Volume 60, Nº 5 (2017)

The aim of this review is to provide, whenever possible, a complete picture of the evolution of methods and systems for data readout, acquisition, and transfer at experimental nuclear physics setups over recent years for specialists who use electronics in experiments or measurements in applied research. In view of the large body of information, this review is divided into two parts; medium (according to the contemporary measures) and large systems for nuclear physics setups and accelerator experiments are considered in this, the second, part. Both parts have a common classification table and common numbering of cited papers and figures.

The VEPP-4M storage ring has been designed for experiments with colliding electron−positron beams, a synchrotron radiation beam, and extracted γ-ray beams at energies of 1−5 GeV. A correct equilibrium beam orbit must be kept in the storage ring to maintain the required experimental conditions. A beam position monitor system is used for this purpose. It includes 54 beam position monitors, monitor signal-processing modules, and synch signals distributors. In 2013–2016, new signal processing modules with a high time resolution were developed and installed at the VEPP-4M storage ring. These have two main advantages over the old modules. First, the new modules allow separate position measurements of electron and positron bunches at an interval between the bunch signals as long as 18 ns. Second, they are able to perform fullfledged turn-by-turn beam position measurements, which is very important for adjustment of the storagering parameters. Turn-by-turn beam position measurements can be performed during injection of a new beam, beam kicking, beam loss, or at an arbitrary instant of time. The structures and main features of the new modules are described, the measurement accuracy is analyzed, and some results of their operation at the storage ring are presented.

Photonuclear methods used earlier in experiments at electron accelerators have been adapted for femtosecond pulsed lasers. In particular, the problem of measuring wide electron spectra under conditions of a high counting rate and, hence, a high probability of pulse pileup has been solved. To provide long-term stability of electron beams from plasma, a magnetic spectrometer combined with a magnetic-induction sensor has been developed. This spectrometer is capable of measuring the electron-beam characteristics in each ultrashort laser pulse. The results of the experiments carried out with the femtosecond laser system at the International Laser Center of the Moscow State University are presented.

The design and results of studies of a fiber-optic-link-based transmission system for transmitting analog signals of nanosecond duration using an external modulation of radiation are presented. Experimental studies that were performed at the Dukhov All-Russia Research Institute of Automatics demonstrated a method for determining the transmission function of an intensity modulator, which is based on the Mach–Zehnder interferometer, simultaneously with the signal transmission. The dynamic range of the system with one intensity modulator is ~70 when recording a single-shot process. The dynamic range of the transmission system with two modulators that form two information channels exceeds 200 with a bandwidth that exceeds 4 GHz and a signal-to-noise ratio of at least 5 for the minimum recorded signal.

Based on the principle of vacuum arc discharge under magnetic field, a novel plasma cathode electron- beam source was designed. This device can be used to regulate electron-beam current so as to improve the extrication efficiency of electron beam through regulating the exciting current and thus controlling the density of the plasma electron beam source. Experiment results showed that the arc current change with the magnetic field, to be specific, the stronger the magnetic field was, the smaller the arc current will be, then the density of plasma that penetrated the anode hole to serve as electron beam will be higher. From this experiment, it can be seen that under the condition of 10⁻³ Pa air pressure, 100 V arc voltage, 30 A exciting current, we can obtain the electron beam of 40 ms pulse width, and 828 mA current in the extraction rate of 6.1%.

A magneto-optical setup for studying the time evolution of nanoscale domain-wall displacements of domain walls in magnetic films with a regular domain structure is described. Methods for spatial filtering of the output optical flux using the Fourier image of the domain structure and the impulse transient response in the real-time mode are applied in the setup. This allowed an increase in the sensitivity to domain-wall displacements of up to 5 nm and registration of their evolution with a temporal resolution of 1 ns.

Inorganic scintillators for use in radiation monitoring devices were investigated. The detection threshold, which is the key characteristic of a γ-ray monitor, was evaluated. The possibility of calculating the effective thickness of a scintillator based on the background characteristic of the detector was shown.

The Ryabina atmospheric electric-field meter is described. Results of its comparative tests are presented, which demonstrate that it is superior to its foreign analog, that is, the EFM550 electric-field meter (from Vaisala, Finland), in a number of parameters. The dynamic range of the meter is ±30 000 V/m, the discreteness of measurable values is 1 V/m, and the measurement rate is 10 s^–1.

A method is described that allows the synthesis of denser samples of a nematically ordered aerogel from commercial Nafen with the effective density of 72 mg/cm³. The method is based on the drying of Nafen pre-immersed in a liquid (water, ethanol, pentane, or liquid nitrogen). The density of the final product is measured as a function of the surface-tension coefficient of the liquid filling the sample.

A device is proposed for the formation of a gas-discharge plasma stream with a sinusoidal distribution of the charged-particle density over the stream cross section, which is achieved by using wavy shapes of the anode and cathode surfaces that are placed coaxially relative to each other at the distance λ_e < h < 3λ_e, where λ_e is the mean free path of an electron in the gas-discharge plasma stream. The anode is a stainless steel grid with mesh dimensions of 1 × 1 mm. The aluminum cathode is 120 mm in diameter and 50-mm thick. The device provides a discharge current of up to 0.6 А at a controlled voltage at the electrodes in the range of 0.21–0.7 kV. In this case, plasma streams propagate to a distance of up to 50λ_e beyond the limits of the electrodes.

This paper presents the results of modernizing an ultrahigh-vacuum multifunctional apparatus that allows one to obtain semiconductor or metallic nanostructures in a single technological cycle and to investigate their optical and magneto-optical properties in a temperature range of 85–900 K. The capabilities of the developed system were demonstrated based on the example of studying the temperature dependence of the bulk Si permittivity via spectral ellipsometric measurements.