METHOD FOR THE DETERMINATION OF K-SHELL FLUORESCENCE FIELDS

A simple method is proposed for determining the K shell fluorescence y ield, omega(K), using an NaI(Tl) detector coupled to an active filter amplifier and a 1K multi-channel analyser. By placing the target and t he source right on the face of the detector, that is, by forming a 2 p i geometrical configuration, the intensities are measured by employing weak radioactive sources of strengths of the order of 10(4) Bq. The t arget criterion is suggested following Bambynek et al.'s prescription for optimization of target thickness. The omega(K) values were determi ned using several trials for each target to demonstrate the reliabilit y and reproducibility of the method. The omega(K) values were obtained for lead, tantalum and gold elemental targets, and also for lead comp ounds and for some rare earth compounds. These values were compared wi th the recent standard fitted values of Hubbell et al. and were found to be in close agreement. The method is discussed in detail. (C) 1997 by John Wiley & Sons, Ltd.