Reconstruction Of Energy Spectrum Research Articles

A generalised algorithm for spectral reconstruction in Compton spectroscopy with corrections for coherent scattering

Reconstruction of primary-photon energy spectra from pulse-height distributions obtained in a Compton spectrometer has earlier been performed under the assumption that coherent scattering in the scatterer is negligible. This holds for most clinical X-ray units operated in the range 40-150 kV-. In mammography, and to some extent in dental radiography, the relatively high frequency of low-energy photons (<30 keV) in the primary beam makes it necessary to extend the algorithms to allow for significant contribution of coherent scattering. This extension is performed as a perturbation calculation to the algorithms developed earlier in which a modified Klein-Nishina scattering cross section was taken as the total scattering cross section. Comparison with energy spectra measured in the primary beam indicates that the Compton spectrometer with the extended algorithm is an excellent instrument for measuring energy spectra with energies down to a few keV.

Quantum Oscillations of Magnetoresistance and Thermomagnetic Power and the Fermi Surface of As‐Sb Alloys

AbstractQuantum oscillations of magnetoresistance and thermomagnetic power of AsxSb1−x (0 ≦ x ≦ 1) alloys in stationary magnetic fields up to 15 T at low temperatures (1.9 ≦ T ≦ 17 K) are investigated. In the alloys, with x ≦ 0.3, the quantum oscillations of thermomagnetic power with a “giant” amplitude are observed. The peculiarities of the energy spectrum reconstruction are determined and the composition range in which a break of the hole necks occurs is defined. It is established that AsSb alloys are semimetals in which overlapping of the hole and electron terms in the first approximation increases linearly with increasing x.