Material Damage Test for ILC Collimators

Simulations were completed to determine the energy deposition of an ILC bunch using FLUKA, Geant4 and EGS4 to a set of different spoiler designs. These shower simulations were used as inputs to thermal and mechanical studies using ANSYS. This paper presents a proposal to optimize the material choice and mechanical design of ILC spoilers jaws using ATF and benchmark the energy deposition simulations and the ANSYS studies giving the researchers valuable data which will help achieve a definitive ILC spoiler design

Simulation of the ILC Collimation System using BDSIM, MARS15 and STRUCT

The simulation codes BDSIM, MARS15 and STRUCT are used to simulate in detail the collimation section of the International Linear Collider (ILC). A comparative study of the collimation system performance for the 250 x 250 GeV machine is conducted, and the key radiation loads are calculated. Results for the latest ILC designs are presented together with their implications for future design iterations

On the influence of the cosmological constant on gravitational lensing in small systems

The cosmological constant Lambda affects gravitational lensing phenomena. The contribution of Lambda to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study in the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Due to Lambda the unresolved images are slightly demagnified, the radius of the Einstein ring decreases and the time delay increases. The effect is however negligible for near lenses. In the case of null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation, references added, results unchanged, in press on PR

Proposal of the Next Incarnation of Accelerator Test Facility at KEK for the International Linear Collider

To reach design luminosity, the International Linear Collider (ILC) must be able to create and reliably maintain nanometer size beams. The ATF damping ring is the unique facility where ILC emittances are possible. In this paper we present and evaluate the proposal to create a final focus facility at the ATF which, using compact final focus optics and an ILC-like bunch train, would be capable of achieving 37 nm beam size. Such a facility would enable the development of beam diagnostics and tuning methods, as well as the training of young accelerator physicists

Performance of a Nanometer Resolution BPM System

International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. The three BPMs are rigidly mounted inside an alignment frame on variable-length struts which allow movement in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a calibration algorithm which is immune to beam jitter. To date, we have been able to demonstrate a resolution of approximately 20 nm over a dynamic range of +/- 20 microns. We report on the progress of these ongoing tests

Selected Topics in Tau Physics from BaBar

Selected results from {tau} analyses performed using the BABAR detector at the SLAC National Accelerator Laboratory are presented. A precise measurement of the {tau} mass and the {tau}{sup +}{tau}{sup -} mass difference is undertaken using the hadronic decay mode {tau}{sup {+-}} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup {+-}}{nu}{sub {tau}}. In addition an investigation into the strange decay modes {tau}{sup -} {yields} K{sub S}{sup 0}{pi}{sup -}{pi}{sup 0}{nu}{sub {tau}} and {tau}{sup -} {yields} K{sub S}{sup 0}{pi}{sup -}{nu}{sub {tau}} is also presented, including a fit to the {tau}{sup -} {yields} K{sub S}{sup 0}{pi}{sup -}{nu}{sub {tau}} invariant mass spectrum. Precise values for M(K*(892)) and {Lambda}(K*(892)) are obtained

B Decays to Open And Hidden Charm at BaBar

A wealth of new measurements of hadronic B decays to open charm and charmonium have been performed on the data sample collected by the BaBar experiment at the PEP-II e{sup +}e{sup -} B-factory. We report the first measurement of the rates for inclusive charm production separately for charged and neutral B mesons. Combining measurements of the decay rate of B{sup 0} {yields} D*{sub s}{sup +}D*{sup -} obtained with a partial reconstruction technique and the complete reconstruction of B{sup 0} {yields} D*{sub s}{sup +}D*{sup -} with D{sub s}{sup +} {yields} {phi}{pi}{sup +}, we obtain the most precise measurement of {Beta}(D{sub s}{sup +} {yields} {phi}{pi}{sup +}). We present an update of the measurements of the branching fractions of exclusive B decays to J/{psi}, {psi}(2S), {chi}{sub c1}, {chi}{sub c2} and a kaon or a K*. In addition, we show preliminary results on exclusive decay rates to final states with baryons, or newly-discovered particles, such as D*{sub sJ}(2317), D{sub sJ}(2460){sup +}, and the X(3872)

Review of Standard Tau Decays From the B-Factory Experiments

B-factories have been successfully operating for more than 8 years, providing an unprecedented data sample of e{sup +}e{sup 0} {yields} hadrons events. The BABAR and Belle experiments have in fact already collected over 550 fb{sup -1} and 800 fb{sup -1} respectively at the {Upsilon}(4s) center-of-mass (CM) energy. At this energy, the cross-section for tau production is of the same order of the cross-section for b production: {sigma}(b{bar b}) {approx} 1.1 nb {approx} {sigma}({tau}{sup +}{tau}{sup -}) {approx} 0.9 nb. For this reason, B-factories can now be considered also Tau-factories. A review of the most recent results on standard tau decays from the BABAR and Belle experiments is presented in this article

Pentaquarks and New Hadron Spectroscopy at BaBar

Recent results on the search for pentaquarks and on charmonium spectroscopy at BABAR are reviewed. The latter includes the observation of the puzzling new state X(3872) {yields} J/{psi} {pi}{sup +} {pi}{sup -} in B decays, and the searches for X(3872) in two-body B decays and initial state radiation events