A quantum time lens for ultracold neutrons

The possibility of creating a time lens, an analogue of the zone plate in X-ray optics, for ultracold neutrons is experimentally demonstrated. The neutron energy was changed by means of a purely quantum effect: the phase modulation of a neutron wave at a variable modulation frequency. The modulator was a phase grating with variable spatial period moving across the neutron beam.     

Flexible polyvinyl chloride neutron guides for transporting ultracold and very cold neutrons

The transmission of ultracold neutrons (UCNs) through flexible polyvinyl chloride (PVC) tubes with lengths of up to 3 m and an internal diameter of 6–8 mm has been studied. High UCN transmission is found even for arbitrarily bent tubes (single bend, double bend, triple bend, figure eight, etc.). The transmission can be improved significantly by coating the inner surface of the tube with a thin layer of liquid fluorine polymer. The prospects of these neutron guides in fundamental and applied research are discussed.     

Quasi-Relativism,the Narrow-Gap Property,and Forced Electron Dynamics in Solids

Narrow-gap semiconductors, used in quantum network engineering, are characterized by small effective electron masses on the Fermi level and hence by high electron mobility in the lattice. We construct an explicitly solvable model that clarifies one possible mechanism for small effective masses to appear. Another mathematical model constructed here describes a possible mechanism for using a traveling wave to control an alternating quantum current in a one-dimensional lattice.     

Experimental verification of the 1/v law for the absorption cross section of ultracold neutrons in natural gadolinium

The results of a new experiment on the transmission of ultracold neutrons through a natural gadolinium film are reported. The results indicate that the transmission of the sample is unchanged when the sample moves parallel to its surface. The neutron velocity in the sample coordinate system varies in a range of 6–35 m/s. It follows from the constancy of the sample transmission that the imaginary part of the scattering length is constant; i.e., the law 1/v is valid for the capture cross section of the free nucleus with an accuracy of about 0.5%.     

Effect of accelerating matter in neutron optics

The results of an experiment on the observation of a new neutron-optical effect are reported. It has been experimentally shown that the energy of a neutron passing through a refracting sample moving with acceleration changes. The magnitude of the effect is in qualitative agreement with theoretical predictions. The experiment was carried out with ultracold neutrons and the energy transform is equal to ±2 × 10^?10 eV.     

Neutron diffraction at a moving grating as a nonstationary quantum phenomenon

The observation of the discrete energy spectrum in a new experiment on the diffraction of ultracold neutrons at a moving phase grating is reported. The results are in quantitative agreement with theoretical predictions and can be treated as additional evidence of the validity of the plane-wave representation of the initial neutron state.     

Space and energy profiling of neutron beams using flexible fluoropolymer neutron guides

Technical Physics - Experimental data have been presented for the spatial deflection and energy profiling of reactor neutron beams using flexible polyvinylchloride tubes, the inner surfaces of...     

Determination of a Dose Absorbed in a Biological Sample under Mixed Gamma–Neutron Irradiation

Technical Physics - A method is proposed and results on determination of absorbed doses under mixed gamma–neutron irradiation of biological samples on a horizontal channel of the IR-8...     

New experimental test of dispersion law for very slow neutrons

The results of an experiment on transmitting UCN through a rotating disc made of silicon single crystal are reported. They demonstrate that the transmission of the sample remains constant if it moves parallel to its surface. The range of neutron velocities in the system of reference associated with the sample is 6–38 m/s$6\text{–}38\text{m}/\text{s}$. It is found that the real and imaginary parts of the effective potential are constant to within 3×10⁻³$3\times {10}^{-3}$.