Under consideration is the influence of various crushing techniques on the particle-size distribution and selectivity of dissociation of basic mineral components in the composition of Dalnegorsk ...complex ore under pretreatment. Distribution of basic elements per size grades is determined in crushing feed and in products of magnetic separation and flotation. Conditions of preparation and separation of disintegration products are described. The authors illustrate the change in the dissociation selectivity criterion in jaw crushing and in disintegration in a press to prepare different-size ore for processing by magnetic separation and flotation.
The authors have determined the causes of drop in performance of induced block caving using fans of blastholes 105 mm in diameter and single blastholes 250 mm in diameter, as well as the sources of ...increased drilling cost and expansion of start-up time of production blocks in Abakan underground mine. Alternatives of improvement in drilling efficiency under current conditions are discussed.
Studies on the steering of particle beams using channeling in aligned bent crystals have been performed at IHEP for many years. Different types of extraction schemes with bent crystals and technical ...equipment have been developed for experiments to test new crystal devices and to study beam collimation processes. A special apparatus has been designed to control the crystal extraction system. In this article, we describe the crystal devices and in-vacuum goniometers, the beam diagnostic tools (intensity and profile measurements), and the beam feedback system.
Recently studies are started on the application of volume reflection of particles in crystals for the steering beams (for extraction and collimation of a circulating beam in accelerators). Volume ...reflection is more efficient than channeling, but requires amplification of the deflection angle by applying multicrystals. The report discusses two new applications of multicrystals made like multistrip structures: (i) the property of effective deflection of particle beam was used to protect the septum magnets of the U-70 in the process of extraction of the proton beam with energy of 50 GeV; (ii) the possibility of generation of gamma radiation was studied in the secondary electron beam with energy of 7 GeV. In both cases, promising preliminary data were obtained.
In view of the successful experience in the generation of pion and kaon secondary beams using a focusing crystal, it has been proposed to build at the U-70 accelerator a new-type channel of secondary ...particles that does not consume electric power. It has been shown experimentally that an extraction septum magnet can be protected from radiation by applying a multistrip crystal device through current septum shadowing by the crystal that involves the bulk reflection regime for the deflection of particles. The listed applications of crystals are novel in the world practice with accelerators.
A radiation source based on the emission of electrons and positrons moving in a short bent crystal has been recently discovered. The emission of particles is due to oscillations of their trajectories ...near the point of reflections, where trajectories approach a tangent to bent atomic planes. In the experiment performed with the secondary electron beam of the U70 accelerator, it has been shown that the emission intensity can be increased by using a sequence of oriented bent crystals. Passing through six 2.5-mm-long silicon crystals, 7-GeV electrons lose on average 2.0 GeV on emission. This value is several times larger than that in an amorphous medium. Thus, an intense source of radiation has been demonstrated with prospects of application at accelerators.
It has recently been realized that the focusing of high-energy particle beams at a distance of about 1 cm is promising. A new idea is proposed in this work to focus the beam at a short distance by ...using a bent plane–parallel silicon plate whose side edges are rotated at a small angle with respect to crystallographic planes. At the U-70 accelerator (IHEP, Protvino), a 50-GeV proton beam has been focused to a narrow line with a width of no more than 30 μm at a distance of 17 cm.
The carbon ion +6C beam with energy 25 GeV nucleon was extracted by bent crystal from the U-70 ring. The bent angle of silicon crystal was 85 mrad. About 2×105 particles for 109 circulated ions in ...the ring were observed in beam line 4a after bent crystal. Geometrical parameters, time structure and ion beam structure were measured. The ability of the bent monocrystal to extract and generate ion beam with necessary parameters for regular usage in physical experiments is shown in the first time.
A beam of six-charged carbon ions with an energy of 24.8 GeV/nucleon is extracted from the U-70 synchrotron by means of a silicon crystal bent through 85 mrad. A total of 200000 particles are ...observed in beamline 4a upon forcing 10
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circulating ions to the crystal. The geometrical parameters, timing structure, and composition of the beam have been measured. It has been shown for the first time that, using a bent single crystal, an ion beam with required parameters can be extracted from the accelerator ring and formed for regular use in physics experiments.
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