Nuclear spin echo in magnetics with inhomogeneous hyperfine and quadrupole interaction

Additional spin-ocho signale from quadrupole nuclei with I=7/2 (Co⁵⁹ nuclei in Co and Fe−Co thin films) were investigated. It has been shown, that the time dependence of the additional ocho signals, arising at the time moments 2nς reflect quadrupole interaction inhomogenety.     

Effect of substituent distribution on water solubility of O-methylcellulose

The effect of substituent distribution on the water solubility of O-methylcellulose (MC) was re-examined to elucidate the lower limit of the degree of substitution (DS) in water-soluble MC. To this end, a series of 2,3-MCs which are regioselectively substituted at the C-2 and C-3 hydroxyl groups were prepared by homogeneous methylation. It was found that the lower limit for the DS value of water-soluble 2,3-MC was almost the same as that for MCs having even distributions of substituents along the cellulose chain as well as in the anhydroglucose units. This revised version was published online in August 2006 with corrections to the Cover Date.     

First results of investigation of radiation from positrons in a crystalline undulator

Radiation emitted by positrons moving in a periodically deformed crystal has been experimentally observed for the first time. Radiation spectra have been measured in a wide energy range. Experimental evidence has been obtained for an undulator peak in a radiation spectrum, which is qualitatively consistent with calculations. Crystalline undulators ensure an equivalent magnetic field of 1000 T and a period in the submillimeter range and can therefore be used to generate x-ray and gamma radiation that is a hundred times harder than radiation in usual undulators.     

X-ray semiconductor (CdTe) spectrometer for solar flare and preflare studies

This paper describes the main parameters of an instrument for X-ray flux measurement and solar flare and preflare spectrum registration. The nontraditional CdTe semiconductor detector was space qualified and has sensitivity 0.5 cm², energy region 3–30 keV, and energy resolutions ～ 1.3 keV for 5.9 keV and ～ 10% for 22.1 keV.     

Determination of Gases Using Polymer-Coated Semiconductor Sensors

Comparative characteristics of Pt-doped SnO₂ sensors with coatings of different depths were studied. It was found that the application of a thin membrane layer enhanced the selectivity and improved the stability of the sensor, as well as its sensitivity in detecting hydrogen in the air.     

Paramagnetism in copper monoxide systems

This paper describes the problem of high-temperature superconductivity related to investigations of the magnetic susceptibility, electron paramagnetic resonance, and O Kα x-ray emission spectra of samples from the following systems based on copper monoxide: CuO-Cu, CuO-Cu₂O and CuO-MgO. In all these systems, thermal processing results in a paramagnetism which is not observed in the individual components of these systems before they are processed. O Kα spectra of the interface of a Cu-single-crystal CuO film structure indicate the presence of not only Cu²⁺ but also Cu¹⁺ ions in the layer of CuO in close contact with Cu. Possible reasons for the appearance of paramagnetism in these systems are discussed. It is proposed that a paramagnetic layer at the contact between the antiferromagnetic copper monoxide and the other copper-oxide phases or with copper could be the cause of the impurity metastability observed previously in the high-T _c superconducting phase. Fiz. Tverd. Tela (St. Petersburg) 40, 295–298 (February 1998)     

Angular distributions in the dimuon hadronic production at 150 GeV/c

From π^- interactions at 150 GeV/c on a heavy target, we present the final analysis of the dimuon decay angular distribution in the mass interval 4.5–8.5 GeV/c². Results are presented and discussed in various reference frames and are also given in terms of the density matrix elements. Finally the possible contribution of higher-twist effects at largex ₁ is discussed; we find that our data are not compatible with higher twist contributions as proposed by the Berger and Brodsky Model.