The teaching profession in Europe : historical and sociological analysis

A possible effect of direct CP violation in D -> K-S(0)pi(+)pi(-) decay on the gamma measurement from B-+/- -> DK +/-, D -> K-S(0)pi(+)pi(-) Dalitz plot analysis is considered. Systematic uncertainty of gamma coming from the current limits on direct CP violation in D -> K-S(0)pi(+)pi(-) is estimated, and a modified model-independent procedure of B-+/- -> DK +/-, D -> K-S(0)pi(+)pi(-) Dalitz plot analysis is proposed that gives an unbiased gamma measurement even in presence of direct CP violation in charm decays. The technique is applicable to other threebody D decays such as D-0 -> (KSK+K-)-K-0, D-0 -> pi(+)pi(-)pi(0), etc

Thermotunnel refrigerator with vacuum/insulator tunnel barrier: A theoretical analysis

The authors use two insulator layers in thermotunnel refrigerator to modify the shape of the tunneling barrier so that electrons with high kinetic energy pass it with increased probability. Theoretical analysis show that the overall tunneling current between the electrodes contains an increased number of high kinetic energy electrons and a reduced number of low energy ones, leading to high efficiency. The particular case of vacuum gap and solid insulator layer is calculated using digital methods. Efficiency remains high in the wide range of the emitter electric field. The cooling coefficient is found to be as high as 40%-50% in the wide range of the emitter electric field.Comment: 9 pages, 3 figure

BODY AERODYNAMICS: CONTRIBUTION TO LONG JUMP PERFORMANCE

A mathematical model of a long jumper flight dynamics is proposed. The model incorporates the factor of the full aerodynamic force exerted during the flight phase under varying conditions. The full aerodynamic force is applied to the body at some angle to the vector of air speed and can be represented as vector sum of drag and lift forces. The magnitudes of the drag and lift components, as well as their role in the length of the jump are affected by a number of parameters, such as flight kinematics, wind velocity, mean altitude, etc., which vary from athlete to athlete, between attempts and competition grounds. Analysis of the video recordings of the jumps of the leading long jumpers were processed using computerized image processing schemes. As the result, the kinematics of the jumps and the aerodynamics of the athletes' bodies at various stages of the flight phase, drag and lift quotients were calculated as the function of the angle of attack of the body, using regression analysis approach. The results obtained make possible determining the influence of the wind velocity and mean altitude. Based on this, the forecast of results and comparable values, derived from the results obtained under specific conditions can be performed. Table gives the results of numerical analysis for three high performance attempts in trial conditions and recalculated to the normalized conditions (zero wind /zero mean elevation). The comparison of the actual and normalized data indicates that the absolute value of the results in long jump during last 24 years might be reconsidered. As another application of the developed model, a series of iso-energetic trajectories was emulated, in order to enhance the performance by optimizing the flight aerodynamics under average conditions

Development of hollow electron beams for proton and ion collimation

Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.Comment: 3 pp. 1st International Particle Accelerator Conference: IPAC'10, 23-28 May 2010: Kyoto, Japa