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This article traces the emergence of ecomedia in Japan's nuclear exclusion zone. I take this emergence as an opportunity to think through the relations of sensing technologies and animals as well as the transformative potential of these relations for critical thought. I turn to the camera trap and the Geiger counter first to understand how these sensor-based media are used to generate data around environmental inquiry as well as how they may be reassembled to help us take measure of the aftereffects of the 3.11 disasters through and with located relationships and encounters among species, human and nonhuman. By exploring how ecomedia invite nonhuman makings to enter the analytical frame, I hope to arrive at an understanding of environmental harm not as a futurological threat but as an ongoing event that calls for new forms of agentic thinking and enactments of multispecies struggle and collaboration. [ABSTRACT FROM AUTHOR]

In the late 1930s, a team of physicists from the National Bureau of Standards (now the National Institute of Standards and Technology) published eight papers on the investigation of cosmic rays in the atmosphere. Payloads launched with weather balloons, also known as radiosondes, were equipped with sensors to measure temperature, relative humidity, pressure, and radiation dose. A battery-operated telemetry system was used to continuously transmit at 60 MHz to a base station. They measured the radiation dose profiles of cosmic radiation in the atmosphere up to 21 km. Calibration of the Geiger-Müller counters with a standard radium source allowed them to calculate a radiation dose rate at an altitude corresponding to 10 kPa that was 180 times the dose rate near sea level in Washington, DC. Ascents in Washington, DC (latitude 39 degrees) and Lima, Peru (near equator) allowed them to demonstrate the effects of Earth's magnetic field on incident galactic cosmic rays; the dose rate in Peru was only half that in Washington, DC. [ABSTRACT FROM AUTHOR]

Abstract When the Geiger-mode avalanche photodiode (Gm-APD) laser detection and ranging (LADAR) carries out the air-to-ground detection, it can detect the echo that is successively reflected by targets and the ground, which causes the false target in the image obtained by the LADAR. In this paper, the echo which is successively reflected by two surfaces is called the secondary reflected echo, and the echo which is just reflected once is called the single reflected echo. Considering the Gm-APD's superior ability to detect photon, we investigate and analyze the triggering characteristics of the Gm-APD for detecting the secondary reflected laser echo from the targets, also, we carry out the experiments on detecting the secondary reflected echo in near field and far field by using array Gm-APD to verify that the array Gm-APD can effectively detect the secondary reflected echo, and this paper lays the foundation for the research of the secondary reflection's influence on the images obtained by Gm-APD. In this paper, firstly, we use the echo triggering model, which contains LADAR ranging equation and Poisson probability model, and the Monte Carlo simulating method to completely verify the possibility of detecting the secondary reflected echo by using Gm-APD, in theory. The theoretical results show that Gm-APD can detect the secondary reflected echo, and the wider the field of view(FOV) is, the longer the detecting range is, besides, the higher the LADAR is located at, the lower the target's secondary reflected echo's intensity is and the higher the ground's single reflected echo's intensity is; then, using the Gm-APD with an array of 64 × 64 and 32 × 32 to detect the indoor scene and the moving van in far field, respectively, the results show that the indoor experiment obtains the complete first and second reflected image and the single pixel can detect the secondary reflected echo from multiple targets, also, for the far-field experiment, the single reflected echo and second reflected echo can be obtained in a single frame image, and under this experimental conditions, two pixels which are studied, realize the range extension of 25.6 m and 41.9 m respectively, which shows that the Gm-APD can likely detect the false target in the far field; finally, the methods that finding the secondary reflected surface by using the multiple-frame statistics for static targets and the image of triggering position in chronological order for moving targets, respectively, are proposed to eliminate the secondary reflected image. This article can provide some theoretical references for eliminating the secondary reflection before target recognition. [ABSTRACT FROM AUTHOR]

Abstract Silicon photomultipliers present saturation effects as they have a limited number of pixels and work in Geiger mode. Their response to light pulses in the nonlinear region is very complex for two reasons: pixel recharging after an avalanche affects the trigger probability and charge multiplication of subsequent avalanches, and non-trivial effects due to crosstalk and afterpulsing. A parametrization of the nonlinear response of silicon photomultipliers was developed where the above effects were readily accounted for. The model was tested on a setup of γ -ray spectrometry using different combinations of scintillation crystals and detectors. The model parameters were interpreted in terms of fundamental characteristics of the setup (e.g., lifetime of the scintillation crystal and pixel recovery time). The proper conversion from signal resolution to energy resolution was provided. [ABSTRACT FROM AUTHOR]

Progress in radioanalytical science, mainly in radiometrics and mass spectrometry technologies for ultra-sensitive analyses of radionuclides applied in natural sciences is shortly reviewed. While in the radiometrics sector the greatest developments have been made in underground Ge gamma-spectrometry, in the mass spectrometry sector the accelerator mass spectrometry had dominant position reaching the status of single atom counting and compound specific analysis for some long-lived radionuclides. [ABSTRACT FROM AUTHOR]

This paper describes our first undergraduate project experience, final report and findings on the subject matter. Initially according to our project title, we were focused on developing a low cost detector which can detect radiation only. To make one of these kinds of detector doesn't take much and can be prepared at fairly low cost being very common project in nuclear science arena. The Geiger-Muller tube, or GM tube, is an extremely useful and inexpensive way to detect radiation. While the GM tube can only detect the presence and intensity of radiation, this is often all that is needed. [ABSTRACT FROM AUTHOR]

The development of new methods and improvements of existing methods for the specific activity determination of 90 Sr and other distinct beta emitters has been of considerable interest. The reason for this interest is that the notably small number of methods that are able to meet all the set criteria, such as reliability of the results, measurement uncertainty and time, and minimum production of radioactive waste, as well as applicability to various samples with reference to their nature, geometry and composition. In this paper, two methods for rapid 90 Sr activity determination based on Monte Carlo simulations are used, one for a Si semiconductor detector for beta spectrometric measurements and the other for the Geiger-Muller (GM) ionization probe. To improve the reliability of the measurement results, samples with high and low strontium activity solutions were prepared in the form of dry residues. The results of the proposed methodology were verified with a standard method using a liquid scintillation counter, and notably good agreements are achieved. [ABSTRACT FROM AUTHOR]

Ionizing radiation is one of the main risks affecting healthcare workers and patients worldwide. Special attention has to be paid to medical staff in the vicinity of radiological equipment or patients undergoing radioisotope procedures. To measure radiation values, traditional area meters are strategically placed in hospitals and personal dosimeters are worn by workers. However, important drawbacks inherent to these systems in terms of cost, detection precision, real time data processing, flexibility, and so on, have been detected and carefully detailed. To overcome these inconveniences, a low cost, open-source, portable radiation measurement system is proposed. The goal is to deploy devices integrating a commercial Geiger-Muller (GM) detector to capture radiation doses in real time and to wirelessly dispatch them to a remote database where the radiation values are stored. Medical staff will be able to check the accumulated doses first hand, as well as other statistics related to radiation by means of a smartphone application. Finally, the device is certified by an accredited calibration center, to later validate the entire system in a hospital environment. [ABSTRACT FROM AUTHOR]

A portable dose rate detector was designed to monitor radioactive pollution and radioactive environments. The portable dose detector can measure background radiation levels (0.1 μ Sv/h) to nuclear accident radiation levels (>10 Sv/h). Both automatic switch technology of a double Geiger–Mueller counter and time-to-count technology were adopted to broaden the measurement range of the instrument. Global positioning systems and the 3G telecommunication protocol were installed to prevent radiation damage to the human body. In addition, the Monte Carlo N-Particle code was used to design the thin layer of metal for energy compensation, which was used to flatten energy response The portable dose rate detector has been calibrated by the standard radiation field method, and it can be used alone or in combination with additional radiation detectors. [ABSTRACT FROM AUTHOR]

A computerized tomography (CT) system using a 0.1μCi Sr-90 beta source, Geiger counter, and low density foam samples was developed. A simple algorithm was used to construct images from the data collected with the beta CT scanner. The beta CT system is analogous to X-ray CT as both types of radiation are sensitive to density variations. This system offers a platform for learning opportunities in an undergraduate laboratory, covering topics such as image reconstruction algorithms, radiation exposure, and the energy dependence of absorption. [ABSTRACT FROM AUTHOR]

Recent reports of Solar modulation of beta-decay have reignited interest in whether or not radioactive half-lives are constants. A numerical approach for filtering instrumental effects on residuals is developed, using correlations with atmospheric conditions recorded while counting 204 Tl emissions with a Geiger-Müller counter. Half-life oscillations and detection efficiency oscillations can be separated provided their periods are substantially different. A partial uncertainty budget for the 204 Tl half-life shows significant decreases to medium-frequency instabilities correlated with pressure and temperature, which suggests that further development may aid general improvements in half-life determinations. [ABSTRACT FROM AUTHOR]

Periodical surveillance, checking, testing, and calibration of the installed Area Gamma Radiation Monitors (AGRM) in the nuclear plants are mandatory. The functionality of AGRM counting electronics and Geiger-Muller (GM) tube is to be monitored periodically. The present paper describes the development of online electronic calibration and testing of the GM tube from the control room. Two electronic circuits were developed, one for AGRM electronic test and another for AGRM detector test. A dedicated radiation data acquisition system was developed using an open platform communication server and data acquisition software. The Modbus RTU protocol on ZigBee based wireless communication was used for online monitoring and testing. The AGRM electronic test helps to carry out the three-point electronic calibration and verification of accuracy. The AGRM detector test is used to verify the GM threshold voltage and the plateau slope of the GM tube in-situ. The real-time trend graphs generated during these tests clearly identified the state of health of AGRM electronics and GM tube on go/no-go basis. This method reduces the radiation exposures received by the maintenance crew and facilitates quick testing with minimum downtime of the instrument. [ABSTRACT FROM AUTHOR]

Methods are developed, which use the pulse-height spectra of SiPMs measured in the dark and illuminated by pulsed light, to determine the pulse shape, the dark-count rate, the gain, the average number of photons initiating a Geiger discharge, the probabilities for prompt cross-talk and after-pulses, as well as the electronics noise and the gain fluctuations between and in pixels. The entire pulse-height spectra, including the background regions in-between the peaks corresponding to different number of Geiger discharges, are described by single functions. As a demonstration, the model is used to characterise a KETEK SiPM with 4384 pixels of 15 μ m × 15 μ m area for voltages between 2.5 and 8 V above the breakdown voltage. The results are compared to other methods of characterising SiPMs. Finally, examples are given, how the complete description of the pulse-eight spectra can be used to optimise the operating voltage of SiPMs, and a method for an in-situ calibration and monitoring of SiPMs, suited for large-scale applications, is proposed. [ABSTRACT FROM AUTHOR]

This paper describes the development of an instrument for radiological monitoring, identified as Gamma Alarm (GAMAL01). The instrument monitors the increment of radiation count rate and produces an alarm signal, when the count rate becomes superior to a fixed threshold value. The threshold is fixed to assure that the signal emission will start when the value of the radiation count rate may cause a non acceptable radiological exposition of the personnel, according to the radiological safety regulations existing in the country. Following the signal the personnel must be evacuated from the affected place. The instrument consists of two sections, an analogical section and a digital one. [ABSTRACT FROM AUTHOR]

Operating systems interface between hardware and the user, random numbers are useful for security and simulation, and file systems form the program access to them in a modern operating system. Blending these items into a remotely accessed infrastructure forms the basis for supporting operating systems projects. This work describes the hardware, software, and communication infrastructure to support student projects by sharing remote hardware to acquire background radiations events with a Geiger counter, transforming those events into random numbers, and providing those numbers through a custom file system. Collectively, the hardware and software provide an inexpensive remote laboratory experience for computing students. [ABSTRACT FROM AUTHOR]

The article discusses the effect of radiation. An overview of the process of radiation is presented. The chemical effects of radiation are attributed to their capacity to break up certain chemical configurations. The author reveals that radiation damage can be detected using instruments like electroscope and Geiger counter, and the main problem is the disposal of radio active wastes. The impact of atomic warfare are enumerated including the total disorganization of communications and civic life resulting from a single explosion and the panic caused by its threat. Due to this, the author emphasized that radiation creates symptoms which can be counteracted by known treatments and it does not mean a sudden death. Civilian defense organization to protect the population is recommended.

Gaseous detectors of ionizing particles have been playing a central role in the progress of fundamental research in nuclear and later particle physics since the invention in 1908 of the very first device: the Geiger Counter. The introduction in 1968 of the Multi-Wire Proportional Chamber (MWPC) concept by G. Charpack provided for the first time fine space resolution and this remained the only option for fine space resolution until the introduction of the solid state trackers. Nowadays gaseous detectors continue to play a key role in frontier particle and nuclei experiments. They provide the only possibility to equip large volumes at a reasonable cost, with good space resolution and limited material budget: an outstanding example is offered by the muon system of the ATLAS experiment at CERN LHC. Resistive Plate Chambers (RPC) provide time resolution better than 1 ns in extended counters and are therefore used in the trigger systems of the largest experiments at CERN LHC: ALICE, ATLAS, and CMS. In the ALICE RPC-based TOF system, the time resolution is as low as 80–110 ps. [ABSTRACT FROM PUBLISHER]

Motivated by the paper of Dandekar (1955), a one-urn model with Polya–Eggenberger sampling scheme is developed, which yields a large number of discrete distributions, including the Dandekar's modified binomial distribution, as particular cases. The model is further modified to some new generalized distributions of order k. Some probable applications of these models were discussed in Dandekar (1955) and Feller (1968) in fields of fertility study and radioactivity. It also has applications in premium determination in insurance sector. [ABSTRACT FROM AUTHOR]

A new G–M counter dead-time model based on the hybrid model is proposed and studied. The new model contains the idealized paralyzable and non-paralyzable dead-time models, but also allows the non-paralyzable dead-time to vary with the true counting rate. To validate this model, the decaying source experiment with a very pure 56 Mn source was used. The calculated true counting rates obtained by fitting the experimental data to the model were compared to the data obtained by table lookup. In general, the fitting was in good agreement (within 4.8% up to 5.35 × 10 6 counts / minute ) for a G–M counter with a paralyzable dead-time component of 85.9 μs and a non-paralyzable dead-time component ranging from 438 μs to 24.3 ms. [ABSTRACT FROM AUTHOR]

Microfabricated radiation detectors can be used to provide first alert information about presence of harmful radiation. This paper describes a micromachined gamma detector that operates in the Geiger–Muller (G–M) regime. Gamma rays eject photoelectrons from the cathode material through the photoelectric effect and/or Compton scattering, which in turn ionize the Ar fill-gas providing a current pulse. The detector utilizes cathode stacks that are micromachined from stainless steel #304 foil. Micromachined glass fingers with thin-film anode metal traces are positioned transversely through aligned perforations in the stacked cathodes. This orthogonal array of anodes and cathodes effectively distinguishes electron avalanche regions from drift regions despite the miniaturization, thereby reducing the likelihood of spurious discharges. Overall, the detector diameter and height are 9 and 2.5 mm, respectively. Detector performance is characterized using a 99- $\mu $ Ci 137Cs source placed at a distance of 3 cm from the detector. In an integration time of 10 min at an applied voltage of 630 V, a source:background ratio of 89:1 is achieved—a fivefold improvement over the previously reported micromachined devices operating in the G–M regime. This architecture also reduces the typical charge per discharge to 6.6 pC, allowing the estimated dead time between detection events to be $\sim 1 \mu $ s. [2014-0333] [ABSTRACT FROM PUBLISHER]

Microfabricated detectors can be used to provide first alert information about the presence of radiation sources. This paper describes a micromachined neutron detector that operates in the Geiger-Muller regime. It utilizes electrodes that are lithographically micromachined from 50- \mu \textm thick stainless steel #304 foil. The cathode is coated with a 2.9- \mu \textm thick layer of Gd on one side to convert thermal neutrons into fast electrons and gamma rays, which are then detected by ionization of the fill gas (Ar). Three electrodes are stacked in a cathode-anode-cathode arrangement, separated by 70- \mu \textm thick Kapton spacers, and assembled within a commercial TO-5 package. The detector diameter and height are 9 and 9.6 mm and it weighs 0.97 g. Detector performance is characterized using a 90 $\mu $ Ci 252Cf neutron source placed at a distance of 10 cm from the detector. Using Pb blocks between the source and detector to block gamma rays, the typical detector response at 285 V bias is \sim 8.7$ counts per minute (cpm), with background radiation count of 1.2 cpm. The typical dead time is 5.3 ms. Compared with commercial devices which operate at >900 V, have detector volumes of 2000–100000 mm ^{3} and can only detect a subset of radiation types (i.e., beta particles, gamma rays, and neutrons), this device offers lower operating voltages smaller volume and the ability to detect all three types of radiation. [ABSTRACT FROM PUBLISHER]

This paper utilized standard two-source method and the simple non-paralyzing model assumption to examine a GM counter's deadtime dependence on applied voltage, operating temperature, and fatigue. Both 60 Co and 137 Cs sources were used for deadtime measurements. The results gathered suggest the presence of three distinct regions of deadtime behavior. At low voltages, the deadtime decreases as the voltage increases (Region I) followed by a region of stable deadtime plateau (Region II) and finally a region of increasing deadtime with increasing voltage. Region II is the best region for operating with a minimum deadtime which is not sensitive to the applied voltage. Typical deadtime values for GM counters were between 100 and 300 μs; the deadtime values in Region II were within this range. The results examined in this study also indicate a strong temperature dependence of deadtime, with a correlation coefficient of 0.93. The GM counter deadtime for various fatigues (aging) were investigated for three fatigue levels with a correlation coefficient of 0.48. The experimental results confirm that deadtime increases as both temperature and fatigue increase. The fundamental nature of deadtime seems to be different for voltages lower than the stable deadtime plateau (Region II) and for voltages higher than the plateau. [ABSTRACT FROM AUTHOR]

The article dsicusses the use of Geiger counters to measure radiation based on the auditory signal clicks produced by electrical discharges within the instrument's ionized gas chamber. The role of Geiger counters in proliferating the employment of auditory signals in nuclear physics, radiation research, and science in general is questioned, the history of the role of senses in scientific measurements is examined, and information is offered on perceived historical divisions between seeing and hearing in the collection of scientific data. Conflict between subjectivity and objectivity in science historiography is analyzed.

Vertical soundings of the atmospheric ion production rate have been obtained from Geiger counters integrated with conventional meteorological radiosondes. In launches made from Reading (UK) during 2013–2014, the Regener–Pfotzer ionisation maximum was at an altitude equivalent to a pressure of (63.1±2.4) hPa, or, expressed in terms of the local air density, (0.101±0.005) kg m −3 . The measured ionisation profiles have been evaluated against the Usoskin–Kovaltsov model and, separately, surface neutron monitor data from Oulu. Model ionisation rates agree well with the observed cosmic ray ionisation below 20 km altitude. Above 10 km, the measured ionisation rates also correlate well with simultaneous neutron monitor data, although, consistently with previous work, measured variability at the ionisation maximum is greater than that found by the neutron monitor. However, in the lower atmosphere (below 5 km altitude), agreement between the measurements and simultaneous neutron monitor data is poor. For studies of transient lower atmosphere phenomena associated with cosmic ray ionisation, this indicates the need for in situ ionisation measurements and improved lower atmosphere parameterisations. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the different types of radiation detectors commonly used for radiation protection purposes as survey meters. The study was performed on survey meters that use different detectors as ionisation chamber, Geiger Mueller (GM) counter and scintillation detector. For each survey meter, energy dependence and angular response in X- and gamma-radiation fields was tested. The following commercially available survey meters were investigated: ionisation chambers Victoreen 451P, Babyline 31 and VA-J-15A, Geiger counter MRK-M87, 6150 AD6 and FAG FH 40F2 and scintillation counter 6150 ADB. As a source of gamma radiation, 137Cs and 60Co were used whereas X-ray radiation fields were generated using an X-ray unit. The radiation characteristics of the survey meters were mostly in compliance with references estimated by standard IEC 1017-2. However, some of them showed larger deviation at lower energies. GM counters exhibit strong energy dependence for low-energy photons. [ABSTRACT FROM AUTHOR]

An experiment was carried out to investigate the changes in ionizing cosmic radiation as a function of altitude. This was carried out using a Geiger–Müller tube on-board a high altitude balloon, which rose to an altitude of 31 685 m. The gathered data show that the Geiger–Müller tube count readings increased to a maximum at an altitude of about 24 000 m; beyond this point they then decreased with increasing altitude. [ABSTRACT FROM AUTHOR]

Measurements of ionizing and nonionizing particles are performed during the rupture tests of steel rods having different diameter. A ZnS(Ag) alpha detector, a Geiger counter and a 3He proportional counter for neutrons are used. From the distributions of the recorded intensity maxima, different particles emissions are suggested to occur in broken and nonbroken samples. A hint for the emission of neutrons at rupture is also obtained. Such neutron emissions are predicted in the framework of the piezonuclear theory. [ABSTRACT FROM AUTHOR]

This paper focuses on the surface contamination control of slightly contaminated property after the Fukushima nuclear accident. The operational level for the unconditional release of contaminated properties is calculated in counts per minute (cpm) to enable the use of a typical Geiger-Muller (GM) survey meter with a 50-mm bore, on the basis of the surficial clearance level of 10 Bq cm−2 for 134Cs and 137Cs derived in the previous studies of the authors. By applying a factor for the conversion of the unit surface contamination to the count rate of a survey meter widely used after the Fukushima accident, the operational level for the unconditional release of contaminated properties was calculated to be 2300 cpm on average and 23 000 cpm at the highest-contamination part. The calculated numerical values of the operational levels are effective as long as the typical GM survey meter is used in the radiation measurement. [ABSTRACT FROM AUTHOR]

Detection limits of sensor networks for moving radioactive sources are characterized, using Bayesian methods in conjunction with computer simulation. These studies involve point sources moving at constant velocity, emulating vehicular conveyance on a straight road. For networks involving ten nodes, respective Bayesian methods are implementable in real time. We probe the increased computational requirements incurred by larger numbers of nodes and source trajectory parameters. The complexity appears quadratic in the number of nodes and, also, numerous trajectory parameters may be used. We investigate the consequences of different levels of background radiation. Simulations are shown to be useful for ranking candidate node layouts. We study the detection capabilities of individual sensors and the scalability of detection with sensor density; near the detection limit, increasing the number of sensors can accrue subproportional network sensitivity. Index Terms--Distributed sensor network, gamma radiation, Geiger-Muller counter, Monte Carlo integration, Poisson statistics, true negative, true positive.

Abstract: This paper deals with the direct measurement of total (fixed plus removable) surface activity in the presence of interfering radiation fields. Two methods based on Monte Carlo simulations are used: one for a Geiger–Muller (GM) ionisation probe and the other for sodium iodide (NaI) detector with lead collimators; equations for the most general case and the geometry models for Monte Carlo simulation of both (GM and NaI) detectors are employed. Finally, an example of application is discussed. [Copyright &y& Elsevier]

Four cylindrical steel bars of 2 cm diameter and 20 cm height were subjected to compression cycles each of them consisting of a loading phase at fixed stress rate followed by a rapid stress release. Different compression rates were used for the same sample. The area surrounding the loaded samples was monitored in order to check whether ionizing particles were emitted. To this aim, three ZnS(Ag) detectors, a Geiger counter, and some polycarbonate CR39 detectors of alpha particles were used. An 3He proportional detector of neutrons was also used. The whole set of results is discussed and proposed as an evidence of alpha particles emission from the bars during the compression cycles. [ABSTRACT FROM AUTHOR]

Ambient gamma dose rates in air were measured at different locations (indoors and outdoors) to demonstrate the ubiquitous nature of natural background radiation in the environment and to show that levels vary from one location to another, depending on the underlying geology. The effect of a lead shield on a gamma radiation field was also demonstrated to emphasize the important role of shielding in radiation protection. The measurements were carried out with a Geiger-Muller (GM)-based dosimeter and a NaI scintillation gamma-ray spectrometer, which are normally available in physics laboratories. Radioactivity in household materials was demonstrated using a gas mantle as an example. [ABSTRACT FROM AUTHOR]

The article discusses the development of the Geiger Counter scientific instrument. It states that it was developed by Walter Müller under the supervision of his doctoral advisor, Hans Geiger in 1928. It mentions that the electrical device is used for protection against radioactivity and can detect α-, β-, and γ- radiations. It adds that it was first introduced to the public under the name electron counting tube in July 1928.

Abstract: This paper discusses the construction of high-performance ground-based gamma-ray Cherenkov telescopes with a Davies–Cotton reflector. For the design of such telescopes, usually physics constrains the field-of-view, while the photo-sensor size is defined by limited options. Including the effect of light-concentrators, it is demonstrated that these constraints are enough to mutually constrain all other design parameters. The dependability of the various design parameters naturally arises once a relationship between the value of the point-spread functions at the edge of the field-of-view and the pixel field-of-view is introduced. To be able to include this constraint into a system of equations, an analytical description for the point-spread function of a tessellated Davies–Cotton reflector is derived from Taylor developments and ray-tracing simulations. Including higher order terms renders the result precise on the percent level. Design curves are provided within the typical phase space of Cherenkov telescopes. The impact of all design parameters on the overall design is discussed. Allowing an immediate comparison of several options with identical physics performance allows the determination of the most cost efficient solution. Emphasis is given on the possible application of solid light concentrators with their typically about two times better concentration compared with hollow cones which allows the use of small photo sensors such as Geiger-mode avalanche photo diodes. This is discussed in more details in the context of possible design options for the Cherenkov Telescope Array. In particular, a solution for a 60mm2 photo sensor with hollow cone is compared to a 36mm2 with solid cone. [Copyright &y& Elsevier]

The term 'thermal flux' implies a Maxwellian distribution of velocity and energy corresponding to the most probable velocity of 2200 m s at 293.4 K. In order to measure the thermal neutron flux density, the foil activation method was used. Thermal neutron flux determination in paraffin phantom by counting the emitted rays of indium foils with two different detectors (Geiger-Muller counter and NaI(Tl)) was the aim of this project. The relative differences of the outcome of the experiments were between 2.5% and 5%. The final results were compared with MCNP4C outputs and the best agreement was generated using NaI(Tl) by a minimum discrepancy of about 0.6% for the foil placed 8.5 cm from the neutron source. [ABSTRACT FROM AUTHOR]

We study the effects of post-selection measurements on both the non-classicality of the state of a mechanical oscillator and the entanglement between two mechanical systems that are part of a distributed optomechanical network. We address the cases of both Gaussian and non- Gaussian measurements, identifying in which cases simple photon counting and Geiger-like measurements are effective in distilling a strongly non-classical mechanical state and enhancing the purely mechanical entanglement between two elements of the network. [ABSTRACT FROM AUTHOR]

There is little known about the short-term dynamics of groundwater-surface water exchange in losing rivers. This is partly due to the paucity of chemical techniques that can autonomously collect high-frequency data in groundwater bores. Here we present two new instruments for continuous in situ 222Rn measurement in bores for quantifying the surface water infiltration rate into an underlying or adjacent aquifer. These instruments are based on 222Rn diffusion through silicone tube membranes, either wrapped around a pole (MonoRad) or strung between two hollow end pieces (OctoRad). They are combined with novel, robust, low-cost Geiger counter 222Rn detectors which are ideal for long-term autonomous measurement. The down-hole instruments have a quantitative response time of about a day during low flow, but this decreases to <12 h during high-flow events. The setup was able to trace river water bank infiltration during moderate to high river flow during two field experiments. Mass-balance calculations using the 222Rn data gave a maximum infiltration rate of 2 m d-1. These instruments offer the first easily constructible system for continuous 222Rn analysis in groundwater, and could be used to trace surface water infiltration in many environments including rivers, lakes, wetlands, and coastal settings. [ABSTRACT FROM AUTHOR]