15310424
A Lifshitz black hole in four dimensional R(2) gravity
We consider a higher derivative gravity theory in four dimensions with a negative cosmological constant and show that vacuum solutions of both Lifshitz type and Schrodinger type with arbitrary dynamical exponent z exist in this system. Then we find an analytic black hole solution which asymptotes to the vacuum Lifshitz solution with z = 3/2 at a specific value of the coupling constant. We analyze the thermodynamic behavior of this black hole and find that the black hole has zero entropy while non-zero temperature, which is very similar to the case of BTZ black holes in new massive gravity at a specific coupling. In addition, we find that the three dimensional Lifshitz black hole recently found by E. Ayon-Beato et al. has a negative entropy and mass when the Newton constant is taken to be positive.
64370202
Observing the origin of superconductivity in quantum critical metals
Despite intense efforts during the last 25 years, the physics of unconventional superconductors, including the cuprates with a very high transition temperature, is still a controversial subject. It is believed that superconductivity in many of these strongly correlated metallic systems originates in the physics of quantum phase transitions, but quite diverse perspectives have emerged on the fundamentals of the electron-pairing physics, ranging from Hertz style critical spin fluctuation glue to the holographic superconductivity of string theory. Here we demonstrate that the gross energy scaling differences that are behind these various pairing mechanisms are directly encoded in the frequency and temperature dependence of the dynamical pair susceptibility. This quantity can be measured directly via the second order Josephson effect and it should be possible employing modern experimental techniques to build a `pairing telescope' that gives a direct view on the origin of quantum critical superconductivity.
17403659
On the z=4 Horava-Lifshitz Gravity
We consider z = 4 Horava-Lifshitz gravity in both 3+1 and 4+1 dimensions. We find black hole solutions in the IR region for a kind of z = 4 Horava-Lifshitz gravity which is inherited from the new massive gravity in three dimensions and an analog of the new massive gravity in four dimensions through the quantum inheritance principle. We analyze thermodynamic properties for the black hole solutions for z = 4 Horava-Lifshitz gravity. We also write out the Friedmann equation in 3+1 dimensions for cosmological solutions.
55036525
Single-pass beam measurements for the verification of the LHC magnetic model
During the 2009 LHC injection tests, the polarities and effects of specific quadrupole and higher-order magnetic circuits were investigated. A set of magnet circuits had been selected for detailed investigation based on a number of criteria. On or off-momentum difference trajectories launched via appropriate orbit correctors for varying strength settings of the magnet circuits under study - e.g. main, trim and skew quadrupoles; sextupole families and spool piece correctors; skew sextupoles, octupoles - were compared with predictions from various optics models. These comparisons allowed confirming or updating the relative polarity conventions used in the optics model and the accelerator control system, as well as verifying the correct powering and assignment of magnet families. Results from measurements in several LHC sectors are presented.
123552488
MRPC detector for the upgrade of BESIII E-TOF
An end-cap Time-of-Flight (E-TOF) system with higher granularity and intrinsic time resolution of better than 50 ps will extend the K/pion separation (2 sigma) pT range to 1.4 GeV/c and enhance the physics capability of Beijing Spectrometer (BESIII). A R&D work was carried out aiming at upgrading the current BESIII E-TOF with the Multi-gap resistive Plate Chamber (MRPC) detector. The latest best test for the prototype MRPC, together with the custom designed Front End Electronics (FEE) and TDC boards, was performed at the BEPC E3 line in July 2012. The test results show that time resolution of less than 50 ps can be achieved with such a system.
7353168
R&D on long-strip MRPC
Multi-gap Resistive Plate Chamber (MRPC), which has excellent performance and relatively low cost per channel, is a good candidate for Time-of-Flight (TOF) system in modern high energy physics experiments. A new kind of MRPC, Long-strip MRPC (LMRPC) with 50 cm × 2.5 cm strips, was tested at GSI-FOPI with secondary beam. The resets show that this LMRPC prototype can achieve 60 to 70 ps σ time resolution and greater than 97% detecting efficiency. The cross talk between readout strips is less than 2%. The measured spatial resolution along the strips is about 0.36 cm σ.
53998460
High-power beam-based coherently enhanced THz radiation source
We propose a compact Smith-Purcell radiation device that can potentially generate high average power THz radiation with high conversion efficiency. The source is based on a train of short electron bunches from an rf photoemission gun at an energy of a few MeV. Particle tracking simulation and analysis show that, with a beam current of 1 mA, it is feasible to generate hundreds of watts of narrow-band THz radiation at a repetition rate of 1 MHz.
55751567
Designs for a Linac-Ring LHeC
We consider three scenarios for the recirculating electron linear accelerator (RLA) of a linac-ring type electron-proton collider based on the LHC (LHeC): (i) a pulsed linac with a final beam energy of 60 GeV ['p-60'], (ii) a higher luminosity configuration with two cw linacs and energy-recovery (ERL) also at 60 GeV ['erl'], and (iii) a high energy option using a pulsed linac with 140-GeV final energy ['p-140']. We discuss parameters, synchrotron radiation, footprints, and performance for the three scenarios.