[en] Authors of paper (1) have suggested developing FEL which uses hot ballistic electrons in a superlattices under the assumption that the superlattices is short, equivalently, one would be dealing with the motion of electrons within a single band. The single-band model is valid if the reflection coefficient of the superlattices less unit. In the present paper analyze a open-quote hotclose quotes-ballistic-electron laser under the condition that there is a Bragg reflection of electrons from the superlattices or, equivalently, under the condition that the energy of a hot electron is close to the bottom of one of the quasibands of the superlattices. In this case the interaction of the electron with the superlattices is not weak and the reflection coefficient is approximately unit. If the photon energy is greater than the width of the quasigap open-quotes verticalclose quotes transitions can occur between the edges of neighboring quasibands, corresponding to a stimulated emission. If the lower quasiband is not filled, there would be essentially no absorption. The IR gain in the area 0.1-0.4 eV is approximately 100 %. The possibility of experimentally observing the effect is discussed for realistic values of the parameters of the superlattices and of the injected electron beam

[en] THE beam of open-quotes hotclose quotes ballistic electrons which were first obtained experimentally in (1) is considered when passing through the heterostructures consisting of two potential barriers in barriers in the presence of FEL tuning in infra-red region. In the presence of the first barrier the electron beam in the FEL electromagnetic field can either absorb or emit the field quanta. The initial electron beam may split into states n=1 (absorption of one quantum), n=0 (the beam energy unchanged), and n=-1 (emission of one quantum). The interference of the states with n=0, n=1 and n=0, n=1 results in the initiation of two traveling modulation waves at electromagnetic frequency w. Beats between these waves in the region of the of their overlapping lead to a periodic dependence of the modulation from w. It has been found that the spontaneous coherent radiation (SCR) intensity oscillates with the period depending on FEL frequency w. It is possible to increase or to decrease the spectral intensity of SCR varying w. The suggested idea of modulation on the first barrier of heterostructures and the radiation of modulated electron beam on the second barrier is a scheme of an quantum optical klistron in infra-red region

[en] A possibility of applying surface muon beam for accurate measurement of π⁺- and K⁺-meson lifetime is shown. Π⁺-or K⁺-mesons produced in proton-nucleus interactions are stopped in the same meson-forming target. During proton microbunch duration (5 ns) π⁺-and K⁺-meson accumulation takes place, and in the intervals between microbunches (T₀=75 ns)-their decay into neutrinos and monoenergy μ-mesons. At the expence of ionization losses in the target material muons escaping from the target have momenta from 0 to 29.8 MeV/c for π→μν decay (the target thickness being ∼12 g/cm² of copper, uranium). Time distribution of the muons selected by magnetic spectrometer relatively to the reference signals linked with a certain phase of HF-accelerator generator high-frequency sinusoid and thus specifying the moments of proton transit through the target, was measured in the experiment. The results obtained are presented, comparison to measurements by other authors using other methods is made

[en] The interaction between nonrelativistic electrons and a standing electromagnetic wave is considered. The modulation amplitude of an electron current in the field of standing or running electromagnetic waves is calculated by quantum theory. An expression for the intensity of spontaneous coherent emission is obtained

[en] An anisotropic irregular semiconductor is under consideration. It is believed that the effective parameter of the interaction-lambda-which determines electron coupling is less or about 0.5. The Eliashberg integral equation system is solved for T→Tsub(c). A simple analytic expression is obtained for Tsub(c). The character of a varying critical temperature in superconductors with impurity atoms is analyzed in detail. The dependence of the critical temperature on parameters describing the phonon spectrum of an impurity system is investigated. The existence of impurity modes with quasilocal and local frequencies in the phonon spectra can lead both to relatively small and to rather noticeable variations in Tsub(c). The first case is typical of the situation when an impurity atom is practically an isotopic defect. If an impurity atom is very heavy (Msub(I)<< Msub(o), where Msub(I) - an impurity atom mass, Msub(o) - a matrix atom mass, the appropriate relative correction delta Tsub(c) to Tsub(c) will be negative, and delta Tsub(c) approximately clp/Msub(o)/Msub(I). For a light defect delta Tsub(c) is positive, however, delta Tsub(c)(<=)c. The second case is realized when an impurity atom is abnormally weakly (γ₁<<γ₀) or strongly (γ₁ >>γ₀) coupled with matrix atoms. A sharp decrease in the effective force constant γ₁ for an impurity atom results in the growth of delta Tsub(c): delta Tsub(c) approximately cγ0/γ₁(lambda - μsup((0)). On the contrary a rise in the γ₁ value requires a negative correction to Tsub(c), and delta Tsub(c) approximately c/(lambda - μsup((0)), where c - an impurity concentration, μ - matrix element of the Coulomb screened interaction averaged over the Fermi surface and multiplied for the density of normal electron states on the Fermi level. Comparison with experimental data is made. A qualitative description of the Tsub(c) change due to the impurity presence is given for a set of solutions. There is a satisfactory quantitative agreement between calculated and experimental values of delta Tsub(c)

[en] The paper describes a time-of-flight method for measuring the mean pulse, the spread over the pulses, and the composition of the secondary particle beams based on the study of the temporal structure of the synchrocyclotron beam. The difference is measured between the time of flight of particles of different mass (e⁺, π⁺, p, D, T, ³He) over the distance from the target to the magnetic channel outlet. To increase the accuracy of time-of-flight measurements, they used amplitude discrimination of signals from the counter, while the time scale of the time-of-flight spectrum was calibrated by the temporal structure of the accelerator beam, the period of which is known to a high degree of accuracy

[en] Differential cross sections for charged pion production in the pΑ→π X reaction have been measured at a proton kinetic energy of 1 GeV with a relative accuracy of 2-5% for the following targets: ¹H, ²D, ¹⁰B, ¹¹B, ¹²C, ¹⁶O, ²⁴Mg, ²⁵Mg, ²⁶Mg, ²⁷Al, ⁶⁴Cu, ¹¹⁶Sn, ¹²⁴Sn, ¹⁸¹Ta, ¹⁸⁴W and ²⁰⁸Pb. The measurements were performed with the help of two independent magnetic spectrometers with an angular acceptance of ΔΩ ≅ 0.01 sr. The momentum resolution was equal to ΔP/P = 1.4% in the range P = 200-950 MeV/c at θ 0⁰ and ΔP/P = 3% in the range P = 75-600 MeV/c at θ = 57.8⁰. The absolute normalisation of the cross sections was carried out using recent LNPI data on dσ/dω for the π⁺d→pp reaction. The contribution of various mechanisms to the inclusive pion spectra is discussed. (author)

[en] Differential cross sections of elastic π⁺p scattering at energies of incident π-mesons of 442, 490, 530, 560, 600 MeV were measured along with those of π^-p scattering at energies of 425, 465, 490, 530, 560, 600, 640 MeV. Data were obtained in the angular range of THETAsub(π)* = 40-176 deg which had characteristic accuracy of 2-5%. The experiment was made on π-meson channel of a synchrocyclotron. The measurements were carried out using a 10-channel hogoscopic installation. Each hodoscope channel switched on the coincidence with the telescope of monitor counters, performed a simultaneous registration of protons and π-mesons escaping from the target at the angles corresponding to the kinematics of elastic πp scattering. The experimental installation is characterized by the usage of the time-of-flight technique in each hodoscope channel. Isospin boundaries for cross sections of the π^-p → π⁰n recharge were calculated based on the data obtained. It is shown that recharge cross sections for large scattering angles are grouped near the lower boundary, and at energies more than 490 MeV they lie outside the region permitted by isotopic invariance. The comparison with predictions of various phase analyses is made, and it is shown that neither of the existing phase analyses may satisfactorily discribe the whole totality of new data. The results of the experiment together with data on elastic π^+-p scattering for lower energies, which have a high accuracy, are a systematic interacoordinated collection of precise data which are the basis for a new phase analysis of πp scattering in the range of Psub(33-), Psub(11-), S₁₁ and D₁₃ resonances

[en] Differential cross sections for π⁺p and π^-p elastic scattering have been measured at 12 energies in the region 277-640 MeV. The data were obtained in the angular range THETAsup(*)π = 40⁰-176⁰, with a typical accuracy of 2-5%. The results for 288 MeV and 292.9 MeV are in good agreement with the data of Bussey et al. Using the data obtained, isopin bounds have been calculated for the charge-exchange scattering. It is shown that the charge-exchange cross sections at large angles are grouped near the bottom isospin limit, and at energies larger than 490 MeV they lie beyond the region allowed by isospin invariance. The comparison was carried out with the predictions of different phase-shift analyses. It is shown that the existing phase-shift analyses do not describe all the set of the new data. A new energy-independent phase-shift analysis has been carried out at 12 energies in the region 240-700 MeV. (orig.)

[en] The biological response on the proton irradiation was investigated at Gatchina synchrocyclotron. The frequency and the intensity of the beam were changed in such a way that the total dose for a certain period of time was preserved constant. The irradiated objects were logarithmically growing mice tumore and DNA-solutions. Our experiments showed that the radiation dose per beam pulse of accelerator fine structure was the main factor affected the relative biological responce. 2 refs