Возможность использования отрицательной спиновой компоненты в нейтронных поляризующих устройствах. Первые результаты

The results of experimental verification of the possibility of increasing the neutron beams luminosity of polarizing devices based on magnetized supermirrors are presented. The essence of the experiment is to use both components of the neutron spins in the beam. The positive component is reflected from one magnetized mirror, and the passing mirror opposite component after turning 180 degree is reflected from another similar mirror. Both beams were recorded with one detector. Taking into account the reflection coefficients of the components by the mirrors and the efficiency of the rotation of the opposite component, an increase in the neutron intensity was obtained approximately twice with an average polarization of about 66%. The experiments were performed on a monochromatic neutron beam.

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1–100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

Linear polarization of hydroxyl masers in circumstellar envelope outer regions

A recent polarimetric survey of OH masers in a large sample of AGB and post-AGB stars revealed widespread occurrence of polarized features. We made a statistical analysis of the polarization properties of this large data set. We discuss the alignment of polarization position angles between the extreme blue- and red-shifted parts of the 1612 MHz spectrum. The average polarization angle of OH masers from the opposite sides of the envelope agrees within 20° for 80% of the sources in the sample. For two objects monitored over ~6 years the polarization position angle at 1612 MHz is constant within measurement uncertainties: this suggests a stable and a very regular structure of the circumstellar magnetic fields. Alternatively, this could indicate a galactic origin of the field which may be amplified by the stellar wind in the outermost parts of the envelopes.

Study of emission mechanism of GRBs probed by the gamma-ray polarization with IKAROS-GAP

We report a polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected a firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5 σ) confidence level, and an average polarization degree (Π) of 27 ± 11% with 99.4% (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. Non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ~ Γ−1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.

Modeling of Pulsar Polarization Properties

In the popularly accepted empirical model for pulsar emission, bunches of charged particles traveling along open field lines near the magnetic pole emit curvature radiation. Such radiation is linearly polarized. Most of the radiation is assumed to be emitted from a ring shaped region centered on the pole (the hollow cone model). We have calculated the expected average polarization using this model and find them to be in disagreement with observations. The addition of a second ring inside the first with orthogonal polarization solves this problem. This new model explains other observed features of pulsar emission including discontinuities in position-angle profiles and multicomponent profiles. Plasma interactions might account for a second ring.

Polarimetric Observations of 20 Weak Pulsars at 1720 Mhz

We present average polarization profiles for 20 pulsars at 1720 MHz made with the 100-m Effelsberg radio telescope. All four Stokes parameters were appropriately delayed in a linear dedisperser to correct the interstellar dispersion on-line. Our sample includes a number of complex profiles which were observed polarimetrically for the first time at a high frequency, with the aim of describing their frequency evolution. Classification of the corrected profiles is attempted according to the empirical pulsar model described earlier by Rankin(1990).

Observation of the Linear Polarization of Pulsar Integrated Pulses and Sub-Pulses at Meter Wavelengths

A brief review of polarization observations at 103, 60, and 40 MHz is given. Our peculiar measurement technique allows us to obtain average polarization profiles as well as statistical distributions of the polarization parameters of individual pulses and subpulses. Some examples are given in this paper.