Clean Prediction of \CP violating processes ψ\psi, ϕ\phi and Υ(1S)\Upsilon(1S) decay to KsKs and KLKL

The ratio of $K_S K_S$ ($K_L K_L$) and $K_S K_L$ production rates is calculated by considering $K^0 - K^0bar$ oscillation in $J/\psi \to K^0K^0bar$ decay. The theoretical uncertainty due to strong interaction in $J/\psi$ decay is completely canceled in the ratio, therefore, the absolute branching fractions of the \CP violating processes of $J/\psi \to K_S K_S$ and $K_L K_L$ can be cleanly and model-independently determined in case that $J/\psi \to K_S K_L$ decay is precisely measured. In the future $\tau$-Charm factory, the expected \CP violating process of $J/\psi \to K_S K_S$ should be reached. It is important to measure $J/\psi$ to $K_S K_S$ and K_S K_L decays simultaneously, so that many systematic errors will be canceled. More precise measurements are suggested to examine the predicted isospin relation in $J/\psi \to KKbar$ decays. All results can be extended to decays of other vector quarkonia, $\phi$, $\psi(2S)$ and $\Upsilon(1S)$ and so on.Comment: Version 2 is the same as published one at PR

Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics

Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10-GPa range, and hence, it is necessary to investigate the phase diagrams of candidate materials under these extreme conditions. Here, we report on an in situ synchrotron X-ray diffraction study in a large-volume press of a modern (α2 + γ) two-phase material, Ti-45Al-7.5Nb-0.25C, under pressures up to 9.6 GPa and temperatures up to 1686 K. At room temperature, the volume response to pressure is accommodated by the transformation γ → α2, rather than volumetric strain, expressed by the apparently high bulk moduli of both constituent phases. Crystallographic aspects, specifically lattice strain and atomic order, are discussed in detail. It is interesting to note that this transformation takes place despite an increase in atomic volume, which is due to the high ordering energy of γ. Upon heating under high pressure, both the eutectoid and γ-solvus transition temperatures are elevated, and a third, cubic β-phase is stabilized above 1350 K. Earlier research has shown that this β-phase is very ductile during plastic deformation, essential in near-conventional forging processes. Here, we were able to identify an ideal processing window for near-conventional forging, while the presence of the detrimental β-phase is not present under operating conditions. Novel processing routes can be defined from these findings. © 2016, Creative Commons

Evidence For The Production Of Slow Antiprotonic Hydrogen In Vacuum

We present evidence showing how antiprotonic hydrogen, the quasistable antiproton-proton (pbar-p) bound system, has been synthesized following the interaction of antiprotons with the hydrogen molecular ion (H2+) in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events, evidence is presented for antiprotonic hydrogen production with sub-eV kinetic energies in states around n=70, and with low angular momenta. The slow antiprotonic hydrogen may be studied using laser spectroscopic techniques.Comment: 5 pages with 4 figures. Published as Phys. Rev. Letters 97, 153401 (2006), in slightly different for

Three Dimensional Annihilation Imaging of Antiprotons in a Penning Trap

We demonstrate three-dimensional annihilation imaging of antiprotons trapped in a Penning trap. Exploiting unusual feature of antiparticles, we investigate a previously unexplored regime in particle transport; the proximity of the trap wall. Particle loss on the wall, the final step of radial transport, is observed to be highly non-uniform, both radially and azimuthally. These observations have considerable implications for the production and detection of antihydrogen atoms.Comment: Invited Talk at NNP03, Workshop on Non-Neutral Plasmas, 200

Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector

In 2002, the ATHENA collaboration reported the creation and detection of cold (~15 K) antihydrogen atoms [1]. The observation was based on the complete reconstruction of antihydrogen annihilations, simultaneous and spatially correlated annihilations of an antiproton and a positron. Annihilation byproducts are measured with a cylindrically symmetric detector system consisting of two layers of double sided Si-micro-strip modules that are surrounded by 16 rows of 12 pure CsI crystals (13 x 17.5 x 17 mm^3). This paper gives a brief overview of the experiment, the detector system, and event reconstruction. Reference 1. M. Amoretti et al., Nature 419, 456 (2002).Comment: 7 pages, 5 figures; Proceedings for the 8th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications (Como, Italy October 2003) to be published by World Scientific (style file included

Positron plasma diagnostics and temperature control for antihydrogen production

Production of antihydrogen atoms by mixing antiprotons with a cold, confined, positron plasma depends critically on parameters such as the plasma density and temperature. We discuss non-destructive measurements, based on a novel, real-time analysis of excited, low-order plasma modes, that provide comprehensive characterization of the positron plasma in the ATHENA antihydrogen apparatus. The plasma length, radius, density, and total particle number are obtained. Measurement and control of plasma temperature variations, and the application to antihydrogen production experiments are discussed.Comment: 5 pages, 4 figures, to be published in Phys. Rev. Let

ATHENA -- First Production of Cold Antihydrogen and Beyond

Atomic systems of antiparticles are the laboratories of choice for tests of CPT symmetry with antimatter. The ATHENA experiment was the first to report the production of copious amounts of cold antihydrogen in 2002. This article reviews some of the insights that have since been gained concerning the antihydrogen production process as well as the external and internal properties of the produced anti-atoms. Furthermore, the implications of those results on future prospects of symmetry tests with antimatter are discussed.Comment: Proc. of the Third Meeting on CPT and Lorentz Symmetry, Bloomington (Indiana), USA, August 2004, edited by V. A. Kostelecky (World Scientific, Singapore). 10 pages, 5 figures, 1 table. Author affiliations cor