118397938
BRANE SOLUTIONS WITH TENSION
In this note, we apply a special metric ansatz to simplify the equations of motion for gravitational systems. Then we construct charged brane solutions in D = n+p+2 dimensions which have spherical symmetry of Sn and translational symmetry along p directions. They are characterized by mass density, uniform tension and electric/magnetic charges, and nonsingular only for specific tension. In particular, we find the limits and the coordinate transformations which reduce the charged brane solutions to M2- and M5-branes. We also obtain the regularity condition for an electrically charged two-brane solution which has two tensions.
16002558
Higher derivative correction to Kaluza–Klein black hole solution
We investigate the attractor mechanism in a Kaluza–Klein black hole solution in the presence of higher derivative terms. In particular, we discuss the attractor behavior of static black holes by using the effective potential approach as well as the entropy function formalism. We consider different higher derivative terms with a general coupling to the moduli field. For the R2 theory, we use an effective potential approach, looking for solutions which are analytic near the horizon and showing that they exist and enjoy attractor behavior. The attractor point is determined by extremization of the modified effective potential at the horizon. We study the effect of the general higher derivative corrections of Rn terms. Using the entropy function we define the modified effective potential and we find the conditions to have the attractor solution. In particular for a single charged Kaluza–Klein black hole solution we show that a higher derivative correction dresses the singularity for an appropriate coupling, and we can find the attractor solution.
113398368
Calabi-Yau Manifolds, Hermitian Yang-Mills Instantons, and Mirror Symmetry
We address the issue of why Calabi-Yau manifolds exist with a mirror pair. We observe that the irreducible spinor representation of the Lorentz group requires us to consider the vector spaces of two forms and four forms on an equal footing. The doubling of the two-form vector space due to the Hodge duality doubles the variety of six-dimensional spin manifolds. We explore how the doubling is related to the mirror symmetry of Calabi-Yau manifolds. Via the gauge theory formulation of six-dimensional Riemannian manifolds, we show that the curvature tensor of a Calabi-Yau manifold satisfies the Hermitian Yang-Mills equations on the Calabi-Yau manifold. Therefore, the mirror symmetry of Calabi-Yau manifolds can be recast as the mirror pair of Hermitian Yang-Mills instantons. We discuss the mirror symmetry from the gauge theory perspective.
117135154
Toroidal AdS Charged Branes and Toda Equations
In this note, we consider the equations of motion for charged branes in AdS space and show that they can be cast into one-dimensional coupled Toda type. Then we solve the equations of motion to construct static charged AdS brane solutions which are invariant under translation along $p$ directions and have toroidal symmetry. The solutions are described by mass, charges and a dilaton coupling constant.
118510404
Symmetry Breaking Phase Transitions in ABJM Theory with a Finite U(1) Chemical Potential
We consider the U(1) charged sector of ABJM theory at finite temperature, which corresponds to the Reissner-Nordstrom AdS black hole in the dual type IIA supergravity description. Including back-reaction to the bulk geometry, we show that phase transitions occur to a broken phase where SU(4) R-symmetry of the field theory is broken spontaneously by the condensation of dimension one or two operators. We construct the composite operators out of fields in ABJM theory and describe the phase transition with the dual gravity solutions. We show numerically and analytically that the relevant critical exponents for the dimension one operator agree precisely with those of mean field theory in the strongly coupled regime of the large N planar limit.
15073869
Non-Supersymmetric Unattractors in Born-Infeld Black Holes
We investigate unattractor behavior in non-extremal black holes in Einstein-Born-Infeld-Dilaton theory of gravity in four-dimensional asymptotically flat spacetime. We obtain solutions which are non-singular near the horizon and dependent on the value of the dilaton field at the infinity, using perturbation method. It is shown that the value of the scalar field at the horizon is determined by its asymptotic value and the charges carried by the black hole. And we also find it is not true in general that the dilaton value at the horizon is a monotonically increasing function of the first coefficient of its series expansion in non-extremal Born-Infeld black holes.
113201344
Design of Machine Protection System for the PEFP 100MeV Linac
37852911
Design of 100 MeV Proton Beam Irradiation Facility for the PEFP 100 MeV Linac
The Proton Engineering Frontier Project (PEFP) will install a 100-MeV proton linear accelerator at Gyeong-ju site. For the beam commissioning of 100 MeV proton linac, the two target rooms (TR 103, TR 23) will be prepared as a starter among 10 target room. To design the irradiation equipment in TR 103, we have investigated general propagation shape and spatial distribution of proton beam, when 100 MeV proton beam extracted from vacuum in the beam lines through beam window by Monte carlo method. On the basis of this result, we have designed beam irradiation components and their configuration. The beam irradiation facility consist of beam window, beam dump, support frame, sample support and beam current monitor. To minimize residual radioactivity induced by incident proton beam, the pure aluminum was selected as the material of beam dump and the aluminum alloy was selected as material of other irradiation equipment. This residual radioactivity of equipment was estimated by Monte carlo method. In this paper, the details of this irradiation equipment design are presented.
62888926
FIVE YEAR OPERATION OF THE 20-MeV PROTON ACCELERATOR AT KAERI*
A 20-MeV proton linear accelerator was operated since 2007 by Proton Engineering Frontier Project (PEFP) at Korea Atomic Energy Research Institute (KAERI), Daejeon site. The performance test of the accelerator itself has been done with limited operation conditions. In addition, the 20-MeV accelerator was used as a test bench of the 100-MeV accelerator components. Besides the machine study itself, it supplied proton beams to more than 1600 samples for users. The 20-MeV accelerator was disassembled at Nov. 2011 and installed at Gyeongju site as an injector for the 100-MeV linac in March 2012. In this paper, five year operation experiences of the 20-MeV linac at Daejeon site are summarized and the technical issues are discussed.
124789806
INSTALLATION AND OPERATION OF THE BEAMLINES FOR THE 100-MeV PROTON LINAC
Beamlines and 100-MeV proton linac have been developed for 1st phase of KOMAC(Korea Multi-purpose Accelerator Complex) at the Gyeong-ju site. The linac supplies either 20-MeV or 100-MeV proton beams for beam applications. Each proton beam can be transported to 2 beamlines for industrial purpose and 3 beamlines for various researches. At the first phase, 2 beamlines were installed and under test.
8187163
Proton beam energy measurement using semiconductor detectors at the 45MeV test beam line of PEFP
For the pilot and feasibility studies on the development of beam utilization technologies of PEFP (proton engineering frontier project), the test beam line was installed at the MC-50 cyclotron of KIRAMS (Korea institute of radiological and medical sciences) [1-2]. The energy measurement of proton beam with high accuracy is very important for the some experiments such as radiation hardness test of semiconductor devices for the spacecraft, detector development and test for the nuclear physics, etc. Energy measurement of 35 MeV and 45 MeV proton beam using a 5 mm thick Si(Li) in air was performed. The energy was controlled by Al degrader in the range of 0.02 mm~6.2 mm. The measured value was compared to the results of code simulation using SRIM 2003.