Synchrotron oscillation damping due to beam-beam collisions

In DA{\Phi}NE, the Frascati e+/e- collider, the crab waist collision scheme has been successfully implemented in 2008 and 2009. During the collision operations for Siddharta experiment, an unusual synchrotron damping effect has been observed. Indeed, with the longitudinal feedback switched off, the positron beam becomes unstable with beam currents in the order of 200-300 mA. The longitudinal instability is damped by bringing the positron beam in collision with a high current electron beam (~2A). Besides, we have observed a shift of \approx 600Hz in the residual synchrotron sidebands. Precise measurements have been performed by using both a commercial spectrum analyzer and the diagnostics capabilities of the DA{\Phi}NE longitudinal bunch-by-bunch feedback. This damping effect has been observed in DA{\Phi}NE for the first time during collisions with the crab waist scheme. Our explanation is that beam collisions with a large crossing angle produce a longitudinal tune shift and a longitudinal tune spread, providing Landau damping of synchrotron oscillations.Comment: 3 pages, 5 figures, talk presented to IPAC'10 - Kyoto - May 24-28 201

Определение оптимальной периодичности технического обслуживания автобусов

For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version). ABSTRACT The article, using the example of LLC ATP Kama analyzes the condition of fleet of the motor transport enterprise, as well as the existing system for ensuring its operability. In particular, normative and actual technical readiness of buses is shown taking into account the terms of their operation, average daily mileage, total number of days of stay for maintenance and repair during the year. The method of adjustment of standards was chosen. Optimal periodicity of maintenance of vehicles was determined. An assessment of intensity of failures, costs for the enterprise of preventive maintenance and repair work, and calculation of economic effectiveness of the proposed solutions are suggested. Keywords: motor transport enterprise, economy, cost reduction, optimal periodicity of maintenance, bus operation, economic-probabilistic method, exponential distribution law.Текст аннотации на англ. языке и полный текст статьи на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии). В статье на примере «АТП Кама» анализируется состояние парка автотранспортного предприятия, а также существующей системы обеспечения его работоспособности. В частности, показана нормативная и фактическая техническая готовность автобусов с учётом сроков их эксплуатации, среднесуточного пробега, суммарного количества дней пребывания на техническом обслуживании и ремонте в течение года. Выбрана методика корректирования нормативов, определена оптимальная периодичность технического обслуживания парка машин. Проведена оценка интенсивности отказов, затрат предприятия на планово- предупредительные и ремонтные работы, сделан расчёт экономической эффективности предлагаемых решений

Natural BNS damping of the fast ion instability

In this paper we discuss the self-stabilization of the so-called fast ion instability of an electron beam in the case when coherent oscillations of bunches can be described in the linear approximation. Such a possibility occurs due to an increase in the number of ions along the electron beam and a proportional increase in the betatron tune shifts of electrons in subsequent bunches. The tune variation along the beam results in the BNS damping of the coherent oscillations of electron bunches