Charm production nearby threshold in pA-interactions at 70 GeV

The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP, Protvino) are presented. Interactions of the 70 GeV proton beam with C, Si and Pb targets were studied to detect decays of charmed $D^0$, $\overline D^0$, $D^+$, $D^-$ mesons and $\Lambda _c^+$ baryon near their production threshold. Measurements of lifetimes and masses are shown a good agreement with PDG data. The inclusive cross sections of charm production and their A-dependencies were obtained. The yields of these particles are compared with the theoretical predictions and the data of other experiments. The measured cross section of the total open charm production ($\sigma _{\mathrm {tot}}(c\overline c)$ = 7.1 $\pm$ 2.3(stat) $\pm$1.4(syst) $\mu$b/nucleon) at the collision c.m. energy $\sqrt {s}$ = 11.8 GeV is well above the QCD model predictions. The contributions of different species of charmed particles to the total cross section of the open charm production in proton-nucleus interactions vary with energy.Comment: 4 pages, 6 pages, 38th International Conference on High Energy Physics 3-10 August 2016, Chicago, US

Quantum depinning of a pancake-vortex from a columnar defect

We consider the problem of the depinning of a weakly driven ($F\ll F_{c}$) pancake vortex from a columnar defect in a Josephson-coupled superconductor, where $F$ denotes the force acting on the vortex ($F_{c}$ is the critical force). The dynamics of the vortex is supposed to be of the Hall type. The Euclidean action $S_{Eucl}(T)$ is calculated in the entire temperature range; the result is universal and does not depend on the detailed form of the pinning potential. We show that the transition from quantum to classical behavior is second-order like with the temperature $T_{c}$ of the transition scaling like $F^{{4}/{3}}.$ Special attention is paid to the regime of applicability of our results, in particular, the influence of the large vortex mass appearing in the superclean limit is discussed.Comment: 11 pages, RevTeX, 4 figures inserte

КОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИЕ ТЕХНОЛОГИЧЕСКОГО ПРОЦЕССА ИЗОТЕРМИЧЕСКОЙ ШТАМПОВКИ СЛОЖНОПРОФИЛЬНЫХ ПАНЕЛЕЙ ИЗ АЛЮМИНИЕВЫХ СПЛАВОВ

Isothermal bulk forming of AMg6 aluminum alloy blanks to produce irregular shape parts has been investigated with DEFORM-3D software. The following boundary conditions were used for the simulation: strain rate of 0,03 mm/s, strain resistance of 60 MPa, friction coefficient of 0,1. The computer model is shown to describe correctly real fabrication process of isothermal bulk forming, thus allowing us to recommend this program for designing the fabrication process to produce die forgings of irregular shape from aluminum alloys.Проведено исследование возможности применения моделирования технологического процесса объемной изотермической штамповки поковки сложной формы из алюминиевого сплава АМг6 с помощью компьютерной программы DEFORM-3D. Для моделирования использовали следующие граничные условия. Скорость деформации составляла 0,03 мм/с, сопротивление деформации — 60 МПа, коэффициент трения — 0,1. Показано, что компьютерная модель корректно описывает реальный технологический процесс объемной изотермической штамповки, что позволяет рекомендовать эту программу для проектирования технологического процесса получения штампованных поковок сложной формы из алюминиевых сплавов

Properties of Neutral Charmed Mesons in Proton--Nucleus Interactions at 70 GeV

The results of treatment of data obtained in the SERP-E-184experiment "Investigation of mechanisms of the production of charmed particles in proton-nucleus interactions at 70 GeV and their decays" by irradiating the active target of the SVD-2 facility consisting of carbon, silicon, and lead plates, are presented. After separating a signal from the two-particle decay of neutral charmed mesons and estimating the cross section for charm production at a threshold energy {\sigma}(c\v{c})=7.1 \pm 2.4(stat.) \pm 1.4(syst.) \mub/nucleon, some properties of D mesons are investigated. These include the dependence of the cross section on the target mass number (its A dependence); the behavior of the differential cross sections d{\sigma}/dpt2 and d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical variables xF, pt2, and plab. The experimental results in question are compared with predictions obtained on the basis of the FRITIOF7.02 code.Comment: 9 pages, 9 figures,3 table