A diamond-detector-based fast-particle spectrometer with digital signal processing

A spectrometer with digital signal processing is intended to make measurements at counting rates that are at least an order of magnitude higher than the limiting counting rate of an analog spectrometer. The tests have shown that the spectrometer operating in the maximum count rate mode compares well with the traditional analog spectrometer in such important characteristics as energy resolution, linearity, and noise immunity. The pilot version of the designed digital spectrometer was successfully used on the JET tokamak for recording energy distributions of fast charge exchange atoms with energies above 40 keV.     

On the active distances of partial unit memory codes based on LDPC codes

Partial unit memory (PUM) convolutional codes constructed from block codes make it possible to obtain convolutional codes with high correcting properties. An ensemble of binary PUM convolutional codes based on low-density parity-check block codes is introduced. This ensemble is specified by semi-infinite parity-check matrices with partial unit memory. The asymptotic bounds on a free distance and active row distances are derived for codes of the specified ensemble. It is proved that the ensemble codes have the positive slope of active row distances.     

Influence of Characteristics of Nickel Complex Compounds on the Rate of Chemical Deposition and Composition of Nickel–Phosphorus Alloy

Theoretical Foundations of Chemical Engineering - The influence of characteristics of ligands and nickel complex compounds on the rate of the autocatalytic (chemical) deposition of...     

Application of the trial-and-error method for solving the inverse radon problem for ITER neutron tomography

A method for solving the inverse 2D Radon problem for a single temporal cross section as applied to the two-aspect-angle ITER neutron tomographic detection system is described. This method allows reduction of the calculation time owing to the formation of the reconstructed image described by models that are as simple as possible in the case of a single plasma filament (a spatial density distribution of the plateau, hill, crater, and banana type). These models are reduced to the approximation of the solution in the form of a superposition of two elliptic Gaussian curves (or the sum of an arbitrary number of circular Gaussian curves).     

Protonated Nickel Bis-Glycine Chelate: Effective Precursor for Electroless Deposition of Nickel–Phosphorus Alloy

Theoretical Foundations of Chemical Engineering - The ionic equilibria in the NiSO4–H2Suc–HGly system were calculated using the Brinkley algorithm to assess the true composition of the...     

The Prospects for Using High-Speed Analog-to-Digital Converters to Analyze the Signals of Ionizing-Radiation Detectors

The potential advantages of recording digital signals from ionizing-radiation detectors are considered. State-of-the-art high-speed analog-to-digital converters operating at sampling frequencies of 400 MHz (2.5 ns) and higher with a buffer storage of up to 4 Gbyte and a data-input rate of up to 400 Mbyte/s are capable of recording continuous pulse sequences with a throughput of >10⁷ pulse/s in less than 10 s. In contrast to standard recording methods in which overlapping pulses are truncated, the recording of complete signal flows allows one to detect and resolve overlapping pulses quite well, provided they arrive within 20–40 ns of one another.     

A diamond-detector-based system for spectrometry of fast atoms on the JET tokamak

To study the evolution of the distribution function of fast ions with an ultimately high time resolution during both injection of neutrals and ion cyclotron plasma heating on the JET tokamak, we have developed a system for spectrometry of fast charge-exchange atoms, which consists of a spectrometric natural-diamond detector and a digital spectrometric channel. The main elements of the spectrometric system—the diamond detector, a noise-immune charge-sensitive preamplifier, and a fast analog-to-digital converter (ADC)—have been manufactured explicitly for use in spectrometry of fast charge-exchange atoms on the JET tokamak at high counting rates. The diamond detector that ensures the spectrometry of hydrogen atoms in the energy range 20–5000 keV is installed in the equatorial plane at an 18-m distance from the plasma axis at the end of the vacuum channel created for X-ray spectroscopy. A fast 14-bit ADC with 100-MHz sampling frequency and a 2-GB memory digitizes the preamplifier output signal. The developed digital spectrometric system can operate at a counting rate of up to ～10⁷ counts/s. Laboratory tests of the developed spectrometric system have shown that its energy resolution is no worse than the resolution of a similar analog system. In the experiments on the JET, the diamond digital spectrometric system ensures recording of the energy distributions of fast charge-exchange atoms with energies >40 keV.     

Optimizing solution composition for the chemical deposition of nickel-copper-phosphorus alloys

We have studied the possibility of obtaining nickel-phosphorus coatings doped with copper (0.5–2 wt %) by chemical deposition from weakly acidic solutions containing nickel and copper salts and sodium hypophosphite, as well as malonic, succinic, and aminoacetic acids as complex-forming and buffering components, and a lead salt as the stabilizer at pH 6.3–7.0 and a temperature of 87–97°C. The solution composition has been optimized using the method of mathematical experiment planning so as to provide the deposition at a maximum rate.