Elastic scattering of 22.1-keV photons by elements in the atomic region 12⩽Z⩽92

Recent experimental studies of photon–atom scattering in the X-ray energy region

“…The differential cross-sections measured at low energies (Shahi et al, 1997;Kumar et al, 2002a;Singh et al, 2004a) were found to be in general agreement with those based on the MF values for most of the elements under investigation, whereas in case of measurements at higher energies (Kumar et al, 2001a;Shahi et al, 1998) the MF values were found to deviate by up to 15% for low-and medium-Z elements and up to 30% for high-Z elements. At all the investigated photon energies, the MF values were found to deviate enormously from the measured values in case of elements having the K/L shell ionisation thresholds in vicinity of the incident photon energy (Shahi et al, 1997;Shahi et al, 1998;Kumar et al, 2002a). Similar deviations were also observed for measurements at backward angles by Nayak et al (1992), Kane et al (1987) and Basavaraju et al (1995).…”

“…The present report embodies a review of recent measurements (Puri et al, 1996;Shahi et al, 1997Shahi et al, , 1998Shahi et al, , 2001Kumar et al, 2001aKumar et al, , 2001bKumar et al, , 2002aKumar et al, , 2002bSingh et al, 2004a, b) of the large-angle total atom elastic, inelastic and resonance Raman scattering differential cross-sections performed by our group in the Xray energy region (o100 keV). These measurements were performed using energy dispersive X-ray fluorescence set up involving radioisotope as a photon source and a solid-state photon detector arranged in an annular geometry suitable for large-angle measurements.…”

“…Our group have performed extensive measurements of the differential cross-sections for elastic scattering of (a) 88.03 keV photons by 17 elements with 30pZp92 at 125 o scattering angle (x ¼ 6.31 Å À1 ) (Kumar et al, 2001a); (b) 59.54 keV photons by 19 elements with 13pZp82 at 1301 angle (x ¼ 4.35 Å À1 ) (Puri et al, 1996); by 42 elements with 12pZp92 at 1211 angle (x ¼ 4.17 Å À1 ) (Shahi et al, 1998); and by 33 elements with 13pZp92 at 591 angle (x ¼ 2.365 Å À1 ) (Singh et al, 2004b); (c) 22.1 keV photons by 30 elements with 12pZp92 at 1171 angle (x ¼ 1.519 Å À1 ) (Shahi et al, 1997) and by 15 elements with 6pZp81 at 1331 angle (momentum transfer, x ¼ 1.638 Å À1 ) (Kumar et al, 2002a); (d) 14.93 keV photons by 30 elements with 6pZp92 at 141 o angle (x ¼ 1.135 Å À1 ) (Singh et al, 2004a) . The uncertainty in the measured values was estimated to be $6-9%.…”

“…In our measurements, the energy shift of the inelastic scattered peak from the elastic scattered peak in the spectrum of a low Z element was used to deduce the scattering angle. To estimate the angular spread in defining the scattering angle for the annularsource geometry in reflection mode used by us, the scattered photon intensity profile was obtained as a function of scattering angle using computer-based simulations (Shahi et al, 1997). It is noteworthy here that the theoretical elastic and inelastic scattering crosssections for different elements at different energies investigated by us exhibited nearly linear angular dependence at backward angles (110-1351).…”

“…The measurements done at large angles are important to probe the ASF corrections to MF's, which become significant at these angles. The experimental set up and evaluation methods used in these measurements have been described elsewhere (Shahi et al, 1997(Shahi et al, , 1998.…”