This report discusses the following topics: Low-energy particle dynamics; QCD dynamics on the lattice; lattice QCD Vacuum; phenomenology & cosmology; the ZEUS Experiment at HERA; neutrino physics at LAMPF; non-accelerator physics; and SSC activity.
NASA Astrophysics Data System (ADS)
Cosmological Constant The cosmological constant, conventionally de� noted by the Greek letter clump together or disperse as it evolves, the energy density in a cosmological constant is a property cosmological constant will cause galaxies to appear to accelerate away from us, in contrast to ...
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... CRYSTAL LATTICES, POROSITY, BUBBLES, RUSSIA, DISTRIBUTION FUNCTIONS, COSMOLOGY, THERMONUCLEAR REACTIONS ...
DTIC Science & Technology
Cosmological observables are used to construct cosmological models and cosmological models are used to interpert cosmological observations. Statements that the expansion of the Universe is accelerating or that dark energy exists are made within the framework of a particular ...
An interactive program to help design accelerator lattices and lattice insertions is described. Present limitations and directions of future development are indicated.
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This paper describes the use of Siberian snake lattice to accelerate polarized beams in the superconducting super collider. (LSP)
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This paper presents, to the author's knowledge, the first graphics processing unit (GPU) accelerated program that solves the evolution of interacting scalar fields in an expanding universe. We present the implementation in NVIDIA's Compute Unified Device Architecture (CUDA) and compare the performance to other similar programs in chaotic inflation models. We report speedups ...
Two cosmological Models for the Poincare Gauge Gravity theory with a non vanishing torsion are proposed. It is shown that the torsion plays an important role in explaining the accelerated expansion of the universe. Some of the cosmological parameters are also expressed in terms of the redshift and the dark energy scenarios are ...
An exact Chameleon cosmological model describing the evolution of a non-singular bouncing cosmology with the phantom divide line crossing is obtained by constructing two independent functions of the scalar field.
We have explored a n + 2 higher-dimensional cosmology dominated by phantom energy with a static traversable wormhole dominated by a time-dependent cosmological constant. Some interesting features are revealed and discussed in some details.
An interactive program to help design accelerator lattices and lattice insertions is described. Present limitations and directions of future development are indicated. (ERA citation 10:044949)
We provide a novel and efficient algorithm for computing accelerations in the periodic large-N-body problem that is at the same time significantly faster and more accurate than previous methods. Our representation of the periodic acceleration is precisely mathematically equivalent to that determined by Ewald summation and is computed directly as an ...
A major obstacle to collaboration on accelerator projects has been the sharing of lattice description files between modeling codes. To address this problem, a lattice description format called Accelerator Markup Language (AML) has been created. AML is bas...
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We propose an explanation for the present accelerated expansion of the universe that does not invoke dark energy or a modification of gravity and is firmly rooted in inflationary cosmology.
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The Universe is expanding ever faster - the effect of 'dark energy', most astronomers believe. Surveys of how galaxies were distributed in the past could provide precise clues to what is driving this acceleration.
Magnetowave Induced Plasma Wakefield Acceleration for Ultra High Energy Cosmic Rays Pisin Chen Kavli Institute for Particle Astrophysics and Cosmology Stanford Linear Accelerator...
In Loop Quantum Cosmology (LQC) there is a discreteness parameter {lambda}, that has been heuristically associated to a fundamental granularity of quantum geometry. It is also possible to consider {lambda} as a regulator in the same spirit as that used in lattice field theory, where it specifies a regular lattice in the real line. A ...
Recently, the tachyon cosmology has been represented as dark energy model to support the current acceleration of the universe without phantom crossing. In this paper, we study the dynamics of the tachyon cosmology in which the field plays the role of tachyon field and also non-minimally coupled to the matter Lagrangian. The model shows ...
This work confirms the stability of a class of domain wall lattice models that can produce accelerated cosmological expansion, with pressure to density ratio w = -1/3 at early times, and with w = -2/3 at late times when the lattice scale becomes large compared to the wall thickness. For walls of tension TI, the ...
A cosmology inspired structure for phase space is introduced, which leads to a lattice-like discretization of position and momentum. Lorentz invariance is broken at very high, inaccessible energies. The divergent integrals of perturbation terms in quantum...
We investigate the cosmology of a recently proposed deformation of Einstein gravity, emerging from quantum gravity heuristics. The theory is constructed to have de Sitter space as a vacuum solution, and thus to be relevant to the accelerating universe. However, this solution turns out to be unstable, and the true phase space of ...
We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature that the universe undergoes a continuous transition from deceleration to acceleration at some ...
We study cosmological constraints on the various accelerating models of the universe using the time evolution of the cosmological redshift of distant sources. The important characteristic of this test is that it directly probes the expansion history of the universe. In this work we analyze the various models of the universe which can ...
A cosmological theory that predicts a late-time accelerated attractor with a constant dark matter to dark energy ratio can be said to solve the coincidence problem. Such cosmologies are naturally generated in the context of nonstandard gravity theories under conformal transformation because of the resulting couplings between scalar ...
We apply the nonstandard loop quantum cosmology method to quantize a flat Friedmann-Robertson-Walker cosmological model with a free scalar field and the cosmological constant ?>0. Modification of the Hamiltonian in terms of loop geometry parametrized by a length ? introduces a scale dependence of the model. The spectrum of the ...
The problem of the doubling of states is investigated in the framework of the theory of discrete quantum gravity under the assumption that the theory has a continuum (macroscopic) limit. It is demonstrated that irregular (in some sense) modes of fields (i.e., modes that change abruptly on scales of a lattice step and have a finite energy when the lattice ...
Observations of supernova explosions halfway back to the Big Bang give plausible evidence that the expansion of the universe has been accelerating since that epoch, approximately 8 billion years ago and suggest that energy associated with the vacuum itself may be responsible for the acceleration.
PubMed Central
A class of Einstein-dilaton-axion models is found for which almost all flat expanding homogeneous and isotropic universes undergo recurrent periods of acceleration. We also extend recent results on eternally accelerating open universes.
for converting the accelerator beam to copious quantities of low-energy neutrons for absorption in a lattice of fertile material and moderator. The fertile material of the lattice...
Recent cosmological observations of unprecented accuracy, by WMAP in particular, have established a 'Standard Model' of cosmology, just as LEP established the Standard Model of particle physics. Both Standard Models raise open questions whose answers are likely to be linked. The most fundamental problems in both particle physics and ...
Cosmology is undergoing a revolution. With recent precise measurements of the cosmic microwave background radiation, large galaxy redshift surveys, better measurements of the expansion rate of the Universe and a host of other astrophysical observations, there is now a standard, highly constrained cosmological model. It is not a ...
PubMed
The presently accelerating universe may keep accelerating forever, eventually run into the event horizon problem, and thus be in conflict with the superstring idea. On the other hand, the current accelerating phase as well as the fate of the universe may be swayed by a negative cosmological constant, which dictates ...
Dark energy cosmology is considered in a modified Gauss-Bonnet model of gravity with and without a scalar field. It is shown that these generalizations of general relativity endow it with a very rich cosmological structure: it may naturally lead to an effective cosmological constant, quintessence or phantom cosmic ...
Series expansions for the time-dependent coverage in random sequential adsorption on a lattice are reviewed. A transformation is carried out, resulting in combinatorial expressions in which only nonrepeating lattice walks are required. Convergence is greatly accelerated, and application is made to the asymptotic coverage of previously ...
An FFAG is a lattice with fixed magnetic fields that has an extremely wide energy acceptance. One particularly simple type of FFAG is based on a FODO lattice, where both quads can be combined-function bending/quadrupole magnets. The spaces between the combined-function magnets are left open for RF cavities and other hardware. This paper describes a general ...
We investigate late time acceleration of the universe in higher dimensional cosmology. The content in the universe is assumed to exert pressure which is different in the normal and extra dimensions. Cosmologically viable solutions are found to exist for simple forms of the equation of state. The parameters of the model are fixed by ...
A solution of the (4+n)-dimensional vacuum Einstein equations is found for which spacetime is compactified on an n-dimensional compact hyperbolic manifold (n> or =2) of time-varying volume to a flat four-dimensional Friedmann-Lemaitre-Robertson-Walker cosmology undergoing a period of accelerated expansion in the Einstein conformal frame. This shows that ...
A main-ring lattice that avoids crossing transition energy during acceleration when injected by a low-energy booster is discussed. Included in the report are a list of parameters, plots of lattice and orbit functions, and output from program SYNCH.
A main-ring lattice that avoids crossing transition energy during acceleration when injected by a low-energy booster is discussed. Included in the report are a list of parameters, plots of lattice and orbit functions, and output from program SYNCH. (ERA c...
The conceptual evolution of the accelerator lattice design is discussed. Indicated are aspects of IR design. We emphasize the cancellation of stop-band width in the cluster design. The case of symmetric vs antisymmetric design is also discussed. The SSC lattice is used as an example. 9 refs.
Jan 6, 2011... Astrophysics and Cosmology, jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University. ...
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Walker (FRW) cosmology. Since we do on average expect at least one string per horizon volume', we must check that these properties are not modified in any ...
& Particle Astrophysics Supernova Acceleration Probe University of California at Berkeley UC Berkeley Physics Department of Energy Universe in the Classroom One Laptop per Child...
A new cosmological scenario driven by a slow rolling homogeneous scalar field whose exponential potential V(Phi) has a quadratic dependence on the field Phi in addition to the standard linear term is discussed. The derived equation of state for the field predicts a transient accelerating phase, in which the Universe was decelerated in the past, began to ...
The Universe seems to be expanding ever faster - a phenomenon generally ascribed to the influence of 'dark energy'. But might the observed acceleration be a trick of the light in an inhomogeneous Universe?
This paper presents a new variety of one-dimensional nonlinear integrable accelerator lattices with periodic and exponential invariants in coordinates and momenta. Extension to two-dimensional transverse motion, based on a recently published approach, is discussed.
In the most recent year of our program on accelerator dynamics we made progress in several areas. Our work on finding integrable lattices has proved to be effective. Using our systematic technique, we were able to find an improved lattice for the Advanced...
... in a one-dimensional, discrete lattice is generated by accelerating the end-most particle from zero to its final velocity in a finite rise time after which ...
A SLIM formalism to deal with a general, linearly coupled accelerator lattice is summarized. Its application to a wide range of accelerator calculations is emphasized.
We elaborate on the proposal that the observed acceleration of the Universe is the result of the backreaction of cosmological perturbations, rather than the effect of a negative-pressure dark energy fluid or a modification of general relativity. Through the effective Friedmann equations describing an inhomogeneous Universe after smoothing, we demonstrate ...
... thermally stable AP and burning rate catalyst ... to produce a solid propellant that ... LATTICES, FERROCENES, FREEZE DRYING, GRINDING, GUIDED ...
The contribution of cosmological perturbations to the time drift of the cosmological redshift is derived. It is shown that the dominant correction arises from the local acceleration of both the emitter and the observer. The amplitude of this effect is estimated to be of the order of 1% of the drift signal at z=2-4, but can easily be ...
Reheating is an important part of inflationary cosmology. It describes the production of Standard Model particles after the phase of accelerated expansion. We review the reheating process with a focus on an in-depth discussion of the preheating stage, which is characterized by exponential particle production due to a parametric resonance or tachyonic ...
The inflationary scenarios suggested by the duality properties of string cosmology in the Brans-Dicke (or String) frame are shown to correspond to accelerated contraction (deflation) when Weyl-transformed to the Einstein frame. We point out that the basic virtues of inflation (solving the flatness and horizon problems, amplifying vacuum fluctuations) have ...
We solve one of the open problems in Einstein-Cartan theory, namely, we find a natural matter source whose spin angular momentum tensor is compatible with the cosmological principle. We analyze the resulting evolution equations and find that an epoch of accelerated expansion is an attractor. The torsion field quickly decays in that period. Our results are ...
For true insight into the nature of dark energy, measurements of the precision and accuracy of the Supernova/Acceleration Probe (SNAP) are required. Precursor or scaleddown experiments are unavoidably limited, even for distinguishing the cosmological cons...
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Topics covered in this annual report are: astrophysics and cosmology, giant resonances in excited nuclei, heavy ions, fundamental symmetries, nuclear reactions, accelerator mass spectrometry, accelerators and ion sources, nuclear instrumentation, computer systems and the booster linac project.
Topics covered in this annual report are: astrophysics and cosmology, giant resonances in excited nuclei, heavy ions, fundamental symmetries, nuclear reactions, accelerator mass spectrometry, accelerators and ion sources, nuclear instrumentation, computer...
This paper looks at how inhomogeneous spacetime models may be significant for cosmology. First it addresses how the averaging process may affect large-scale dynamics, with backreaction effects leading to effective contributions to the averaged energy-momentum tensor. Second, it considers how local inhomogeneities may affect cosmological observations in ...
We solve for the behavior of cosmological perturbations in the Dvali-Gabadadze-Porrati (DGP) braneworld model using a new numerical method. Unlike some other approaches in the literature, our method uses no approximations other than linear theory and is valid on large scales. We examine the behavior of late-universe density perturbations for both the ...
In the present work, motivated by the work of Cai and Su [Phys. Rev. D 81 (2010) 103514], we propose a new type of interaction in dark sector, which can change its sign when our universe changes from deceleration to acceleration. We consider the cosmological evolution of quintessence and phantom with this type of interaction, and find that there are some ...
Regular inflationary Big Bang scenario with accelerating stage of cosmological expansion at asymptotics proposed earlier in the framework of the Poincar� gauge theory of gravity is investigated. Analysis of regular inflationary cosmological models with two torsion functions filled with scalar field with quadratic potential and ...
The absence of guidance from fundamental physics about the mechanism behind cosmic acceleration has given rise to a number of alternative cosmological scenarios. These are based either on modifications of general relativistic gravitation theory on large scales or on the existence of new fields in Nature. In this Letter we investigate the observational ...
A self-consistent system of interacting nonlinear spinor and scalar fields within the scope of a Bianchi type-I cosmological model filled with perfect fluid is considered. Exact self-consistent solutions to the corresponding field equations are obtained. A role of the spinor field in the evolution of the Universe is studied. It is shown that the spinor field gives rise to an ...
Holography is expected as one of the promising descriptions of quantum general relativity. We present a model for a cosmological system involving two holographic screens and find that their equilibrium exactly yields a standard Friedmann-Robertson-Walker universe. We discuss its cosmological implications by taking into account higher order quantum ...
We investigate cosmological consequences of a class of exponential f(R) gravity in the Palatini formalism. By using the current largest type Ia Supernova sample along with determinations of the cosmic expansion at intermediary and high-z we impose tight constraints on the model parameters. Differently from other f(R) models, we find solutions of transient ...
For the description of the early inflation and acceleration expansion of the universe that are compatible with observational data, the 5D noncompact Kaluza-Klein cosmology is investigated. It is proposed that the 5D space is filled with a null perfect fluid, resulting in a perfect fluid in a 4D universe, plus one along the fifth dimension. By analyzing the ...
The accelerating expansion of the universe presents an exciting, fundamental challenge to the standard models of particle physics and cosmology. I highlight some of the outstanding challenges in both developing theoretical models and interpreting without bias the observational results from precision cosmology experiments in the next ...
It is now about 10 years since the evidence, based on Type Ia supernovae, for the acceleration of the expansion of the Universe was discovered. I will discuss some aspects of the work and events in the Supernova Cosmology Project (SCP), during the period 1988 to 1998, which led to this discovery.
In this note we consider a variable G cosmology which is consistent with observation and which had successfully predicted an ever expanding accelerating universe with a small cosmological constant amongst other things. Three further tests are proposed in this note: First, the inexplicable anomalous accelerations of ...
This Resource Letter provides a guide to the literature on dark energy and the accelerating universe. It is intended to be of use to researchers, teachers, and students at several levels. Journal articles, books, and websites are cited for the following topics: Einstein's cosmological constant, quintessence or dynamical scalar fields, modified cosmic ...
Graphics Processing Units (GPUs) offer a new way to accelerate numerical calculations by means of on-board massive parallelisation. We discuss two examples of GPU implementation relevant for cosmological simulations, an N-Body Particle-mesh solver and a radiative transfer code. The latter has also been ported on multi-GPU clusters. The range of ...
An FRW like cosmological model in the non commutative Seiberg-Witten space-time is proposed. The pure NCG dynamical apparent horizon and Hawking temperature are obtained and explicit expressions of the scale factor, Hubble and deceleration parameters are derived. The accelerated expansion of the universe scenario is also discussed.
The dynamics of Dvali-Gabadadze-Porrati (DGP) braneworld with an anisotropic brane is studied. The Friedmann equations and their solutions are obtained for two branches of anisotropic DGP model. The late time behavior in DGP cosmology is examined in the presence of anisotropy which shows that universe enters a self-accelerating phase much later compared to ...
If general relativity (GR) describes the expansion of the Universe, the observed cosmic acceleration implies the existence of a "dark energy." However, while the Universe is on average homogeneous on large scales, it is inhomogeneous on smaller scales. While GR governs the dynamics of the inhomogeneous Universe, the averaged homogeneous Universe obeys modified Einstein ...
Harmonic number jump acceleration of muon beams in scaling FFAG rings is studied. General considerations about harmonic number jump acceleration lead to the necessity of designing rings with dispersion suppressed insertions, and in which both ?+ and ?- can be circulated in the same direction. Design principles of such a scaling FFAG ring are described. ...
frequency acceleration system. Ac- ceptance is enhanced by the use only of linear lattice ele- ments move across the magnet aperture during acceleration. The three types of structures used in FFAG latticeRECENT PROGRESS ON FFAGS FOR RAPID ACCELERATION C. Johnstone , FNAL, Batavia, IL 60510, USA ...
We study stability conditions of the full Hamiltonian constraint equation describing the quantum dynamics of the diagonal Bianchi I model in the context of loop quantum cosmology. Our analysis has shown robust evidence of an instability in the explicit implementation of the difference equation, implying important consequences for the correspondence between the full loop ...
We discuss the cosmological consequences of QCD phase transition(s) on the early universe. We argue that our recent knowledge about the transport properties of quark-gluon plasma (QGP) should thraw additional lights on the actual time evolution of our universe. Understanding the nature of QCD phase transition(s), which can be studied in lattice gauge ...
This document reports the past year's achievements and the present directions of the activities of Boston University researchers in seven projects in high energy physics research: study of high energy electron-positron annihilation, using the SLD detector at SLAC; search for proton decay and neutrinos from point astrophysical sources, as well as the study of cosmic ray muons and neutrinos ...
We show that the factor ordering ambiguities associated with the loop quantization of the gravitational part of the cosmological Hamiltonian constraint disappear at the level of the Wheeler-DeWitt equation only for a particular choice of lattice refinement model, which coincides with constraints imposed from phenomenological and consistency arguments.
The recently observed acceleration of the expansion of the universe is a topic of intense interest. The favoured causes are the "cosmological constant" or "dark energy". The former, which appears in the Einstein equations as the term [lambda]g[subscript [mu]v], provides an extremely simple, well-defined mechanism for the acceleration. ...
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EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). This paper describes the design of the EMMA lattice. We begin with a summary of the experimental goals that impact the lattice design, and then outline what ...
A conformally flat accelerated charge metric is found in an arbitrary dimension D. It is a solution of the Einstein-Maxwell-null fluid equations with a cosmological constant in D ? 4 dimensions. When the acceleration is zero, our solution reduces to the Levi-Civita-Bertotti-Robinson metric. We show that the charge loses its energy, for ...
The values of orbit functions for accelerator lattices as computed with accelerator design programs may differ between different programs. For a simple lattice, consisting of identical constant-gradient bending magnets, the functions (horizontal and vertical betatron tunes, dispersions, closed orbit offsets, orbit ...
We examine the properties of a recently proposed observationally viable alternative to homogeneous cosmology with smooth dark energy, the timescape cosmology. In the timescape model cosmic acceleration is realized as an apparent effect related to the calibration of clocks and rods of observers in bound systems relative to ...
CSR, a new Cooler-Storage-Ring project, is the post-acceleration system of the Heavy Ion Research Facility in Lanzhou (HIRFL). It consists of a main ring (CSRm) and an experimental ring (CSRe). From the HIRFL cyclotron system the heavy ions will be accumulated, cooled and accelerated in the CSRm, then extracted fast and injected into the CSRe for many ...
We present lattice studies for a proposed femtosecond synchrotron radiation X-ray source based on a recirculating accelerator. After a general description, we cover specific aspects of the lattice that are relevant to this type of machine and show preliminary results of particle tracking and briefly describe a new code developed for a ...
Medium energy (1 to 30 GeV) accelerators are often confronted with transition crossing during acceleration. A lattice without transition is presented, which is a design for the Fermilab Main Injector. The main properties of this lattice are that the {gamma}{sub t} is an imaginary number, the maxima of the ...
Assuming the equation of state for quintessential matter, p=w(z)?, we analyze the dynamical behavior of the scale factor in Friedmann-Robertson-Walker cosmologies. It is shown that its dynamics is formally equivalent to that of a classical particle under the action of a 1D potential V(a). It is shown that the Hamiltonian method can be easily implemented to obtain a ...
In this paper we study the possibility of sustaining an evolving wormhole via exotic matter made of phantom energy in the presence of a cosmological constant. We derive analytical evolving wormhole geometries by supposing that the radial tension of the phantom matter, which is negative to the radial pressure, and the pressure measured in the tangential directions have ...
This 48-minute radio broadcast discusses the future of cosmology with scientists from a meeting on that subject in Cleveland in October 2003. The conference aimed to tackle some big questions for thinking about the universe - from the prospects for the existence of extra dimensions, to the best tools to push the frontiers of astrophysics. Topics discussed include dark energy ...
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Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has ...
In this paper we derive, directly from the Nambu-Goto action, the relevant components of the acceleration of cosmological featureless p-branes, extending previous analysis based on the field theory equations in the thin-brane limit. The component of the acceleration parallel to the velocity is at the core of the velocity-dependent ...
The standard big bang cosmology has been greatly successful in explaining many observational aspects of the real universe. However, two great difficulties faced by it are the so-called ``horizon'' and ``flatness'' problems. By assuming that the recently found cosmic acceleration to be a genuine and ever present effect, we show that, the resultant ...
Several cosmological models have been proposed in order to explain the current acceleration of the Universe. Recently, the normal branch of the DGP (after Dvali, Gabadadze, and Porrati) brane model with a generalized Chaplygin gas was studied as a model which can cross the phantom divide line avoiding the future singularity. In the present work, we wish to ...
We show that the accelerated expansion of the universe can be viewed as a crossover phenomenon where the Newton constant and the cosmological constant are actually scaling operators, dynamically evolving in the attraction basin of a non-Gaussian infrared fixed point, whose existence has been recently discussed. By linearization of the renormalized flow it ...
We study a five dimensional FLRW type Kaluza-Klein cosmological model with static extra dimension. Accelerated expansion is found by assuming a linear relationship p b = mp a between pressures ` p a ' corresponding to the usual four dimension, and ` p b ' corresponding to the extra dimension. The field equations are obtained and solved, for different ...
It has been suggested that the acceleration of the Universe may be due to the backreaction of perturbations to the Friedmann-Robertson-Walker background. For a universe dominated by cold dark matter, it is known that the backreaction of superhorizon perturbations cannot drive acceleration. We extend this result to models with cold dark matter together with ...
EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). I will give a basic review of the EMMA lattice parameters. Then I will review the different lattice configurations that we would like to have for EMMA. ...
EMMA is a 10 to 20MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). I will give a basic review of the EMMA lattice parameters. Then I will review the different lattice configurations that we would like to have for EMMA. ...
In this paper, invariant metrics are constructed for Hamiltonian systems. These metrics give rise to norms on the space of homeogeneous polynomials of phase-space variables. For an accelerator lattice described by a Hamiltonian, these norms characterize the nonlinear content of the lattice. Therefore, the performance of the ...
The goal of this study was to select an optimal lattice for the NLC main linac, based on the analysis and comparison of several lattice options. In this study, we examined the FODO and doublet optics, combinations of 2 vs. 3 accelerator structures per girder, three options for the phase advance per cell and various configurations for ...
A major obstacle to collaboration on accelerator projects has been the sharing of lattice description files between modeling codes. To address this problem, a lattice description format called Accelerator Markup Language (AML) has been created. AML is based upon the standard eXtensible Markup Language (XML) format; ...
Cosmic acceleration has come to be a standard, and perhaps required, ingredient in our current understanding of the universe. In the early universe, under the name of inflation, a phase of accelerated expansion is used to solve many problems with the standard Hot Big Bang cosmology. In the late universe, cosmic ...
The harmonic number jump acceleration in scaling FFAG rings is considered in this paper. Constraints fixed by the acceleration scheme on the lattice design are detailed. An example of a 3.6 to 12.6 GeV muon lattice which satisfy these constraints is presented.
An electronuclear reactor is described in which a very high-energy particle accelerator is employed with appropriate target structure to produce an artificially produced material in commercial quantities by nuclear transformations. The principal novelty resides in the combination of an accelerator with a target for converting the ...
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After reviewing many alternatives, the SPS design team selected a FODO separated function lattice for the SPS. Periodicity and Q were chosen bearing in mind cost of construction, space for major accelerator components, extraction and the provision of adequate beam acceptance in spite of the influence of non-linear stop-bands.
EMMA is a 10 to 20MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). I will give a basic review of the EMMA lattice parameters. Then I will review...
EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). This paper describes the design of the EMMA lattice. We begin with a summary...
Performances of several tracking or/and analysis codes are compared. The basic purpose of this program was to assess reliability and accuracy of these codes, i.e., to determine the so-called error bars for the predicted values of tunes and other lattice f...
A workshop titled "Scientific Challenges for Understanding the Quantum Universe" was held December 9-11, 2008, at the Kavli Institute for Particle Astrophysics and Cosmology at the Stanford Linear Accelerator Center-National Accelerator Laboratory. The primary purpose of the meeting was to examine how computing at the extreme scale can ...
Dark energy cosmology is considered in a modified Gauss-Bonnet (GB) model of gravity where an arbitrary function of the GB invariant, f(G), is added to the general relativity action. We show that a theory of this kind is endowed with a quite rich cosmological structure: it may naturally lead to an effective cosmological constant, ...
We find a cosmological solution corresponding to the compactification of 10D supergravity on a warped conifold that easily circumvents the "no-go" theorem given for a warped or flux compactification, providing new perspectives for the study of supergravity or superstring theory in cosmological backgrounds. With fixed volume moduli of the internal space, ...
We find a cosmological solution corresponding to the compactification of 10D supergravity on a warped conifold that easily circumvents the ''no-go'' theorem given for a warped or flux compactification, providing new perspectives for the study of supergravity or superstring theory in cosmological backgrounds. With fixed ...
The elements of microwave linear accelerators are introduced starting with the principles of acceleration and accelerating structures. Considerations for microwave structure modeling and design are developed from an elementary point of view. Basic elements of microwave electronics are described for application to the ...
The accelerating expansion of the Universe points to a small positive vacuum energy density and negative vacuum pressure. A strong candidate is the cosmological constant in Einstein's equations of general relativity. Possible contributions are zero-point energies and the condensates associated with spontaneous symmetry breaking. The vacuum energy density ...
The latest cosmological data point to a model of the universe that is self-consistent but deeply weird. It seems that most matter in our universe is non-baryonic and hidden from direct view. Meanwhile, a repulsive "dark energy" causes the expansion of the universe to proceed at an accelerating rate. Sources of current data include studies of the ...
There are many different phenomenological models describing the cosmological dark energy and accelerating Universe by choosing adjustable functions. In this paper we consider a specific model of scalar tachyon field which is derived from the NSR string field theory and study its cosmological applications. We find that in the effective ...
In this paper the implications of a recently proposed phenomenological model of cosmology, the Asymptotic Cosmological Model (ACM), on the behavior of scalar perturbations are studied. Firstly we discuss new fits of the ACM at the homogeneous level, including fits to the Type Ia Supernovae UNION dataset, first CMB peak of WMAP5 and BAOs. The linearized ...
We consider the cosmological models for the higher dimensional space-time which includes the curvatures of our space as well as the curvatures of the internal space. We find that the condition for the integrability of the cosmological equations is that the total space-time dimensions are D=10 or D=11 which is exactly the conditions for superstrings or M ...
General very special relativity (GVSR) is the curved space-time of very special relativity (VSR) proposed by Cohen and Glashow. The geometry of general very special relativity possesses a line element of Finsler geometry introduced by Bogoslovsky. We calculate the Einstein field equations and derive a modified Friedmann-Robertson-Walker cosmology for an osculating Riemannian ...
This is the report of the Working Group on Early Universe Cosmology and tests of Fundamental Physics, group P4.8 of the of the Snowmass 2001 conference. Here we summarize the impressive array of advances that have taken place in this field, and identify opportunities for even greater progress in the future. Topics include Dark Energy, Cosmic Acceleration, ...
We study the cosmology of a covariant scalar field respecting a Galilean symmetry in flat space-time. We show the existence of a tracker solution that finally approaches a de�Sitter fixed point responsible for cosmic acceleration today. The viable region of model parameters is clarified by deriving conditions under which ghosts and Laplacian ...
We study the cosmology of a covariant scalar field respecting a Galilean symmetry in flat space-time. We show the existence of a tracker solution that finally approaches a de Sitter fixed point responsible for cosmic acceleration today. The viable region of model parameters is clarified by deriving conditions under which ghosts and Laplacian instabilities ...
We study conditions for the existence of asymptotic observables in cosmology. With the exception of de Sitter space, the thermal properties of accelerating universes permit arbitrarily long observations, and guarantee the production of accessible states of arbitrarily large entropy. This suggests that some asymptotic observables may exist, despite the ...
In this work, we explore some cosmological implications of the model proposed by M. Visser in 1998. In his approach, Visser intends to take into account mass for the graviton by means of an additional bimetric tensor in the Einstein's field equations. Our study has shown that a consistent cosmological model arises from the Visser's approach. The most ...
We develop the general scheme for modified f(R) gravity reconstruction from any realistic Friedmann-Robertson-Walker (FRW) cosmology. We formulate several versions of modified gravity compatible with solar system tests where the following sequence of cosmological epochs occurs: (a) matter dominated phase (with or without usual matter), transition from ...
