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Space Charge Waves as a Diagnostic To Measure Transverse Beam Size of Space Charge Dominated Beams
http://inspirehep.net/record/1329563
BIW08-TUPTPF024<br /><br />by: Thangaraj, Jayakar C. T. (Maryland U.) et al.<br /><br /><strong>Abstract:</strong> <br />Intense charged particle beams are of great interest to many wide areas of application ranging from high-energy physics, light sources and energy recovery linacs, to medical applications. The University of Maryland Electron Ring (UMER) is a scaled model to investigate the physics of such intense beams. It uses a 10 keV electron beam along with other scaled beam parameters that model the larger machines but at a lower cost. Multi turn opera- tion of the ring (3.6 m diameter) has been achieved for highly space charge dominated beams. Such, multi-turn operation requires a non-intercepting diagnostic for measuring the transverse beam size. Localized density or velocity variations on a space-charge dominated beam travel as space charge waves along the beam. The speed at which the space charge waves separate from each other depends on the beam current, energy and g-factor. In this work, we propose a diagnostic using deliberately-induced space charge waves to measure the beam size with multi-turn operation. We present and compare experimental results with self-consistent simulation.Thangaraj, Jayakar C. T.Sun, 23 Nov 2014 19:17:46 GMThttp://inspirehep.net/record/1329563Magnet Misalignment Studies for the Front-end of the Neutrino Factory
http://inspirehep.net/record/1329562
IPAC-2013-TUPFI019<br /><br />by: Prior, G. (CERN) et al.<br /><br /><strong>Abstract:</strong> <br />In the Neutrino Factory front-end the muon beam coming from the interaction of a high-power (4 MW) proton beam on a mercury jet target is transformed through a buncher, a phase rotator and an ionization cooling channel before entering the downstream acceleration system. The muon front-end channel is densely packed with solenoid magnets, normal conducting radio-frequency cavities and absorber windows for the cooling section. The tolerance to the misalignment of the different components has to be determined in order on one hand to set the limits beyond which the performance of the front-end channel would be degraded; on the other hand to optimize the design and assembly of the front-end cells such that the component alignment can be checked and corrected for where crucial for the performance of the channel. In this paper we show the results of some of the simulations of the front-end channel performance where the magnetic field direction has been altered compared to the baseline.Prior, G.Sun, 23 Nov 2014 18:56:30 GMThttp://inspirehep.net/record/1329562John Bell and the Nature of the Quantum World
http://inspirehep.net/record/1329561
physics.hist-pharXiv:1411.5322<br />J. Phys. A: Math. Theor. 47, 424007 (2014)<br /><br />by: Bertlmann, Reinhold A.<br /><strong>Abstract:</strong> <br />I present my encounter with John Bell at CERN, our collaboration and joint work in particle physics. I also will recall our quantum debates and give my personal view on Bell's fundamental work on quantum theory, in particular, on contextuality and nonlocality of quantum physics. Some mathematical and geometric aspects of entanglement are discussed as influence of Bell's Theorem. Finally, I make some historical comments on the experimental side of Bell inequalities.Bertlmann, Reinhold A.Sun, 23 Nov 2014 18:23:01 GMThttp://inspirehep.net/record/1329561Using Graphics Processing Units to solve the classical N-body problem in physics and astrophysics
http://inspirehep.net/record/1329560
astro-ph.IMarXiv:1411.5234<br /><br />by: Spera, Mario<br /><strong>Abstract:</strong> <br />Graphics Processing Units (GPUs) can speed up the numerical solution of various problems in astrophysics including the dynamical evolution of stellar systems; the performance gain can be more than a factor 100 compared to using a Central Processing Unit only. In this work I describe some strategies to speed up the classical N-body problem using GPUs. I show some features of the N-body code HiGPUs as template code. In this context, I also give some hints on the parallel implementation of a regularization method and I introduce the code HiGPUs-R. Although the main application of this work concerns astrophysics, some of the presented techniques are of general validity and can be applied to other branches of physics such as electrodynamics and QCD.Spera, MarioSun, 23 Nov 2014 18:22:53 GMThttp://inspirehep.net/record/1329560AstroCloud, a Cyber-Infrastructure for Astronomy Research: Data Archiving and Quality Control
http://inspirehep.net/record/1329559
astro-ph.IMarXiv:1411.5071<br /><br />by: He, Boliang<br /><strong>Abstract:</strong> <br />AstroCloud is a cyber-Infrastructure for Astronomy Research initiated by Chinese Virtual Observatory (China-VO) under funding support from NDRC (National Development and Reform commission) and CAS (Chinese Academy of Sciences){\url{http://astrocloud.china-vo.org}}\citep{O8-5_Cui_adassxxiv}. To archive the astronomical data in China, we present the implementation of the astronomical data archiving system (ADAS). Data archiving and quality control are the infrastructure for the AstroCloud. Throughout the data of the entire life cycle, data archiving system standardized data, transferring data, logging observational data, archiving ambient data, And storing these data and metadata in database. Quality control covers the whole process and all aspects of data archiving.He, BoliangSun, 23 Nov 2014 18:22:41 GMThttp://inspirehep.net/record/1329559Introduction to astroML: Machine Learning for Astrophysics
http://inspirehep.net/record/1329558
astro-ph.IMarXiv:1411.5039<br /><br />by: VanderPlas, Jacob T.<br /><strong>Abstract:</strong> <br />Astronomy and astrophysics are witnessing dramatic increases in data volume as detectors, telescopes and computers become ever more powerful. During the last decade, sky surveys across the electromagnetic spectrum have collected hundreds of terabytes of astronomical data for hundreds of millions of sources. Over the next decade, the data volume will enter the petabyte domain, and provide accurate measurements for billions of sources. Astronomy and physics students are not traditionally trained to handle such voluminous and complex data sets. In this paper we describe astroML; an initiative, based on Python and scikit-learn, to develop a compendium of machine learning tools designed to address the statistical needs of the next generation of students and astronomical surveys. We introduce astroML and present a number of example applications that are enabled by this package.VanderPlas, Jacob T.Sun, 23 Nov 2014 18:22:21 GMThttp://inspirehep.net/record/1329558ASSOCIATED PRODUCTION OF H0γ- AND H0Z0-PAIRS IN µ+µ−COLLISIONS
http://inspirehep.net/record/1329555
<br />by: Litvin, V. A. (State Research Center of Russia, IHEP) et al.<br /><br /><strong>Abstract:</strong> <br />We calculate the cross-sections for the production of Standard Model Higgs Boson in associa- tion with the neutral gauge bosons (photon and Z-boson). For the case of reaction μ+μ− → γH0, complete and compact analytical expressions for the differential and total cross-sections, applicable also (at high energies, when initial state masses can be safely neglected) for the case of any (pseudo)scalar particle with mass-coupling proportionality, in particulary, for an axion are given. Reaction μ+μ− → Z0H0 is some ”generalization” of the well-known ”Bjorken process” for the case of e+e−-collisions. Various distributions for both the processes above are illustrated for the energies, which will be reached at future μ+μ−-colliders. From the theoretical point of view it demonstrates the efficiency of modern electroweak interaction scheme. Study of those processes will be evidently complementary to the precision measurements at the Higgs resonance region.Litvin, V. A.Sun, 23 Nov 2014 14:12:42 GMThttp://inspirehep.net/record/1329555Photoproduction of the coherent $J/\psi$ accompanied by the forward neutron emission in ultra-peripheral PbPb collisions at 2.76~TeV
http://inspirehep.net/record/1329081
CMS-PAS-HIN-12-009<br /><br />by: CMS Collaboration<br /><strong>Abstract:</strong> <br />The cross section of coherent $J/\psi$ photoproduction accompanied by forward neutrons is measured in ultra-peripheral PbPb collisions at $\sqrt{s_{NN}} = 2.76$ TeV with the CMS experiment at the LHC. $J/\psi$ mesons are reconstructed by their decay into muon pairs while the neutrons are measured by Zero Degree Calorimeters. The analysis is based on a data sample collected during the 2011 PbPb run, corresponding to an integrated luminosity of 159 $\mu$b$^{-1}$. The cross section for coherent $J/\psi$ photoproduction in the rapidity region 1.8~$<|y|<$~2.3, in association with at least one neutron, is measured to be $\frac{d\sigma^{coh}_{X_{n}0_{n}}}{dy}($J/\psi$) = $ 0.37 $\pm$ 0.04 (stat) $\pm$ 0.04 (syst)~mb. This result is found to be in agreement with models that include nuclear gluon shadowing.CMS CollaborationSun, 23 Nov 2014 11:01:11 GMThttp://inspirehep.net/record/1329081Operational Studies of the 10 keV Electron Storage Ring UMER
http://inspirehep.net/record/1329079
AIP Conf.Proc. 1086 (2009) 738-743<br /><br />by: Bernal, S. (Maryland U.) et al.<br /><br /><strong>Abstract:</strong> <br />The University of Maryland Electron Ring (UMER) is now operational. UMER can operate with currents from 0.6 mA to 100 mA, ranging from the emittance dominated to the heavily space charge dominated regimes. Multiple turns have been achieved at all operating currents, from 250 turns at 0.6 mA to about 12 turns at 100 mA, but not yet optimized for operation above 25 mA. Machine development in the past year has been on understanding the single particle behavior in order to establish a strong basis for studying the effects of space charge. The effect of the earth's field has been studied and compensation implemented. Basic machine parameters such as the tune, equilibrium orbit, chromaticity and dispersion have been measured over a range of currents. We report here on these measurements and corresponding simulations.Bernal, S.Sat, 22 Nov 2014 23:11:37 GMThttp://inspirehep.net/record/1329079Complete Muon Cooling Design and Simulations
http://inspirehep.net/record/1329078
IPAC-2013-TUPFI060<br /><br />by: Yoshikawa, C. (MUONS Inc., Batavia) et al.<br /><br /><strong>Abstract:</strong> <br />While considerable progress has been made in developing promising subsystems for muon beam cooling channels to provide the extraordinary reduction of emittances, there is no end-to-end design that is capable of matching between or within the various subsystems. We present concepts to match emittances between and within muon beam cooling subsystems via the Helical Cooling Channel (HCC), which allows a general analytic approach to guide designs of transitions from one set of cooling channel parameters to another. These principles are demonstrated between segments in an existing cooling channel design, resulting in better performance (elimination of particle losses and colder muons) achieved in a channel approximately half its original length! These techniques will allow for a design of a complete cooling channel in a Muon Collider (MC) applicable to a Higgs Factory and an Energy Frontier machine.Yoshikawa, C.Sat, 22 Nov 2014 20:14:02 GMThttp://inspirehep.net/record/1329078Space Charge Simulation in COSY Using Fast Multipole Method
http://inspirehep.net/record/1329077
PAC-2013-MOPBA11<br /><br />by: Loseth, B. (Michigan State U.) et al.<br /><br /><strong>Abstract:</strong> <br />A method is presented that allows the computation of space charge effects of arbitrary and large distributions of particles in an efficient and accurate way based on a variant of the Fast Multipole Method (FMM). It relies on an automatic multigrid-based decomposition of charges in near and far regions and the use of high-order differential algebra methods to obtain decompositions of far fields that lead to an error that scales with a high power of the or- der. Given an ensemble of N particles, the method allows the computation of the self-fields of all particles on each other with a computational expense that scales as O(N). Using remainder-enhanced DA methods, it is also possible to obtain rigorous estimates of the errors of the methods. Furthermore, the method allows the computation of all high-order multipoles of the space charge fields that are necessary for the computation of high-order transfer maps and all resulting aberrations. This method has been implemented in COSY Infinity, and the progress of applying it to simulating the 6D cooling channel for the Muon Collider is reported.Loseth, B.Sat, 22 Nov 2014 19:39:23 GMThttp://inspirehep.net/record/1329077Algorithms and Self-consistent Simulations of Beam-induced Plasma in Muon Cooling Devices
http://inspirehep.net/record/1329076
PAC-2013-MOPBA06<br /><br />by: Samulyak, R. (SUNY, Stony Brook) et al.<br /><br /><strong>Abstract:</strong> <br />A code called SPACE for the simulation of beam-induced plasma in gas-filled RF cavities has been developed. The core code uses the particle-in-cell (PIC) method for the Maxwell equations coupled to the dynamics of particles. In the SPACE code, the electromagnetic PIC methods are coupled with probabilistic treatment of atomic physics processes. The aim of the project is to demonstrate the feasibility of the RF cavity with muon collider beams. The most critical part is investigating how intense muon beams influence the plasma dynamics. Initial phase of sim- ulations demonstrating the plasma generation and its short time dynamics in the high pressure hydrogen filled RF test cell has been performed.Samulyak, R.Sat, 22 Nov 2014 19:07:36 GMThttp://inspirehep.net/record/1329076Elliptical Muon Helical Cooling Channel Coils
http://inspirehep.net/record/1329075
PAC-2013-THPBA26<br /><br />by: Kahn, S. A. (MUONS Inc., Batavia) et al.<br /><br /><strong>Abstract:</strong> <br />A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoid, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional phase space reduction for muon beams. The most effective approach to implementing the desired magnetic field is a helical solenoid (HS) channel composed of short solenoid coils arranged in a helical pattern. The HS channel along with an external solenoid allows the B$_z$ and B$_{\phi}$ components along the reference orbit to be set to any desired values. To set dB$_{\phi}$/dr to the desired value for optimum focusing requires an additional variable to tune. We shall show that using elliptical shaped coils in the HS channel allows the flexibility to achieve the desired dB$_{\phi}$/dr on the reference orbit without significant change to B$_z$ and B$_{\phi}$.Kahn, S. A.Sat, 22 Nov 2014 18:49:51 GMThttp://inspirehep.net/record/1329075Investigation on the holographic principle
http://inspirehep.net/record/1329071
<br />by: Li, Jiang (U. Texas, Austin (main))<br /><br /><strong>Abstract:</strong> <br />The holographic principle asserts that any given codimension two space- like surface limits the information content of adjacent regions. We first re- view various entropy bounds which lead to the formulation of this conjecture, putting great emphasis on the UV-IR connection. We propose to use non- commutative field theory as a toy model to study the holographic mapping mechanism. In particular, we investigate how the fundamental dipole struc- ture emerges in noncommutative gauge theories by using matrix formulation. The momentum dependent growing behavior of the dipoles can provide a sim- ple way to map the bulk degrees of freedom onto the boundary. In the con- text of the AdS/CFT correspondence, which is the best known example of a holographic theory, we study the thermodynamics of N = 4 supersymmetric Yang-Mills theory at two-loop level and compare the result to the supergrav- ity calculation. This provides an excellent example to illustrate the idea of strong/weak duality. Questions about a possible large N phase transition still remain unsolved.Li, JiangSat, 22 Nov 2014 18:26:00 GMThttp://inspirehep.net/record/1329071Coherent Phenomenon over a Range of Beam Intensities in the Electron Storage Ring UMER
http://inspirehep.net/record/1329070
PAC09-FR5PFP063<br /><br />by: Sutter, D. (Maryland U.) et al.<br /><br /><strong>Abstract:</strong> <br />The University of Maryland Electron Ring (UMER) is designed for operation over a broad range of beam intensities, including those normally achieved only in linacs [1]. This is possible thanks to a combination of low-energy (10 keV) electrons and a high density of magnetic quadrupoles (72 over an 11.5 m circumference) that allow operation from 0.5 mA to 100 mA; that is, from the emittance dominated to the highly space charge dominated regimes. We present results of basic beam centroid-motion characterization, including measurements of the momentum compaction factor and natural chromaticity and dispersion. These are compared with results from computer simulations employing the code ELEGANT [2]. We discuss the techniques and challenges behind the measurements with fast beam-position and wall-current monitors.Sutter, D.Sat, 22 Nov 2014 17:00:15 GMThttp://inspirehep.net/record/1329070Bianchi Type-I Universe with Wet Dark Fluid
http://inspirehep.net/record/1329069
gr-qcarXiv:1006.5613<br />Pramana 71 (2008) 447-458<br /><br />by: Singh, T.<br /><strong>Abstract:</strong> <br />The Bianchi type-I universe filled with dark energy from a wet dark fluid has been considered. A new equation of state for the dark energy component of the universe has been used. It is modeled on the equation of state $p=\gamma (\rho -\rho_\star)$ which can describe a liquid, for example water. The exact solutions to the corresponding field equations are obtained in quadrature form. The solution for constant deceleration parameter have been studied in detail for power-law and exponential forms both. The cases $\gamma =1$ and $\gamma =0$ have been also analysed.Singh, T.Sat, 22 Nov 2014 13:06:22 GMThttp://inspirehep.net/record/1329069Reduction of couplings and its application in particle physics. Finite theories. Higgs and top mass predictions.
http://inspirehep.net/record/1329068
PoS Higgs&top (2014) 001<br /><br />by: Sibold, KlausSibold, KlausSat, 22 Nov 2014 12:23:19 GMThttp://inspirehep.net/record/1329068SISSA2014-09-09Space Charge Waves in Mismatched Beams
http://inspirehep.net/record/1329067
PAC09-TH5PFP035<br />LLNL-CONF-412506<br /><br />by: Poole, B. R. (LLNL, Livermore) et al.<br /><br /><strong>Abstract:</strong> <br />Mismatch oscillations resulting from the propagation of space charge waves in intense beams may lead to halo generation, beam loss, and modification of longitudinal beam properties. These oscillations have amplitudes and frequencies different from that of the main beam and are particularly important in machines such as the University of Maryland Electron Ring (UMER), in which the beam dynamics scales to parameters associated with heavy ion fusion drivers. To study these effects, we use the particle in cell code LSP [1] to simulate space charge wave dynamics in an intense electron beam propagating in a smooth focusing channel with 2-D cylindrical symmetry. We examine the evolution of linear and nonlinear density perturbations for both matched and mismatched beams. Comparisons between LSP simulations and numerical models are presented.Poole, B. R.Sat, 22 Nov 2014 01:23:48 GMThttp://inspirehep.net/record/1329067Indirect searches for dark matter
http://inspirehep.net/record/1329066
Physics of the Dark Universe 4 (2014) 41-43<br /><br />by: Donato, Fiorenza (Turin U.)<br /><br /><strong>Abstract:</strong> <br />The indirect detection of particle dark matter(DM)is based on the search for anomalous components in cosmic rays(CRs)due to the annihilation of DM pairs in the galactic halo, on the top of the standard astro- physical production. We revise here the most recent results on the DM searches for γ-rays,antiprotons, antideuterons and positrons in CRs.Donato, FiorenzaSat, 22 Nov 2014 00:13:00 GMThttp://inspirehep.net/record/13290662-14-09Wonderful Compactifications in Quantum Field Theory
http://inspirehep.net/record/1329065
1411.5583<br /><br />by: Berghoff, Marko<br /><strong>Abstract:</strong> <br />This article reviews the use of DeConcini-Procesi wonderful models in
renormalization of ultraviolet divergences in position space as introduced by
Bergbauer, Brunetti and Kreimer. In contrast to the exposition there we employ
a slightly different approach; instead of the subspaces in the arrangement of
divergent loci, we use the poset of divergent subgraphs as the main tool to
describe the whole renormalization process. This is based on an article by
Feichtner, where wonderful models were studied from a purely combinatorial
viewpoint. The main motivation for this approach is the fact that both,
renormalization and the model construction, are governed by the combinatorics
of this poset. Not only simplifies this the exposition considerably, but also
allows to study the renormalization operators in more detail. Moreover, we
explore the renormalization group in this setting by studying how the
renormalized distributions behave under a change of renormalization points.Berghoff, MarkoFri, 21 Nov 2014 23:13:29 GMThttp://inspirehep.net/record/1329065Resonance Phenomena over a Broad Range of Beam Intensities in an Electron Storage Ring
http://inspirehep.net/record/1329062
PAC09-FR5PFP059<br /><br />by: Bernal, S. (Maryland U.) et al.<br /><br /><strong>Abstract:</strong> <br />The University of Maryland Electron Ring (UMER) can operate over a broader range of beam intensities than other circular machines. Naturally, transverse and longitudinal space charge effects limit the ability to store beams. In UMER, the resonance properties of the machine in the two regimes of operation, emittance- and space charge- dominated transport, differ significantly. We report on experiments at 10 keV, with beams from 0.6 mA to 23 mA, corresponding to theoretical space charge incoherent tune shifts well over the Lasslet limit.Bernal, S.Fri, 21 Nov 2014 21:41:47 GMThttp://inspirehep.net/record/1329062Computational Physics
http://inspirehep.net/record/1329056
<br />by: Newman, M. E. J.Newman, M. E. J.Fri, 21 Nov 2014 20:42:54 GMThttp://inspirehep.net/record/1329056urn:ISBN:9781480145511Createspace2012Fundamentals of Attosecond Optics
http://inspirehep.net/record/1329055
<br />by: Chang, ZenghuChang, ZenghuFri, 21 Nov 2014 20:35:42 GMThttp://inspirehep.net/record/1329055urn:ISBN:9781420089370CRC Press2011A Novel Beam Steering Algorithm with Orbit Response Matrix
http://inspirehep.net/record/1329053
PAC09-FR5REP029<br /><br />by: Wu, C. (Maryland U.) et al.<br /><br /><strong>Abstract:</strong> <br />Beam centroid control is an important method for op- timizing the performance for accelerators, including the University of Maryland Electron Ring (UMER), which is a scaled high-current(0.6-100 mA),low-energy (10 keV) storage ring. The conventional response matrix and sin- gular value decomposition approach do not work well on UMER because of the unique ring structure. One of the purposes of this work is to verify that the beam centroid could be controlled in the presence of very strong space charge. In this paper, we present a novel algorithm which is based on the singular value decomposition, but uses a dif- ferent response matrix. The response matrix is computed from the beam positions for the first four turns in the multi- turn beam circulation. Implementation of this algorithm leads to significant improvement on the beam positions and multi-turn operation.Wu, C.Fri, 21 Nov 2014 20:12:28 GMThttp://inspirehep.net/record/1329053Matching and Injection of Beams with Space Charge into the University of Maryland Electron Ring (UMER)
http://inspirehep.net/record/1329051
PAC09-FR5PFP061<br /><br />by: Kishek, R. A. (Maryland U.) et al.<br /><br /><strong>Abstract:</strong> <br />Beam matching is critical for avoiding envelope mismatch oscillations that can lead to emittance growth and halo formation, especially if the beam has significant space charge. Matching is rendered difficult for the University of Maryland Electron Ring (UMER) by the space charge, the compactness of the lattice, and the unique injection scheme where an offset oversized quadrupole is shared between the ring and the injector. This paper explores several schemes for optimizing the matching at injection, both analytical and beam-based. The approaches are tested using a particle-in-cell (PIC) code as well as experimentally.Kishek, R. A.Fri, 21 Nov 2014 19:33:39 GMThttp://inspirehep.net/record/1329051