119484972
Multi-harmonic test setup for RF breakdown studies
A multi-harmonic asymmetric cavity is predicted to obtain lower RF breakdown probability than a conventional pillbox cavity, when driven by two or more external RF harmonic sources. Experimental efforts are underway to study RF breakdown in a bimodal asymmetric cavity powered by dual frequency test stand. Details of design of the test stand are described.
122386462
RF undulator for compact X-ray SASE source of variable wavelength
A room-temperature RF undulator, fed by Ka-band radiation and intended to produce ∼1 nm wavelength radiation using moderate energy electrons, is considered. The necessary electron bunches with energy 0.2-1 GeV could be produced by petawatt laser pulses injected into plasma bubbles.
109831879
Modified magnicon for high-gradient accelerator R&D
A design is presented of a modified 34.3 GHz magnicon amplifier with a TE311-mode output cavity, to replace the existing magnicon at Yale Beam Physics Lab Test Facility whose output cavity operates in the TM310 mode. The main goal for the new design is to achieve robust day-to-day reliable operation at pulsed power levels up to 25 MW.
118172840
Search for the electron electric dipole moment
Extensions to the Standard Model (SM) typically include new heavy particles and new mechanisms for CP violation. These underlying phenomena can give rise to electric dipole moments of the electron and other particles. Tabletop‐scale experiments used to search for these effects are described. Present experiments are already sensitive to new physics at the TeV scale, and new methods could extend this range dramatically. Such experiments could be among the first to show evidence for physics beyond the SM.
54984617
Preliminary results from the Yale microwave cavity experiment
We present the first preliminary measurements from the Yale Microwave Cavity Experiment from a search for galactic halo axion like particles at about 34 GHz. The experiment can be run in two modes, a single cavity search or a two cavity search. We give estimated sensitivities for axions and axion like particles in this experimental setup.
110779089
Multi-harmonic RF test stand for RF breakdown studies
A multi-harmonic RF test stand is under construction at Yale Beam Physics Laboratory. It includes a frequency multiplier which can generate high power harmonics efficiently that are phase locked to the fundamental drive frequency. In a bi-modal asymmetric cavity powered by this RF source, the cavity may experience reduced exposure time to peak fields and sweeping of peak fields across their surfaces, and strong asymmetry between surfaces that may experience cathode-and anode-like fields; these phenomena are to be assessed for their influence on RF breakdown probabilities.
119190000
Wigner solution of the quark gap equation at nonzero current quark mass and partial restoration of chiral symmetry at finite chemical potential
According to the generally accepted phase diagram of QCD, at low temperature and high baryon number density the chiral phase transition of QCD is of first order and the co-existence of the Nambu-Goldstone phase and the Wigner phase should appear. This is in conflict with the usual claim that the quark gap equation has no Wigner solution in the case of nonzero current quark mass. In this paper we analyze the reason why the Wigner solution does not exist in the usual treatment and try to propose a new approach to discuss this question. As a first step, we adopt a modified Nambu-Jona-Lasinio (NJL) model to study the Wigner solution at finite current quark mass. We then generalize this approach to the case of finite chemical potential and discuss partial restoration of chiral symmetry at finite chemical potential and compare our results with those in the normal NJL model.
120218128
Time-dependent harmonic oscillator in a magnetic field and an electric field on the non-commutative plane
In the non-commutative space, wave functions and geometric phases are derived for the time-dependent harmonic oscillator in external time-dependent magnetic and electric field. Explicit forms of the coherent states are also given, which are not the minimum uncertainty states for the coordinates and momenta.
121590649
Chiral phase transition of QCD at finite chemical potential
A bstractIn the framework of Dyson-Schwinger equation (DSE) approach, we propose a chemical potential dependent effective gluon propagator and the quark gap equation is solved with such a gluon propagator. It is found for the first time in DSE approach that with light current quark mass m ≠ 0, the Wigner solution will appear at some chemical potential μW. Based on this, the chiral phase transition at finite chemical potential is studied and the result shows that it is a first-order phase transition. The results are compared with the known results in the literature.
119297551
Influence of gauge boson mass on the staggered spin susceptibility
Based on the study of the linear response of the fermion propagator in the presence of an external scalar field, we calculate the staggered spin susceptibility in the low-energy limit in the framework of the Dyson-Schwinger approach. We analyze the effect of a finite gauge boson mass on the staggered spin susceptibility in both the Nambu phase and the Wigner phase. It is found that the gauge boson mass suppresses the staggered spin susceptibility in the Wigner phase. In addition, we try to give an explanation for why the antiferromagnetic spin correlation increases when the doping is lowered.
120455304
A DYNAMICAL, CONFINING MODEL AND BULK VISCOSITY OF QCD MATTER AT FINITE TEMPERATURE
In this paper we calculate the thermodynamic quantities and bulk viscosity in a simple confining Dyson–Schwinger equation model of two-flavor QCD. Our results show that the velocity of sound shows a sharp increase around and at the phase transition temperature the derivative of the velocity with respect to T has a distinct change. It is also found that the trace anomaly increases sharply below the phase transition point and the bulk viscosity has a peak located at which is almost the same as the peak of the trace anomaly. A comparison of our results with those in the previous literature is given.