The effect of nanosecond ultrawideband electromagnetic radiation on xenogeneic erythrocytes

Experiments were the intention to investigate the effect of short-pulse ultrawideband electromagnetic radiation on biological objects. An insulated rod antenna excited by a high-current electron beam (E ~ 0.5 to 1.0 MeV, I ~ 4 to 10 kA, τ ≈ 15 ns) served as a radiation source. The objects to be irradiated, i.e., erythrocytes of both donors and diabetics, were put in the regions with field intensity varying from 100 to 1000 V/cm. The effect of radiation on the lifetime and shape of erythrocytes on the permeability of erythrocyte membranes for the penetrating nonelectrolyte (1 M glycerin) and the state of intracorpuscular hemoglobin was investigated by the methods of small-angle light scattering, UV spectrometry and phase-contrast microscopy

Development of a pulsed bremsstrahlung source on a base of a nanosecond and microsecond REB accelerators

In the paper the preliminary results on measuring parameters of a pulsed bremsstrahlung source developed for investigation of physical-mechanical properties of reactor materials are given. Generation of γ-radiation with parameters γ ∼ 0.4...1.0 MeV was carried out at microsecond and nanosecond high-current REB accelerators. The absolute values of an absorbed dose are determined for both nanosecond and microsecond sources of γ-radiation.Приведено попередні результати по вимірюванню параметрів імпульсного джерела гальмованого випромінювання, якій створюється для дослідження фізико-механічних властивостей матеріалів реакторобудівництва. Генерація НЖР-випромінювання з параметрами 0,4<γ<1,0 МеВ здійснювалась мікросекундному і наносекундному сильнострумових прискорювачах РЕП. Визначені абсолютні значення дози поглинання, як для наносекундного, так і мікросекундного джерел γ-випромінювання.Приведены предварительные результаты по измерениям параметров импульсного источника тормозного излучения, создаваемого для исследования физико-механических свойств материалов реакторостроения. Генерация СЖР излучения с параметрами 0,4<γ<1,0 МэВ осуществлялась на микросекундном и наносекундном сильноточных ускорителях РЭП. Определены абсолютные значения поглощенной дозы, как для наносекундного так и микросекундного источников γ-излучения

Status of the Lake Baikal Experiment

We review the present status of the Baikal Underwater Neutrino Experiment and report on neutrino events recorded with the detector stages NT-36 and NT-96.Comment: 5 pages, 4 PostScript figures, uses here.sty and mine.sty, submitted to the Proc. of 5th Int. Workshop on Topics in Astroparticle and Underground Physics (LNGS INFN, Assergi, September 7-11, 1997

Registration of atmospheric neutrinos with the Baikal neutrino telescope

We present first neutrino induced events observed with a deep underwater neutrino telescope. Data from 70 days effective life time of the BAIKAL prototype telescope NT-96 have been analyzed with two different methods. With the standard track reconstruction method, 9 clear upward muon candidates have been identified, in good agreement with 8.7 events expected from Monte Carlo calculations for atmospheric neutrinos. The second analysis is tailored to muons coming from close to the opposite zenith. It yields 4 events, compared to 3.5 from Monte Carlo expectations. From this we derive a 90 % upper flux limit of 1.1 * 10^-13 cm^-2 sec^-1 for muons in excess of those expected from atmospheric neutrinos with zenith angle > 150 degrees and energy > 10GeV.Comment: 20 pages, 11 figure

High-voltage modulator of the Linac injector with voltage pulse stabilization

The high-voltage pulse modulator based on the modern semiconductor elements is described. The modulator is intended for use in the power supply system of LINAC helium ions injector and has the ability to smoothly adjust the amplitude (110…150 kV) and the pulse duration (0.5…1 ms). The use of a pulse-to-peak stabilization scheme, made on the basis of a parametric stabilizer with parallel switching of the load, made it possible to increase the accelerated current at the accelerator output by 2 times.Описано високовольтний імпульсний модулятор, виконаний на сучасній напівпровідниковій елементній базі. Модулятор призначений для використання в системі живлення інжектора лінійного прискорювача іонів гелію. Модулятор дозволяє плавно регулювати амплітуду (110…150 кВ) і тривалість імпульсу (0,5…1 мс) напруги. Використання схеми стабілізації імпульсу напруги, виконаної на основі параметричного стабілізатора з паралельним перемиканням навантаження, дозволило збільшити прискорений струм пучка на виході прискорювача в 2 рази.Описан высоковольтный импульсный модулятор, выполненный на современной полупроводниковой элементной базе. Модулятор предназначен для использования в системе питания инжектора линейного ускорителя ионов гелия. Модулятор позволяет плавно регулировать амплитуду (110…150 кВ) и длительность импульса (0,5…1 мс) напряжения. Использование схемы стабилизации импульса напряжения, выполненной на основе параметрического стабилизатора с параллельным переключением нагрузки, позволило увеличить ускоренный ток пучка на выходе ускорителя в 2 раза

The Lake Baikal neutrino experiment

We rewiew the present status of the Baikal Neutrino Project and present the results of a search for high energy neutrinos with the detector intermediate stage NT-96.Comment: 3 pages, 2 figures, to appear in the Proceedings of Sixth International Workshop on Topics in Astroparticle and Underground Physics (TAUP99), September 6-10, 1999, Pais, Franc

The Baikal Deep Underwater Neutrino Experiment: Results, Status, Future

We review the present status of the Baikal Underwater Neutrino Experiment and present results obtained with the various stages of the stepwise increasing detector: NT-36 (1993-95), NT-72 (1995-96) and NT-96 (1996-97). Results cover atmospheric muons, first clear neutrino events, search for neutrinos from WIMP annihilation in the center of the Earth, search for magnetic monopoles, and -- far from astroparticle physics -- limnology.Comment: Talk given at the Int. School on Nuclear Physics, Erice, Sept.199

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters