B. S. Sandhu

Experimental study of angular dependence in double photon Compton scattering

Abstract The collision differential cross-section and energy of one of the final photons for double photon Compton scattering have been measured as a function of scattering angle θ1. The incident photon energy is 0.662 MeV and thin aluminium foils are used as a scatterer. The two simultaneously emitted photons in this higher order process are detected in coincidence using two NaI(Tl) scintillation spectrometers and 30 ns timing electronics. The measured values for energy and collision differential cross-section agree with theory within experimental estimated error. The present data provide information of angular dependence in this higher order process.

A non-destructive scattering technique for investigation of pulmonary edema

In many biomedical studies, the density of a biological system is of great importance to investigate its structure or functioning. In the present work, for the density measurement of lung phantom, the scattering of 59.54 and 662keV gamma photons are studied using HPGe and NaI(Tl) detectors, respectively. Phantoms simulating lung density are prepared by mixing appropriate amount of saw dust and distilled water. The regression lines, obtained from experimental data of scattered spectra, provide the amount of excessive water storage in lungs, hence the technique has the potential for a measure of pathological state like pulmonary edema. The technique is quite sensitive for small change (∼23Kgm(-3)) in the density of lung phantom. Also, Compton scatter profile measurements (in case of 59.54keV) results that the technique is less sensitive beyond chest wall thickness of ∼26mm due to overlying scatter components in the measured spectrum. A portable non-invasive system described presently may be used for various industrial applications also.

Albedo factors of 279, 320, 511 and 662 keV backscattered gamma photons

The backscattered peak and albedos are important for the estimation of exposure distribution and for better understanding the phenomenon of the backscattering of gamma photons. To characterize the backscattering probability of gamma photons interacting with different atomic numbers (Z), number (A N), energy (A E) and dose (A D) albedos are experimentally evaluated. The response function converts the observed pulse-height distribution of a NaI(Tl) scintillation detector to a true photon spectrum. For each of the incident gamma photon energies, the number and energy albedos show an increase with the increasing target thickness, and finally saturate. The energy albedos are found to be decreasing with the increase in the atomic number of the target material and incident gamma photon energy. The dose albedos do not differ significantly from the energy albedos for the chosen incident gamma photon energies.

Investigations of Angular Distribution in Two-Photon Compton Scattering

The cross-section for two-photon Compton scattering for incident photons of energy 0.662 MeV and two emitted photons having energies greater than 50 keV has been measured at different scattering angles θ 1 =30° to 150° and θ 2 =π/2; φ 2 =π. Our measured results, although of same magnitude, are consistently higher as compared to theory of Mandl and Skyrme. Some calculations of energy and direction of the recoil electron are also carried out to understand the important features of this weak process.

Energy and intensity distributions in double photon Compton scattering

The energy and intensity distributions of the gamma rays scattered in the double photon Compton scattering process are measured experimentally for 0.662 MeV incident photons. The two scattered photons are detected in coincidence using two NaI(Tl) scintillation spectrometers and 30 ns timing electronics. The results are in agreement with the theory of Mandl and Skyrme (1952).

Collision Integral Cross Sections in Double Photon Compton Scattering and a Possible Method for Their Measurement

Abstract The collision integral cross sections are obtained and computed for several experimentally realizable cases to understand the various features of the higher-order process known as double photon Compton scattering. The computational work carried out using the Mathematica software package generally corresponds to three different incident gamma photon energies of 137Cs (661.65 keV), 65Zn (1.12 MeV), and that from the radiative capture of 19F (6.14 MeV). The characteristic features revealed a need to be investigated experimentally to check for their support to the currently acceptable theory of this quantum electrodynamics process. An experimental technique has been suggested for the measurement of these collision integral cross sections.

Experimental Study of Energy Distribution in Double Photon Compton Scattering

Abstract The energy distribution of gamma photons scattered in double photon Compton scattering is measured experimentally for 0.662-MeV incident gamma photons. The two simultaneously emitted gamma quanta are investigated using a slow-fast coincidence technique. The experimental data on energy distribution do not suffer from inherent energy resolution of the gamma detector and confirm the continuous nature of energy spectra for the emitted photons. The present results are in agreement with the current theory of this higher-order process.

Measurement of double-photon Compton scattering cross-sections of 662 keV gamma rays

The cross-section for double-photon Compton scattering for incident photons of energy 662 keV and two emitted photons having energies ⩾ 100 keV has been measured at different scattering angles θ1 = 30° to 150° and θ2 = φ2 = π2. The experimental results are compared with the theory of Mandl and Skyrme. Some calculations are also carried out to understand the important features of the phenomenon.

Experimental measurement of intensity distribution in two-photon Compton scattering

Abstract Cross-sections of two-photon Compton scattering process for 0.662 MeV incident photons have been measured at θ1 = 70°, θ2 = π2 = 90° and at θ1 = θ2 = 90°, π2 = 135°. The two scattered photons are detected in coincidence using two NaI(Tl) scintillation spectrometers and 30 ns timing electronics. The cross-section values, although of same magnitude, are consistently higher. Some calculations are also carried out to understand the important features of this weak process.

Double-photon Compton scattering of 662 keV gamma-rays

SummaryThe double-photon Compton scattering cross-section of 662 keV gamma-rays is measured for photons having energy ≥50 keV and emitted at 90° to the incident beam and 180° to each other. The experimental result is compared with the theory of Mandl and Skyrme.RiassuntoSi misura la sezione durto di scattering di Compton a due fotoni di raggi gamma a 662 keV per fotoni con energia ≥50 keV e emessi a 90° rispetto al fascio incidente e a 180° uno rispetto allaltro. Si confronta il risultato sperimentale con la teoria di Mandl e Skyrme.