116926076
Some fundamental aspects of fluctuations and coherence in charged‐particle beams in storage rings
A conceptual survey and exposition is presented of some fundamendal aspects of fluctuations and coherence, as well as the interplay between the two, in coasting charged‐particle beams—both continuous and bunched—in storage rings. A detailed study is given of the spectral properties of the incoherent phase‐space Schottky fluctuations, their propagation as waves in the beam, and the analytic complex coherent beam electromagnetic response or transfer function. The modification or distortion of these by collective interactions is examined in terms of simple regeneration mechanisms. Collective or coherent forces in the beam–storage‐ring system are described by defining suitable impedance functions or propagators, and a brief discussion of the coherent collective modes and their stability is provided, including a general and rigorous description of the Nyquist stability criterion. The nature of the critical fluctuations near an instability threshold is explored. The concept of Landau damping and its connection ...
55975443
Accelerator physics experiments at Aladdin
DISCLAIMER LBL--19905 DE86 005847 -J or un or _ames my 1epI liability or reaponli- bility for the accuracy com~ '. or usefuloeu or uy information, apparatus product, or r- _ _ _ _ or ~ts tbat Its UJe would not • I i · · eoce herein to any SpccUlC COOImercial oil ID nnse !, Ya!ely owned rishts. Refer- manufa<1urer, or othcr1¥ise does not PI' .~ pr~, or se~ by trade name, trademark, riI Y mendation, or favorinS by the United Go constItute or Imply its endorsement, recom- es veroment or an v agen thereof Th . e VIews a nd optDlODS of authors ex-..... b . d r'~ erelD 0 not necessarily late flee UDlted States Goveroment or any agency thereof. S or re t those of tbe or work IpOIIIOred b Gom-nmcnl Neilllcr Ik United St.tcs r _ _ y u aaency or the United States -- mUea any ......... ty exPRU JJDJc:nt DOl' uy .... .-~ thereof. or t heir cm.......-. . plied, DOl' any This n:port . . . prepm:d U .. _at ne;;::- ACCELERATOR PHYSICS EXPERIMENTS AT ALADDIN* S. Chattopadhyay, K. Cornacchia, A. Jackson, and K.S. Zisman Lawrence Berkeley Laboratory University of California Berkeley, California 94720 July 1985 This work vas partiaUy supported by the Direcloc-. Office of Enct'yllcl wlib ft.M IlJ.S. hH
124556579
Motivation and goals of ERL 2005
Various types of ERL sources are introduced, the relevant beam physics and accelerator technology issues noted, innovative areas of development identified and current and future goals of ERL research and development established.
56152176
CEBAF-ER: Extending the Frontier of Energy Recovery at Jefferson Lab
A successful GeV scale energy recovery demonstration with a high ratio of peak-to-injection energies (50:1) was recently carried out on the CEBAF (Continuous Electron Beam Accelerator Facility) recirculating superconducting linear accelerator in an effort to address issues related to beam quality preservation in a large scale energy recovery system. To gain a quantitative understanding of the beam behavior through the machine, an intense effort was made to characterize the 6D phase space during the CEBAF-ER (CEBAF with Energy Recovery) experimental run. A scheme was implemented to measure the transverse emittance of the energy recovered beam prior to being sent to the dump, as well as in the injector and in each arc. The emittance provides a figure of merit in this context inasmuch as it characterizes the extent to which beam quality is preserved during energy recovery. In addition to describing the transverse phase space, the momentum spread was measured in the injector and arcs to characterize the longitudinal phase space. Measurements also included the RF system's response to the energy recovery process. And by using a novel technique employing wire scans in conjunction with PMTs (Photomultiplier Tubes) to accurately measure the beam profile at the dump, we can qualitativelymore » characterize beam preservation through the recirculator. One of the salient conclusions from the experiment is that the energy recovery process does not contribute to the emittance degradation since the emittance of the recirculating pass is consistent with that of the accelerating pass.« less
51748746
Proposal for a one GeV plasma wakefield acceleration experiment at SLAC
Abstract A plasma-based wakefield acceleration experiment E-157 has been approved at SLAC to study acceleration of parts of an SLC bunch by up to 1 GeV/m over a length of 1 m. A single SLC bunch is used to both induce wakefields in the 1 m long plasma and to witness the resulting beam acceleration. The experiment will explore and further develop the techniques that are needed to apply high-gradient plasma wakefield acceleration to large-scale accelerators. The 1 m length of the experiment is about two orders of magnitude larger than for other high gradient plasma wakefield acceleration experiments and the 1 GeV/m accelerating gradient is roughly ten times larger than that achieved with conventional metallic structures. Using existing SLAC facilities, the experiment will study high gradient acceleration at the forefront of advanced accelerator research.
136682515
Hydrogen in materials and vacuum systems : First International wordshop on hydrogen in materials and vacuum systems, Newport News, Virginia 11-13 November 2002
All papers were peer-reviewed. Hydrogen plays a key role in materials, beneficial in some cases, problematic in others. In all such systems a detailed understanding of the hydrogen-based interaction is necessary for control, improvements, and for possible new applications. This hydrogen workshop proceeding incorporates contributions from semi-conducting, normal conducting (metals) and superconducting materials, as well as vacuum communities who deal with the hydrogen-materials issue. The technical areas covered in these proceedings include hydrogen in materials, hydrogen interactions and dynamics in semiconductors, hydrogen adsorption-storage-generation and distribution, hydrogen in niobium, hydrogen in vacuum systems, gaseous hydrogen accelerator structures, and magnetically suspended liquid hydrogen transfer lines.
119793009
A holographic reconstruction of the modifiedf(R) Horava-Lifshitz gravity with scale factor in power-law form
This paper is devoted to the study of holographic reconstruction of the modified f(R) Horava-Lifshitz gravity in the flat universe. For this purpose, we assume a scale factor in the form of exact power-law solution. A reconstructed model is obtained which may provide reasonable qualitative description of some cosmological era satisfying the sufficient condition for a realistic model. We represent the graphical description of this model exhibiting increasing behavior. We also discuss the evolution of the accelerated expansion of the universe through equation of state parameter (EoS) for the reconstructed model. Its graphical representation depicts about a quintessence dominated era in near future. The stability of the model is observed initially, however it becomes unstable after a small interval of time.
121983267
Behavior of Holographic Ricci Dark Energy in Scalar Gauss-Bonnet Gravity for Different Choices of the Scale Factor
In this paper, we studied the cosmological application of the interacting Ricci Dark Energy (RDE) model in the framework of the scalar Gauss-Bonnet modified gravity model. We studied the properties of the reconstructed potential Vt$V\left (t \right )$, the Strong Energy Condition (SEC), the Weak Energy Condition (WEC) and the deceleration parameter q for three different models of scale factor, i.e. the emergent, the intermediate and the logamediate one. We obtained that Vt$V\left (t \right )$, for the emergent scenario, has a decreasing behavior, while, for the logamediate scenario, the potential start with an increasing behavior then, for later times, it shows a slowly decreasing behavior. Finally, for the intermediate scenario, the potential has an initial increasing behavior, then for a time of t≈1.2, it starts to decrease. We also found that both SEC and WEC are violated for all the three scale factors considered. Finally, studying the plots of q, we derived that an accelerated universe can be achieved for the three models of scale factor considered.
118506068
Systematics of antimagnetic rotation in even–even Cd isotopes
Abstract A model based on classical particle plus rotor has been used to explore the underlying systematics of even–even Cd isotopes and a self consistent picture for the observed behaviors of 106, 108, 110 Cd has been reported. This systematic study also helps to estimate the strengths of particle–hole and hole–hole interactions of this mass region.
119244873
Reciprocal NUT spacetimes
In this paper, we study the Ehlers' transformation (sometimes called gravitational duality rotation) for reciprocal static metrics. First, we introduce the concept of reciprocal metric. We prove a theorem which shows how we can construct a certain new static solution of Einstein field equations using a seed metric. Later, we investigate the family of stationary spacetimes of such reciprocal metrics. The key here is a theorem from Ehlers', which relates any static vacuum solution to a unique stationary metric. The stationary metric has a magnetic charge. The spacetime represents Newman-Unti-Tamburino (NUT) solutions. Since any stationary spacetime can be decomposed into a 1 + 3 time-space decomposition, Einstein field equations for any stationary spacetime can be written in the form of Maxwell's equations for gravitoelectromagnetic fields. Further, we show that this set of equations is invariant under reciprocal transformations. An additional point is that the NUT charge changes the sign. As an instructive example, by starting from the reciprocal Schwarzschild as a spherically symmetric solution and reciprocal Morgan–Morgan disk model as seed metrics we find their corresponding stationary spacetimes. Starting from any static seed metric, performing the reciprocal transformation and by applying an additional Ehlers' transformation we obtain a family of NUT spaces with negative NUT factor (reciprocal NUT factors).
119097172
Propagation of Fluctuations in Au+Au Collisions at FAIR energy
Variable Energy Cyclotron Centre, Kolkata India(Dated: August 25, 2014)Event by event ﬂuctuations of particle multiplicities and their ratios are considered to be sensitiveprobes to the exotic phenomena in high energy heavy ion collisions like phase transtion or theoccurence of critical point. These phenomena might take place at diﬀerent time after the collisionbased on fulﬁlling the required conditions at a particular time. Fluctuations are therefore expectedto show non-monotonic behaviour at the of time of occurence of these phenomena. Experimentally,ﬂuctuations are measured at freezeout. In this work, using the hybrid version of the UrQMD eventgenerator, we have investigated the propagation of ﬂuctuations of particle multiplicities, their ratiosand the ratio of total positive and negative charges in AuAu collisions at E