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1.
V. A. Varlachev G. N. Dudkin Yu. F. Krechetov V. N. Padalko E. N. Shuvalov 《JETP Letters》2004,80(3):149-151
A nuclear-reactor experiment on the search for the emission of neutral pions from the neutron-induced fission of 235U nuclei has been carried out. To this end, an experimental setup for searching for the emission of π0 mesons with high sensitivity to this process has been designed and produced. This setup consisted of two Cherenkov total-absorption spectrometers for the detection and measurements of the energy of two gamma-ray photons from π 0-meson decay. The spectrometers were placed at the exits of two coaxial horizontal experimental channels. To protect the detectors from low-energy β and γ rays and neutron fluxes, 3.5-m-long water filters were situated in the channels. To reject the cosmic background, large-area scintillation counters operating in the anticoincidence mode were placed over each spectrometer. The energy and time resolution of the spectrometers, as well as the efficiency of detecting charged particles by scintillation counters, were tested on the secondary electron beam of the Tomsk electron synchrotron Sirius. Runs of measurements of the effect on the operating reactor (duration of 805 h) were alternated with runs of measurements of background on the stopped reactor (duration of 403 h). Statistical processing of the experimental results yields an upper limit of ≤5.3×10 ?12 with a 90% confidence level for the probability of the emission of neutral pions from the neutron-induced fission of 235U nuclei. This result and results of other works carried out with sources of spontaneously fissioning 252Cf nuclei show that the probabilities of the emission of π0 mesons from spontaneous fission and fission induced by fission-spectrum neutrons are equal to each other. 相似文献
2.
Lomaev M. I. Nechaev B. A. Padalko V. N. Kuznetsov S. I. Sorokin D. A. Tarasenko V. F. Yalovets A. P. 《Technical Physics》2012,57(1):124-130
Neutron emission during a nanosecond deuterium discharge formed at the nonuniform electric field is investigated. A stable
neutron yield is observed when the cathode is made of metallic plates covered by a layer of deuterated zirconium and the anode
is made of stainless steel in the form of a tube. It is shown that, when the deuterium pressure equals several Torr, neutrons
are emitted from both deuterated and deuterium-free cathodes. The influence of the anode design on the neutron yield is studied. 相似文献
3.
V. M. Bystritsky Vit. M. Bystritskii G. N. Dudkin V. V. Gerasimov A. R. Krylov G. A. Mesyats B. A. Nechaev V. M. Padalko S. S. Parzhitsky F. M. Pen’kov N. A. Ratakhin J. Wozniak 《Physics of Atomic Nuclei》2005,68(11):1777-1786
The pd reaction (pd → He + γ (5.5 MeV)) is studied in the astrophysical energy collision range of protons with deuterons using the hydrogen liner in the inverse Z-pinch configuration at the pulsed power generator MIG (HCEI, Tomsk). Fundamental characteristics of this and other light-nucleus reactions at ultralow energies are important for problems of basic physics and astrophysics. The knowledge of the energy distribution of the nuclei participating in these reactions is important due to their exponential type of dependence on the collision energy. Two experimental techniques were designed and tested for recovering the energy distribution of liner protons incident on the CD2 target by using optical detectors and ion collectors. It is shown that the combined use of these two techniques could provide relevant information on the energy distribution of the accelerated protons in the liner. The estimates of the upper limits for the astrophysical S factor and effective cross section of the pd reaction in the proton-deuteron collision energy range of 2.7–16.7 keV are obtained: $\bar S_{pd} (E_{pd} = 10.2 keV) \leqslant 2.5 \times 10^{ - 7} MeV b;\overline \sigma _{pd} (2.7 \leqslant E_{pd} \leqslant 16.7 keV) \leqslant 4 \times 10^{ - 33} cm^2 $ . 相似文献
4.
V. A. Varlachev G. N. Dudkin V. N. Padalko 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(11):1635-1639
The spectrum of γ rays from the neutron-induced fission reaction of 235U nuclei has been investigated in the energy range 10–90 MeV. The experiment was performed in the horizontal channel of a nuclear reactor. The energy spectra was measured using a single-crystal NaI(Tl) spectrometer. The data on the energy dependence of the yield of γ rays have been obtained in the energy range 10–36 MeV. The upper limit of the probability of γ-ray emission has been determined for the range 36–90 MeV. 相似文献
5.
V. M. Bystritsky G. N. Dudkin E. G. Emets M. Filipowicz A. R. Krylov B. A. Nechaev A. Nurkin V. N. Padalko A. V. Philippov A. B. Sadovsky 《Physics of Particles and Nuclei Letters》2017,14(4):560-570
The astrophysical S-factor of the reaction T(4He, γ)7Li is measured for the first time at the center of mass energy E cm = 15.7 keV, lower than the energy range of the Standard Big Bang Nucleosynthesis (SBBN) model. The experiment is performed on a Hall pulsed accelerator (TPU, Tomsk). An acceleration pulse length of 10 μs allows one to suppress the background of cosmic radiation and the ambient medium by five orders of magnitude. A beam intensity of ~ 5 × 1014 4He+ ions per pulse allows one to measure an extremely low reaction yield. The yield of γ-quanta with the energies E γ 0 = 2483.7 keV and E γ 1 = 2006.1 keV is registered by NaI(Tl) detectors with the efficiency ε = 0.331 ± 0.026. A method for direct measurement of the background from the chain of reactions T(4He, 4He)T→T(T, 2n)X→(n, γ) and/or (n, n′γ) which ends by neutron activation of materials surrounding the target is proposed and implemented in this study. The value of the astrophysical S-factor of the reaction T(4He, γ)7Li S αt (E cm = 15.7 keV) = 0.091 ± 0.032 keV b provides the choice from the set of experimental data for the astrophysical S αt -factor in favor of experimental data [4] with S αt (E cm = 0) = 0.1067 ± 0.0064 keV b. 相似文献
6.
Vnukov I. E. Kalinin V. N. Naumenko G. A. Padalko D. V. Potylitsyn A. P. 《Russian Physics Journal》2001,44(3):263-275
A simple model for calculating the contribution of diffraction of actual photons to the measured spectrum of parametric x radiation (PXR) from relativistic electrons in mosaic crystals is suggested. It is shown that the diffraction of real photons of bremsstrahlung and transition radiation in mosaic crystals whose thickness t is about 0.01 of the radiation length makes a significant contribution to the measurable emission spectrum. The spectra and angular distributions of PXR from electrons with energies 500 and 900 MeV have been measured in mosaic pyrolytic graphite crystals. It is demonstrated that with consideration of diffraction of actual photons in the mosaic crystal, including diffraction of PXR photons, all experimental data presently available agree well with the results of calculations for the suggested model. 相似文献
7.
Investigations of the effect of thermal processing in vapors of components (Se, Hg, and Te) on the magnetic susceptibility of Hg1–XMnXTe1–ySey crystals which were conducted in the temperature interval T=77–360 K indicate an increase in uniformity with respect to cluster content during annealing in Se vapor, an increase in the paramagnetism of the samples when annealed in Hg vapor, and a significant degradation of the uniformity of the samples after thermal processing in Te vapor (up to second phase formation). The obtained results are explained by transformations in the cluster and defect subsystems of the crystals taking place during thermal processing.Chernovitskii State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 48–51, May, 1993. 相似文献
8.
9.
V.A. Ivanov E.A. UgolkovaO.N. Pashkova V.P. SanyginA.G. Padalko 《Journal of magnetism and magnetic materials》2006
Spintronics materials may be classified under concentrated magnetic semiconductors, semimetals and half-metals, semimagnetic semiconductors, and dilute magnetic semiconductors (DMS). The nature of ferromagnetism, that occurs in p-type DMS with an increase in the transition metal content, is governed by the proposed kinematic exchange involving the kinetic energy gain of the heavy hole carriers caused by their hybridization with 3d electrons of impurities. The synthesis of DMS (In,Mn)Sb is proposed on the basis of hint at its TC from kinematic mechanism. The effect of the dimensionality-driven TC increase is derived for spintronics materials such as delta-doped DMS (DDMS) and DMS heterostructures. The state-of-the-art in the field of synthesis and research of “new” DMS with announced “high TC” is also outlined with particular attention to chalcopyrite-based systems. 相似文献
10.
I. E. Vnukov B. N. Kalinin G. A. Naumenko D. V. Padalko A. P. Potylitsyn O. V. Chefonov 《JETP Letters》1998,67(10):802-807
The optical diffraction radiation of ultrarelativistic electrons at the boundary of a conducting medium is observed experimentally.
Backward diffraction radiation, which, like transition radiation, is emitted at the angle of specular reflection from the
target, is detected.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 10, 760–764 (25 May 1998) 相似文献