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Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

Description: The Large Hadron Collider (LHC) at CERN promises a major step forward in the understanding of the fundamental nature of matter. The ATLAS experiment is a general-purpose detector for the LHC, whose design was guided by the need to accommodate the wide spectrum of possible physics signatures. The major remit of the ATLAS experiment is the exploration of the TeV mass scale where groundbreaking discoveries are expected. In the focus are the investigation of the electroweak symmetry breaking and li… more
Date: November 28, 2011
Creator: Aad, G.; Abat, E.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A. et al.
Partner: UNT Libraries Government Documents Department
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Slowly Varying Dilaton Cosmologies and Their Field Theory Duals

Description: We consider a deformation of the AdS{sub 5} x S{sup 5} solution of IIB supergravity obtained by taking the boundary value of the dilaton to be time dependent. The time dependence is taken to be slowly varying on the AdS scale thereby introducing a small parameter {epsilon}. The boundary dilaton has a profile which asymptotes to a constant in the far past and future and attains a minimum value at intermediate times. We construct the sugra solution to first non-trivial order in {epsilon}, and fin… more
Date: June 28, 2011
Creator: Awad, Adel; Das, Sumit R.; Ghosh, Archisman; Oh, Jae-Hyuk & Trivedi, Sandip P.
Partner: UNT Libraries Government Documents Department
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Comparative genomics of citric-acid producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

Description: The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compels additional exploration. We therefore undertook whole genome sequencing of the a… more
Date: April 28, 2011
Creator: Grigoriev, Igor V.; Baker, Scott E.; Andersen, Mikael R.; Salazar, Margarita P.; Schaap, Peter J.; Vondervoot, Peter J.I. van de et al.
Partner: UNT Libraries Government Documents Department
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Amplification of current density modulation in a FEL with an infinite electron beam

Description: We show that the paraxial field equation for a free electron laser (FEL) in an infinitely wide electron beam with {kappa}-2 energy distribution can be reduced to a fourth ordinary differential equation (ODE). Its solution for arbitrary initial phase space density modulation has been derived in the wave-vector domain. For initial current modulation with Gaussian profile, close form solutions are obtained in space-time domain. In developing an analytical model for a FEL-based coherent electron co… more
Date: March 28, 2011
Creator: Wang, G.; Litvinenko, V. N. & Webb, S. D.
Partner: UNT Libraries Government Documents Department
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Baseline suppression problems for high precision measurements using optical beam profile monitors

Description: The use of fluorescent screens (e.g. YAG screens) and Optical Transition Radiation (OTR) screens for beam profile monitors provides a simple and widely used way to obtain detailed two dimensional intensity maps. What makes this possible is the availability of relatively inexpensive CCD cameras. For high precision measurements many possible error contributions need to be considered that have to do with properties of the fluorescent screens and of the CCDs. Saturation effects, reflections within … more
Date: March 28, 2011
Creator: Thieberger, P.; Gassner, D.; Glenn, J.; Minty, M. & Zimmer, C.
Partner: UNT Libraries Government Documents Department
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Beam losses due to abrupt crab cavity failures in the LHC

Description: A major concern for the implementation of crab crossing in a future High-Luminosity LHC (HL-LHC) is machine protection in an event of a fast crab-cavity failure. Certain types of abrupt crab-cavity amplitude and phase changes are simulated to characterize the effect of failures on the beam and the resulting particle-loss signatures. The time-dependent beam loss distributions around the ring and particle trajectories obtained from the simulations allow for a first assessment of the resulting bea… more
Date: March 28, 2011
Creator: Baer, T.; Barranco, J.; Calaga, R.; Tomas, R.; Wenninger, B.; Yee, B. et al.
Partner: UNT Libraries Government Documents Department
open access

New HOM coupler design for high current SRF cavity

Description: Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass … more
Date: March 28, 2011
Creator: Xu, W.; Ben-Zvi, Ilan; Belomestnykh, S.; Hahn, H. & Johnson, E.
Partner: UNT Libraries Government Documents Department
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DESIGN AND PRELIMINARY TEST OF THE 1500 MHZ NSLS-II PASSIVE SUPERCONDUCTING RF CAVITY

Description: NSLS-II is a new ultra-bright 3 GeV 3rd generation synchrotron radiation light source. The performance goals require operation with a beam current of 500mA and a bunch current of at least 0.5mA. Ion clearing gaps are required to suppress ion effects on the beam. The natural bunch length of 3mm is planned to be lengthened by means of a third harmonic cavity in order to increase the Touschek limited lifetime. Earlier work described the design alternatives and the geometry selected for a copper pr… more
Date: March 28, 2011
Creator: Rose, J.; Gash, W.; Kosciuk, B.; Ravindranath, V.; Sikora, B.; Sharma, S. et al.
Partner: UNT Libraries Government Documents Department
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Charge Separation for Muon Collider Cooling

Description: Most schemes for six dimensional muon ionization cooling work for only one sign. It is then necessary to have charge separation prior to that cooling. Schemes of charge separation using bent solenoids are described, and their simulated performances reported. It is found that for efficient separation, it should take place at somewhat higher momenta than commonly used for the cooling. Charge separation using bent solenoids can be effective if carefully designed. Bent solenoids can generate disper… more
Date: March 28, 2011
Creator: Palmer, R. B.
Partner: UNT Libraries Government Documents Department
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Performance of the new EBIS preinjector

Description: The construction and initial commissioning phase of a new heavy ion preinjector was completed at Brookhaven in September, 2010, and the preinjector is now operational. This preinjector, using an EBIS source to produce high charge state heavy ions, provided helium and neon ion beams for use at the NASA Space Radiation Laboratory in the Fall of 2010, and gold and uranium beams are being commissioned during the 2011 run cycle for use in RHIC. The EBIS operates with an electron beam current of up t… more
Date: March 28, 2011
Creator: Alessi, J.; Beebe, E.; Binello, S.; Gardner, C.; Gould, O.; Hoff, L. et al.
Partner: UNT Libraries Government Documents Department
open access

The dipole corrector magnets for the RHIC fast global orbit feedback system

Description: The recently completed RHIC fast global orbit feedback system uses 24 small 'window-frame' horizontal dipole correctors. Space limitations dictated a very compact design. The magnetic design and modelling of these laminated yoke magnets is described as well as the mechanical implementation, coil winding, vacuum impregnation, etc. Test procedures to determine the field quality and frequency response are described. The results of these measurements are presented and discussed. A small fringe fiel… more
Date: March 28, 2011
Creator: Thieberger, P.; Arnold, L.; Folz, C.; Hulsart, R.; Jain, A.; Karl, R. et al.
Partner: UNT Libraries Government Documents Department
open access

A high-order finite-volume method for hyperbolic conservation laws on locally-refined grids

Description: We present a fourth-order accurate finite-volume method for solving time-dependent hyperbolic systems of conservation laws on Cartesian grids with multiple levels of refinement. The underlying method is a generalization of that in [5] to nonlinear systems, and is based on using fourth-order accurate quadratures for computing fluxes on faces, combined with fourth-order accurate Runge?Kutta discretization in time. To interpolate boundary conditions at refinement boundaries, we interpolate in time… more
Date: January 28, 2011
Creator: McCorquodale, Peter & Colella, Phillip
Partner: UNT Libraries Government Documents Department
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Stable Non-Supersymmetric Throats in String Theory

Description: We construct a large class of non-supersymmetric AdS-like throat geometries in string theory by taking non-supersymmetric orbifolds of supersymmetric backgrounds. The scale of SUSY breaking is the AdS radius, and the dual field theory has explicitly broken supersymmetry. The large hierarchy of energy scales in these geometries is stable. We establish this by showing that the dual gauge theories do not have any relevant operators which are singlets under the global symmetries. When the geometrie… more
Date: June 28, 2011
Creator: Kachru, Shamit; Simic, Dusan; /Stanford U., ITP /SLAC /Santa Barbara, KITP; Trivedi, Sandip P. & /Tata Inst. /Stanford U., ITP /SLAC
Partner: UNT Libraries Government Documents Department
open access

NSLS-II RF SYSTEMS

Description: The NSLS-II is a new third generation light source being constructed at Brookhaven Lab. The storage ring is optimized for low emittance by use of damping wigglers to reduce the emittance to below 1 nm-rad. The RF systems are designed to provide stable beam through tight RF phase and amplitude stability requirements.
Date: March 28, 2011
Creator: Rose, J.; Gash, W.; Holub, B.; Kawashima, Y.; Ma, H.; Towne, N. et al.
Partner: UNT Libraries Government Documents Department
open access

PROGRESS WITH NSLS-II INJECTION STRAIGHT SECTION DESIGN

Description: The NSLS-II injection straight section (SR) consists of pulsed and DC bumps, septa system, beam trajectory correction and diagnostics systems. In this paper we discuss overall injection straight layout, preliminary element designs, specifications for the pulsed and DC magnets and their power supplies, vacuum devices and chambers and diagnostics devices. Prior to selecting the current 'conventional' design of the injection straight section we analyzed an option of injection via pulsed multipole … more
Date: March 28, 2011
Creator: Shaftan, T.; Blednykh, A.; Casey, B.; Dalesio, B.; Faussete, R.; Ferreira, M. et al.
Partner: UNT Libraries Government Documents Department
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Design and Factory Test of the E /E- Frascati Linear Accelerator for DAFNE

Description: The electron-positron accelerator for the DAFNE project has been built and is in test at Titan Beta in Dublin, CA. This S-Band RF linac system utilizes four 45 MW sledded klystrons and 16-3 m accelerating structures to achieve the required performance. It delivers a 4 ampere electron beam to the positron converter and accelerates the resulting positrons to 550 MeV. The converter design uses a 4.3T pulsed tapered flux compressor along with a pseudo-adiabatic tapered field to a 5 KG solenoid over… more
Date: November 28, 2011
Creator: Anamkath, H.; Lyons, S.; Nett, D.; Treas, P.; Whitham, K.; Zante, T. et al.
Partner: UNT Libraries Government Documents Department
open access

Design of coupler for the NSLS-II storage ring superconducting RF cavity

Description: NSLS-II is a 3GeV, 500mA, high brightness, 1 MW beam power synchrotron facility that is designed with four superconducting cavities working at 499.68 MHz. To operate the cavities in over-damped coupling condition, an External Quality Factor (Qext) of {approx}65000 is required. We have modified the existing coupler for the CESR-B cavity which has a Qext of {approx}200,000 to meet the requirements of NSLS-II. CESR-B cavity has an aperture coupler with a coupler 'tongue' connecting the cavity to t… more
Date: March 28, 2011
Creator: Yeddulla, M. & Rose, J.
Partner: UNT Libraries Government Documents Department
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Lifetime Measurement of the 2{sup +}{sub 1} state in {sup 20}C

Description: Establishing how and when large N/Z values require modified or new theoretical tools is a major quest in nuclear physics. Here we report the first measurement of the lifetime of the 2{sup +}{sub 1} state in the near-dripline nucleus {sup 20}C. The deduced value of {tau}{sub #28;2{sup +}{sub 1}} = 9.8 ± 2.8(stat){sup +0.5}{sub −1.1}(syst) ps gives a reduced transition probability of B(E2;2{sup +}{sub 1}{yields}0{sup +}{sub g.s.}) = 7.5{sup +3.0}{sub −1.7}(stat){sup +1.0}{sub −0.4}(syst) e{sup 2}… more
Date: June 28, 2011
Creator: Petri, Marina-Kalliopi; Fallon, Paul; Macchiavelli, Augusto; Paschalis, Stephanos; Starosta, Krzysztof; Baugher, Travis et al.
Partner: UNT Libraries Government Documents Department
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STRIPLINE KICKER DESIGN FOR NSLS2 STORAGE RING

Description: In the NSLS2 storage ring, there are four stripline kickers/pickups. Two long striplines with electrode length of 30cm will be used as bunch-by-bunch transverse feedback actuators. Two short stripline kickers/pickups with 15cm length will mainly used for tune measurement excitation or signal pickup for the beam stability monitor. High shunt impedance of the long stripline kickers is demanded to produce 200 {micro}s damping time. Meanwhile the beam impedance should be minimized. The design work … more
Date: March 28, 2011
Creator: Cheng, W.; Blednykh, A.; Krinsky, S. & Singh, O.
Partner: UNT Libraries Government Documents Department
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LOW HORIZONTAL BETA FUNCTION IN LONG STRAIGHTS OF THE NSLS-II LATTICE

Description: The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 short straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this paper, we explore the possibility of maintaining three long straights with large hori… more
Date: March 28, 2011
Creator: Fanglei, L.; Bengtsson, J.; Guo, W.; Krinsky, S.; Li, Y. & Yang, L.
Partner: UNT Libraries Government Documents Department
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Testing a GaAs cathode in SRF gun

Description: RF electron guns with a strained superlattice GaAs cathode are expected to generate polarized electron beams of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface and lower cathode temperature. We plan to install a bulk GaAs:Cs in a SRF gun to evaluate the performance of both the gun and the cathode in this environment. The status of this project is: In our 1.3 GHz 1/2 cell SRF gun, the vacuum can be maintained at nearly 10{sup -12… more
Date: March 28, 2011
Creator: Wang, E.; Kewisch, J.; Ben-Zvi, Ilan; Burrill, A.; Rao, T.; Wu, Q. et al.
Partner: UNT Libraries Government Documents Department
open access

Helium pressures in RHIC vacuum cryostats and relief valve requirements from magnet cooling line failure

Description: A catastrophic failure of the RHIC magnet cooling lines, similar to the LHC superconducting bus failure incident, would pressurize the insulating vacuum in the magnet and transfer line cryostats. Insufficient relief valves on the cryostats could cause a structural failure. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the vacuum cryostat and discharging via the reliefs into the R… more
Date: March 28, 2011
Creator: Liaw, C. J.; Than, Y. & Tuozzolo, J.
Partner: UNT Libraries Government Documents Department
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High power RF systems for the BNL ERL project

Description: The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a t… more
Date: March 28, 2011
Creator: Zaltsman, A. & Lambiase, R.
Partner: UNT Libraries Government Documents Department
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Comparison of 1D and 2D CSR Models with Application to the FERMI@ELETTRA Bunch Compressors

Description: We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces [1]. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for t… more
Date: March 28, 2011
Creator: Bassi, G.; Ellison, J. A. & Heinemann, K.
Partner: UNT Libraries Government Documents Department
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