Purpose: The paper aims to discuss the response of the Micro-Mesh gaseous Structure (Micromegas) detector to high-energy X-ray with 2. 3 MeV energy using photon to neutron converters in addition to optimization of the detector components by Monte Carlo simulation. Materials and Methods: Methods of using Micromegas are different in terms of energy and intensity of high-energy X-ray. Response of Micromegas detector to X-ray with 2. 3 MeV by different photoneutron converters was calculated by Monte Carlo N Particle X-Version (MCNPX) code. The number of electrons in the drift and multiplication regions and the depth-dose in the various regions of the detector were measured to study the response of the Micromegas detector to high energy X-ray. Also, the thickness of the upper electrode, and the type of gas in the detector were studied and optimized. Results: D2O with 2×10-5 efficiency is the best target to convert photons with 2. 3 MeV energy to neutrons. It is the proper convertor to change the high energy X-ray into a photoneutron that can be detected by Micromegas. The optimum thickness of the upper electrode is 0. 0026 cm for air and P10 gas in the detector. Conclusion: The results show that this detector can detect high-energy X-rays with energy above 2 MeV. The Monte Carlo results showed the output current of the Micromegas detector is 5. 12 pA per one input hard X-ray photon.

In this paper we consider a gaseous detector and supposed, because of pass of an ionizing radiation, an electron created inside it. By numerical simulation with monte carlo method and concluding the impacts, scatterings and creation of secondary electrons, we find the trajectory of initial and secondary electrons. Dependence of number of secondary electrons to applied electrical field is investigated. Finally we study the dependence of number of secondary electrons to number of initial electrons created by ionizing radiation (as a measure of the radiation energy), then we try to investigate the possibility of spectrometry by this detectors.

The aim of this paper is to design, manufacture and test the first triple RETGEM detector. Using resistive electrode in RETGEM detectors made them more robust against the electrical discharge with respect to THGEM detectors. However, even these robust detectors are not protected against electrical discharge at gains higher than 105. Studying the role of dimensions of the triple RETGEMS detectors and also the effect of pressure and gas mixtures on the gain level of detectors, we will show, the triple RETGEM detectors can reach the gains up to 106 without worrying about electrical discharge. We also compare the result of all tests for single and triple RETGEM detectors.

In this study, the role of arrangement of electric fields in the Electron Multiplier Assembly as a geometrical quenching in the gaseous position-sensitive detector has been presented. Using of two geometrical and cascade configuration of this micro pattern structure, the electric fields were simulated at threshold voltage when the visible streamers appeared in front of a radioactive source in the presence of P10 gas. In this simulation, the minimum necessary electric field strength to multiply electrons and the variation of electric fields in the distance between the Electron Multiplier Assembly electrodes from a maximum value in the center of each hole and its decrease at the surface of the electrodes is shown. The convergence of the electric field lines in the center of each hole and its divergence near the anode and cathode electrodes lead to the formation of a non-destructive self-sustaining plasma region in the form of a visible streamer in the enclosed space inside the electrode holes which its light intensity is equal to the number of electrons that they have participated in the electron avalanches.

By expanding the applications of GEM detectors, a newer pattern of such detectors was introduced in 2004, named THGEM detectors. In this work, a sample of an X-ray detector was designed and constructed using 2cm×2cm THGEMs domestically produced with a thickness of 250 μm, a hole diameter of 300 μm and a pitch of 500 μm, for the first time. The triple THGEM detector working in Ar/CO2 gas mixture was characterized. Influence of gas pressure and gas mixture on gain of the detector was investigated. Results show the detector operated in a stable mode with no discharges. The gain of the detector increased with high voltage across the THGEM electrodes exponentially. This verified the performance of a detector as a proportional counter. Also, the detector’s gain is maximum at Ar/CO2 (80/20) gas mixture and voltage of 700 V applied to each multiplier. The detector is promising for localization applications such as particle physics experiments.

Misplacement of tracheal tube in the esophagus remains a significant cause of morbidity and mortality in anesthesia despite decades of effort aimed at prevention or (more importantly) detection of such an event. We have evaluated a cheap, simple and quick device (Esophageal detector Device; EDD) which relies mainly on the relation or otherwise of an evacuated elastic bulb applied to the supposed (tracheal) or (esophageal) tube.Identical tracheal tubes were passed into the trachea and esophagus of 100 patients, the left and right position in the mouth was chosen at random.The test was conducted by a second person, not present at intubations and unaware of the tube placed in the trachea. There were no false negatives (relation of elastic bulb applied to the tracheal tubes) probably due to bronchospasm early after induction of anesthesia. Correct deduction of the tracheal tube position was achieved in 98 patients using the device. We conclude that EDD could be a very sensitive (100%) and reliable method for detection of esophageal intubations however, it is recommended in further studies to test the tubes immediately after intubations (when bronchospasm is most probable) to find the exact specificity and accuracy of the device.

Resistive plate chamber (RPC) is a gaseous particle detector primarily developed for particle physics experiments and found vast applications in industry. We have constructed a prototype of a single gap glass RPC, with gap width of 2 mm. For simplicity, this prototype has a single 10×10 cm2 Al pad to readout the detector’, s signals. An electronic board is designed and built at our laboratory to receive, amplify and register pulses as counts per unit time at the computer. In this study, we have used the count rate (noise) as an indicator of the detector's performance. We observed that the count rate reduced in the presence of Fe shields above the detector, due to the absorption of particles related to the cosmic rays. We also studied the sensitivity of the detector to the 60 keV gammas of the Am source. Although an increase in the count rate in the presence of the 241Am source is evident, the efficiency of the detector to 60 keV gammas is very small. All of the measurements are performed at several high voltages between 1 kV and 3 kV.