178 MHz cavity with HOM damping for the DFELL storage ring

Design of the new cavity produced for the DUKE FELL storage ring is presented. The fundamental and higher order modes (HOMs) parameters are shown. The HOMs are substantially damped in a special load with absorbers made of conductive ceramics. Experimental studies of the absorbing material properties were carried out on models. The results are described. The cavity cold measurements results are presented as well.Представлено конструкцію, параметри, і результати розрахунку спектра вищих мод резонатора, виготовленого для накопичувального кільця лазера на вільних електронах в університеті ДЮКЕ (США). У цьому резонаторі вищі моди сильно подавлені за допомогою спеціального навантаження, що використовує провідну кераміку. Описано результати досліджень властивостей поглинаючого матеріалу, проведених на макеті. Приведено результати холодних вимірів резонатора і його іспитів на високому рівні потужності.Представлена конструкция, параметры и результаты расчета спектра высших мод резонатора, изготовляемого для накопительного кольца лазера на свободных электронах в университете ДЮКЕ (США). В этом резонаторе высшие моды сильно подавлены с помощью специальной нагрузки, использующей проводящую керамику. Описаны результаты исследований свойств поглощающего материала, проведенных на макете. Приведены результаты холодных измерений резонатора и его испытаний на высоком уровне мощности

RF system of the race-track microtron – recuperator for high power free electron laser

A brief description of the RF system of 100 MeV race-track microtron-recuperator being built in Novosibirsk for the Free Electron Laser project at Siberian center of Photochemistry research is presented. The frequency of RF system is 180.4 MHz. The RF system consists of 2 parts: the RF system of 2 MeV injector and the RF system of microtron. The injector RF system includes 3 RF cavities - one buncher cavity and two accelerating cavities. RF cavities are driven by a 2.5 kW amplifier and two high power single-tube 130 kW RF amplifiers respectively. The RF system of microtron includes 16 RF cavities operating at a gap voltage of 850kV each. Two 4-tubes power amplifiers supply the RF power of 600 kW each to the cavities via distribution feeders. In the high power amplifier stages the tetrodes GU-101A are used. The control system controls the amplitude and phase of RF voltage in the cavities and provides signals for synchronization of the electron gun. The results of the operation of the injector RF system and status of large RF system for the microtron are discussed

Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

First experimental results obtained using the highpower free electron laser at the siberian center for photochemical research

The first lasing near the wavelength of 140 µm was achieved in April 2003 using a high-power free electron laser (FEL) constructed at the Siberian Center for Photochemical Research. In this paper we briefly describe the design of the FEL driven by an accelerator–recuperator. Characteristics of the electron beam and terahertz laser radiation, obtained in the first experiments, are also presented in the paper.У Сибірському центрі фотохімічних досліджень навесні 2003 року отримана генерація випромінювання з довжиною хвилі 140 мкм на потужному лазері на вільних електронах (ЛВЕ). У роботі коротко описана конструкція ЛВЕ на базі прискорювача рекуператора і представлені результати вимірювання деяких параметрів електронного пучка і терагерцового випромінювання.В Сибирском центре фотохимических исследований весной 2003 года получена генерация излучения с длиной волны 140 мкм на мощном лазере на свободных электронах (ЛСЭ). В работе кратко описана конструкция ЛСЭ на базе ускорителя рекуператора и представлены результаты измерения некоторых параметров электронного пучка и терагерцового излучения

Searches for electroweak neutralino and chargino production in channels with Higgs, Z, and W bosons in pp collisions at 8 TeV

Searches for supersymmetry (SUSY) are presented based on the electroweak pair production of neutralinos and charginos, leading to decay channels with Higgs, Z, and W bosons and undetected lightest SUSY particles (LSPs). The data sample corresponds to an integrated luminosity of about 19.5 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV collected in 2012 with the CMS detector at the LHC. The main emphasis is neutralino pair production in which each neutralino decays either to a Higgs boson (h) and an LSP or to a Z boson and an LSP, leading to hh, hZ, and ZZ states with missing transverse energy (E-T(miss)). A second aspect is chargino-neutralino pair production, leading to hW states with E-T(miss). The decays of a Higgs boson to a bottom-quark pair, to a photon pair, and to final states with leptons are considered in conjunction with hadronic and leptonic decay modes of the Z and W bosons. No evidence is found for supersymmetric particles, and 95% confidence level upper limits are evaluated for the respective pair production cross sections and for neutralino and chargino mass values

Study of physical processes in laser-irradiated porous targets of different microstructure

New results obtained in experiments on laser irradiation (${\rm I}=10^{14}$ W/cm$^{2}$, ${\rm \lambda} =1.055 {\rm \mu}$m) of low-density (1-30 mg/cm$^{3})$ fibrous and foam-like materials are presented and discussed. The effect of low-density material microstructure of irradiated samples on physical processes in high-temperature plasma was investigated. Using a variety of complementary X-ray and optical methods the pronounced effect of material microstructure on the parameters and dynamics of produced plasma was found