Instruments and Experimental Techniques最新文献

A diagnostic system has been developed on the gas dynamic trap (GDT) for detecting deuterium fusion products as well as X rays and γ rays produced by interactions of superheated electrons with structural elements of GDT and by capture of neutrons by nuclei of surrounding materials. The diagnostic system consists of the following three subsystems. The first subsystem is used to measure the longitudinal intensity profile of the dd-fusion reaction. It is based on diode detectors of 3.02-MeV protons and preamplifiers capable of operating with large-area diodes mounted in specially developed detector modules. The detectors are located inside the vacuum chamber of the GDT; they operate in the counting mode, which allows absolute measurements of the reaction-product flux with a time resolution of ~100 μs. Such detectors were created taking into account the operating experience of a proton detector based on an experimental diode in the GDT experiment. The second subsystem is composed of detectors developed earlier on the basis of SPM-5 plastic scintillator and a photomultiplier tube (PMT). These detectors are operated in the current mode and are intended to measure the neutron-generation intensity with a time resolution as high as 25 μs. These detectors are used jointly with the proton detectors in experiments with the additional heating to determine the contribution of γ rays and hard X rays. The third subsystem is a new neutron and γ-ray spectrometer based on a stilbene scintillator and a PMT, which was used for the first time in the experiment with deuterium plasma at the GDT facility. The detector is capable of separating particles of different types, in particular, under the operating conditions of the facility when superheated electrons are generated.

The temperature effect plays an important role in the response function and efficiency of detectors. In this study, the behavior of doped NaI (Tl) and plastic scintillators was evaluated and compared with temperature changes, in a similar condition, for the first time. The detection system uses an experimental setup consisting of a ⁶⁰Co source, NaI (Tl) detector, and a plastic scintillation detector. The results show that the recorded count rates from NaI (Tl) detector have a direct relation with temperature and lead to a 0.15%/°C error in the count rate. But in the same condition, the acquired count rates from the plastic scintillator detector were reduced with temperature increasing with a 0.57%/°C error in the count rate (inverse relation). Also, in this work, Linear and second-order polynomial regression were implemented on the recorded count rates from scintillators to compensate temperature effect. Finally, the acquired results were evaluated using the relative error (%) and diagram slope which expressed the superiority of the polynomial regression. Using this correction technique, the count rate changes reached to least and are stable with temperature fluctuations. The results of this research can be suitable for the industrial application of NaI (Tl) and plastic scintillators in level gauging, thickness gauging, and other nuclear gauging systems.

Space optical clock is an important device for future space science experiments. Inevitably, the micro-vibration level in the order of micro-g (μg) is required for ultra-stable optical reference cavity of space optical clock. However, the existing research on active vibration isolators of space optical clock is still in the laboratory development stage, and their vibration isolation control algorithms still rely on high-performance commercial real-time controllers, making it difficult to meet the application requirements for isolators of space optical clock. On the basis of the previous work, this paper describes the development an active vibration isolator that meets the experimental requirements of the space optical clock. Based on the DSP embedded vibration isolation controller, an anti-saturation control algorithm is designed, which solves the problems of high order of robust controllers, large computing resources and difficult parameter debugging. The active vibration isolation experimental system is further developed, and the experimental results validate the effectiveness of the developed active vibration isolator and anti-saturation control algorithm.

The article is devoted to the study of a methane leak detector based on absorption spectroscopy. An LED matrix with a wavelength of ~3.3 μm was used as a radiation source, where one of the methane absorption lines is located. The system is temperature stabilized. A threshold sensitivity of approximately 60 ppm CH₄ was obtained.

The equipment for studying the formation of jets of volatile liquids in a rarefied environment is described. The equipment was created on the basis of a gas-dynamic installation with high pumping capacity designed for the study of supersonic gas flows. The description and results of testing of equipment and verification of photo and video recording techniques of ethanol nozzle outflow for studying the shape and structure of liquid jets under various conditions under long flow conditions from submillimeter diameter nozzles are given.

The characteristics of neutron scintillation detectors built on monolithic and heterogeneous scintillators containing ⁶Li were studied. The detectors were tested on a thermal neutron beam and on a stand with a source of γ-quanta ⁶⁰Co. To process the signals received from the detector with a monolithic scintillator, three different γ-radiation discrimination algorithms were used: registration of pulses at a constant threshold and selection according to the pulse shape using two digital signal separation methods: charge integration and pulse duration measurement. For a homogeneous scintillator, pulse shape selection methods work approximately the same when separating thermal neutrons and γ-quanta and are significantly inferior to the method of registration at a constant threshold. In this case, the quality of the n/γ separation is worse than the result obtained with a heterogeneous scintillator when recording at a constant threshold. The purpose of the work is to compare the results of using digital methods for discrimination of gamma-quanta with the results obtained using heterogeneous scintillators.

A source of fast and epithermal neutrons was constructed on the Prometheus medical accelerator at an energy of 200 MeV, and measurements of the yield of fast and epithermal neutrons were made using the BDMN-100 detector. A heavy NaI target was used to obtain fast neutrons. Based on the five developed different protective materials from neutrons, a channel of fast and epithermal neutrons was formed. Using the BDMN-100 neutron detector, the dose profiles at the outlet of the neutron channel were measured. The neutron source has a possible application for research work on the creation of new radiopharmaceuticals. Fast neutrons can be used for remote therapy and reliability control of electronic boards and microcircuits. The neutron beam can also be used to study biological objects and cells.

The chopper control system which is synchronized by the White Rabbit timing network is designed and implemented to meet the requirements of the chopper of ion source for the High-Intensity Heavy Ion Accelerator Facility (HIAF). The hardware system consists of timing modulation controller, waveform acquisition, parameter setting, and remote control of the chopper power supply. The software includes low-level drivers and top-level applications which are based on Experimental Physics and Industrial Control System (EPICS). The combination of hardware and software completes the interaction of timing messages with the White Rabbit network, waveform acquisition, the setting of timing modulation parameters in several running modes, and remote control of the chopper power supply, etc. The test results show that the system can achieve timing modulation with a resolution of 8 ns and waveform acquisition of embedded EPICS IOC (input/output controller) at a 125 MHz sample rate. The design, implementation, and test of the chopper control system are described in this paper.

The described system is designed to measure the field map of pulse bending magnets of accelerators. As an example, the magnet, which is an element of the particle bypass channel from the booster to the nuclotron of the NICA complex, which is being created at JINR, is chosen. Analyzing the capabilities of various methods in pulsed-field measurements and requirements for measurement errors in bending magnets better than 10^–3 have led to the development of a method based on the use of Hall probes. The article substantiates the developed method, describes its capabilities, and the hardware developed for conducting measurements. In the conclusions, results of measurements of pulsed bending magnets of the booster–nuclotron channel are presented and analyzed.

The article proposes a methodology for creating a coupling element for a whispering gallery mode microresonator based on a polished optical fiber that does not require the use of expensive components and technologies. It is demonstrated that the proposed coupling element provides coupling efficiency up to 30% and allows for control of the polarization state of the input illumination into the microresonator.