119100477
Thermodynamic geometry and critical behavior of black holes
Based on the observations that there exists an analogy between the Reissner–Nordstrom–Anti-de Sitter (RN–AdS) black holes and the van der Waals–Maxwell liquid-gas system, in which a correspondence of variables is (ϕ,q) ↔ (V,P), we study the Ruppeiner geometry, defined as Hessian matrix of black hole entropy with respect to the internal energy (not the mass) of black hole and electric potential (angular velocity), for the RN, Kerr and RN–AdS black holes. It is found that the geometry is curved and the scalar curvature goes to negative infinity at the Davies' phase transition point for the RN and Kerr black holes. Our result for the RN–AdS black holes is also in good agreement with the one about phase transition and its critical behavior in the literature.
119186601
Various types of phase transitions in the AdS soliton background
We study the basic holographic insulator and superconductor phase transition in the AdS soliton background by generalizing the spontaneous breaking of a global U(1) symmetry to occur via Stuckelberg mechanism. We construct the soliton solutions with backreaction and examine the effects of the backreaction on the condensation of the scalar hair in the generalized Stuckelberg Lagrangian. We disclose rich physics in various phase transitions. In addition to the AdS soliton configuration, we also examine the property of the phase transition in the AdS black hole background.
124897627
Different Quantum Entropies for Two Kinds of Extreme Two-Dimensional Lowe–Strominger Black Holes*
It is shown that both the classical entropy of two-dimensional extremal Lowe–Strominger black hole and the quantum entropy of the scalar field in the background of this black hole are different by using Hawking's treatment as wel as Zaslavskii's treatment respectively. This result supports our previous suggestion that there are two kinds of extreme black holes in the nature. A new divergent term emerges in the quantum entropy in Zaslavskii's treatment and its physical meaning has been discussed.
118997018
Probing the curvature of the Universe from supernova measurement
We study the possibility to probe the spatial geometry of the Universe by supernova measurement. We illustrate with an accelerating universe model with infinite-volume extra dimensions, for which the 1σ level supernova results indicate that the Universe is closed.
30079794
Stability of the event horizon in (2+1)-dimensional black holes.
118198563
Dark Energy: Relating the Evolutions of the Universe from the Past to the Future
Using the evolution history of the universe, one can make constraint on the parameter space of dynamic dark energy models. We discuss two different parameterized dark energy models. Our results further restrict the combined constraints obtained from supernova and the first-year Wilkinson-microwave-anisotropy-probe observations. From the allowed parameter space, it is found that our universe will experience an eternal acceleration. We also estimate the bound on the physically relevant regions both in the re-inflationary and inflationary phases.
121278811
Entropies of a Toroidal Black Hole Due to Scalar and Dirac Fields
Using the thin film brick-wall model, the entropies of a toroidal black hole due to scalar and Dirac fields are investigated. The entropy due to the scalar field is one fourth of the horizon area, and that due to the Dirac field is seven eighth of the area. These results are similar to that in black holes with horizon topology S2. The cutoff in toroidal black hole is chosen as the same as one in black holes with horizon topology S2, which seems to mean that the thin film brick-wall model is universal.
119239888
Physical design of superconducting magnet for ADS injection I
A superconducting solenoid prototype magnet for Accelerator Driven Subcritical System (ADS) Injection I has been designed and fabricated, which has also been tested in a liquid Helium state inside a vertical Dewar in the Haerbin institute of Technology in November 2012. The design current was 210 A, when the test current reached 400 A no quench occurred so the solenoid magnet was forced to quench by the embedded heaters. The integral field strength, leakage field at the nearby upstream and downstream superconducting spoke cavities all meet the design requirements. At the same time, it also checked the reliability of the vertical test Dewar and the quenched detection system. The superconducting prototype magnet has accumulated valuable experiences for the coming batch magnets production and cryogenic test.
119434810
Ly-alpha forests and cooling outflow from dwarf galaxies
We propose that cooling outflows from star-forming dwarf galaxies that are spatially correlated with but unbound to bright galaxies may account for the low column QSO Ly$\alpha$ forests, providing an explanation for both the heavy elements recently detected in them and the large sizes associated with them. Thus, we suggest that structure formations in the early universe on scales where matters collapse gravitationally and the gas forms stars are responsible for the Ly$\alpha$ forests (cf. the mini-halo model). Supernovae shock the interstellar gas to high temperature, and the resulting gas outflows from the dwarfs owing to their shallow potential wells. The gas cools radiatively as the radiative cooling time shortens because of adiabatic expansion. Subsequent thermal instability results in condensation of clouds. The clouds inherit the kinetic energy of the flow and coast to large distances, providing regions of the absorbing gas with sizes of up to hundreds of kpc. We calculate the Ly$\alpha$ absorption line profiles and the neutral column distribution, and show that they are consistent with observations. We suggest that the Ly$\alpha$ forests are caused by the faint blue galaxies found in the deep extragalactic surveys.
59425513
Bunch by Bunch Beam Diagnostics in SSRF
A set of broadband beam instruments including filling pattern monitor, scope based BPM processor and streak camera has been implemented in the storage ring of SSRF. Several parameters such as charge, lifetime, transverse position, betatron tune and beam length, can be measured for individual bunch by these devices. The operation experience and measurement results will be introduced. The preliminary effort to retrieve wake field information from these measurements will be presented as well. INTRODUCTION Shanghai Synchrotron Radiation Facility (SSRF), as a 3.5 GeV third generation light source, started user operation with seven beamlines since 2009 [1]. Couple thousands of experiment proposals have been performed during past three years. Meanwhile almost the same number of proposals were rejected or delayed due to limited beamlines and beam time. In order to take full advantage of SSRF an upgrade project of adding more than twenty beamlines has been planed. Lots of in vacuum insertion devices with small gap will involve in this upgrading. Beam instability introduced by multibunch interaction will be a very series issue in this case. Study of machine impedance and wake field became a high priority job. Several broad band instruments with bunch by bunch capability was developed and implemented for this purpose and showed very good potential in recent machine studies. Table 1 shows the primary specification of broad band diagnostics devices equipped in SSRF ring. Table 1: Specification of Bunch by Bunch Instruments Measurement Devices Resolution Charge Button pickup + digitizer 0.1% Position Button pickup + Scope 50 um Length Streak Camera 2 ps During a typical SSRF user shift, beam in storage ring will be filled up to 210 mA with equivalent 500 bunches then decays to 140 mA. A lots of history data produced by above instruments have been accumulated. Detailed analyze of these data will give us some knowledge of multi-bunch interaction.
120034276
de Broglie–Bohm interpretation for wave function of a toroidal black hole
The mass function of a toroidal black hole as a dynamical variable is given by using Kuchar’s approach. Then the toroidal black hole is investigated by using the de Broglie–Bohm approach, and its quantum potential and quantum trajectories are obtained. In our process the vector potential of the electromagnetic field in the toroidal black hole is treated as a canonical variable.