A multipurpose tunable source of monochromatic X-rays

The emission of characteristic X-rays from any chemical element induced by beta particles of high energy (10(5)-10(6) eV) is much higher than photon excitation. with the possible exception of selective excitation. This work describes the properties of a variable energy X-ray generator that uses (90)Sr as a source of beta particles and a multitarget array in a transparent source geometry. This compact device provides, through suitable selection of the target material, over 30 monoenergetic lines spread uniformly in the energy range of between 6 and 100 keV. The X-ray photon flux thus generated has an intensity of between 10(2)-10(3) s(-1) sr(-1) per MBq of the beta source activity. With this single beta source, the X-ray yield is higher as compared with generators using (241)Am or other X- or gamma-ray sources with the same activity, and the line's intensity changes by less than a factor of three over the whole energy range. (C) 2002 Elsevier Science B.V. All rights reserved.