In this proceeding we present a high throughput single photon counting system able to detect at high photon count rates with the potential to enhance the effectiveness of stellar intensity interferometry (SII) measurements. The system consists of a photon detection module, PhotonPix (TM), and a time-tagging acquisition unit, LINTag, and enables nearly dead time free photon acquisition. PhotonPix (TM) is a sensor with an active area of 8 mm diameter, based on a microchannel plate (MCP) photomultiplier tube (PMT) supported by fast integrated electronics. A quantum efficiency (QE) of over 30% in the UV and visible is reachable at the desired wavelength by choosing a matching photocathode. Here we report temporal resolution measurements of the system at various count rates. We observe a resolution better than 40 ps full width at half maximum (FWHM) at count rates of up to 10 MHz with a marginal degradation down to 50 ps FWHM at 97 MHz detected rate. This combination of high temporal resolution, fast acquisition and large sensitive area, enables SII measurements with higher significance and/or on dimmer stars.

We will describe the characteristics of the afterpulsing effect seen in the optical intensifiers. It can be caused by either secondary electrons produced by primary photoelectrons hitting the micro-channel plate surface or by electron emission from the photocathode induced by the ion feedback. The result of this effect are additional pulses delayed with respect to the primary parent pulses. Using a fast data-driven camera, Tpx3Cam, we were able to clearly show afterpulsing present in the data at short time differences and small distances from the primary pulse, as well as to show the evolution of the afterpulsing effect with increasing time difference. We also studied the afterpulsing spatial distribution and observed an azimuthal asymmetry, which we attribute to the afterpulsing ion component.

Thanks to a large set of available photocathodes with first in class QE, high gain, high collection efficiency, high dynamic range while keeping low dark count rate and single photon resolution capability with excellent timing, MCP-PMTs have emerged as candidates for LIDAR receivers.We present results of Ageing tests and Radiation tests carried out with Photonis and Airbus Defence & Space on High QE, and High linearity MCP-PMT for UV LIDAR receivers.Ageing of the photocathode is usually due to electron-induced ion feedback and molecule desorption from the MCP and anode, causing degradation of the photocathode layer leading to a progressive loss of QE related to the quantity of electron charges generated along lifetime.Expected Coulomb charges generated along a typical and worst-case mission were estimated from the atmosphere profiles.Thanks to a design change of the MCP-PMT and the implementation of Long-Lifetime MCP technology, ageing of the photocathode was drastically reduced.The new design showed no Quantum Efficiency nor Collection Efficiency degradation up to 20 C. Proton radiation tests were performed to evaluate false signal generated, end-of-life impact on performance, loss of transmission depending on the photocathode glass substrate as well as cathodoluminescence and photoluminescence at the photocathode.Quantum Efficiency, Collection Efficiency, PHD shape, Gain, and Linearity were found to be unchanged for fluences of 5x10 11 p+/cm² with 60 MeV protons.Only small increase of DCR for about 120 cps/cm² was recorded about 8 weeks after the radiation.

We report the development and testing of a photon-counting detector for space-borne quantum communication applications with an ultra-low dark count rate (10 counts per second) and low timing jitter (40 ps FWHM, 17 ps σ, 140 ps 1%) at a non-cryogenic temperature of -60°C.

The intrinsic background of a LaBr3(Ce) scintillator with a diameter of 5 mm and a height of 10 mm has been studied in comparison with LYSO and CeBr3 scintillators. It is shown that due to its high energy resolution the detector based on a LaBr3(Ce) crystal exhibits the lowest background count rate in a specified amplitude range. The measured energy resolution of the detector based on a LaBr3(Ce) crystal with dimensions of Ø5 mm × 10 mm in combination with a silicon photomultiplier with an active area of 3 × 3 mm2 are presented. It is demonstrated that a detector array with the proposed configuration (a scintillator + a silicon photomultiplier enclosed in a common container) exhibits an energy resolution of 4% for 661.7-keV γ rays and a background count rate of ~0.39 cps in the energy range of (140 ± 3σ) keV.

The miniature gamma counter based on a cylindrical LaBr3(Ce) crystal (5 mm diameter and 10 mm length) and SensL FC30035 silicon photomultiplier (SiPM) is introduced. The main counter characteristics such as relative efficiency, LaBr3(Ce) self-radioactivity and energy resolution are presented. Capability of using such detector for gamma spectrometry applications is discussed.

Results of investigations of the scintillation detector based on a LaBr3:Ce crystal and a ФЭУ-184 photomultiplier tube are presented. It is shown that, optimizing the ФЭУ-184 photomultiplier tube circuit by reading out the signal from the next to last dynode, it is possible to utilize the spectrometric properties of the LaBr3:Ce crystal.

Представлены результаты исследований сцинтилляционного детектора на основе кристалла LaBr3:Ce и фотоумножителя ФЭУ-184. Показано, что оптимизация схемы подключения ФЭУ-184, заключающаяся в регистрации сигнала с предпоследнего динода, позволяет реализовать спектрометрические возможности кристалла LaBr3:Ce.

Experimental examples demonstrate a significant improvement of the most important parameters (sensitivity; spatial, spectrometric, and time resolution; and radiation hardness) of radiation detectors with sensitive elements based on fiber and nanocrystalline scintillators instead of conventional bulk single crystals. This improvement is related to several specific features of the new scintillator types: improved homogeneity of activator distribution, larger soft X-ray component in the secondary emission due to the high frequency of hot electron collisions with the nanoparticle surface, formation of high-quality optical nanocavities, and enhanced annihilation of radiation defects at their rapid motion to the surface.

The intrinsic background was measured in LaBr3:Ce and CeBr3 scintillating crystals grown at the Institute of Solid-State Physics of the Russian Academy of Sciences. The measurements were taken in the range of γ-ray energies from 20 keV to ∼5 MeV. Cylindrical samples with dimensions of Ø 1.5 × 1.8 cm for LaBr3:Ce and Ø 0.5 × 1.5 cm for CeBr3 were used. Well-known peculiarities due to the 138La radioactive iso-tope and actinide contaminants were reproduced in the recorded background spectrum of the LaBr3:Ce crystal. The detailed spectrum of the intrinsic background in the CeBr3 crystal was measured for the first time. At energies of >200 keV, the background rate of CeBr3 appeared to be much lower than that of LaBr3:Ce both in the continuum and in the peculiarities associated with the radioactivity of possible contaminants.

Neutron detectors comprising a new type of photosensors—silicon photomultipliers—coupled to a single-crystal LiI(Eu) scintillator and a 6LiF/ZnS(Ag) scintillation screen are described. These detectors are compact, which improves their usability. Some parameters of the detectors are presented, their sensitivity to thermal neutrons and γ rays is estimated, and their possible applications are proposed.

Представлены результаты разработки нейтронных детекторов, созданных с применением нового типа фотоприемников – кремниевых твердотельных фотоумножителей. В качестве сцинтилляторов детекторов использовались монокристалл LiI(Eu) и сцинтилляционный экран 6LiF/ZnS(Ag). Описываемые детекторы компактны, и это расширяет возможности их использования. Приведены некоторые параметры детекторов, дана оценка их чувствительности к тепловым нейтронам и -излучению, указаны возможные способы их применения.

A model of directed crystallization is developed that considers the stability of the phase boundary to periodic (temporal and spatial) temperature and concentration perturbations. In the case of instability, i.e., increase in the amplitude of perturbations with time, the dependence of the eutectic structure period on the crystallization rate is determined from the model. A possible shape of the crystallization front and the structure of the solid phase formed are considered qualitatively. The corresponding model calculation of experimentally observed eutectic structures is presented.

In our previous works [Computat. Mater. Sci. 17 (2000) 555–559; Lett. Appl. Phys. 27 (11) (2001) 86–91], we have obtained an expression for a periodic distribution component under directed crystallization of eutectic alloys. This expression coincides with the experimental dependences obtained by Minford et al. [J. Am. Ceram. Soc. (1979) 154–162]. It was obtained from a model of directed crystallization which includes equations of heat conduction and diffusion. The model of directed crystallization contains in the common form a kinetic boundary condition. Dispersion equation of this problem contains a kinetic factor that is a derivative of the interface velocity with respect to temperature. This factor is contained in the expression of period dependence of eutectic pattern on interface velocity. But the dependence of interface velocity on temperature is related to kinetics of molecules addition of material to interface. Using the works by Cahn et al. [Acta Metall. 12 (1964) 1421, 8 (1960) 554], we found the dependence of the kinetic factor on parameters of kinetic theory of crystallization. In consequence, we have obtained dependences between parameters of a kinetic problem, i.e. problem that describes process of crystallization on microscopic level, and the problem of macrostructure formation.