Sharif Digital Repository

In this Thesis, a nuclear borehole logging tool has been designed and constructed for measuring the bulk density of a formation by the use of gamma rays. One of the main applications of this tool is obtaining of porosity. It also is useful in the detection of formations containing oil and gas. This tool consists of: a gamma ray source 60Co, a single gamma ray detector NaI(Tl), lead shield and electronic modules. The cylindrical sond is entered into a borehole and the surrounding formation is subjected to the emitted gamma rays from the source. The formation density can be determined from the measurement of the scattered photons reaching the detector from the formation. The purpose of the... 

Bohmian mechanics (or de Broglie–Bohm theory) is a causal version of the quan-tum mechanics which its main idea was expressed for the first time by Louis de Broglie in 1927, and then rediscovered by David Bohm in 1952 with a different approach.In this theory, the state of a system of particles, is described by the position of the particles, and a wavefunction evolving according to the Schrödinger equation. John Bell in 1987, considering the double-slit experiment and emphasizing the importance of the Bohm’s wave-particle theory said: ”Is it not clear from the smallness of the scintillation on the screen that we have to do with a particle? And is it not clear,from the diffraction and... 

In this project a dual density logging tool has been designed and constructed for measuring the bulk density of a formation using gamma rays. One of the main applications of this tool is obtaining porosity. It also is useful in the detection of formations containing oil and gas. In this work, MCNP Monte Carlo code was used to simulate the performance of the scattered gamma rays under various sond-formation parametric condition. The results coming from this code are applied to determine the fundamental parameters of gamma-gamma density tools like, Energy window, thickness of lead, optimum distance between each detectors. Furthermore, a novel method based on summation of back scatter and... 

A bolometer is a device for measuring electromagnetic waves, which uses the heating of a material with variable resistance to temperature. Due to the existing limitations and quality improvement, superconducting materials are used in the manufacture of these devices. In this dissertation, the construction and improvement of the components of a high temperature transient edge superconducting radiometer with terahertz detection capability is discussed. In the construction of these detectors, the superconducting material YBa2Cu3O7-x is used as a thermal sensor with a transition temperature of 93.5K. In order to characterize these detectors, an automatic system for measuring the voltage response... 

In this thesis, we are focusing on the heat transport mechanism in one of the most applicable kinds of superconducting detectors called, YBa2Cu3O7-x (YBCO) transition-edge bolometer. The Time Domain Thermoreflectance (TDTR) method is described as a tool for investigating the thermal boundary conductance and thermal conductivity of the materials, and the measured thermal conductivity of our YBCO films is reported here. Although some recent papers have shown a dependence of the thermal conductivity of the YBCO films to their thickness, our results on many samples with different substrates didn’t show the reported thickness dependency and we have obtained the thermal conductivity of the YBCO... 

In this thesis a digital electronic readout system is designed and constructed for MWPC detector. This detector is aimed to be used in ILSF synchrotron. The detector readout system is based on delay line and position of incoming photon can be underestood from delay of cathode signals arrivals. The detector has two dimentional position detecting system and the instruments used in every dimention are identical. Every dimention has a start and stop signal, the time difference between these two signals can be detected by time to amplitude converter or time to digital converter. In this thesis time to digital converter has been used and the time diference of start and stop signals arrivals is... 

Gas detection systems are now recognized as an essential component of safety in process units.but their successful performance depends strongly on the number and location of the detectors.As for the limited resources available (detectors), the placement of gas detectors can be considered as an optimization problem with different objective functions. In this research, an attempt was made to provide models and methods that quantitatively and from a practical point of view to optimum locate the detectors. Initially, a risk-based method was presented that defines the necessary steps for the arrangement of fire gas detectors with the aim of covering the maximum risk of leakage scenarios (risk:...