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A New Approach to Improving the Efficiency of FEL Oscillator Simulations (open access)

A New Approach to Improving the Efficiency of FEL Oscillator Simulations

During the last year we have been benchmarking FEL oscillator simulation codes against the measured performance of the three Jefferson Lab oscillator FELs. While one might think that a full 4D simulation is de facto the best predictor of performance, the simulations are computationally intensive, even when analytical approximations to the electron bunch longitudinal distribution are used. In this presentation we compare the predictions of the 4D FEL interaction codes Genesis and Medusa, in combination with the optical code OPC, with those using a combination of the 2D & 3D versions of these codes, which can be run quickly on a single CPU core desktop computer.
Date: May 1, 2013
Creator: Shinn, Michelle D.; Benson, Stephen V.; Watson, Anne M.; Freund, Henry P.; Nyugen, Dinh C. & van der Slot, Peter J.M.
System: The UNT Digital Library
Using an Energy Performance Based Design-Build Process to Procure a Large Scale Low-Energy Building: Preprint (open access)

Using an Energy Performance Based Design-Build Process to Procure a Large Scale Low-Energy Building: Preprint

This paper will review a procurement, acquisition, and contract process of a large-scale replicable net zero energy (ZEB) office building. The owners developed and implemented an energy performance based design-build process to procure a 220,000 ft2 office building with contractual requirements to meet demand side energy and LEED goals. We will outline the key procurement steps needed to ensure achievement of our energy efficiency and ZEB goals. The development of a clear and comprehensive Request for Proposals (RFP) that includes specific and measurable energy use intensity goals is critical to ensure energy goals are met in a cost effective manner. The RFP includes a contractual requirement to meet an absolute demand side energy use requirement of 25 kBtu/ft2, with specific calculation methods on what loads are included, how to normalize the energy goal based on increased space efficiency and data center allocation, specific plug loads and schedules, and calculation details on how to account for energy used from the campus hot and chilled water supply. Additional advantages of integrating energy requirements into this procurement process include leveraging the voluntary incentive program, which is a financial incentive based on how well the owner feels the design-build team is meeting the RFP …
Date: May 1, 2011
Creator: Pless, S.; Torcellini, P. & Shelton, D.
System: The UNT Digital Library
Optics measurements and corrections at RHIC (open access)

Optics measurements and corrections at RHIC

The further improvement of RHIC luminosity performance requires more precise understanding of the RHIC modeling. Hence, it is necessary to minimize the beta-beat, deviation of measured beta function from the calculated beta functions based on an model. The correction of betabeat also opens up the possibility of exploring operating RHIC polarized protons at a working point near integer, a prefered choice for both luminosity as well as beam polarization. The segment-by-segment technique for reducing beta-beat demonstrated in the LHC operation for reducing the beta-beat was first tested in RHIC during its polarized proton operation in 2011. It was then fully implemented during the RHIC polarized proton operation in 2012. This paper reports the commissioning results. Future plan is also presented.
Date: May 20, 2012
Creator: M., Bai; Aronson, J.; Blaskiewicz, M.; Luo, Y.; Robert-Demolaize, G. & White, S.
System: The UNT Digital Library
Status Update of the Power Conditioning System in the National Ignition Facility (open access)

Status Update of the Power Conditioning System in the National Ignition Facility

None
Date: May 24, 2012
Creator: Galloudec, B. L.; Arnold, P.; James, G.; Pendleton, D.; Petersen, D.; Arellano-Womack, G. et al.
System: The UNT Digital Library
Heat load of a P-doped GaAs photocathode in SRF electron gun (open access)

Heat load of a P-doped GaAs photocathode in SRF electron gun

Many efforts were made over the last decades to develop a better polarized electron source for the high energy physics. Several laboratories operate DC guns with the Gallium-Arsenide photo-cathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved using a Superconducting RF electron gun, which delivers beams of higher brightness than DC guns does, because the field gradient at the cathode is higher. SRF guns with metal cathodes and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since the cathode will be normal conducting, the problem about the heat load stemming from the cathode arises. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and the verification by measuring the quality factor of the gun with and without cathode.
Date: May 23, 2010
Creator: Wang, E.; Ben-Zvi, Ilan; Kewisch, J.; Burrill, A.; Rao, T.; Wu, Q. et al.
System: The UNT Digital Library
Longitudinal Emittance Growth Due to Nonlinear Space Charge Effect (open access)

Longitudinal Emittance Growth Due to Nonlinear Space Charge Effect

None
Date: May 10, 2012
Creator: Lau, Y. Y.; Yu, S. S.; Barnard, J. J. & Seidl, P. A.
System: The UNT Digital Library
Electron-cloud Build-up Simulations in the Proposed PS2: Status Report (open access)

Electron-cloud Build-up Simulations in the Proposed PS2: Status Report

A replacement for the PS storage ring is being considered, in the context of the future LHC accelerator complex upgrade, that would likely place the new machine (the PS2) in a regime where the electron-cloud (EC) effect might be significant. We report here our current estimate of the EC density ne in the bending magnets and the field-free regions at injection and extraction beam energy, for both proposed bunch spacings, tb = 25 and 50 ns. The primary model parameters exercised are the peak secondary emission yield (SEY) delta max, the electron-wall impact energy at which the SEY peaks, Emax, and the chamber radius a in the fieldfree regions. We present many of our results as a function of the bunch intensity Nb, and we provide a tentative explanation for the non-monotonic behavior of ne as a function of Nb.
Date: May 5, 2010
Creator: Furman, M. A.; De Maria, R.; Papaphilippou, Y. & Rumolo, G.
System: The UNT Digital Library
Heavy Quarkonium Production at LHC through W Boson Decays (open access)

Heavy Quarkonium Production at LHC through W Boson Decays

The production of the heavy (c{bar c})-quarkonium, (c{bar b})-quarkonium, and (b{bar b})-quarkonium states [({bar Q}') quarkonium for short], via the W{sup +} semi-inclusive decays, has been systematically studied within the framework of the nonrelativistic QCD. In addition to the two color-singlet S-wave states, we also discuss the production of the four color-singlet P-wave states |(Q{bar Q}')({sup 1}P{sub 1}){sub 1}> and |(Q{bar Q}')({sup 3}P{sub J}){sub 1}> [with J = (0,1,2)] together with the two color-octet components |(Q{bar Q}')({sup 1}S{sub 0}){sub 8}> and |(Q{bar Q}')({sup 3}S{sub 1}){sub 8}>. Improved trace technology is adopted to derive the simplified analytic expressions at the amplitude level, which shall be useful for dealing with the following cascade decay channels. At the LHC with the luminosity L {proportional_to} 10{sup 34} cm{sup -2} s{sup -1} and the center-of-mass energy {radical}S = 14 TeV, sizable heavy-quarkonium events can be produced through the W{sup +} boson decays; i.e., 2.57 x 10{sup 6} {eta}{sub c}, 2.65 x 10{sup 6} J/{Psi}, and 2.40 x 10{sup 6} P-wave charmonium events per year can be obtained, and 1.01 x 10{sup 5} B{sub c}, 9.11 x 10{sup 4} B*{sub c}, and 3.16 x 10{sup 4} P-wave (c{bar b})-quarkonium events per year can be obtained. Main …
Date: May 22, 2012
Creator: Liao, Qi-Li; U., /Chongqing; Wu, Xing-Gang; /SLAC, /Chongqing U.; Jiang, Jun; Yang, Zhi et al.
System: The UNT Digital Library
The MuCool Test Area and RF Program (open access)

The MuCool Test Area and RF Program

The MuCool RF Program focuses on the study of normal conducting RF structures operating in high magnetic field for applications in muon ionization cooling for Neutrino Factories and Muon Colliders. This paper will give an overview of the program, which will include a description of the test facility and its capabilities, the current test program, and the status of a cavity that can be rotated in the magnetic field which allows for a more detailed study of the maximum stable operating gradient vs. magnetic field strength and angle.
Date: May 1, 2010
Creator: Bross, A. D.; Jansson, A.; Moretti, A.; Yonehara, K.; Huang, D.; Torun, Y. et al.
System: The UNT Digital Library
METAL MEDIA FILTERS, AG-1 SECTION FI (open access)

METAL MEDIA FILTERS, AG-1 SECTION FI

One application of metal media filters is in various nuclear air cleaning processes including applications for protecting workers, the public and the environment from hazardous and radioactive particles. To support this application the development of the ASME AG-1 FI Standard on Metal Media has been under way for more than ten years. Development of the proposed section has required resolving several difficult issues associated with operating conditions (media velocity, pressure drop, etc.), qualification testing, and quality acceptance testing. Performance characteristics of metal media are dramatically different than the glass fiber media with respect to parameters like differential pressures, operating temperatures, media strength, etc. These differences make existing data for a glass fiber media inadequate for qualifying a metal media filter for AG-1. In the past much work has been conducted on metal media filters at facilities such as Lawrence Livermore National Laboratory (LLNL) and Savannah River National Laboratory (SRNL) to qualify the media as High Efficiency Particulate Air (HEPA) Filters. Particle retention testing has been conducted at Oak Ridge Filter Test Facility and at Air Techniques International (ATI) to prove that the metal media meets or exceeds the 99.97% particle retention required for a HEPA Filter. Even with his testing, …
Date: May 23, 2012
Creator: Adamson, D.
System: The UNT Digital Library
Muon Acceleration with RLA and Non-scaling FFAG Arcs (open access)

Muon Acceleration with RLA and Non-scaling FFAG Arcs

Recirculating Linear Accelerators (RLA) are the most likely means to achieve the rapid acceleration of shortlived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. In this paper, we present a novel return-arc optics design based on a Non Scaling Fixed Field Alternating Gradient (NS-FFAG) lattice that allows 5 and 9 GeV/c muons of both charges to be transported in the same string of magnets. The return arcs are made up of super cells with each super cell consisting of three triplets. By employing combined function magnets with dipole, quadrupole, sextupole and octupole magnetic field components, each super cell is designed to be achromatic and to have zero initial and final periodic orbit offsets for both 5 and 9 GeV/c muon momenta. This solution would reduce the number of arcs by a factor of 2, simplifying the overall design.
Date: May 1, 2010
Creator: Vasiliy Morozov,Alex Bogacz,Dejan Trbojevic
System: The UNT Digital Library
Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics (open access)

Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics

In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.
Date: May 1, 2012
Creator: Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V. & /Fermilab
System: The UNT Digital Library
Measurement of the Inclusive and Dijet Cross-sections of b-jets in pp Collisions at sqrt(s) = 7 TeV with the ATLAS Detector (open access)
Smart buildings with electric vehicle interconnection as buffer for local renewables? (open access)

Smart buildings with electric vehicle interconnection as buffer for local renewables?

Some conclusions from this presentation are: (1) EV Charging/discharging pattern mainly depends on the objective of the building (cost versus CO{sub 2}); (2) performed optimization runs show that stationary batteries are more attractive than mobile storage when putting more focus on CO{sub 2} emissions because stationary storage is available 24 hours a day for energy management - it's more effective; (3) stationary storage will be charged by PV, mobile only marginally; and (4) results will depend on the considered region and tariff. Final research work will show the results for 138 different buildings in nine different climate zones and three major utility service territories.
Date: May 1, 2011
Creator: Stadler, Michael; Cardoso, Goncalo; DeForest, Nicholas; Donadee, Jon; Gomez, Tomaz; Lai, Judy et al.
System: The UNT Digital Library
Analysis and Design of MEBT Beam Absorber for Project-X (open access)

Analysis and Design of MEBT Beam Absorber for Project-X

A beam absorber is needed for a new high power accelerator to be built in Fermilab. It is called Project-X and should replace the existing linac and the 8 GeV Booster synchrotron. The beam absorber is part of the bunch-by-bunch chopper assigned to create an arbitrary bunch sequence required by experimental program. It will be located in the middle of the medium energy beam transport (MEBT) and has to remove the unnecessary bunches from the initially uniform bunch structure supplied by 2.1 MeV CW RFQ. At nominal RFQ beam current of 5 mA, the maximum power delivered to the beam absorber is about 10 kW. Beam optics requirements result in that the length allocated to the beam absorber is short ({approx}400 mm) and the beam size is small ({sigma}{approx}2mm). That yields high power density of the beam arriving to the absorber. The paper presents the thermal and mechanical analysis of one of proposed designs.
Date: May 1, 2012
Creator: Awida, Mohamed H.; Lebedev, Valeri & Yakovlev, Vyacheslav P.
System: The UNT Digital Library
THE JLAMP VUV/SOFT X-RAY USER FACILITY AT JEFFERSON LABORATORY (open access)

THE JLAMP VUV/SOFT X-RAY USER FACILITY AT JEFFERSON LABORATORY

Jefferson Lab (JLab) is proposing JLAMP (JLab Amplifier), a 4th generation light source covering the 10-100 eV range in the fundamental mode with harmonics stretching towards the oxygen k-edge. The new photon science user facility will feature a two-pass superconducting LINAC to accelerate the electron beam to 600MeV at repetition rates of 4.68MHz continuous wave. The average brightness from a seeded amplifier free electron laser (FEL) will substantially exceed existing light sources in this device's wavelength range, extended by harmonics towards 2 nm. Multiple photon sources will be made available for pump-probe dynamical studies. The status of the machine design and technical challenges associated with the development of the JLAMP are presented here.
Date: May 1, 2010
Creator: Benson, S. V.; Douglas, D.; Evtushenko, P.; Gubeli, J.; Hannon, F. E.; Jordan, K. et al.
System: The UNT Digital Library
HIGH-RESOLUTION ATMOSPHERIC ENSEMBLE MODELING AT SRNL (open access)

HIGH-RESOLUTION ATMOSPHERIC ENSEMBLE MODELING AT SRNL

The High-Resolution Mid-Atlantic Forecasting Ensemble (HME) is a federated effort to improve operational forecasts related to precipitation, convection and boundary layer evolution, and fire weather utilizing data and computing resources from a diverse group of cooperating institutions in order to create a mesoscale ensemble from independent members. Collaborating organizations involved in the project include universities, National Weather Service offices, and national laboratories, including the Savannah River National Laboratory (SRNL). The ensemble system is produced from an overlapping numerical weather prediction model domain and parameter subsets provided by each contributing member. The coordination, synthesis, and dissemination of the ensemble information are performed by the Renaissance Computing Institute (RENCI) at the University of North Carolina-Chapel Hill. This paper discusses background related to the HME effort, SRNL participation, and example results available from the RENCI website.
Date: May 10, 2011
Creator: Buckley, R.; Werth, D.; Chiswell, S. & Etherton, B.
System: The UNT Digital Library
A High-power 650 MHz CW Magnetron Transmitter for Intensity Frontier Superconducting Accelerators (open access)

A High-power 650 MHz CW Magnetron Transmitter for Intensity Frontier Superconducting Accelerators

None
Date: May 1, 2012
Creator: Treado, T. A.; Chase, B.; Nagaitsev, S.; Pasquinelli, R. J.; Yakovlev, V. P.; Flanagan, G. et al.
System: The UNT Digital Library
Transport from the Recycler Ring to the Antiproton Source Beamlines (open access)

Transport from the Recycler Ring to the Antiproton Source Beamlines

In the post-NOvA era, the protons are directly transported from the Booster ring to the Recycler ring rather than the Main Injector. For Mu2e and g-2 project, the Debuncher ring will be modified into a Delivery ring to deliver the protons to both Mu2e and g-2 experiments. Therefore, it requires the transport of protons from the Recycler Ring to the Delivery ring. A new transfer line from the Recycler ring to the P1 beamline will be constructed to transport proton beam from the Recycler Ring to existing Antiproton Source beamlines. This new beamline provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. This paper presents the Conceptual Design of this new beamline.
Date: May 14, 2012
Creator: Xiao, M.
System: The UNT Digital Library
6 Batch Injection and Slipped Beam Tune Measurements in Fermilab?s Main Injector (open access)

6 Batch Injection and Slipped Beam Tune Measurements in Fermilab?s Main Injector

During NOVA operations it is planned to run the Fermilab Recycler in a 12 batch slip stacking mode. In preparation for this, measurements of the tune during a six batch injection and then as the beam is decelerated by changing the RF frequency have been carried out in the Main Injector. The coherent tune shifts due to the changing beam intensity were measured and compared well with the theoretically expected tune shift. The tune shifts due to changing RF frequency, required for slip stacking, also compare well with the linear theory, although some nonlinear affects are apparent at large frequency changes. These results give us confidence that the expected tunes shifts during 12 batch slip stacking Recycler operations can be accommodated.
Date: May 1, 2012
Creator: Scott, D. J.; Capista, D.; Kourbanis, I.; Seiya, K. & Yan, M.-J.
System: The UNT Digital Library
ELECTROSTATIC MODELING OF THE JEFFERSON LABORATORY INVERTED CERAMIC GUN (open access)

ELECTROSTATIC MODELING OF THE JEFFERSON LABORATORY INVERTED CERAMIC GUN

Jefferson Laboratory (JLab) is currently developing a new 500kV DC electron gun for future use with the FEL. The design consists of two inverted ceramics which support a central cathode electrode. This layout allows for a load-lock system to be located behind the gun chamber. The electrostatic geometry of the gun has been designed to minimize surface electric field gradients and also to provide some transverse focusing to the electron beam during transit between the cathode and anode. This paper discusses the electrode design philosophy and presents the results of electrostatic simulations. The electric field information obtained through modeling was used with particle tracking codes to predict the effects on the electron beam.
Date: May 1, 2010
Creator: P. Evtushenko ,F.E. Hannon, C. Hernandez-Garcia
System: The UNT Digital Library
Pressure Sensitivity Characterization of Superconducting Spoke Cavities (open access)

Pressure Sensitivity Characterization of Superconducting Spoke Cavities

None
Date: May 1, 2012
Creator: Awida, M.H.; Gonin, I.V.; Ristori, L.; Yakovlev, V.P.; /Fermilab; Passarelli, D. et al.
System: The UNT Digital Library
Search for Lepton-Number Violating Processes in B+ to h- l+ l+ Decays (open access)

Search for Lepton-Number Violating Processes in B+ to h- l+ l+ Decays

We have searched for the lepton-number violating processes B{sup +} {yields} h{sup -}{ell}{sup +}{ell}{sup +} with h{sup -} = K{sup -}/{pi}{sup -} and {ell}{sup +} = e{sup +}/{mu}{sup +}, using a sample of 471 {+-} 3 million B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90% confidence level upper limits on their branching fractions B (B{sup +} {yields} {pi}{sup -}e{sup +}e{sup +}) < 2.3 x 10{sup -8}, {Beta}(B{sup +} {yields} K{sup -}e{sup +}e{sup +}) < 3.0 x 10{sup -8}, {Beta}(B{sup +} {yields} {pi}{sup -}{mu}{sup +}{mu}{sup +}) < 10.7 x 10{sup -8}, and {Beta}(B{sup +} {yields} K{sup -}{mu}{sup +}{mu}{sup +}) < 6.7 x 10{sup -8}.
Date: May 17, 2012
Creator: Lees, J.P.
System: The UNT Digital Library