Instruments and Experimental Techniques最新文献

The design of a prototype front-end card (FEC) of the ALICE/CERN photon spectrometer (PHOS) is described. The development of the new FEC is associated with an increase in the luminosity of the Large Hadron Collider beams and the need to improve the accuracy of time-of-flight measurements for better identification of detected particles. The available PHOS FEC does not meet the new requirements and must be replaced according to the PHOS upgrade plan. The improvement of the PHOS FEC measurement characteristics is achieved by measuring the flight time instead of processing the digitization codes of the photodetector waveform offline. The FEC prototype contains eight measuring channels and all the functional units needed for operation in the PHOS spectrometer. The functional units are described. The FEC prototype characteristics measured in the laboratory and on the electron component of secondary particle beams at the PS proton synchrotron (CERN) in the momentum range of 1−10 GeV/c are presented. Based on the results obtained, it is concluded that the FEC prototype fully meets the requirements for the FEC of the upgraded PHOS. Based on this design, the development of a full-scale PHOS FEC with 32 measuring channels has been started.

A polarization-modulation method for determining the pitch angle of an aircraft using emitted horizontally polarized beacon signals is considered. The polarization modulator placed in the microwave channel of the airborne receiving antenna is a Faraday rotator for the polarization plane of received beacon signals. The pitch angle is determined by the second-harmonic phase of the polarization-plane rotation frequency, which is contained in the envelope spectrum of the receiver output signal. A prototype of the experimental setup implementing this method is described. Results of aircraft pitch angle measurements are presented, and the measurement accuracy is estimated.

A binary gas-mixture composition sensor is described using the dependence of the velocity of sound in a gas on its molecular weight and an adiabatic index using an acoustic resonator. For analysis of the mixture composition, one of the gases must be available in a pure form. In this case, the measurement error is no worse than 10^–4. A mixture with a known composition can also be used as a reference one.

This paper presents a technique and an experimental setup that implements it for the optical diagnostics of pulsed plasma initiated by YAG:Nd³⁺ laser radiation in a laser-controlled high-voltage gas switch, which is used as a primary switch of a RADAN-type high-current high-voltage pulsed electron accelerator–generator. The studies were performed in a natural atmosphere. The first results of measurements of the dynamics of the laser-radiation absorption coefficient in a plasma produced using this installation. These data indicate the implementation of the conditions for the nonlinear absorption of laser radiation by plasma at excitation energy densities higher than 240 J/cm². They will make it possible to develop recommendations for selecting the gas-gap triggering parameters in order to minimize jitter.

The article presents the results of studies into the repetitively pulsed formation of aluminum, chromium, and titanium ion beams of submillisecond duration based on a plasma generated by a continuous vacuum arc discharge. High pulse power density in the ion beam is achieved due to the ballistic focusing of ions using a single-electrode mesh extractor in the form of a part of a sphere. To purify the ion beam in the region of its crossover from the droplets of the vacuum arc plasma, the method based on the solar eclipse effect is used. The features and regularities of generating ion beams of three metals at pulse durations of 450 µs, accelerating voltage up to 40 kV, with pulse power density exceeding 10⁵ W/cm² have been studied. It has been established that stable formation of repetitively pulsed high intensity metal ion beams of submillisecond duration based on vacuum arc plasma is achieved due to the ion-electron emission compensating for the escape of plasma electrons into the accelerating gap.

The design of a setup intended for studying the interaction features of vortex flows generated by capillary-gravity waves on the surface of liquid helium ⁴He in normal and superfluid states with injected charges is described. An example of the results of studying the influence of vortex flows generated by waves in a layer of superfluid helium He-II with a depth of 2.5 cm at temperatures T ≥ 1.5 K for the distribution of negative ion currents across five segments of a receiving collector immersed in liquid is given.

The article describes a prototype sensor for measuring the velocity vector of micrometeoroids and space debris particles based on grid metal electrodes. The results of an experimental study and proposals for further modification of the measurement system are presented.

The results of the first experiments on generation of ions of several light and heavy chemical elements using a new laser-plasma ion source, which is included in a heavy-ion injector of synchrotrons that is currently being developed at the NRC Kurchatov Institute, are described. This ion source is based on the FOCUS pulsed–periodic CO₂ laser system and includes a vacuum target chamber with a drift space and a high-voltage system for the extraction and formation of a charged particle beam. The design of the setup and the characteristics of laser radiation and Al, Fe, and Bi ion beams are presented. The high efficiency of this ion source in producing intense ion beams of a wide range of elements and the ability to quickly switch the ion type can be successfully used in injectors of synchrotrons for complex research and testing the radiation hardness of electronic components.

A detector of pulsed neutron radiation of the activation type with continuous recording of registered pulses of secondary electrons in real time is described. As activation material, 0.3-mm-thick silver foil is used. An industrial grade SBM-19 gas-discharge Geiger–Muller counter, sensitive to hard beta and gamma radiation, was used to register secondary electrons. The recording interval of the accumulated number of registered secondary electron pulses is 10 s. The circular memory buffer used to record the secondary electron pulses is 16 MB, providing continuous recording for 2.5 years. A modern LiSOCl₂ galvanic cell with a voltage of 3.6 V and a capacity of 2.1 A h was used as a power source for the pulsed neutron radiation detector. The estimated operating time without replacing the battery is 5 years.

This work describes and verifies a method for measuring the intensity in the cross-section of a molecular beam. A scheme has been proposed to take into account the background gas’s influence and was tested. Measurements in argon and nitrogen flow demonstrated a direct dependence on the shape, width, and average size of the transverse profile of the molecular beams under conditions of supersonic jet condensation on the Mach number at the entrance to the skimmer.