Quantum and classical correlations in high temperature dynamics of two coupled large spins

We study dynamical correlations of two coupled large spins depending on the time and on the spin quantum numbers. In the high-temperature approximation, we obtain analytical expressions for the mutual informations, quantum and classical parts of correlations. The latter was obtained performing the non-orthogonal projective (POVM) measurements onto the spin coherent states of two spins or one spin, as well as by means of the orthogonal projective measurement of von Neumann. Contribution from quantum correlations is much less than that from classical ones and decreasing with the increase in spin quantum numbers at short times. However, it is not so in a time equal to half of the quantum period.Comment: 10 pages, 3 figures, Corrected typos in formula

High Luminosity Issues for DAPhNE Upgrade

We give an overview of presentations and discussions during the Accelerator Working Group Session dedicated to High Luminosity Issues for a future upgrade of the Frascati e+e- Phi-Factory DAPhNE at the Workshop "e+e- in the 1-2 GeV range: Physics and Accelerator Prospects" held at Alghero (Italy) on 10-13 September 2003.Comment: Invited talk at the Workshop on e+e- in the 1-2 GeV range, Alghero, Italy, September 2003 (eConf c0309101

Numerical Calculations of Wake Fields and Impedances of LHC Collimators' Real Structures

The LHC collimators have very complicated mechanical designs including movable jaws made of higly resistive materials, ferrite materials, tiny RF contacts. Since the jaws are moved very close to the circulating beams their contribution in the overall LHC coupling impedance is dominant, with respect to other machine components. For these reasons accurate simulation of collimators' impedance becomes very important and challenging. Besides, several dedicated tests have been performed to verify correct simulations of lossy dispersive material properties, such as resistive wall and ferrites, benchmarking code results with analytical, semi-analytical and other numerical codes outcomes. Here we describe all the performed numerical tests and discuss the results of LHC collimators' impedances and wake fields calculations.Comment: Invited Talk at ICAP 2015, Shanghai, China, 11 pages, 11 figure

Aplication of Frequency Map Analysis to Beam-Beam Effects Study in Crab Waist Collision Scheme

We applied Frequency Map Analysis (FMA) - a method that is widely used to explore dynamics of Hamiltonian systems - to beam-beam effects study. The method turned out to be rather informative and illustrative in the case of a novel Crab Waist collision approach, when "crab" focusing of colliding beams results in significant suppression of betatron coupling resonances. Application of FMA provides visible information about all working resonances, their widths and locations in the planes of betatron tunes and betatron amplitudes, so the process of resonances suppression due to the beams crabbing is clearly seen.Comment: 11 pages, 10 figure