109125768
A feedback circuit for the stochastic extraction of protons from the U-70 synchrotron: Development and beam tests
Results of research efforts in 2005 that were directed toward developing a system for stochastic (noise) slow extraction of the beam from the U-70 proton synchrotron of the Institute for High Energy Physics are presented. The goal of the study was to develop a full-function prototype of the stochastic slow extraction system and test it on the beam. This prototype, designed for trial operation during machine runs, is capable of producing lengthy flat-topped smooth spills and suppressing their ripple. Approaches to design of the feedback loop that affects the waiting beam stack (which is neither a linear nor time-invariant system) are discussed. A circuit model of the beam being extracted is proposed and analyzed. A dedicated electronic system for beam experiments is described. Results of the beam tests during the U-70 machine run of 2005, which confirm the serviceability of the noise extraction system prototype, are presented.
218611448
A STOCHASTIC SLOW EXTRACTION SCHEME FOR U70 SYNCHROTRON
Outcomes of a feasibility study for a low-budget stochastic slow extraction system in the U70 proton synchrotron of IHEP are reported. The existing 200 MHz (spill) RF system is to be employed as a longitudinal kicker. It will be driven by a sum of a non-random RF carrier plus an additive random amplitude-modulated signal — either quadrature or in-phase, or both. A few novel solutions to be implemented in the longitudinal diffusion technique that would force protons into the conventional 3-rd order transverse extraction resonance are foreseen so as to comply with the technical constraints inherent in U70. Getting a-few-seconds-long and high-quality spills is assessed as being viable with the system in question.
115315717
Analysis of the Feedback-Loop Stability in the RF System of the U-70 Synchrotron
We present a systematic approach for investigating the stability of the accelerating system used in the U-70 proton synchrotron (Institute for High-Energy Physics). This system employs tunable ferrite-loaded cavities and is encircled by six feedback loops (both dedicated and spurious) with a cross-talk through a heavy beam loading, high accelerating rate, and the overlapping of the loop passbands. Ensuring the safety margin against self-excitation of the RF system imposes constraints on the limiting intensity of the beam that is accelerated in the synchrotron
126255062
EXPERIMENTAL STUDY OF COHERENT TRANSVERSE BEAM INSTABILITY AT THE IHEP ACCELERATOR
16682747
Constraints on R-parity Violation from Precision Electroweak Measurements
We constrain the size of R–parity violating couplings using precision electroweak data.
117878917
Spontaneous CP-Violation in Two Higgs Doublet Supersymmetric Models
Physics (ABSTRACT) An alternative approach to the problem of CP-violation is presented. It is based on the possibility of spontaneous CP-breakdown in models with two Higgs doublets. General features of the phenomenon such as stability of the vacuum and the existence of a light axion are discussed. We investigate the feasibility of spontaneously broken CP in the minimal supersymmetric models-the MSSM and NMSSM. The latter is shown to be experimentally viable. The phenomenological implications of the model such as CP-violating effects in the kaon systems and a nonzero neutron electric dipole moment are studied. Acknowledgements I am deeply indebted to Prof. Lay Nam Chang for sharing his intimate knowledge of physics, his keen insight into fundamental problems and, constant support. I greatly appreciate the help and attention of the Department's secretaries in various matters. I am very grateful to the members of my Ph.D. committee for their supervision and efforts to make this work possible.
43232371
CP -violating invariants in supersymmetry
I study the weak basis CP-violating invariants in supersymmetric models, in particular those which cannot be expressed in terms of the Jarlskog--type invariants, and find basis--independent conditions for CP conservation. With an example of the K-anti-K mixing, I clarify what are the combinations of supersymmetric parameters which are constrained by experiment.
121021896
A Finite-Size Magnetic Monopole in Double-Potential Formalism
Using the double-potential formalism developed by Zwanziger, it is possible to construct nonsingular four-potentials corresponding to a given distribution of magnetic charge without violating the Bianchi identity. In this letter, we study a ball-like monopole with uniform distribution of magnetic charge. The corresponding four-potentials are found explicitly. We also construct the angular momentum operator of an electron in the field of such a monopole, which can be used to investigate the problem of electron-monopole scattering and to rectify Kazama–Yang–Goldhaber singularity.
17675664
Heterotic Yukawa couplings and continuous Wilson lines
Realistic heterotic string models require the presence of the Wilson lines. We study the effect of continuous Wilson lines on the heterotic Yukawa couplings for Abelian orbifold compactifications and find that the presence of continuous Wilson lines affects the magnitude of the twisted Yukawa couplings resulting in their stronger hierarchy.