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We realized an embedded system, easy to install and to calibrate, remote controlled and adjustable in order to equip an extracted beam line of a precise Inelastic Nuclear Interactions (INI) counter. The system made up of the Nuclear Interaction Detector (NID) and of a motorized, two arms, translation stage which allows precise positioning and scan of different inelastic nuclear scattering angles. The NID is based on twin small scintillators (5x10x25 mm3 of BC-408), as nuclear interaction counters, every coupled with two Hamamatsu SiPMs (MPPC,multi-pixel photon counter), to get readout redundancy and to use coincidence strategy for minimizing the system noise. The signal readout is provided by Arduino Mega-based system, which makes available four pairs of bias voltage channel and analog readout channel for as many 3x3 mm2 SiPMs. A constant fraction system enables getting fine timing coincidence both between scintillators and between beam’s trigger signal and scintillators to minimize the fake counts on the radiative environment. Remote gap adjustment makes possible to set the nuclear scattering angle of measurement as well as to make an angular scan.The system was used as new nuclear interaction counter for the H8 telescope of the UA9 experiment. This CERN-SPS experiment aim to test the crystal assisted collimation for both protons and lead ion beam collimation in the LHC. The NID fulfill the precise measurements of nuclear interactions probability between crystal and particles in the various channeling regimes (channeling, volume reflection etc.).

In this paper, we present a stable single-photon detection method based on Si-avalanche photodiode (Si-APD) operating in Geiger mode with a large temperature variation range. By accurate temperature sensing and direct current (DC) bias voltage compensation, the single-photon detector can work stably in Geiger mode from −40 °C to 35 °C with an almost constant avalanche gain. It provides a solution for single-photon detection at outdoor operation in all-weather conditions.

The amplitude and timing properties of a Geiger discharge in a stand-alone SiPM cell have been investigated in detail. Use of a single stand-alone SiPM cell allows us to perform measurements with better accuracy than the multicell structure of conventional SiPMs. We have studied the dependence of the output charge and amplitude from an SiPM cell illuminated by focused light vs the number of primary photoelectrons. We propose a SPICE model which explains the amplitude over saturation (when the SiPM׳s amplitude is greater than the sum over all cells) characteristics of SiPM signals for more than one initial photoelectrons. The time resolutions of a SiPM cell have been measured for the case of single (SPTR) and multiphoton light pulses. The Full Width Half Max (FWHM) for SPTR has been found to be at the level of 30 ps for focused and 40 ps for unfocused light (100 μm cell size).

To meet the increasing demand from quantum communications and other photon starved applications, we have developed various InP-based single-photon detectors, including discrete single-photon avalanche diodes (SPADs), negative feedback avalanche diodes (NFADs), and Geiger-mode avalanche photodiode (GmAPD) arrays. A large quantity of InP SPADs have been fabricated. Out of 1000 devices with a 25-μm active area diameter, operated under gated mode at temperature of 233 K, with a pulse repetition rate of 1 MHz and pulse width of 1 ns, the average dark count rate and afterpulsing probability are 30 kHz and 8 × 10 -5 , respectively. Smaller (16-μm active area diameter) and larger (40-μm active area diameter) discrete devices have been fabricated as well, and their performances are presented along with the 25-μm diameter devices. NFAD devices can operate in free running mode and photon detection efficiency of 10-15% can be achieved without applying any hold-off time externally. When the temperature decreases from 240 to 160 K, the noise equivalent power (NEP) decreasesfrom1.9 × 10 -16 to 1.8 × 10 -18 WHz -1/2 , with the activation energy being 0.2 eV. The very low NEP at 160 K makes NFAD devices an ideal choice for long distance, entanglement-based quantum key distributions. GmAPD arrays provide an enabling technology for many active optical applications, such as 3-D laser detection and ranging (LADAR) and photon starved optical communications. Both 32 × 32 and 128 × 32 GmAPD arrays have been fabricated with high performance and good uniformity. GmAPD focal plane arrays (FPAs) with framed readout mode have enabled very high-performance flash LADAR systems. GmAPD FPAs with asynchronous readout mode will enable high rate quantum key distributions and other quantum communications applications.

The performance of detector limits the overall performance of laser ranging system. And the design of multi-hit detector is one of the feasible ways to promote the performance of detector. Currently, the segmentation method or the recursive method is commonly used to analyze the multi-hit detector model. To the best of our knowledge, this paper is the first to propose a combinatorial method to solve the multi-hit detector model from the perspective of discrete time. Then, universal formulas of total signal detection probability and the average count are deduced based on the Poisson distribution signal. Furthermore, analysis is made to figure out how the average count changes with different parameters, such as the dead time, gating time, rate intensity. As a result, for GM-APD, the multi-hit detector model is verified advantageously compared to the single-hit detector model in improving the average count theoretically. Meanwhile, a discrete step feature is presented when average count changes with dead time or the gating time, which is of great significance in gating time optimization.

We demonstrate a $256 \times 256$ passive photon counting imager based on hybridization of back-illuminated silicon Geiger-mode avalanche photodiodes to an all-digital CMOS counting chip. Photon detection efficiencies in the 10%–20% are observed at visible wavelengths. The detection efficiency is currently limited by optical crosstalk that leads to elevation of dark count rates as the bias voltage on the photodiodes is increased. Both the time dependence of dark count activity during a gate time and the spatial structure of dark images were successfully explained using crosstalk-based models.

We demonstrated a photon-counting chirped amplitude modulation (CAM) Lidar at 1550 nm. In the previous studies, the CAM bandwidth was limited

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 60Co and 137Cs 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.

Radioactive measurements in the decay process of any radioactive sample can be predicted by radioactive-decay law. This predication is based over its average behavior. In actual practice, the radioactive measurements show fluctuations about the average value. For any radioactive sample, there is an exact number which disintegrates in any given unit of time fluctuates around the average value. In counting applications, it is important to estimate this fluctuation because it indicates the repeatability of results of a measurement. This will identify it by using periodogram analysis that depicts the periodicity in the radioactive decay of the given sample of Americium-241. Statistical distributions that the given sample followed with goodness-of-fit tests are examined. Maximum-Likelihood Estimator (MLE) has been used to find the population parameters. The randomness in radioactive decay has been verified by non-parametric method. These statistical analyses are based over the amount of internal fluctuation in the given radioactive source that is consistent with the predictions obtained. These measurements are obtained by measuring the decay of 300 counts per 10 sec. of Americium-241 using a Geiger Muller (GM) Counter in the teaching laboratory, at the | department of Physics, University of Karachi, Karachi, Pakistan.

We present a new physical principle to design an optoelectronic device, which consists of a multilayered semiconductor structure, where the necessary conditions for generation of photoelectrons are met, such that it will enable sequential avalanche multiplication of electrons and holes inside two depletion slabs created around the p — n junctions of a reverse biased pn — i — pn structure. The mathematical model and computer simulations of this Semiconductor Photo-electron Multiplier (SPEM) for different semiconductor materials are presented. Its performance is evaluated and compared with that of conventional devices. The Geiger operational mode is briefly discussed which may be used in Silicon Photomultiplier (SiPM) as an elementary photo detector to enhance its performance.

Silver-activated Geiger counters together with a polyethylene layer as neutron moderator are frequently used in pulsed neutron flux measurements in research studies with plasma focus (PF) devices. In this study, an array of seven counters was used at seven different angles (0°, ±30°, ±60° and ±90°) to the PF-axis for which a software and a 10-channel data acquisition hardware (PCT2660) compatible with NIM standards have been designed and fabricated. In the proposed PCT2660, the preset timing algorithms are considered as general and they can be programmed for required detector calibrations and neutron flux measurements. The calibration constant measurement has been undertaken with a 16.5 Ci Am–Be source of 35 mm diameter by 70 mm cylindrical active volume located at anode top whilst the neutron flux at zero degree of PF device axis at 13.5 kV operating voltage and 13.54 × 10−2 PSI pressure is measured as (2.88 ± 0.29) × 108 neutrons per shot. Accordingly, the studies on the angular distribution of the PF neutron emission within the pressure range of 7.73 × 10−2–15.47 × 10−2 PSI confirm an anisotropy ranging from 1.53 ± 0.09 to 2.95 ± 0.24 and a symmetry of angular distribution around the anode axis.

We have tested the performance of two types of the latest Multi-Pixel Photon Counters (MPPCs; measuring 3×3 mm 2 in size) developed by Hamamatsu Photonics K.K. The new S12572-050C is a successor to the S10362-33-050C (i.e., conventional 3×3-mm 2 pixel MPPC of 50 μm pitch), comprises 3600 Geiger mode avalanche photodiodes (APDs), and also features high gain (up to 1.25×10 6 ), a low dark count (up to 10 6 cps), and improved photon detection efficiency (PDE) by up to 30%. The S12572-015C is a new type of fine-pitch (15 μm) MPPC featuring a wide dynamic range and fast timing response. This paper first presents the detailed performance of these latest MPPCs as photon counting devices. It then describes our fabrication of a prototype detector consisting of a MPPC optically coupled with a Ce:GAGG scintillator. We obtained average FWHM energy resolutions of 7.3% (15 μm) and 6.7% (new-50 μm), as compared to 6.9% (old-50 μm) for 662-keV gamma rays from the 137 Cs source, as measured at 20 °C. Moreover, the number of fired pixels for 662-keV gamma rays increased by 30% for the new-50 μm (as compared to the old-50 μm). We confirmed that the low energy threshold improved from 10 keV to 4 keV, when using the latest MPPC device (new-50 μm). We also confirmed that the timing resolution of the new MPPC is 50 ps or even better, as compared to 89 ps of the old MPPC. The results thus confirm that these new types of MPPCs are promising for various applications as scintillation detectors.

The Earth's upper atmosphere is suffused by radiation caused primarily by a bombardment of Cosmic Rays, as a result of which it is hazardous for human beings as well as sensitive electronic equipment on board flight vehicles. A series of ground based as well as airborne experiments were performed using Polylactic Acid (PLA), Acrylonitrile-Butadiene-Styrene (ABS) and High Impact Polystyrene (HIPS), in order to investigate the applicability of polymers that can meet today's needs for lightweight, multifunctional, and cost efficiency in radiation shielding of electronic equipment. It was found that PLA at 8 mm thickness has an effectiveness of 66% against gamma radiation (i.e., it blocked 66% of the gamma radiation). Therefore, it was decided to proceed with a high altitude balloon experiment with an 8 mm thickness of PLA. The shield was demonstrated to be reasonably effective in attenuating radiation from cosmic rays.

The heightened utilization of ionizing radiation for diagnostic and beneficial purposes, the expeditious progress in nuclear reactors, as well as the risks of radioactive waste have raised significant safety and health concerns for the people working with radiation and the general public. While some exposure to radiation is acceptable, radiation monitoring should be done to keep the levels of radiation exposure to a minimum. In this paper, we intend to monitor and measure the radiation levels that a specific area is exposed to using a radiation sensor, and to send the data to a cloud from where the values can be accessed by the concerned authorities. In order to meet the objectives we utilize GM counters, which are radiation sensors that detect and measure the amount of radiation present in the radiation environment. The GM counter is interfaced to a NodeMCU to update the detected and measured radiation to a radiation IoT platform that can store and retrieve data across a network. Further, a GPS module is interfaced with the NodeMCU to locate the location data of the radiation emitted from the radiation sources under such radiation environment. The radiation values are remotely monitored in real time through web server configured with the radiation IoT platform to remote monitor the radiation level and mapping the location of such radiations.

In this study, an assessment of indoor radon concentration and gamma dose rates were carried out in 16 Portuguese thermal spas. Indoor gamma dose rates measurements were made using a Geiger counter (Gamma Scout – GS3) and radon concentration measurements were carried out using CR-39 detectors. The detectors were exposed for an extended period of time (in average 42 days). The results showed that gamma doses rates are generally low but, in several cases, radon concentration exceeded national as well as international standards, namely the reference level recommended by the Directive 2013/59/EURATOM (300 Bq/m3) and the threshold for protection (400 Bq/m3) from the Portuguese legislation. The annual effective doses deriving from external radiation (gamma dose rates) and indoor radon concentration showed the need to implement measures to optimize the radiation protection of the workers against ionizing radiation.

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 gamma-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., 4 pages (two columns), 3 figures, contribution to the 8th International Conference on New Developements in Photodetection (NDIP17), Tours, France, 3-7 July, 2017

In reference to its desired use, the materials’ properties are described. A particular attention is paid to the description of experimental methods for the material characterization. A short list of possible behavior models is given.

In the hills of the Fukushima region the radiation fall out was significant. (1) Geiger counter reading shows radiation levels remain elevated. (2) Contaminated soil is being relocated and buried under a track. (3) Removal of contaminated soil.

This paper describes a recent art project in which a uniform allows to detect and display nuclear radiation. Here, wearable technology is interpreted as contemporary samurai gear. The uniform comprises of a helmet with an ornament, a handheld scanning device and a box with a microcontroller. It is completed by a protective suit. The ground scanning device contains a Geiger counter kit which sends signals through the microcontroller to the ornament on the helmet which is equipped with an LED-strip. The ornament lights up in response to the measurements coming from the device. The major part of this artwork is a full HD single channel video of about 15 minutes duration that shows a young man wearing the uniform and scanning the devastated areas near the nuclear power stations in Fukushima. The video was filmed on location in May 2016.

This work presents a physical model describing the IV curves of SiPM detectors allowing to easily determine important device parameters like breakdown voltage VBD and the shape of Geiger triggering probability PGeiger. We measured IV curves and tested our IV model in a temperature range − 35 ° C T + 35 ° C on various SiPMs from two vendors (Hamamatsu devices of 3 × 3 mm 2 total area and 50 × 50 μ m 2 μcell size, 2011 and 2015 year production runs and KETEK devices of 0.5 × 0.5 mm 2 total area and 50 × 50 μ m 2 μcell size, 2015 production run). The shape of IV curve can be described in terms of Geiger probability and afterpulsing in a very large current range of 10 − 12 A I post − BD 10 − 5 A over the full working range of all tested devices. It has also been found that VBD from IV curves is slightly higher (few hundred mV) than the “breakdown voltage” determined from the usual method of linear fit of gain as a function of bias voltage, this discrepancy reflecting the fundamental difference in the physical significance of the “breakdown voltage” determined by these two methods. The recent generation of SiPMs have very wide working range and there is an evidence phenomena beyond afterpulsing like heating or non-quenched pulses contributing to the fast increase of the current at high bias voltages.

Common source localization algorithms assume a straight-wave propagation path. If the straight connection between source and sensor passes air, this straight connection surely does not represent the wave propagation path. A crack can be such an air barrier between source and sensor. However, in case of complex specimens (e.g., T-shaped or C-shaped cross section) the straight connection between source and sensor can also pass the air surrounding the specimen. FastWay is a novel source localization method, based on multi-segmented path analysis and a heterogeneous velocity model. In order to determine the source location, the fastest wave travel path between the sensor and an estimated source location is determined. This wave travel path is multi-linear, bypasses air, and is based on a heterogeneous velocity model. In this chapter, the estimated source location of acoustic emissions within a numerically simulated T-shaped concrete beam, determined with FastWay, is compared with the results provided by a homogeneous and a heterogeneous Geiger method.

Ionisation is one of the most common processes used today for radiation detection and measurement. Ionisation of gases and liquids forms the basis for a large number of devices that have been developed over a span of several decades. This Chapter presents the physics principles of ionisation, the properties of transport of electrons and ions in gases, and how these properties are exploited in common devices from the simplest, the Geiger counter, to the Time Projection Chamber.

International audience; In this paper, we present a two-layered silicon sensor working in Geiger-mode avalanche regime and designed for charged particle detection. Each position-sensitive element is comprised of two vertically aligned pixels, exploiting the coincidence between two simultaneous avalanche events to discriminate between particle triggers and dark counts. This approach potentially offers several advantages. First, a low material budget can be achieved thanks to the thinning of the detector down to a few tens of microns (e.g. 50 μm) as the avalanche starts in a shallow region just a few microns deep. Operation in a regime of quenched avalanche allows for an excellent timing resolution and provides an internal gain that makes a front-end amplification stage unnecessary, thus dramatically reducing the power consumption. Fine detector segmentation is possible as the (horizontal) inter-pixel cross-talk in the detection plane can be reduced to a comfortable level while the vertical cross-talk is totally eliminated using a metal light-shield layer. The detector is also insensitive to background light. A number of applications could benefit from a detector with these characteristics, including particle tracking and vertex reconstruction in particle physics experiments at accelerators and in space, as well as ionizing radiation imaging in nuclear medicine and life-sciences.

Detection and quantification of emitted radioactive particles such as alpha, beta or high energy gamma and X-rays from a contaminated sample or source can easily be achieved by using different qualitative and quantitative approaches. In contrast to qualitative approach, quantitative methods of radioactivity detection are widely used because of their potential to identify and detect high as well as low radioactivity levels with increased sensitivity and counting accuracy. Gamma /X-Ray spectroscopy, Alpha/r Beta counters, Scintillation detectors including GM counter and LSC detectors are the well-recognized quantitative methods employed for this purpose.

Since the very first measurements with \(\alpha \) particles performed by H. Geiger, E. Marsden and E. Rutherford [1], scattering experiments have become one of the most important tools in experimental particle physics. Increasing collision energies allow to resolve smaller and smaller structures, and to probe the fundamental constituents of matter and their interactions.

The operation of avalanche photodiodes in Geiger mode provides single-photon detection with excellent timing accuracy on a scalable semiconductor device platform. The use of arrays of Geiger-mode detectors for light detection and ranging (LiDAR) from airborne platforms enables the high-rate collection of 3D point cloud imagery from extremely long (>10 km) standoff distances and has resulted in order-of-magnitude increases in performance metrics such as area coverage rate and 3D image resolution. More recently, we have applied Geiger-mode technology to shorter range low-cost LiDAR systems designed for automotive applications. The combination of two factors—single-photon sensitivity and the greater eye-safety of lasers at wavelengths beyond 1400 nm—provides disruptive automotive LiDAR performance that will be essential to future autonomous vehicle navigation.

In recent years, Silicon Photomultipliers (SiPMs) have proven to be very performing devices, especially for those applications where high sensitivity to low intensity light and fast responses are required. A SiPM consists of a system of hundreds or even thousands of p-n junctions connected in parallel and operating in Geiger mode. We performed a modeling of the Near Ultraviolet High Density (NUV-HD) devices produced by Fondazione Bruno Kessler (FBK), trying to infer on the cell capacitance, quenching resistance and parasitic capacitances values. We measured the I-V and C-V responses and carefully studied waveforms acquired from sensors conditioned by a simple trans-impedance amplifier, thus obtaining information on the microscopic characteristic of the device. Results regarding the modeling as a function of the overvoltage will be presented and compared with simulations.

We report the timing response of a sinusoidal-gated Geiger mode InGaAs/InP avalanche photodiode both in synchronous mode and free-running mode. It is found that the temporal peak of photon counts is dependent on the avalanche build-up and decay times, and the break down probability is a function of the separation between the photon arrival time and the peak of the excess bias gate. We observe broadening of timing jitter and lowering the total detection efficiency in the free-running mode relative to synchronous detection.

A Cs-137/Ba-137m isotope generator is used to demonstrate the properties of radioactive decay. In this experiment, we investigate and verify the random behavior of radioactive decay and determine the half-life of a radioactive isotope. The half-life of a radioisotope is measured in this experiment. The purpose of this experiment is to determine the half-life of Ba-137m by using several methods and to determine the percent error for each determination. Ba-137m decays by gamma emission (662 keV) with a half-life of 2.6 minutes to the stable Ba-137 element. During elution, Ba-137m is selectively “milked” from the generator, leaving behind the Cs-137 parent. Each generator is supplied with 250 mL of an eluting solution (0.9% NaCl in 0.04M HCl). A Geiger counter interfaced with a computer is used to acquire and record the activity at set time intervals. The half-life of the radioactive isotope Ba-137m is determined by measuring the activity of a sample as it decays. The half-life of Ba-137m, which has been extracted from the radioisotope Cs-137, is detected by using AktivLab. The theoretical half-life of Ba-137m is approximately 2.56 minutes, and the result from the experiment is 2.6 minutes. In summary, a radioisotope generator containing Cs-137 produces Ba-137m, which is extracted in a solution. The Ba-137m has a half-life of about 2.6 minutes as measured during this research.

Liquid scintillation multivariate, gamma spectrometry and radiochemical separation techniques were used for estimating 3H, 90Sr and 137Cs in bore well samples. Using multivariate technique, 3H, 90Sr and 137Cs has been assayed in triple labeled samples. The same samples were also estimated by other routinely used techniques, like gamma spectrometry to estimate 137Cs, radio-chemical separation followed by subsequent counting using GM counter for 90Sr. The samples were distilled for 3H and its activity was estimated using liquid scintillation counting with the prepared calibration curve. Our results show that liquid scintillation multivariate is an easy and rapid method capable of estimating 3H, 90Sr and 137Cs in water samples with ±10 % deviation for 3H and ±13 % deviation for 137Cs. However, in case of 90Sr the results obtained by conventional method and the simultaneous analysis by liquid scintillation multivariate technique are varying around ±29 %. This could be attributed to error introduced by matrix interference in the conventional analysis.

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, Cs-137 and Co-60 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. 2nd International Conference on Radiation and Dosimetry in Various Fields of Research RAD and The 2nd East European Radon Symposium (SEERAS), May 27-30, 2014, Nis, Serbia

Employment of additional multiplication region in the structure of quantum dots-in-well (DWELL) intersubband photodetectors can be a useful alternative for amplification of the photocurrent and giving higher gain to detected optical signal. For such detector the photocurrent of DWELL detector is increased by avalanche multiplication to achieve higher responsivity and resonant tunneling barriers are used in absorption region to reduce the dark current. In this paper the linear and Geiger mode operation of proposed detector is studied for operation at λ = 11 μm. In linear operation, the specific detectivity ( D * ) is increased about one order of magnitude in comparison to experimentally reported conventional DWELL detectors. We also report the single photon detection around mid and long infrared wavelength by gated mode operation of this detector with single photon quantum efficiency of about 3%.

We experimentally studied photon-counting laser ranging at 1550 nm using InGaAs/InP avalanche photodiode based single-photon detectors (SPDs). The SPDs operated in the passive quenching and 1-GHz sinusoidal gating Geiger modes, corresponding to continuous and quasi-continuous photon-counting ranging, respectively. Despite that the passively quenched SPD provided relatively high effective detection efficiency, quasi-continuous photon-counting ranging excelled the continuous one with fast acquisition speed and improved depth resolution due to the short deadtime and low timing jitter of the SPD in 1-GHz sinusoidally gated mode.

In accordance with the general trend of the miniaturization of electronic components and devices, this paper shows the model for calculating the type A measurement uncertainty of the Geiger–Mueller (GM) counter. As a consequences of device miniaturization, reduction of the GM counting tube size results in a change in the reliability of the GM counter for radiation detection. Based on the enlargement law applied to distributions of extreme values (such as the Weibull distribution) the paper shows the derived theoretical expression which describes the trend of the type A measurement uncertainty followed by the GM counting tube reduction. In an experimental procedure, carried out under well controlled laboratory conditions, the area and volume effects caused by the change in the counting tube size were observed separately. Experiments were carried out on commercial counting tubes as well as on in-house counting tube models, both made in cylindrical geometry. The experimental results obtained, which are in compliance with the theoretically derived model, indicated that the random variable pulse rate, which belongs to the normal distribution due to its nature, with regard to modelling according to area and volume enlargement probability law, should be treated by the three-parameter Weibull distribution. All the obtained results in the paper have been explained based on elementary processes of electrical discharge in gases and are significant for engineering practice since they define the trend of GM counter measurement uncertainty of type A, and thus its functionality as a radiation instrument, during the course of device miniaturization.

Taking advantage of previous measurements by Geiger and co-workers, we discuss the possibilities and problems of measuring vibrational modes of energy loss in a transmission electron microscope fitted with a monochromator and a high-resolution energy-loss spectrometer. The tail of the zero-loss peak is seen to be a major limitation, rather than its full-width at half-maximum. Because of the low oscillator strengths and small cross-sections involved, radiation damage will limit the spatial resolution if this technique is applied to organic specimens. Delocalization of the inelastic scattering may also be a limitation, if a dipole description of the scattering process is valid.

This chapter presents the detectors based on ionization in gases and liquids. Ionization detectors are discussed starting from the ionization in gases, the basis of several detectors of this class: the incident particles produces electron-ion pairs that undergo avalanche multiplication in high electric fields. Ionization chambers, proportional counters and Geiger counters are based on the above principle, but are operating at different electric fields. The evolution of these systems has lead to the building of Multi Wire Proportional Chambers and drift chambers. Liquid ionization detectors, that rely on the higher density of the ionizing medium, are discussed. The energy resolution capability of gas and liquid based detectors is presented.

A prototype intensity interferometer readout for single-photon detectors is presented as a time-to-digital converter (TDC) implemented on a field-programmable gate array (FPGA). We briefly discuss the history and scientific motivations for the instrument. A comparison is drawn between the use of photomultiplier tubes in linear mode and single-photon avalanche diodes (SPAD) in Geiger mode. Different FPGA-based TDC configurations are discussed. We describe the design and implementation of a four-phase FPGA-based TDC. The paper concludes with the application of the design to investigate SPAD after-pulsing and a description of future work.