Progress with PXIE MEBT Chopper

A capability to provide a large variety of bunch patterns is crucial for the concept of the Project X serving MW-range beam to several experiments simultaneously. This capability will be realized by the Medium Energy Beam Transport's (MEBT) chopping system that will divert 80% of all bunches of the initially 5mA, 2.1 MeV CW 162.5 MHz beam to an absorber according to a pre-programmed bunch-by-bunch selection. Being considered one of the most challenging components, the chopping system will be tested at the Project X Injector Experiment (PXIE) facility that will be built at Fermilab as a prototype of the Project X front end. The bunch deflection will be made by two identical sets of travelling-wave kickers working in sync. Currently, two versions of the kickers are being investigated: a helical 200 Ohm structure with a switching-type 500 V driver and a planar 50 Ohm structure with a linear 250 V amplifier. This paper will describe the chopping system scheme and functional specifications for the kickers, present results of electromagnetic measurements of the models, discuss possible driver schemes, and show a conceptual mechanical design.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012) 20-25 May 2012. New Orleans, Louisian

Research of impact input rate random variations on macroscopic characteristics of non-stationary queuing system

The results of research of input stream rate random variations influence on the macroscopic characteristics of a nonstationary queuing system (NQS) are discussed in this paper. Statistical information obtained during the football match between the football clubs "Krylia Sovetov" and "Dynamo" at the stadium "Metallurg" in Samara is available. The characteristics of the stochastic component of the variation in the input rate were chosen on the basis of this information. The probability density function and the cumulative distribution function of random variations in the input rate of applications were estimated using the Rosenblatt-Parzen approximation. NQ's characteristics was studied such as the maximum queue length, the maximum waiting time in the queue, the time point at which the maximum queue length is reached, and the time point at which waiting time in the queue the longest, the number of visitors who entered at the time of the match beginning, the time needed to service the entire queue. The results of the statistical simulation shown that taking into account the random component of the variation input rate does not affect this macroscopic characteristics. © Published under licence by IOP Publishing Ltd

Cooling in a compound bucket

Electron cooling in the Fermilab Recycler ring is found to create correlation between longitudinal and transverse tails of the antiproton distribution. By separating the core of the beam from the tail and cooling the tail using 'gated' stochastic cooling while applying electron cooling on the entire beam, one may be able to significantly increase the overall cooling rate. In this paper, we describe the procedure and first experimental results

Modelling stochastic bivariate mortality

Stochastic mortality, i.e. modelling death arrival via a jump process with stochastic intensity, is gaining increasing reputation as a way to represent mortality risk. This paper represents a first attempt to model the mortality risk of couples of individuals, according to the stochastic intensity approach. On the theoretical side, we extend to couples the Cox processes set up, i.e. the idea that mortality is driven by a jump process whose intensity is itself a stochastic process, proper of a particular generation within each gender. Dependence between the survival times of the members of a couple is captured by an Archimedean copula. On the calibration side, we fit the joint survival function by calibrating separately the (analytical) copula and the (analytical) margins. First, we select the best fit copula according to the methodology of Wang and Wells (2000) for censored data. Then, we provide a sample-based calibration for the intensity, using a time-homogeneous, non mean-reverting, affine process: this gives the analytical marginal survival functions. Coupling the best fit copula with the calibrated margins we obtain, on a sample generation, a joint survival function which incorporates the stochastic nature of mortality improvements and is far from representing independency.On the contrary, since the best fit copula turns out to be a Nelsen one, dependency is increasing with age and long-term dependence exists

Simulation of the pulse current passage through the neck

Настоящая статья посвящена процессу моделирования прохождения импульсного тока через ткани шейного отдела, главным образом через нервы, методом конечных элементов. Моделирование производилось в среде Ansys Maxwell. Рассмотренный процесс моделирования учитывает физические характеристики тканей, а так же окружающей среды и анатомию шеи. Итогом моделирования являются построенные картины интегральной плотности тока в разрезе шеи для разных частот, а так же графики зависимости максимальной плотности тока в нервных тканях от частоты.This article is devoted to the process of simulation of the pulse current passage through the neck, mainly through the nerves, by finite element method. For modelling was used - Ansys Maxwell environment. The above process of modeling takes into account the physical characteristics of the tissues, environment and the anatomy of the neck. The results of the simulation are figures of the integral current density in the neck section at different frequencies, as well as graphs of the maximum current density in the nerve tissues on frequency