Amandeep Sharma

Incoherent scattering of gamma photons for non-destructive tomographic inspection of pipeline.

A scanner system, operating in a non-destructive and non-invasive way, is presented for pipeline to determine its location in land soil, wall thickness, type of liquid flowing and crack/blockage position. The present experiment simulates a real case where pipe corrosion (wall thinning) under insulation can be known from the study of incoherent scattering of 662 keV gamma photons. The incoherent scattered intensity, obtained by unfolding (deconvolution) the experimental pulse-height distribution of NaI(Tl) scintillation detector with the help of inverse response matrix, provides the desired information. The method is quite sensitive for small change (approximately 1 mm) in the thickness of pipe wall, locating a defect of 1mm width under insulation and a small change (approximately 0.1 gm cm(-3)) in the density of liquid flowing through pipe.

Coherent and incoherent scatterings for measurement of mandibular bone density and stable iodine content of tissue

The aim of present study is to investigate the feasibility of gamma ray scattering for measurements of mandibular bone density and stable iodine content of tissue. Scattered spectra from solutions of K2HPO4 in distilled water (a phantom simulating the mandibular bone) and KI in distilled water filled in a thin plastic vial (a phantom simulating the kinetics of thyroid iodine) are recorded for 59.54 and 145 keV incident gamma rays, respectively. A high-purity germanium detector is placed at various angular positions to record the scattered spectra originating from interactions of incident gamma rays with the phantom. The measured intensity ratio of coherent to incoherent scattered gamma rays, corrected for photo-peak efficiency of HPGe detector, absorption of gamma rays in air column present between phantom and detector, and self-absorption in the phantom, is found to be increasing linearly with increase in concentration of K2HPO4 and KI in distilled water within experimental estimated error of <6%. The regression lines, obtained from experimental data for intensity ratio, provide the bone density and stable iodine contents of thyroid. The present non-destructive technique has the potential for a measure of mandibular bone density and stable iodine contents of thyroid.

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.

Performance evaluation of Mobile Ad hoc Network routing protocols under various security attacks

Few characteristics of a Mobile Ad hoc Network, such as dynamic topology and shared wireless medium, pose various security challenges. This paper focuses on the performance investigation of reactive and proactive MANET routing protocols, namely, AODV and OLSR, under various the security attacks, where two types of attacks have been investigated. Network performance is evaluated in terms of end to end delay, retransmission attempts, network load and throughput, when a percentage of nodes misbehave. Simulation results show that under the passive attacks, proactive protocols perform well and under the active attacks, performance of reactive protocols is robust.

A gamma-ray scattering technique for estimation of density and moisture content of wood

ABSTRACT A densitometer system, operating in a non-destructive and non-invasive way, is presented to investigate the density and moisture variation in wood samples of Pinus roxburghii (known as chir pine). The inherent ability of Compton scattering can ascertain quantitative information of electron density of the target material. A well collimated beam of 662 keV gamma rays from 137Cs radioactive source has been used to extract the information of density from interior of sample by recording scattered spectra with NaI(Tl) scintillation detector. An inverse matrix approach for unfolding of observed pulse-height distribution to a true photon spectrum is used, by choosing bin mesh (E1/2) of 0.025 (MeV)1/2, for the measurements of scattered spectra. The regression lines, obtained from data of scattered spectra, provide the density and moisture content of selected wood sample. The adjusted R2 value 0.984 for fitted curve, justifies the linear dependence of scattered intensity upon wood density. Also, Compton scatter measurements results that the technique is less sensitive beyond wood thickness of ∼110 mm due to overlying scatter components in the measured spectrum.

Coherent to incoherent cross section ratio for 59.54 keV gamma rays at scattering angle of 110

The coherent (Rayleigh) to incoherent (Compton) scattering cross-section ratio of elements, in the range 13 ≤ Z ≤ 82, are determined experimentally for 59.54 keV incident gamma photons. An HPGe (High purity germanium) semiconductor detector is employed, at scattering angle of 110°, to record the spectra originating from interactions of incident gamma photons with the target under investigation. The intensity ratio of Rayleigh to Compton scattered peaks observed in the recorded spectra, and corrected for photo-peak efficiency of gamma detector and absorption of photons in the target and air, along with the other required parameters provides the differential cross-section ratio. The measured values of cross-section ratio are found to agree with theoretical predictions based upon non-relativistic form factor, relativistic form factor, modified form factor and S-matrix theory.