Detection Of Elements Research Articles

Biosensors to Monitor Water Quality Utilizing Insect Odorant-Binding Proteins as Detector Elements.

In the developing world, the identification of clean, potable water continues to pose a pervasive challenge, and waterborne diseases due to fecal contamination of water supplies significantly threaten public health. The ability to efficiently monitor local water supplies is key to water safety, yet no low-cost, reliable method exists to detect contamination quickly. We developed an in vitro assay utilizing an odorant-binding protein (OBP), AgamOBP1, from the mosquito, Anopheles gambiae, to test for the presence of a characteristic metabolite, indole, from harmful coliform bacteria. We demonstrated that recombinantly expressed AgamOBP1 binds indole with high sensitivity. Our proof-of-concept assay is fluorescence-based and demonstrates the usefulness of insect OBPs as detector elements in novel biosensors that rapidly detect the presence of bacterial metabolic markers, and thus of coliform bacteria. We further demonstrated that rAgamOBP1 is suitable for use in portable, inexpensive “dipstick” biosensors that improve upon lateral flow technology since insect OBPs are robust, easily obtainable via recombinant expression, and resist detector “fouling.” Moreover, due to their wide diversity and ligand selectivity, insect chemosensory proteins have other biosensor applications for various analytes. The techniques presented here therefore represent platform technologies applicable to various future devices.

New eye lens dosemeters for integration in radiation protection glasses

With the annual dose limit for the lens of the eye being lowered to 20 mSv from 2019, both new efforts to improve radiation protection for this part of the body and new approved dosemeters for official dose monitoring are required. The individual monitoring services at the Helmholtz Zentrum München and Dosilab AG, together with MAVIG, have developed a mechanical interface to integrate eye lens dosemeters into radiation protection glasses. MAVIG has designed a new type of radiation protection glasses featuring this dosemeter interface. The two individual monitoring services have independently developed two new types of eye lens dosemeters for the interface. The Munich solution for the eye lens dosemeter is a BeOSL dosemeter for photon radiation with a new detector element introduced by Dosimetrics GmbH in 2018. The Dosilab approach is based on a TLD dosemeter for photon and beta radiation. This work describes the concepts for radiation protection glasses and interface, the new dosemeters, and presents the performance characteristics of the dosemeters in accordance with IEC requirements.

Rapid simulation of X-ray scatter measurements for threat detection via GPU-based ray-tracing

Scatter-based X-ray imaging has increased in prominence in areas ranging from cancer diagnostics to threat detection in aviation security, due largely to the development of new algorithms and components over the last decade. However, system design and algorithm development are often hindered by an inability to generate a sufficient amount of accurate data. To further the development of scatter-based systems, we created a rapid X-ray scatter simulation tool built with a GPU-centric, parallel ray-tracing framework (NVIDIA OptiX). This tool models a full range of X-ray imaging components and describes 3D objects formed with heterogeneous media using polygon meshes. The scatter simulation algorithm we used is similar to the previously-described hybrid approach; however, instead of employing Monte Carlo techniques, we developed a purely analytical algorithm to sample the distribution of single-scatter events throughout the region of interest. The contribution of scattered photons to the measured signal is then calculated using the first-Born approximation. The accuracy of the implemented pipeline has been validated by comparing simulated against experimental data obtained with a laboratory X-ray scattering system and phantoms of varied materials. Using a single desktop computer with an NVIDIA GTX 770 GPU, we show that the scatter signal generated by an incident fan beam and recorded by a 125×125 element detector array can be simulated in on the order of a few to tens of minutes (depending on the object extent and complexity). As a point of comparison, simulations performed via CPU-based Monte Carlo tools, such as GEANT4 (i.e., the gold standard), can take up to tens of hours to achieve comparable results.

REGIONAL PECULIARITIES OF TRACE ELEMENTS IN THE BIOSPHERE AND THE HUMAN BODY

From literary data it is known the investigation of contents and influence on an organism of chemical elements to be urgent, the carrying out such researches in the urbanized territories is especially important. The Orenburg region as production and processing of minerals (metal ore, hydrocarbons, etc.) undoubtedly treats such territories having been conducted since the 12th century. In this regard in the territory of the Orenburg region, the complex large-scale research of the trace element status of the territory is implemented. In 35 administrative regions of area samples of a surrounding environment and biosubstrate (hair) of constantly living population was taken. Research on the detection of chemical elements (Zn, Cu, Cd, Pb) in biosubstrate were carried out in the Autonomous non-profit organization “Center for Biotic Medicine”, and samples of a surrounding environment were examined in laboratories of the Exploring Center "All-Russian scientific research institute of meat cattle breeding" of the Russian Academy of Agrarian Sciences. Results of researches show factors of natural and technogenic character to have an impact on the maintenance of essential and toxic minerals in the environment. In underground waters, there was established the minimum content of zincum, copper, cadmium, and lead to be revealed in samples from areas of the Western and the Central Orenburg region. Moreover, the concentration of zincum, copper, cadmium, and lead in water of East zone, achieves the threshold limit value. The concentration in soils of zincum and copper was found to correspond to the maximum allowable concentration in samples from the East Orenburg region. The performed research of trace element structure of hair of the population of the Orenburg region showed both the content of the vital chemical elements (Zincum and copper) in an organism of the studied population to fail to correspond to reference values, the increased level of the studied elements (woman) in inhabitants of East zone, and the lower level zincum and copper in the examined population of the Central and Western area. The correlation and regression analysis allowed to establish the content of chemical elements in the soil to have the significant, reliable (p ≤ 0.05) influence on the element status of the examined residents of the Orenburg region.

Spectroscopic performance of a Sr co-doped 3” LaBr3 scintillator read by a SiPM array

Abstract LaBr3:Ce crystals represent a key element for high-resolution gamma-ray detectors based on indirect conversion. Recent developments in crystal technologies have brought to the market Sr2+ co-doped 3” scintillators with a light yield 28% higher than standard LaBr3 crystals. Concurrently, high-density silicon photo-multipliers (SiPMs) have enabled the possibility of solid-state readout of these crystals, providing state-of-the-art energy resolution and wide dynamic range. In order to assess the performance of a solid-state readout of a large LaBr crystal, we developed a low-noise readout instrument based on a 12 × 12 array of 6 mm × 6 mm NUV-HD SiPMs produced by FBK. The array of photo-detectors was coupled to a custom-developed 8-channel ASIC with automatic gain switching named GAMMA. Detector biasing, data acquisition, processing and transfer are performed by a compact microcontroller-based unit. The resulting instrument was tested with two different crystals: a standard 3”LaBr3:Ce3+ and the Sr2+ co-doped version. Thanks to the low-noise performance of SiPMs and of the electronics it has been possible to investigate the ultimate noise performance of the crystal and compare the results between the two crystals. A 3.4% FWHM energy resolution at the 137Cs 662 keV photopeak was measured with the standard LaBr3 crystal, while it improved to 2.6% at 662 keV with the co-doped crystal. Beyond presenting the unprecedented spectroscopic performance of the 3” co-doped crystal, this work is a further demonstration of the SiPM consolidating technology suitability to replace photo-multiplier tubes (PMT) for demanding applications in nuclear physics and astrophysics.

Designing an adjustable THz absorber

ABSTRACTIn this paper, a new approach to effective detection of THz radiation is proposed using a configuration of thin metal and thin dielectric films; to this end, the design and performance of an effective composite absorber of THz radiation that can be used as the sensing element of a thermal detector are presented. A composite absorber consists of a set of two double-layered elements of a thin metal layer located on a dielectric material and is designed through a fine-tuning process. The results indicate that the proposed low-cost absorber can be widely tuned based on the metal layer sheet resistance and the thickness of various dielectric media. The development of a proper non-linear system of equations has as input the desired frequency and bandwidth of the absorbed THz radiation and output the required metrics of dielectric refractive index, the dielectric thickness and the metal’s sheet resistance that comprise the absorber.

Аналіз сучасного стану забезпечення пожежної безпеки промислових будівель та складів

Проаналізовано світовий досвід у царині забезпечення пожежної безпеки промислових будівель та складів, що головно базується на огляді публікацій за останні 5 років, зокрема і тих, що індексуються в наукометричній базі Scopus. Актуальним завданням у царині пожежної безпеки є розвиток уявлення про можливі перспективні напрями розвитку систем протипожежного захисту промислових будівель та складів, що має базуватися на ґрунтовному аналізі світового досвіду у цій площині. Проаналізовано вплив чинників пожежної безпеки підприємств нафтохімічної промисловості, підземного зберігання дизельного палива, складів текстильної промисловості та складів тютюну з точки зору аспектів свідомості та обізнаності персоналу в царині пожежної безпеки, протипожежних об'єктів (об'єктових пожежно-рятувальних частин, добровільних пожежних команд тощо), управління пожежною безпекою та технічного забезпечення, а також наведено причинно-наслідковий аналіз цієї системи. Встановлено, що забезпечення пожежної безпеки підприємств ґрунтується на ефективному функціонуванні систем протипожежного захисту, а також принципах раннього виявлення пожеж шляхом застосування сучасних систем пожежної сигналізації. З'ясовано, що перспективи розвитку в окресленій проблематиці мають базуватися на застосуванні сучасних технологій, досконалості нормативно-технічної бази, а також застосуванні новітніх підходів до організації системи протипожежного захисту промислових будівель та складів.

Improving the performance of computational ghost imaging by using a quadrant detector and digital micro-scanning

Computational ghost imaging systems reconstruct images using a single element detector, which measures the level of correlation between the scene and a set of projected patterns. The sequential nature of these measurements means that increasing the system frame-rate reduces the signal-to-noise ratio (SNR) of the captured images. Furthermore, a higher spatial resolution requires the projection of more patterns, and so both frame-rate and SNR suffer from the increase of the spatial resolution. In this work, we combat these limitations by developing a hybrid few-pixel imaging system that combines structured illumination with a quadrant photodiode detector. To further boost the SNR of our system, we employ digital micro-scanning of the projected patterns. Experimental results show that our proposed imaging system is capable of reconstructing images 4 times faster and with ~33% higher SNR than a conventional single-element computational ghost imaging system utilizing orthogonal Hadamard pattern projection. Our work demonstrates a computational imaging system in which there is a flexible trade-off between frame-rate, SNR and spatial resolution, and this trade-off can be optimized to match the requirements of different applications.

MXCuBE2: the dawn of MXCuBE Collaboration.

MXCuBE2 is the second-generation evolution of the MXCuBE beamline control software, initially developed and used at ESRF - the European Synchrotron. MXCuBE2 extends, in an intuitive graphical user interface (GUI), the functionalities and data collection methods available to users while keeping all previously available features and allowing for the straightforward incorporation of ongoing and future developments. MXCuBE2 introduces an extended abstraction layer that allows easy interfacing of any kind of macromolecular crystallography (MX) hardware component, whether this is a diffractometer, sample changer, detector or optical element. MXCuBE2 also works in strong synergy with the ISPyB Laboratory Information Management System, accessing the list of samples available for a particular experimental session and associating, either from instructions contained in ISPyB or from user input via the MXCuBE2 GUI, different data collection types to them. The development of MXCuBE2 forms the core of a fruitful collaboration which brings together several European synchrotrons and a software development factory and, as such, defines a new paradigm for the development of beamline control platforms for the European MX user community.

SIMULATION OF OSL AND TLD DOSEMETER RESPONSE FOR THE DEVELOPMENT OF NEW EXTREMITY DOSEMETERS.

The individual monitoring service at the Helmholtz Zentrum München is currently developing a new eye lens dosemeter to be integrated in radiation protection glasses and a new ring dosemeter using a new BeOSL detector element for extremity dosimetry developed by Dosimetrics. In the design process for the new eye lens dosemeter, MCNP6 Monte Carlo simulations were used to model the energy and angular response of new dosemeters before ordering the expensive tools for injection molding. This study describes the simulation of the dosemeter and detector, and the involved calculations do obtain the response in terms of the radiation protection quantity Hp(3). Simulations were carried out also for existing whole body dosemeters and TLD rings in order to verify the MC tools. With the final dosemeter prototypes becoming available earlier this year, all MC models could be verified and show very good agreement with experimental data.

Non-stationary model of oblique x-ray incidence in amorphous selenium detectors: I. Point spread function.

In previous work, a theoretical model of the point spread function (PSF) for oblique x-ray incidence in amorphous selenium (a-Se) detectors was proposed. The purpose of this paper is to develop a complementary model that includes two additional features. First, the incidence angle and the directionality of ray incidence are calculated at each position, assuming a divergent x-ray beam geometry. This approach allows the non-stationarity of the PSF to be modeled. Second, this paper develops a framework that is applicable to a digital system, unlike previous work which did not model the presence of a thin-film transistor (TFT) array. At each point on the detector, the incidence angle and the ray incidence direction are determined using ray tracing. Based on these calculations, an existing model for the PSF of the x-ray converter (Med Phys. 1995;22:365-374) is generalized to a non-stationary model. The PSF is convolved with the product of two rectangle functions, which model the sampling of the TFT array. The rectangle functions match the detector element (del) size in two dimensions. It is shown that the PSF can be calculated in closed form. This solution is used to simulate a digital mammography (DM) system at two x-ray energies (20 and 40keV). Based on the divergence of the x-ray beam, the direction of ray incidence varies with position. Along this direction, the PSF is broader than the reference rect function matching the del size. The broadening is more pronounced with increasing obliquity. At high energy, the PSF deviates more strongly from the reference rect function, indicating that there is more blurring. In addition, the PSF is calculated along the polar angle perpendicular to the ray incidence direction. For this polar angle, the shape of the PSF is dependent upon whether the ray incidence direction is parallel with the sides of the detector. If the ray incidence direction is parallel with either dimension, the PSF is a perfect rectangle function, matching the del size. However, if the ray incidence direction is at an oblique angle relative to the sides of the detector, the PSF is not rectangular. These results illustrate the non-stationarity of the PSF. This paper demonstrates that an existing model of the PSF of a-Se detectors can be generalized to include the effects of non-stationarity and digitization. The PSF is determined in closed form. This solution offers the advantage of shorter computation time relative to approaches that use numerical methods. This model is a tool for simulating a-Se detectors in future work, such as in virtual clinical trials with computational phantoms.

Nonstationary model of oblique x-ray incidence in amorphous selenium detectors: II. Transfer functions.

One limitation of experimental techniques for quantifying resolution and noise in detectors is that the measurement is made in a region-of-interest (ROI). With theoretical modeling, these properties can be measured at a point, allowing for quantification of spatial anisotropy. This paper calculates nonstationary transfer functions for amorphous selenium (a-Se) detectors in breast imaging. We use this model to demonstrate the performance advantage of a "next-generation" tomosynthesis (NGT) system, which is capable of x-ray source motion with more degrees of freedom than a clinical tomosynthesis system. Using Swank's formulation, the optical transfer function (OTF) and presampled noise power spectra (NPS) are determined based on the point spread function derived in Part 1. The modulation transfer function (MTF) is found from the normalized modulus of the OTF. To take into account the presence of digitization, the presampled NPS is convolved with a two-dimensional comb function, for which the period along each direction is the reciprocal of the detector element size. The detective quantum efficiency (DQE) is then determined from combined knowledge of the OTF and NPS. First, the model is used to demonstrate the loss of image quality due to oblique x-ray incidence. The MTF is calculated along various polar angles, corresponding to different orientations of the input frequency. The MTF is independent of the incidence angle if the polar angle is perpendicular to the ray incidence direction. However, along other polar angles, oblique incidence results in MTF degradation at high frequencies. The MTF degradation is most substantial along the ray incidence direction. Unlike the MTF, the normalized NPS (NNPS) is independent of the incidence angle. To measure the relative signal-to-noise, the DQE is also calculated. Oblique incidence yields high-frequency DQE degradation, which is more pronounced than the MTF degradation. This arises because the DQE is proportionate with the square of the MTF. Ultimately, this model is used to evaluate how the image quality varies over the detector area. For various projection images, we calculate the variation in the incidence angle over this area. With the NGT system, the source can be positioned in such a way that this variation is minimized, and hence the DQE exhibits less anisotropy. To achieve this improvement in the image quality, the source needs to have a component of motion in the posteroanterior (PA) direction, which is perpendicular to the conventional direction of source motion in tomosynthesis. In a-Se detectors, the DQE at high frequencies is degraded due to oblique incidence. The DQE degradation is more pronounced than the MTF degradation. This model is used to quantify the spatial variation in DQE over the detector area. The use of PA source motion is a strategy for minimizing this variation and thus improving the image quality.

A fully parametric option in the LHCb simulation framework

Faster alternatives to a detailed, GEANT4-based simulation are being pursued within the LHCb experiment. In this context the integration of the Delphes toolkit in the LHCb simulation framework is intended to provide a fully parameterized option. Delphes is a modular software designed for general-purpose experiments such as ATLAS and CMS to quickly propagate stable particles using a parametric approach and to provide reconstructed physical objects as output. It includes propagation inside a magnetic field and parameterized response for tracking and muon systems as well as calorimeters. Particle energies are computed by smearing the initial visible particles momentaaccording to detector resolution. The present contribution illustrates the current status of the Delphes toolkit in Gauss, the LHCb simulation framework. In this integration the particle transport performed by GEANT4 and subsequent mimicking of detector response and reconstruction has been replaced with a parametric response of the various detector elements. The implementation required sig-nificant changes to Delphes itself to constrain the particle transport inside the detector acceptance and to match the LHCb dipole magnetic field. The configuration of various parametrisations of resolution and efficiency is also a major aspect of the work to provide a fully functional simulation. The output of the resulting fast simulation is formatted in such a way that can be used in the LHCb physics analysis framework.

О влиянии давления воздуха на параметры тока пучка и рентгеновского излучения, генерируемых в газовом диоде

The results of studies of the parameters of the beam of runaway electrons and X-rays generated in a gas diode at different pressures of atmospheric air are presented. It has been confirmed that the maximum values of the beam current, as well as the x-ray intensity, are recorded at air pressure hundreds Pa. The energy distribution of the beam electrons is determined by the method of attenuation of the beam current using aluminum filters of different thickness. The distribution maximum corresponds to an electron energy of ~ 100 keV. The maximum exposure dose of X-rays behind an anode made of copper foil with a thickness of 30 μm was ~ 107 mR. It was found that when the beam current density is more than 35 A / cm2, the effect of the beam electrons absorbed by the elements of the X-ray detector on the shape and amplitude of the registered signal from the detector is observed. M.I. Lomaev, V.F. Tarasenko, E.Kh. Baksht

Knowledge and Technology Transfer in KM3NeT

The status of the construction of the KM3NeT detector components and the experience gained from the detector units deployed underpin the dissemination of innovative technological solutions to industry, Institutions and other potentially interested parties. KM3NeT is now entering a phase during which the design of the detector elements is being finalized and testing procedures for controlling the quality of the different components are settled. In addition, a few KM3NeT detection units have been deployed successfully and many more are coming, data have been recorded and are currently being analysed. The maturity and scalability of the technological solutions developed or modified by KM3NeT has been demonstrated and therefore justifies their exposure to relevant technology developers or users.

A highly granular SiPM-on-tile calorimeter prototype

The Analogue Hadron Calorimeter (AHCAL) developed by the CALICE collaboration is a scalable engineering prototype for a Linear Collider detector. It is a sampling calorimeter of steel absorber plates and plastic scintillator tiles read out by silicon photomultipliers (SiPMs) as active material (SiPM-on-tile). The front-end chips are integrated into the active layers of the calorimeter and are designed for minimizing power consumption by rapidly cycling the power according to the beam structure of a linear accelerator. 38 layers of the sampling structure are equipped with cassettes containing 576 single channels each, arranged on readout boards and grouped according to the 36 channel readout chips. The prototype has been assembled using techniques suitable for mass production, such as injection-moulding and semi-automatic wrapping of scintillator tiles, assembly of scintillators on electronics using pick-and-place machines and mass testing of detector elements. The calorimeter was commissioned at DESY and was taking data at the CERN SPS at the time of the conference. The contribution discusses the construction, commissioning and first test beam results of the CALICE AHCAL engineering prototype.

277. A software toolset for quality control in digital mammography and DBT

Purpose The aim is to introduce a software toolset compliant with European protocols for quality control of physical and technical aspects of mammography screening (2DFFDM) and Digital Breast Tomosynthesis (DBT) Systems. Methods The toolset is developed as a suite of plugins of the well-known free software ImageJ. The mammographic systems under study are Hologic Selenia Value+ and Siemens Mammomat Inspiration PRIME and the ARTINIS EU DBT Test Set is used to perform QC sessions. IQWorks and OBJ_IQ softwares are used to investigate the consistence for NPS and MTF values while the plugins for analysis of the remaining parameters are directly derived from EUREF guidelines. Results The toolset allows full analysis of the parameters specified in european protocols, especially AEC steps and short term reproducibility, AEC long term reproducibility by SNR referred to 2D ROI and 3D voxel, SDNR, local dense area, image receptor response function, noise, image receptor homogeneity and stability based on 2D ROI and 3D voxel calculation, detector elements failure through text files analysis for visualization and comparison of bad pixel map, uncorrected defective detector elements, inter plate sensitivity variations, AGD from DICOM headers, MTF with edge and wire techniques, NPS from 2DFFDM images, NPS for full 3DDBT slices as well as by extraction. The toolset also evaluates distortions and tilt of the reconstructed 3DDBT planes. The sorting and renaming of a set of dicom images based on their acquisition time or slice position and the evaluation of homogeneity in every DBT focal plane (PV, variance, SNR variations) are also achievable. Conclusions The aim is to introduce a software toolset compliant with European protocols for quality control of physical and technical aspects of mammography screening (2DFFDM) and Digital Breast Tomosynthesis (DBT) Systems. The toolset is developed as a suite of plugins of the well-known free software ImageJ. The mammographic systems under study are Hologic Selenia Value+ and Siemens Mammomat Inspiration PRIME and the ARTINIS EU DBT Test Set is used to perform QC sessions. IQWorks and OBJ_IQ softwares are used to investigate the consistence for NPS and MTF values while the plugins for analysis of the remaining parameters are directly derived from EUREF guidelines. The toolset allows full analysis of the parameters specified in european protocols, especially AEC steps and short term reproducibility, AEC long term reproducibility by SNR referred to 2D ROI and 3D voxel, SDNR, local dense area, image receptor response function, noise, image receptor homogeneity and stability based on 2D ROI and 3D voxel calculation, detector elements failure through text files analysis for visualization and comparison of bad pixel map, uncorrected defective detector elements, inter plate sensitivity variations, AGD from DICOM headers, MTF with edge and wire techniques, NPS from 2DFFDM images, NPS for full 3DDBT slices as well as by extraction. The toolset also evaluates distortions and tilt of the reconstructed 3DDBT planes. The sorting and renaming of a set of dicom images based on their acquisition time or slice position and the evaluation of homogeneity in every DBT focal plane (PV, variance, SNR variations) are also achievable.

The SHiP Experiment: Search for New Physics in the Neutrino Sector

The SHiP experiment (for Search for Hidden Particles) which will operate at the CERN Super Proton Synchrotron (SPS) is one of the most promising projects in the field of particle physics. The SPS 400-GeV/c proton beam will be dumped onto the molybdenum–tungsten target of the SHiP detector, and the data corresponding to 2 × 1020 protons on the target will be accumulated in five years of running. The experiment is aimed at a search for very weakly interacting neutral particles beyond the Standard Model framework referred to as novel physics particles: massive neutral leptons, axions, and “dark” photons. Possible existence of such particles can help explain such firmly established phenomena as the baryon asymmetry of the Universe, nonzero neutrino masses, and the presence of dark matter. Beyond that, the experimental program envisages extensive studies in neutrino physics. In particular, we aim at directly detecting the tau antineutrino—the only Standard Model particle which until now has escaped experimental detection. The envisaged search for the right-handed neutrino partners is particularly interesting: theoretically, their existence can help explain some observed phenomena not predicted by the Standard Model. Experimental investigations in the fields of tau-neutrino interactions (as the least studied sector of neutrino physics) and production of charmed particles and a search for interactions of particles of light dark matter will be carried out with a neutrino detector based on relativistic nuclear emulsion. The τ- and τ+ production events will be discriminated (whereby the production of tau antineutrinos will be directly detected) using special magnets developed for the SHiP emulsion detector. Presently, a prototype of the emulsion detector as a key element of the SHiP neutrino detector is being simulated, constructed, and tested. The nuclear-emulsion technology provides a record-high spatial resolution as required for detecting charged particles with extremely short lifetimes. The nuclear-emulsion data will be processed with the advanced automatic equipment available at the participating laboratories. Efficient scanning of large areas on nuclear emulsion relies on modern scanning equipment such as the PAVICOM measuring complex developed at the Lebedev Physical Institute. Thereby, one can efficiently process the data collected with any track detectors, including those irradiated by accelerator beams. On the whole, the construction of the SHiP detector poses a number of nontrivial physical and technical problems addressed by physicists from 62 laboratories operating in 16 countries.

S3-prototype of reactor antineutrino detector

In recent years, much attention has been focused on neutrino research because it can shed new light on greatest mysteries in physics. A new experiment devoted to detection and investigation of reactor antineutrinos is being performed at the Institute of Experimental and Applied Physics, Czech Technical University in Prague using a highly segmented scintillating detector S3. This detector is polystyrene based and does not contain any dangerous or flammable materials and is absolutely safe to be placed in the close vicinity of the reactor. The most important feature of plastic scintillators for this experiment is the amount of photoelectrons per deposited energy, which defines the final energy resolution of the detector and a lot of effort has been put into improvement of detector element overall quality. The detector has been constructed as a result of these optimization experiments.

Nanowire photodetectors with embedded quantum heterostructures for infrared detection

Nanowires offer remarkable opportunities for realizing new optoelectronic devices because of their unique fundamental properties. The ability to engineer nanowire heterostructures with large bandgap variations is particularly interesting for technologically important broadband photodetector applications. Here we report on infrared photodetectors based on arrays of InP nanowires with embedded InAsP quantum discs. We demonstrate a strongly reduced dark current in the detector elements by compensating the unintentional n-doping in the nominal intrinsic region of the InP nanowires by in-situ doping with Zn, a crucial step towards realizing high-performance devices. The optimized array detectors show a broad spectral sensitivity at normal incidence for wavelengths from visible to far-infrared up to 20 μm, promoted by both interband and intersubband transitions. Optical simulations show that the unexpected normal incidence response at long wavelengths is due to non-zero longitudinal modes hosted by the nanowires.