Corrections to the usual xray scattering factors in rare gases: Experiment and theory
Abstract
The ratio of the total xray scattering from Ne to that from He has been determined for photon energies in the range 415 keV at scattering angles of 45 and 90 degrees (corresponding to momentum transfers ranging from 0.90 to 5.69 a.u.). An arrangement of two gas cells in series was employed, allowing simultaneous measurements on both gases at the same scattering angle, which eliminates possible errors due to fluctuating beam intensity. Pairs of measurements corresponding to the same momentum transfer (at momentum transfers of 1.67 and 3.08 a.u.) but to different energies, provide a direct test of the corrections to the (momentumtransferdependent) formfactor incoherentscatteringfactor theory. These corrections include the anomalous p.A contributions, which are found to be important. We also consider corrections to the usual approximations made within the inelastic A^{2} theory (the incoherentscattering factor, using closure approximation, and the impulse approximation, assuming freeparticle kinematics with a given momentum distribution). In these cases an incoherentscatteringfactor treatment is generally adequate, while anomalous scattering factor corrections to form factors are needed for elastic scattering.
 Publication:

Physical Review A
 Pub Date:
 May 2001
 DOI:
 10.1103/PhysRevA.63.052718
 Bibcode:
 2001PhRvA..63e2718Y
 Keywords:

 32.80.Cy;
 Atomic scattering cross sections and form factors;
 Compton scattering