Electron-deuteron scattering in the equal-time formalism: beyond the impulse approximation

Using a three-dimensional formalism that includes relativistic kinematics, the effects of negative-energy states, approximate boosts of the two-body system, and current conservation, we calculate the electromagnetic form factors of the deuteron up to Q^2 of 4 GeV^2. This is done using a dynamical boost for two-body systems with spin. We first compute form factors in impulse approxmation, but then also add an isoscalar meson-exchange current of pion range that involves the gamma-pi contact operator associated with pseudovector pi-N coupling. We also consider effects of the rho-pi-gamma meson-exchange current. The experimentally measured quantities A, B, and t20 are calculated over the kinematic range probed in recent Jefferson Laboratory experiments. The rho-pi-gamma meson-exchange current provides significant strength in A at large Q^2 and the gamma-pi contact-term exchange current shifts t20, providing good agreement with the JLab data. Relativistic effects and the gamma-pi meson-exchange current do not provide an explanation of the B observable, but the rho-pi-gamma current could help to provide agreement if a nonstandard value is used for the tensor rho-N coupling that enters this contribution.Comment: 15 pages, 10 figures. (v2) Added references on rho-pi-gamma current as well as comparison to recent Novosibirsk data on T20. Implemented \includegraphics in place of \BoxedEPSF. (v3) Modified in order to clarify the nature of the boost we implemented for particles with spin. Other minor changes. Version to be published in Physical Review

Calculation of thermal parameters of SiGe microbolometers

The thermal parameters of a SiGe microbolometer were calculated using numerical modeling. The calculated thermal conduction and thermal response time are in good agreement with the values found experimentally and range between 2x10$^-7$ and 7x10$^-8$ W/K and 1.5 and 4.5 ms, respectively. High sensitivity of microbolometer is achieved due to optimization of the thermal response time and thermal conduction by fitting the geometry of supporting heat-removing legs or by selection of a suitable material providing boundary thermal resistance higher than 8x10$^-3$ cm$^2$K/W at the SiGe interface.Comment: 11 pages, 6 figure

ЭЛЕКТРОФИЗИЧЕСКИЕ И ФОТОЭЛЕКТРИЧЕСКИЕ ХАРАКТЕРИСТИКИ МДП–СТРУКТУР НА ОСНОВЕ ГЕТЕРОЭПИТАКСИАЛЬНОГО HgCdTe, ПОЛУЧЕННОГО МЕТОДОМ МОЛЕКУЛЯРНО–ЛУЧЕВОЙ ЭПИТАКСИИ, C НЕОДНОРОДНЫМ РАСПРЕДЕЛЕНИЕМ СОСТАВА

The electro-physical and photoelectrical properties of MIS structures based on HgCdTe MBE with non-uniform distribution of composition were experimentally investigated. It is shown that near-surface graded-gap layers with elevated composition strongly affect on dependencies of the capacitance and the photo-emf versus the bias voltage and frequency for the MIS structures based on n-Hg1-xCdxTe (x = 0.21—0.23). The characteristics of MIS structures based on n-Hg0.7Cd0.3Te with periodically located regions with high composition were investigated and it is shown that these regions are most strongly affect the characteristics of MIS structures when their location near the boundary of the insulator−semiconductor. The electrical properties of MIS structures based on n-Hg1-xCdxTe (x = 0.62—0.73) with region with lower composition were experimentally studied.Экспериментально исследованы электрофизические и фотоэлектрические свойства МДП-структур на основе HgCdTe, полученного методом молекулярно-лучевой эпитаксии, с неоднородным распределением состава. Показано, что для МДП-структур на основе n-Hg1-xCdxTe (x = 0,21-0,23) приповерхностные варизонные слои с увеличенным содержанием СdTe на поверхности сильно влияют на зависимости емкости и фотоЭДС от напряжения смещения и частоты. Исследованы характеристики МДП-структур на основе n-Hg0,7Cd0,3Te с периодически расположенными областями резко повышенного содержания CdTe барьерного типа и показано, что эти области оказывают влияние на характеристики МДП-структур при их расположении вблизи границы раздела диэлектрик—полупроводник. Экспериментально изучены электрические свойства МДП-структур на основе n-Hg1-xCdxTe (x = 0,62-0,73) с областями пониженного содержания CdTe в приповерхностной области типа потенциальных ям

Electron-deuteron scattering in a current-conserving description of relativistic bound states: formalism and impulse approximation calculations

The electromagnetic interactions of a relativistic two-body bound state are formulated in three dimensions using an equal-time (ET) formalism. This involves a systematic reduction of four-dimensional dynamics to a three-dimensional form by integrating out the time components of relative momenta. A conserved electromagnetic current is developed for the ET formalism. It is shown that consistent truncations of the electromagnetic current and the $NN$ interaction kernel may be made, order-by-order in the coupling constants, such that appropriate Ward-Takahashi identities are satisfied. A meson-exchange model of the $NN$ interaction is used to calculate deuteron vertex functions. Calculations of electromagnetic form factors for elastic scattering of electrons by deuterium are performed using an impulse-approximation current. Negative-energy components of the deuteron's vertex function and retardation effects in the meson-exchange interaction are found to have only minor effects on the deuteron form factors.Comment: 42 pages, RevTe

Influence of a high-frequency pulsed nanosecond diffusion discharge in the nitrogen atmosphere on the electrical characteristics of a CdHgTe epitaxial films

The effect of a high-frequency nanosecond volume discharge forming in an inhomogeneous electrical field at atmospheric pressure on the CdHgTe (CMT) epitaxial films is studied. The measurement of the electrophysical parameters of the CMT specimens upon irradiation shows that that the action of pulses of nanosecond volume discharge leads to changes in the electrophysical properties of CMT epitaxial films due to formation of a near-surface high-conductivity layer of the n-type conduction. The preliminary results show that it is possible to use such actions in the development of technologies for the controlled change of the properties of CMT narrow-band solid solutions and production of structures heterogeneous with respect to conduction

Neutron charge form factor at large q2q^2

The neutron charge form factor $G_{En}(q)$ is determined from an analysis of the deuteron quadrupole form factor $F_{C2}$ data. Recent calculations, based on a variety of different model interactions and currents, indicate that the contributions associated with the uncertain two-body operators of shorter range are relatively small for $F_{C2}$, even at large momentum transfer $q$. Hence, $G_{En}(q)$ can be extracted from $F_{C2}$ at large $q^2$ without undue systematic uncertainties from theory.Comment: 8 pages, 3 figure