126255062
EXPERIMENTAL STUDY OF COHERENT TRANSVERSE BEAM INSTABILITY AT THE IHEP ACCELERATOR
182123800
Characteristics of Transversal Coherent Beam Instability on the Plateau of 386-Oe Magnetic Field at the SERPUKHOV Accelerator. (Talk, in Russian)
59025092
Decreasing transient beam loading in RF cavities of U-70 accelerator
The U-70 RF system was worked out to operate with the injector-linac at 100 MeV energy. A wide RF range was (2.6-6.1) MHz. For the U-70 injector Booster the wide RF range decreased and now it is (5.5-6.1) MHz. This fact and simplest method of changing the parameters in RF ferrite dominated cavities allow one to increase of the equivalent value of the cavity capacitance for the main frequency by about a factor of 2.7 and increase of the value of the cavity gap capacitance by about a factor of 5. The experimental investigation of the U-70 RF cavities due to the injection of bunches from the Booster into the U-70 orbit, near transition and on main flat-top is presented.
122053065
Coasting Beam in HERA-p Ring
This document is a report on stud ies of production/tr ansport mechanisms resulting in and of cures against a coasting beam halo observed at the HERA proton ring of DESY. Noises in the 208 MHz RF system, drift beyond RF buckets due to energy loss through synchrotron radiation of the highenergy protons and effect of adding the 52 MHz RF voltage are claimed to account for the diverse observations over the halation effect available by now. The work was performed under Attachment #63 to the Agreement between DESY (Hamburg, Germany) and IHEP (Protvino, Russia), re: Coasting Beam in HERA-p Ring, June 2000.
53956287
Upgrading the RF Cavity for U-70 Accelerator 0 -
This paper presents the results on the experimental invcstigation of the IJ-70 R.I: cavity with additional short circuit loops in thr RF magnetic field. These loops introduce a negative inductance impedanre into t,hc RF cavit,y circuit, and decreascx the cquivalcnt value of cavity inductance by about a factor of 10. This method allows at a low cost ‘,-fold increase the caparity of the accelerating gap for the 1!-70 cavity operating with the booster injection complex. ‘l’he lechnique of measuring the ferrite-dominated cavity pararncters is described.
110736460
UPGRADING LONGITUDINAL BEAM BEHAVIOR IN IHEP BOOSTER
Operation of 1.5 GeV fast-cycling Booster proton synchrotron of IHEP has been long hampered by unwanted oscillations in bunch length. To identify the reason of such beam behavior, a dedicated beam-dynamics research program has been initiated. The scope of this activity has covered a variety of the might-be mechanisms behind — coherent instabilities, malfunction of voltage amplitude feedbacks, quality of the voltage program, etc. Ultimately, phase loop encircling the VCO has been upgraded, which resulted in a noticeably suppressed scale of both, dipole and quadrupole oscillations of beam. BEAM OBSERVATIONS Coherent oscillations in bunch length were incidentally observed during routine operation of the machine. These were monitored as a distortion of bunch shape prior to beam transfer. The process was accompanied by an occurrence of asymmetry in longitudinal density distribution. This picture had a rather uncertain cycle-to-cycle recurrence. Each time, the beam conduct was subject to improving noticeably with finer tuning the initial value of radio-frequency in the Booster. Still, a mismatch with phase-plane trajectories of the accepting ring, U70, persisted. It hampered subsequent accumulation and acceleration of a high intensity beam in U70. To this end, a dedicated R&D program was launched to study beam longitudinal oscillations through the entire cycle and elaborate technical cures against oscillations in bunch length, specifically.
119440877
B Decays as a probe of spontaneous cp-violation in SUSY models
We consider phenomenological implications of susy models with spontaneously broken CP-symmetry. In particular, we analyze CP-asymmetries in B decays and find that the predictions of these models are vastly different from those of the SM. These features are common to NMSSM-like models with an arbitrary number of sterile superfields and the MSSM with broken R-parity.
17840929
Torsion constraints in the Randall-Sundrum scenario
Torsion appears due to fermions coupled to gravity and leads to the strongest particle physics bounds on flat extra dimensions. In this work, I consider torsion constraints in the case of a warped extra dimension with brane and bulk fermions. From current data I obtain a $3\ensuremath{\sigma}$ bound on the TeV-brane mass scale ${\ensuremath{\Lambda}}_{\ensuremath{\pi}}g~2.2 (10) \mathrm{TeV}$ for the anti-de Sitter curvature $k=1(0.01)$ in (reduced) Planck units. If Dirac or light sterile neutrinos reside on the brane, the bound increases to 17 (78) TeV.
119110072
Higgs-induced lepton flavor violation
Abstract Due to the smallness of the lepton Yukawa couplings, higher dimensional operators can give a significant contribution to the lepton masses. In this case, the lepton mass matrix and the matrix of lepton–Higgs couplings are misaligned leading to lepton flavor violation (LFV) mediated by the Standard Model Higgs boson. We derive model-independent bounds on the Higgs flavor violating couplings and quantify LFV in decays of leptons and electric dipole moments for a class of lepton–Higgs operators contributing to lepton masses. We find significant Higgs-mediated LFV effects at both 1-loop and 2-loop levels.
17081623
Metastable vacua in flux compactifications and their phenomenology
In the context of flux compactifications, metastable vacua with a small positive cosmological constant are obtained by combining a sector where supersymmetry is broken dynamically with the sector responsible for moduli stabilization, which is known as the F-uplifting. We analyze this procedure in a model-independent way and study phenomenological properties of the resulting vacua.
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.