[en] Recent developments in the theoretical treatment of Compton scattering from bound electrons will be examined. The utility of simple approximate methods in calculating single ionization have recently been investigated using a relativistic S matrix computer code. The region of validity of the A² term of the nonrelativistic photon electron interaction has been determined. The extension of this approximation to the calculation of double ionization will be discussed. Particular emphasis will be placed on the double ionization of helium. However, some consideration will also be given to the double ionization of other atoms

[en] The application of high intensity synchrotron sources of radiation has extended the investigation of the effects of correlations on atomic processes into the x-ray regime. At these energies scattering and other photon-atom interactions become increasingly important. A theoretical investigation of these effects on elastic and inelastic photon-atom scattering processes and on the electron-positron pair production process is presented

[en] Recent developments in the theoretical treatment of Compton scattering from bound electrons are examined. These include the investigation of electron-electron effects in scattering from helium and the application of relativistic S matrix techniques to the process. The possibility of extending the use of Compton scattering to the investigation of correlations in other systems is discussed. The contributions of resonant terms, not usually considered in calculations of integrated cross sections, are examined. (orig.)

[en] A brief introduction to the topic of Compton scattering from bound electrons is presented. The fundamental nature of this process in understanding quantum phenomena is reviewed. Methods for accurate theoretical evaluation of the Compton scattering cross section are presented. Examples are presented for scattering of several keV photons from helium

[en] When the atomic physicist measures or computes, applications of their results may not be immediately obvious. However, atomic data form the basis of many mature and developing applications. Two of these applications and their dependence on data are reviewed here. In particular, the national standard for radiation exposure and the processing of the United States mail with radiation are discussed

[en] Recently, Botero and Macek developed a new perturbation theory for electron atom scattering with arbitrary boundary conditions, resulting in a modified effective charge Coulomb-Born series, and applied it to the electron impact ionization of the K shell of light neutral atoms. We examine the utility of this approach in the case of electron impact excitation. We calculate the first term of this perturbation series (including exchange) and apply it to the excitation of K shell electrons to the L shell. We compare our results with data from scattering experiments on light elements

[en] We discuss modifications to the incoherent scattering factor clue to contributions corresponding to the rvec p sm-bullet rvec A terms in the photon-atom interaction Hamiltonian. In the case of elastic photon-atom scattering, these terms have been investigated leading to the anomalous scattering factors which are particularly prominent in the near threshold regions. Similarly, we find large corrections to the usual inelastic scattering results are necessary, particularly for incident photon energies below the K shell photoionization threshold. We discuss methods for evaluating these contributions

[en] This paper discusses theoretical approaches for investigating Compton scattering from bound atomic electrons. It particularly emphasizes the understanding of methods currently used to obtain the scattered photon energy distribution at fixed scattering angle. This distribution is dominated by three features: the Compton line or peak, the resonant-Raman-Compton scattering and the infrared divergence at soft scattered photon energies. No single common approximation accesses all three regions, though they are all exhibited analytically in the nonrelativstic hydrogenic case. S-matrix calculations describe all of these features. The usual approximations utilized for Compton scattering are discussed and assessed in comparison with the more exact, relativistic S-matrix calculations. Finally, some recent developments in the theory of Compton scattering from bound electrons are noted. (author)

[en] Ionizing radiation is utilized in many industrial, medical and research applications. The term ionizing radiation implies that the interaction of the radiation with the object of interest occurs at the atomic level, through the removal of electrons from atoms and molecules. In trying to understand, enhance and develop technologies that utilize ionizing radiation, atomic data and tools to utilize these data sets are essential. In this paper some current applications of ionizing radiation are discussed. The computational tools applied to these situations are outlined. Currently available data sets are reviewed. Data needs are discussed as are some of the efforts underway at the National Institute of Standards and Technology (NIST) to enhance both data and tools

[en] NIST's Ionizing Radiation Division maintains and operates three electron accelerators used in a number of applications including waste treatment and sterilization, radiation hardness testing, detector calibrations and materials modification studies. These facilities serve a large number of governmental, academic and industrial users as well as an active intramural research program. They include a 500 kV cascaded-rectifier accelerator, a 2.5 MV electron Van de Graaff accelerator and a 7 to 32 MeV electron linac, supplying beams ranging in energy from a few keV up to 32 MeV. In response to the recent anthrax incident, NIST along with the US Postal Service and the Armed Forces Radiobiology Research Institute (AFRRI) are working to develop protocols and testing procedures for the USPS mail sanitization program. NIST facilities and personnel are being employed in a series of quality-assurance measurements for both electron- and photon-beam sanitization. These include computational modeling, dose verification and VOC (volatile organic compounds) testing using megavoltage electron and photon sources