Academic literature on the topic 'Geiger-Muller tube'

Abstract This study presents a detailed measurement of indoor and outdoor terrestrial gamma radiation levels in different cities of Pakistan. The measurements covered dwellings in 27 cities, covering all provinces and region of Azad Kashmir. Most of the houses were of attached type, made of brick walls and concrete roofs. The measurements were made by a handheld radiation survey meter containing Geiger–Muller tube. The average absorbed dose rate in air was 100 ± 32 nGy h−1 for indoor and 74 ± 30 nGy h−1 for outdoor. The population-weighted mean terrestrial dose rates were 90 nGy h−1 for indoor and 78 nGyh−1 for outdoor. The ratio of indoor to outdoor absorbed dose rate was 1.5 as compared to 1.3 for the world average. The estimated average annual effective dose rate was 0.58 ± 0.18 mSv a−1 and the mean excess life time cancer risk was 2.0 × 10−3.

In response to the Fukushima Daiichi Nuclear Power Plant accident, there has occurred the unabated growth in the number of airborne platforms developed to perform radiation mapping—each utilising various designs of a low-altitude uncrewed aerial vehicle. Alongside the associated advancements in the airborne system transporting the radiation detection payload, from the earliest radiological analyses performed using gas-filled Geiger-Muller tube detectors, modern radiation detection and mapping platforms are now based near-exclusively on solid-state scintillator detectors. With numerous varieties of such light-emitting crystalline materials now in existence, this combined desk and computational modelling study sought to evaluate the best-available detector material compatible with the requirements for low-altitude autonomous radiation detection, localisation and subsequent high spatial-resolution mapping of both naturally occurring and anthropogenically-derived radionuclides. The ideal geometry of such detector materials is also evaluated. While NaI and CsI (both elementally doped) are (and will likely remain) the mainstays of radiation detection, LaBr3 scintillation detectors were determined to possess not only a greater sensitivity to incident gamma-ray radiation, but also a far superior spectral (energy) resolution over existing and other potentially deployable detector materials. Combined with their current competitive cost, an array of three such composition cylindrical detectors were determined to provide the best means of detecting and discriminating the various incident gamma-rays.

In this study, the equivalent dose rate of natural radionuclides ( H T ) in 99 spring water and surface soil samples was determined using an alpha, beta, and gamma high sensitivity detector up within a Geiger-Muller tube and with an external probe NaI (Tl). The samples were collected in the Crati basin (southern Italy), and during sample collection, water quality parameters were detected in situ and at the University of Calabria laboratories. A Pearson correlation coefficient analysis was applied to identify and clarify the relationships between water physical-chemical properties and soil and water radioactivity. Results show that the mean H T for spring waters is 97.07 μSv/h. Furthermore, the mean H T for surface soils is 97.92 μSv/h, thus evidencing higher mean H T values than worldwide ones reported in a previous literature. Low correlation coefficients were detected between water H T and conductivity and pH. On the contrary, a reasonable correlation was found between H T in spring water and in soil. This relationship is associated with some rocks of the Sila Massif and of Coastal Chain, i.e., plutonic and metamorphic crystalline rocks. Finally, the estimation of the health risk was calculated: results did not evidence serious dangers for people living in the studied environment. The results from this survey for the H T evaluation provide an extensive assessment of the background exposure levels in the investigated area.

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 The rate of export of recent photoassimilate from source leaves of Pima cotton (Gossypium barbadense L.) is inhibited by ozone (O3). To characterize these effects on export, source leaves of Pima cotton were exposed to pulses (0.75 h) of O3 (0.0, 0.2, 0.5 and 0.8 L L–1) followed by pulses of 14CO2. Leaves were monitored by gas exchange and with a Geiger–Muller tube, for a sufficient period to characterize carbon assimilation (A) and a rapid and a slower phase of export. Double exponential decay functions (two-compartment model) were fitted and a compartmental analysis conducted. O3 reduced by half the fast rate constant describing export from a transport pool, without affecting the rate constants for transport from or to a storage compartment. Measured soluble sugar contents increased slightly from control concentrations (1.2 g C m–2) by about 5–10% at all O3 concentrations. The calculated soluble sugar content in the transport pool increased from about 200 to 300 mg C m–2 with increasing exposure to O3. The calculated storage pool did not respond to O3 but exceeded measured contents. This discrepancy is attributed to starch deposition and mobilization, which are not considered in the two-compartment model, uncertainties in slower decay parameters, and non-steady-state A induced by O3 exposure. Specific inhibition of rapid efflux suggests oxidant damage at the plasmalemma or plasmodesmata of mesophyll or phloem companion cells, and little effect on the tonoplast. A was affected less than export. Future research should target oxidation of components involved in phloem loading.

A Computer Numerical Control (CNC) system for Printed Circuit Board (PCB) design using Proteus Design Suite has been presented. A schematic diagram and single-sided PCB layout of a high voltage circuit for Geiger– Muller (GM) tube is designed using Proteus software. Subsequently, the PCB layout of the circuit is converted into Gerber files that are decoded into G-code through Flat CAM software. The G-code is introduced to the CNC system consisting of a computer, a CNC controller and a CNC machine. The code is stored in the memory of the computer and is uploaded to the CNC controller byMach3 software. The controller operates the CNC machine to perform isolation routing, drilling and milling for PCB as per the instructed design. It is noticed that the CNC system associated with Proteus makes the PCB designing process automated and easier by reducing the process of printing as well as etching. This study reveals that the proposed system can eliminate human error to achieve better accuracy and higher productivity as compared to the conventional methods of PCB design.

Background: Diagnostic radiology studies in children harbor more radiation hazards than in adults due to their small size and higher cellular proliferation rate. Therefore, reducing the radiation burden to children should be top priority. Measurement of radiation dose is the first step to this goal. Nevertheless, we do not know whether the radiation of portable radiographs at our hospital meets the standards or not. Objectives: This study aims at measuring the primary and scattered radiation at different distances from patients. This eventually would help us to keep the radiation to minimum. Methods: This study was conducted on 84 patients from 4 different wards (U1-U2) in our hospital in 2017. After obtaining ethical approval from ethical committee and also written consent from parents, all patients who needed portable X-ray were included in our study. A thermo-luminescent dosimeter was placed on the patient’s chest to measure the entrance surface dose (ESD), while Geiger-Muller dosimeters located at one and two-meter distances from the X-ray tube used to scale the scattered radiation. Then, data were analyzed in SPSS 16. Results: The average ESD was 0.3873, 0.3867, 0.3700, and 0.4033 millisievert (mSv) in U1 to U4 respectively, whereas the scattered radiation doses measured as 0.00986, 0.00750, 0.01250, 0.1014 at one-meter and 0.00250, 0.00220, 0.00238, 0.00314 mSv at two-meter distances. There was no significant difference in radiation dose between those units (P > 0.05). Conclusions: Radiation received by patients in this study was three to four times higher than the standard dose. Significant scattered radiation was also detected at one and two-meter distances. To reduce radiation, improvement of exposure protocols such as reducing mAs and using proper shielding is emphasized.

Este trabalho descreve a montagem de um detector Geiger Muller (GM) a partir de um tubo comercial, SBM19, e com flexibilidade nos componentes eletrônicos agregados. Muitas referências citadas são de domínio público e disponíveis na internet, permitido ao leitor uma maior facilidade ao acesso às informações e a outras possibilidades de montagem de um detector GM. O detector proposto é uma ferramenta em potencial para o ensino de física moderna no Ensino Médio e uma proposta de demonstração em feiras de ciências. São apresentados resultados de medidas em camisas de lampião, Am de um detector de fumaça e de um cinzeiro enriquecido com urânio.

The design and construction of a state-of-the-art ultra-high vacuum spectrometer for the performance of angle-resolved inverse photoemission spectroscopy is presented. Detailed descriptions of its most important components are included, especially the Geiger-Muller ultraviolet photodetectors. By building on recent developments in the literature, we expect our spectrometer to achieve resolution comparable or superior to that of other prominent groups, and in general be one of the foremost apparatus for studying the momentum dependence of the unoccupied states in strongly correlated materials. Summaries of the theory of angle-resolved inverse photoemission spectroscopy and the basics of ultra-high vacuum science are also included.

The paper describes an automated non-destructive assay (NDA) system for the measurement and characterization of radioactive waste. The Waste Characterisation System (WCS) can be adapted to measure a variety of drum sizes: 60, 220 (55 gallon) and 440 liter, the latter with a maximum weight of 1500 kg (1.5 tonnes). The NDA system includes a Tomographic Segmented Gamma Scanner (TSGS) and an active/passive neutron Differential Die-away (DDA or DDT). The system can assay a wide variety of waste types in a range of waste matrices. The assay stations are linked by a heavy duty roller conveyor which incorporates a 20 drum buffer store, a load cell (built into the conveyor), bar code readers and a dose rate measurement station. The Tomographic Segmented Gamma Scanner (TSGS) combines conventional high resolution gamma spectrometry and a tranission source to interrogate a waste drum in vertical slices (segments) as for Segmented Gamma Scanner (SGS) measurements. However, in the case of the TSGS, while the drum is rotated, it is also moved in the horizontal direction leading to an enhanced ability to correct the gamma ray energies, from the nuclides of interest, for the attenuation of the matrix. The TSGS can also be operated as a conventional SGS for the measurement of homogeneous waste drums. The DDA is a very sensitive active neutron interrogation method that uses thermalised neutrons from a pulsed source within the chamber to irradiate a waste drum. Prompt neutrons from fissile material present in the waste (e. g. 239Pu, 235U) are detected and provide a measure of the fissile content in the drum. In passive mode, the DDA determines the even Pu nuclides exhibiting significant spontaneous fission (e.g. 240Pu). Measurement accuracy depends on correction algorithms to compensate for self-shielding and matrix effects in waste drums containing hydrogenous materials. In addition, the DDA will be provided with the Fission-Fission Neutron Correlation Analysis System (FFnC) which is an absolute technique eliminating the need for matrix dependent mass calibrations, and allowing separate U and Pu determination using delayed neutron counting. The FFnC technique will be tested for the first time on the WCS. The NDA system incorporates integrated stations to determine the weight and dose rate of each drum, the former built into the conveyor the latter as part of the TSGS. Six Geiger Muller tubes measure the surface dose at three positions on the drum side, one at 1 metre from the drum and one each measuring the surface dose of the top and bottom of the drum. The assay instruments are linked to a heavy duty conveyor system onto which up to 20 waste drums can be loaded for delivery to the various measurement stations, thus permitting unattended, automated operation. Once measured, the drums remain on the conveyer in a holding system waiting to be unloaded. Automation is provided using a programmable logic controller (PLC) and associated computers. A central computer and associated software is used for data acquisition and management.