124531703
Progress on plasma lens experiment at the final focus test beam
The Plasma Lens Collaboration proposed and has been approved to perform the Plasma Lens Experiment at the Final Focus Test Beam (SLAC E-150bis). The experiment is a revised and simplified proposition which reflects the pertinent scientific and technological advances since an earlier proposal (1) was submitted. The goals of the experiment are to study plasma focusing of high energy, high density particle beams: to investigate plasma beamsstrahlung suppression: and to develop technologies for plasma lens applications in present and future linear colliders.
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.
55285360
Optimization of the Parameters of a Storage Ring for a High Power XUV Free Electron Laser
In this paper we describe the operation of an XUV high gain FEL operating within a bypass of an electron storage ring, and discuss the implications on storage ring optimization imposed by FEL requirements. It transpires that, in the parameter regime of interest, collective effects within the beam play an important role. For example, intrabeam scattering dilutes the transverse emittance of the beam and the microwave instability increases the momentum spread. Both phenomena reduce the effectiveness of the FEL. A computer code, ZAP, has been written which, for a given lattice design, takes all such effects into consideration and produces a figure of merit for FEL operation for that machine. We show the results of ZAP for several storage ring designs, all optimized for FEL operation, and present a design example of a facility capable of producing coherent radiation at 400 Å with tens of megawatts of peak power.
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
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.
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
118391197
EMERGENT UNIVERSE IN THE CHAMELEON, f(R) AND f(T) GRAVITY THEORIES
In this work, we consider an emergent Universe in generalized gravity theories like the chameleon, f(R) and f(T) gravities. We reconstruct the potential of the chameleon field under the emergent scenario of the Universe and observe its increasing nature with the evolution of the Universe. We reveal that in the emergent Universe scenario, the equation-of-state parameter behaves like quintessence in the case of f(R) gravity and like phantom in the case of f(T) gravity.
56560251
A Study on the Interacting Ricci Dark Energy in f(R, T) Gravity
The present work reports study on the interacting Ricci dark energy in a modified gravity theory named f(R, T) gravity. In the specific model f(R, T) = μR + νT we have observed a quintom-like behavior of the equation of state parameter and a transition from matter dominated to dark energy density has been observed through fraction density evolution. The statefinder parameters reveal that the model interpolates between dust and $$\Uplambda\hbox{CDM}$$ΛCDM phases of the universe.
119545056
A study on the role of f(G) gravity on the emergent universe
Motivated by the recent work of Rastkar et al. (in Astrophys. Space Sci. 337:487, 2012) the present study has attempted to study the role of f(G) gravity in the emergent universe. Different energy conditions are examined for the effective energy density and violation of strong energy condition is observed. Also, the behavior of the equation of state parameter is studied for the effective energy density and dark energy density. It is found that the equation of state parameter behaves like phantom in both of the cases.
124870077
Abrupt change of rotation axis inAg109
The electromagnetic transition rates for all the high spin levels of the yrast sequence of 109 Ag have been measured. The observed behavior of the magnetic dipole transition rates as a function of angular momentum establishes that there is a sudden change in rotation axis associated with rotational alignment of two neutrons. The projected shell model calculations give a consistent picture of the observed phenomena in 109 Ag.
53965347
New holographic reconstruction of scalar-field dark-energy models in the framework of chameleon Brans–Dicke cosmology
Motivated by the work of Yang et al. (Mod. Phys. Lett. A 26:191, 2011), we report on a study of the new holographic dark energy (NHDE) model with energy density given by $$\rho _D\!=\!\frac{3\phi ^2}{4\omega }(\mu H^2\!+\!\nu {\dot{H}})$$ρD=3ϕ24ω(μH2+νH˙) in the framework of chameleon Brans–Dicke cosmology. We have studied the correspondence between the quintessence, the DBI-essence, and the tachyon scalar-field models with the NHDE model in the framework of chameleon Brans–Dicke cosmology. Deriving an expression of the Hubble parameter $$H$$H and, accordingly, $$\rho _D$$ρD in the context of chameleon Brans–Dicke chameleon cosmology, we have reconstructed the potentials and dynamics for these scalar-field models. Furthermore, we have examined the stability for the obtained solutions of the crossing of the phantom divide under a quantum correction of massless conformally invariant fields, and we have seen that the quantum correction could be small when the phantom crossing occurs and the obtained solutions of the phantom crossing could be stable under the quantum correction. It has also been noted that the potential increases as the matter–chameleon coupling gets stronger with the evolution of the universe.