Sub-THz radiation from dielectric capillaries with reflectors

In this report we present experimental investigations of THz radiation generated from a corrugated and a non-corrugated capillary with reflectors, using a femtosecond electron beam of LUCX accelerator at KEK, Japan. We discuss measurements of radiation angular distributions and their comparison with Particle In Cell simulations, and also investigate an off-central propagation of the beam in the capillaries based on experimental measurements and simulations.Comment: 5 pages, 5 figure

Особенности DC и низкочастотной AC проводимости в монокристаллах LiCu 2O 2+δ

The temperature dependences of DC and low-frequency AC conductivities of single crystals LiCu 2O 2 + δ in range from 4.5 K to 360 K were studied. The observed properties of conductivity indicated strong localization and influences of the spin, lattice and charge degrees of freedom on charge transport.Проведено детальное исследование температурных зависимостей DC и AC низкочастотной проводимости монокристаллов LiCu 2O 2 + δ в диапазоне температур от 4.5 К до 360 К. Обнаруженные особенности проводимости свидетельствуют о сильной автолокализации и влиянии спиновых, решёточных и зарядовых степеней свободы на транспорт заряда

RF photogun and Cherenkov decelerating system for a high power radiation source in sub-mm region

Some results of RF photogun and Cherenkov decelerating system research and design are discussed. This R&D is providing to construct a high power pulse radiation source in sub-mm region. It is well known that the conducting capillary filled by dielectric skin can be used as a Cherenkov radiation generator. One needs very short (less than 1 mm) and high brightness electron bunch to provide the coherent radiation. The short bunch can be generated by means of a photogun. The electrons should be accelerated to the energy equal to 1…4 MeV in compact section and injected to the decelerating structure. This radiation source can be used for inspection systems or as a laboratory generator.Рассмотрены некоторые результаты исследования и разработки СВЧ-фотокатода и черенковской замедляющей системы, предназначенных для генерации мощных импульсов излучения субмиллиметрового диапазона. Как известно, проводящий капилляр, покрытый изнутри слоем диэлектрика, может быть использован в качестве источника черенковского излучения. Для получения монохроматического излучения необходимо иметь очень короткий (меньше 1 мм) сгусток электронов, который может быть получен при использовании фотокатода. Электроны должны быть ускорены в короткой системе до энергии 1…4 МэВ и инжектированы в замедляющую систему. Такой источник излучения может быть использован в досмотровой системе или в качестве лабораторного генератора.Розглянуто деякі результати дослідження та розробки НВЧ-фотокатода і черенківської уповільнюючої системи, призначених для генерації потужних імпульсів випромінювання субміліметрового діапазону. Як відомо, проводячий капіляр, покритий зсередини шаром діелектрика, може бути використаний як джерело черенківського випромінювання. Для отримання монохроматичного випромінювання необхідно мати дуже короткий (менше 1 мм) згусток електронів, який може бути отриманий при використанні фотокатода. Електрони мають бути прискорені в короткій системі до енергії 1…4 МеВ і інжектовані в уповільнюючу систему. Таке джерело випромінювання може бути використано в оглядовій системі або в якості лабораторного генератора

Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_\mu \equiv (g_\mu-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency $\omega_a$ between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ${\tilde{\omega}'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $\omega_a / {\tilde{\omega}'^{}_p}$, together with known fundamental constants, determines $a_\mu({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both $\mu^+$ and $\mu^-$, the new experimental average of $a_\mu({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviationsComment: 10 pages; 4 figure

Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

Study of the propagation of laser radiation and diagnostics of a randomly irregular troposphere

The interference and diffraction methods are considered for measuring the structure constant for fluctuations in the refractive index of a medium with random irregularities and results are given of an experimental study of the propagation of laser radiation over near-earth paths. © 1975 Plenum Publishing Corporation

Study of the propagation of laser radiation and diagnostics of a randomly irregular troposphere

The interference and diffraction methods are considered for measuring the structure constant for fluctuations in the refractive index of a medium with random irregularities and results are given of an experimental study of the propagation of laser radiation over near-earth paths. © 1975 Plenum Publishing Corporation

The use of diffraction antennas in the visible region to investigate the propagation of laser light in the atmosphere

[No abstract available

New method of surface analysis using spin-polarized electrons

A summary is given of recent achievements in the methods for production and detection of spin-polarized electron beams. Examples are provided to show the application of the new techniques based on spin-polarized electron beams to studying surface properties