Academic literature on the topic 'Geiger counter'

This work considers the manifestation of spontaneous breakdowns of Geiger-Mueller counters. This is an experimental type of work. The reasons leading to the spontaneous breakdowns of Geiger-Mueller counters have been analysed under controlled laboratory conditions. The experiments were carried out under the ?constant voltage?. The tested Geiger-Mueller chambers were commercial chambers of the radial electric field and homogenous electric field. The experimental-statistical methods were used in order to choose the chambers with identical features (with 0.1 % of statistical reliability).The results of experiments showed that the spontaneous breakdown of the Geiger-Mueller counter happens even in the conditions of shielding. They also showed that those breakdowns have cumulative features. The reason for that is a positive feedback between the spontaneous breakdowns. The explanation is confirmed and quantified by the working gas filtering experiments.

In this paper, the aging effect of commercially available Geiger-Muller counters under working conditions is being considered from both theoretical and experimental point of view. In the experimental part lifetime curves for the commercial Geiger-Muller counter chamber are first recorded. After detection of the aging phenomena, the commercial chamber response to an impulse voltage is tested along with recording of the same response of the Geiger-Muller chamber model with conductive particles included. The law of similarity for the gaseous discharge is fulfilled both by the commercial Geiger-Muller chamber and by the chamber model with conductive particles. The results obtained from the U-test indicate that the aging of the Geiger-Muller chamber is mainly caused by the occurrence of a great number of conductive particles hovering inside the chamber. Some suggestions of how to reduce the aging effect due to conductive particles inside the Geiger-Muller chamber are given in the conclusion.

This paper discusses the process of functional aging of Geiger-Muller counters. Two types of Geiger-Muller counter chambers were characterized in an experiment using a combined constant voltage. Chamber A had a coaxial geometry and chamber B had a plan-parallel geometry. The experimental results indicate that the aging process was faster in the case of chambers with a coaxial geometry. The results are explained based on the process of electrical discharges in gasses.

X-ray diffraction has many applications in the chemical and metallurgical industries, but its techniques have been confined until recently to the laboratory and to highly trained personnel. Conventional procedure entails photographic exposure, processing, and density comparisons of the finished film strips.The Geiger counter spectrometer described below measures x-ray intensities and diffraction angles directly, without intermediate photographic steps. It is simple enough for unskilled operators performing routine industrial processes yet also meets the precise requirements of laboratory research. The instrument was developed at the Naval Research Laboratory, where it has been in regular use for the past two years.

A portable Geiger counter was evaluated for tracing the movements of radiolabeled Heliothis zea (Boddie) larvae in cotton and corn. In cotton, larvae used were labeled by injection of the parent females and phosphorus-32. These could easily be located using the Geiger counter. In corn, larvae were labeled topically so that pupation sites in the soil could be labeled. The percentage of these that could be located proved variable.

Роботу присвячено розробці портативного дозиметра радіаційного випромінювання. Проаналізовано завдання на роботу та принцип роботи дозиметрів. На основі цього розроблено структурну та функціональну схеми дозиметра, основним елементом якого є мікроконтролер. Проаналізовано варіанти схемного виконання дозиметрів різних типів та розроблено варіант конструкції. Проведено розрахунки елементів схеми електричної принципової та вибрано елементну базу, яка включає навісні та без корпусні елементи. На основі цього розроблено топологію друкованої плати та друкованого вузла. Основні технічні параметри, яким задовольняє дозиметр: діапазон гамма-випромінювання1 – 999 мкЗв/год; час вимірювання, 23с; діапазон робочих температур, -20°С. ..+60; час виходу в робочий режим,40 с; напруга живлення, 3,6 В ; максимально споживаний струм, 100мА .<br>The work is devoted to the development of a portable radiation dosimeter. Tasks for work and the principle of work of dosimeters are analyzed. Based on this, a structural and functional scheme of the dosimeter is developed, the main element of which is a microcontroller. Variants of circuit execution of dosimeters of different types are analyzed and a variant of design is developed. Calculations of elements of the electric basic scheme are carried out and the element base which includes hinged and without case elements is chosen. Based on this, the topology of the printed circuit board and the printed circuit board is developed. The main technical parameters satisfied by the dosimeter: gamma radiation range, μSv / h 1 - 999; measurement time, p 23; operating temperature range, ° C -20. .. + 60; time of exit to a working mode, with 40; supply voltage, B 3.6; maximum current consumption, mA 100.<br>Вступ 7 1 Основна частина 9 1.1 Аналіз технічного завдання 9 1.2 Аналіз принципу роботи дозиметрів радіаційного випромінювання 9 1.3 Аналіз схемо-технічних варіантів розробки дозиметра 11 1.4 Розробка структурної та функціональної схеми дозимерта 20 1.5 Синтез та розрахунки схеми електричної принципової 23 1.6 Вибір елементної бази 34 1.7 Розробка компоновки друкованої плати дозиметра 39 2 Безпека життєдіяльності, основи охорони праці 47 2.1 Особливості електротравматизму, електричний струм, як чинник небезпеки при виробництві портативного дозиметра радіоактивного випромінювання 47 2.2 Вимоги пожежної безпеки при гасінні електроустановок для виготовлення портативного дозиметра радіоактивного випромінювання 50 2.3 Здійснення заходів щодо зниження дії радіоактивних випромінювань 52 Висновки 56 Список використаних джерел 57 Додатки

2008/2009<br>Remarkable interest has recently arisen about the search for Weakly Inter- acting Sub-eV Particles (WISPs), such as axions, Axion Like Particles (ALPs), Minicharged and chameleon particles, all of which are not included in the Stan- dard Model. Precision experiments searching for WISPs probe energy scales as high as 10^6 TeV and are complementary to accelerator experiments, where the energy scale is a few TeV. The axion, in particular, is the oldest studied and has the strongest theoretical motivation, having its origin in Quantum Chromodynamics. It was introduced for the first time in 1973 by Peccei and Quinn to solve the strong CP problem, while later on the cosmological implications of its postulated existence also became clear: it is a good candidate for the cold dark matter, and it is necessary to fully explain the evolution of galaxies. Among the different interactions of axions, the most promising for its detection, from an experimental point of view, is the coupling to two photons (Primakoff effect). Using this coupling, several bounds on the axion mass and energy scale have been set by astrophysical observations, by laboratory experiments and by the direct observation of celestial bodies, such as the Sun. Most of these considerations, as was recently recognized, not only constrain the mass and coupling of the axion, but are more generally applicable to all ALPs. The current best limits on the coupling, over a wide range of ALP masses, come from the the CAST (Cern Axion Solar Telescope) experiment at Cern, which looks for ALPs produced in the solar core. The experiment is based on the Primakoff effect in a high magnetic field, where solar ALPs can be reconverted in photons. The CAST magnet, a 10 T, 10 m long LHC superconducting dipole, is placed on a mobile platform in order to follow the Sun twice a day, during sunrise and sunset, and has two straight bores instrumented with X-ray detectors at each end. The re- generated photon flux is, in fact, expected to be peaked at a few keV. On the other hand, there are suggestions that the problem of the anomalous temperature profile of the solar corona could be solved by a mechanism which could enhance the low energy tail of the regenerated photon spectrum. A low energy photon counter has, for this reason, been designed and built to cover one of the CAST ports, at least temporarily. Low energy, low background photon counters such as the one just mentioned, are also crucial for most experiments searching for WISPs. The low energy photon counting system initially developed to be coupled to CAST will be applicable, with proper upgrades, to other WISPs search experiments. It consists of a Galilean telescope to match the CAST magnet bore cross section to an optical fiber leading photons to the sensors, passing first through an optical switch. This last device allows one to share input photons between two different detectors, and to acquire light and background data simultaneously. The sensors at the end of this chain are a photomultiplier tube and an avalanche photodiode operated in Geiger mode. Each detector was preliminary characterized on a test bench, then it was coupled to the optical system. The final integrated setup was subsequently mounted on one of the CAST magnet bores. A set of measurements, including live sun tracking, was carried out at Cern during 2007-2008. The background ob- tained there was the same measured in the test bench measurements, around 0.4 Hz, but it is clear that to progress from these preliminary measurements a lower background sensor is needed. Different types of detectors were considered and the final choice fell on a Geiger mode avalanche photodiode (G-APD) cooled at liquid nitrogen temperature. The aim is to drastically reduce the dark count rate, al- though an increase in the afterpulsing phenomenon is expected. Since the detector is designed to be operated in a scenario where a very low rate of signal photons is predicted, the afterpulsing effect can be accepted and corrected by an increase in the detector dead time. First results show that a reduction in background of a factor better than 10^4 is obtained, with no loss in quantum e ciency. In addition, an optical system based on a semitransparent mirror (transparent to X-rays and re ective for 1-2 eV photons) has been built. This setup, covering the low energy spectrum of solar ALPs, will be installed permanently on the CAST beamline. Current work is centered on further tests on the liquid nitrogen cooled G-APD concept involving different types of sensors and different layouts of the front-end read-out electronics, with a particular attention to the quenching cir- cuit, whether active or passive. Once these detector studies are completed, the final low background sensor will be installed on the CAST experiment. It is important to note that the use of a single photon counter for low energy photons having a good enough background (<1 Hz at least) is not limited to the CAST case, but is of great importance for most WISPs experimental searches, with special regard for photon regeneration experi- ments, and, in general, for the field of precision experiments in particle physics.<br>Negli ultimi tempi è riemerso un notevole interesse nel campo della ricerca di particelle leggere debolmenti interagenti (Weakly Interacting Sub-eV Particles - WISPs), come ad esempio assioni, particelle con comportamenti simili agli assioni (Axion Like Particles - ALPs), particelle con carica frazionaria e particelle camaleonte; tutti tipi di particelle non inclusi nel Modello Standard. Vista la loro natura debolmente interagente, la scala di energia coinvolta è dell'ordine dei 10^6 TeV, queste particelle non sono visibili nelle collisioni realizzabili negli attuali acceleratori e possono invece essere studiate in esperimenti di precisione, che, sotto questo punto di vista, diventano complementari agli esperimenti su acceleratori. L'assione in particolare è la prima particella, da un punto di vista cronologico, ad essere stata ipotizzata, ed inoltre la sua esistenza è supportata da forti basi teoriche: la sua origine va infatti ricercata all'interno della Cromodinamica Quantistica (QCD). L'assione fu introdotto per la prima volta nel 1973 da Peccei e Quinn come soluzione del problema di violazione di CP nelle interazioni forti, mentre le sue implicazioni cosmologiche risultarono chiare solo in seguito. L'assione infatti può essere considerato un buon candidato per la materia oscura fredda e la sua introduzione è necessaria per spiegare l'evoluzione delle galassie. Tra le diverse interazione degli assioni con la materia e la radiazione, la più interessante da un punto di vista sperimentale è l'accoppiamento con due fotoni (effetto Primakoff). Usando questo tipo di accoppiamento numerosi limiti, sia sulla massa dell'assione che sulle scale di energia coinvolte, possono essere ottenuti da osservazioni astrofisiche e da esperimenti di laboratorio così come dalla diretta osservazione di oggetti celesti tipo il Sole. Queste considerazioni possono essere applicate non solo all'assione ma più in generale a tutte le ALPs. Attualmente i limiti migliori sulla costante di accoppiamento, su un largo spettro di masse di ALPs, si sono ottenuti dall'esperimento CAST (Cern Axion Solar Tele- scope) al Cern, che guarda agli ALPs prodotti nel Sole. L'esperimento è basato sull'effetto Primakoff in un campo magnetico elevato, dove gli ALPs solari sono riconvertiti in fotoni. Il magnete dell'esperimento CAST è costituito da un prototipo per un dipolo superconduttore di LHC, lungo 10 m e con un campo magnetico totale di 10 T. Il magnete è posto su di un affusto mobile per poter seguire il sole durante le fasi di alba e tramonto. Alle due estremità del magnete sono disposti quattro rivelatori sensibili nel campo degli X molli. Il picco del usso di fotoni rigenerato è infatti atteso a pochi keV. Tuttavia, ci sono suggerimenti che il prob- lema ancora aperto del profilo di temperatura della corona solare può essere risolto tramite un meccanismo che contemporaneamente incrementerebbe le code a bassa energia dell'atteso usso di fotoni rigenerati. A questo scopo un contatore di fotoni sensibile nell'intervallo del visibile è stato progettato ed assemblato per coprire una delle quattro porte del magnete di CAST, almeno temporaneamente. I contatori di fotoni studiati hanno un largo campo di applicazione e possono essere usati in altri tipi di esperimenti per la ricerca di WISPs. Il sistema inizialmente sviluppato per CAST consiste in un telescopio Galileiano per accoppiare una fibra ottica all'apertura del magnete di CAST, la fibra ottica è quindi collegata ad un interruttore ottico che permette di utilizzare due rivelatori contemporaneamente. La fibra in ingresso è infatti collegata alternativamente a due fibre in uscita, in questo modo ciascun rivelatore acquisisce per metà del tempo segnale e per metà del tempo fondo, lasciando inalterato il tempo totale di integrazione. I sensori utilizzati fino ad ora al termine della catena ottica sono un tubo fotomoltiplicatore e un avalanche photodiode operato in modalità Geiger. Ciascun rivelatore è stato preliminarmente caratterizzato su un banco di prova e quindi collegato al sistema ottico. Il sistema finale è stato quindi installato su CAST. Una serie di misure, che includono reali prese dati, sono state condotte al Cern durante il 2007-2008. La misura del fondo ottenuta a CAST è stata la stessa misurata durante i test di prova a Trieste, circa 0.4 Hz, ma risulta chiaro che il vero sviluppo futuro è basato su un sensore a fondo molto più basso. A questo scopo sono stati considerati diversi tipi di sensore e la scelta finale è ricaduta su di un avalanche photodiode operato in modalità Geiger e raffreddato all'azoto liquido. Lo scopo è quello di ridurre drasticamente i conteggi di fondo, sebbene a queste temperature sia atteso un incremento del rateo di afterpulses. Tuttavia il rivelatore è pensato per essere utilizzato in un applicazione a basso rateo e quindi il fenomeno degli afterpulses può essere ridotto agendo direttamente sul tempo morto del rivelatore, cioè aumentandolo. I primi test condotti sul rivelatore mostrano un decremento del fondo pari ad un fattore meglio di 10^4, senza rilevabili variazioni in efficienza. In aggiunta a questo sistema, per ottenere un'installazione permanente sul fascio di CAST, è stato realizzato uno specchio semitrasparente, che lascia pressocchè inalterato il fascio di raggi X e invece de ette il fascio di fotoni con energia nel visibile. Il lavoro attuale è incentrato sullo sviluppo del rivelatore a basso fondo raffreddato all'azoto liquido, includendo anche lo studio di diversi tipi di sensore e diversi tipi di elettronica di lettura, con particolare attenzione all'elettronica di quenching del circuito con le varianti attiva e passiva. Una volta terminati gli studi sui diversi tipi di rivelatori, l'apparato finale sarà installato su CAST. E' comunque importante notare che l'uso di un rivelatore a singolo fotone sensibile tra 1-2 eV con un fondo sufficientemente basso (<1 Hz almeno) non è limitato all'uso su CAST ma in tutti gli altri esperimenti per la ricerca di WISPs, con particolare riguardo agli esperimenti di rigenerazione risonante, e in generale, nel campo di applicazione degli esperimenti di precisione alla fisica delle particelle.<br>1982

Made available in DSpace on 2014-10-09T12:36:49Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T13:57:26Z (GMT). No. of bitstreams: 1 04327.pdf: 2200991 bytes, checksum: 4359f2ee2a626eaa629feb45cdeebc50 (MD5)<br>Dissertacao (Mestrado)<br>IPEN/D<br>Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ - COPPE

The detonation of a radiological dispersal device (RDD) may result in casualties receiving exposure of radioactive materials. Assessments of potentially contaminated personnel are necessary to determine the level of contamination received in order to prioritize and treat individuals. The use of improvised explosive devices (IEDs) and the number of orphan sources in deployed and combat areas such as Iraq, present an opportunity for terrorists to use an RDD against deployed ground forces. There is limited capability in Iraq to assess radiological casualties, as the process of obtaining and analyzing bioassays is time consuming and not readily available in country. Military units are equipped with AN/VDR-2 and AN/PDR-77 radiac detectors which are capable of detecting gamma radiation. Therefore, a study of the use of these radiac sets in assessing internal contamination was conducted. A model of the detector probe was created using the Los Alamos National Laboratory Monte Carlo N-Particle transport code, MCNP Version 5. This model was experimentally validated and used in conjunction with both reference male and reference female computational Medical Internal Radiation Dose (MIRD) phantoms to compute internal dose. The instrument model was evaluated at the following locations, the posterior upper right torso, the anterior upper right torso, the lateral upper left thigh and the anterior of the neck. Nuclides were distributed throughout the phantoms using the Oak Ridge National Laboratory Dose and Risk Calculation (DCAL) software for inhalation pathways. Based on the likelihood for use in RDDs and the capabilities of the instrument, Co-60, Cs-137 and Ir-192 were evaluated.

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Frédéric Joliot discovered artificial radioactivity on January 11, 1934, when he bombarded aluminum with polonium alpha particles and produced a radioactive isotope of phosphorus that decayed by emitting a positron. He detected it with a Geiger–Müller counter that Wolfgang Gentner had constructed for him. Two months later, Enrico Fermi, motivated in part by an insight of his first assistant, Gian Carlo Wick, decided to see if neutrons also could produce artificial radioactivity. The transformation of a neutron into a proton in a nucleus should create an electron, so to increase their number and hence the probability of creating an electron, he bombarded various elements with intense sources of neutrons, and on March 20, 1934, with aluminum he observed the created electrons and thereby discovered neutron-induced artificial radioactivity. Less than four months later, Marie Curie died on July 4, 1934, at age sixty-six.

A silver activation counter has been constructed by plastic scintillator plates along with silver foils for determination the neutron yield of a 2.48kJ plasma focus device, SBUPF1. This counter was calibrated by source removal method with an Am-Be 5 Ci neutron source which was placed above the anode of plasma focus device. Deuterium gas up to 8mbar pressure was injected to this device, and the neutron yield produced by pulsed D-D fusion of plasma focus device was measured by the counter. the neutron yield of SBUPF1 in 8mbar pressure was obtained 3.71±0.32×107 neutrons per shot. This result has relatively agreed with the neutron yield measured by silver activation Geiger counters.

This paper introduces an interactive simulation developed using the Wolfram Mathematica software package for determination of the device F-factor for the Geiger-Müller counter component LARA 10, within the context of the LR-M2 radiation laboratory. LR-M2, a military-origin laboratory established in the early 1980s, houses the LARA 10 device, which is crucial for radiation detection and measurement. The simulation focuses on computing the F-factor based on the registered radiation intensity with different radiation filters. Through an interactive interface, users can explore the impact of varying radiation levels and filter types on F-factor calculations, providing valuable insights into the device’s performance characteristics. This interactive approach enhances understanding and facilitates experimentation, enabling users to optimize radiation detection processes in the LR-M2 laboratory setting. The findings contribute to the advancement of radiation monitoring technology, particularly in civilian applications, ensuring enhanced capabilities for effective radiation hazard management.

We report the Geiger operation of a nanophotonic silicon APD, quantify its dark counts rate and detection probability at 300K. While characterized in free space, simulations of coupling to a nanophotonic waveguide quantify future improvements.