Axial structure of DC glow discharge negative glow in nitrogen

We registered axial profiles of electron temperature, plasma potential and concentration of the direct current glow discharge in nitrogen at different gas pressure and discharge current values. We observed that in a broad range of experimental conditions the plasma concentration experiences 15…16 times decrease along the negative glow length. Maximum values of plasma concentration and electron temperature are registered at the cathode end of the negative glow, and the electric field strength is small. On leaving the cathode the plasma concentration and electron temperature in the negative glow are decreasing, here a region with a negative field may also form.Осевые профили температуры электронов, потенциала и плотности плазмы тлеющего разряда постоянного тока в азоте измерены методом ленгмюровского зонда при различных значениях давления газа и разрядного тока. Показано, что в широком диапазоне экспериментальных условий на длине отрицательного свечения плотность плазмы уменьшается в 15-16 раз. Максимальные плотность плазмы и температура электронов наблюдаются на катодном конце отрицательного свечения, а напряженность электрического поля мала. При удалении от катода плотность плазмы и температура электронов в отрицательном свечении уменьшаются, здесь же может сформироваться область с отрицательным полем.Осьові профілі температури електронів, потенціалу і густини плазми тліючого розряду постійного струму в азоті виміряні методом ленгмюрівського зонда при різних значеннях тиску газу і розрядного струму. Показано, що в широкому діапазоні експериментальних умов на довжині негативного світіння густина плазми зменшується в 15-16 разів. Максимальні густина плазми і температура електронів спостерігаються на катодному кінці негативного світіння, а напруженість електричного поля мала. При віддаленні від катода густина плазми і температура електронів в негативному світінні зменшуються, тут же може сформуватися область із негативним полем

Phase separation in the two-dimensional electron liquid in MOSFETs

We show that the existence of an intermediate phase between the Fermi liquid and the Wigner crystal phases is a generic property of the two-dimensional pure electron liqd in MOSFET's at zero temperature. The physical reason for the existence of these phases is a partial separation of the uniform phases. We discuss properties of these phases and a possible explanation of experimental results on transport properties of low density electron gas in Si MOSFET's. We also argue that in certain range of parameters the partial phase separation corresponds to a supersolid phas e discussed in [AndreevLifshitz].Comment: 11 pages, 3 figure

Spin injection into a ballistic semiconductor microstructure

A theory of spin injection across a ballistic ferromagnet-semiconductor-ferromagnet junction is developed for the Boltzmann regime. Spin injection coefficient $\gamma$ is suppressed by the Sharvin resistance of the semiconductor $r_N^*=(h/e^2)(\pi^2/S_N)$, where $S_N$ is the Fermi-surface cross-section. It competes with the diffusion resistances of the ferromagnets $r_F$, and $\gamma\sim r_F/r_N^*\ll 1$ in the absence of contact barriers. Efficient spin injection can be ensured by contact barriers. Explicit formulae for the junction resistance and the spin-valve effect are presented.Comment: 5 pages, 2 column REVTeX. Explicit prescription relating the results of the ballistic and diffusive theories of spin injection is added. To this end, some notations are changed. Three references added, typos correcte

Measurement of RudsR_{\text{uds}} and RR between 3.12 and 3.72 GeV at the KEDR detector

Using the KEDR detector at the VEPP-4M $e^+e^-$ collider, we have measured the values of $R_{\text{uds}}$ and $R$ at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than $3.3\%$ at most of energy points with a systematic uncertainty of about $2.1\%$. At the moment it is the most accurate measurement of $R(s)$ in this energy range

New precise determination of the \tau lepton mass at KEDR detector

The status of the experiment on the precise $\tau$ lepton mass measurement running at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the $\tau^+\tau^-$ cross section behaviour around the production threshold. The preliminary result based on 6.7 pb$^{-1}$ of data is $m_{\tau}=1776.80^{+0.25}_{-0.23} \pm 0.15$ MeV. Using 0.8 pb$^{-1}$ of data collected at the $\psi'$ peak the preliminary result is also obtained: $\Gamma_{ee}B_{\tau\tau}(\psi') = 7.2 \pm 2.1$ eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton Physics, Tau0

The effect of nanosecond ultrawideband electromagnetic radiation on xenogeneic erythrocytes

Experiments were the intention to investigate the effect of short-pulse ultrawideband electromagnetic radiation on biological objects. An insulated rod antenna excited by a high-current electron beam (E ~ 0.5 to 1.0 MeV, I ~ 4 to 10 kA, τ ≈ 15 ns) served as a radiation source. The objects to be irradiated, i.e., erythrocytes of both donors and diabetics, were put in the regions with field intensity varying from 100 to 1000 V/cm. The effect of radiation on the lifetime and shape of erythrocytes on the permeability of erythrocyte membranes for the penetrating nonelectrolyte (1 M glycerin) and the state of intracorpuscular hemoglobin was investigated by the methods of small-angle light scattering, UV spectrometry and phase-contrast microscopy

Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)

The products of the electron width of the J/\psi meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron-positron collider. The results are \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV, \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV. Their combinations \Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100) keV, \Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve theaccuracy of the leptonic and full widths and test leptonic universality. Assuming e\mu universality and using the world average value of the lepton branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure