the multichannel pulse-height analyzer, it was simpler to adjust the area under the americium peak for the Compton contribution from the cesium radiation than with a single channel pulse-height analyzer. Water content and density changes in both a swelling and nonswelling soil illustrate the utility of the system.

¹ Contribution from the Savannah River Laboratory, E. I. du Pont de Nemours and Company, Aiken, South Carolina 29801. The information contained in this article was developed during the course of work under Contract AT(07-2)-1 with the US Atomic Energy Commission.

² Research Physicist and Research Chemists, respectively.

Received for publication September 10, 1970. Accepted for publication December 22, 1970.