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Toward fully self-consistent simulation of the interaction of E-Clouds and beams with WARP-POSINST (open access)

Toward fully self-consistent simulation of the interaction of E-Clouds and beams with WARP-POSINST

To predict the evolution of electron clouds and their effect on the beam, the high energy physics community has relied so far on the complementary use of 'buildup' and 'single/multi-bunch instability' reduced descriptions. The former describes the evolution of electron clouds at a given location in the ring, or 'station', under the influence of prescribed beams and external fields [1], while the latter (sometimes also referred as the 'quasi-static' approximation [2]) follows the interaction between the beams and the electron clouds around the accelerator with prescribed initial distributions of electrons, assumed to be concentrated at a number of discrete 'stations' around the ring. Examples of single bunch instability codes include HEADTAIL [3], QuickPIC [4, 5], and PEHTS [6]. By contrast, a fully self-consistent approach, in which both the electron cloud and beam distributions evolve simultaneously under their mutual influence without any restriction on their relative motion, is required for modeling the interaction of high-intensity beams with electron clouds for heavy-ion beam-driven fusion and warm-dense matter science. This community has relied on the use of Particle-In-Cell (PIC) methods through the development and use of the WARP-POSINST code suite [1, 7, 8]. The development of novel numerical techniques (including adaptive mesh refinement, …
Date: April 9, 2012
Creator: Lawrence Livermore National Laboratory
System: The UNT Digital Library
Model-Independent Results for the Decay B \to L Nu(L) Gamma at BaBar (open access)

Model-Independent Results for the Decay B \to L Nu(L) Gamma at BaBar

We present a search for the radiative leptonic decays B{sub +} {yields} e{sup +} {nu}{sub e}{gamma} and B{sup +} {yields} {mu}{sup +}{nu}{sub {mu}}{gamma} using data collected by the BABAR detector at the PEP-II B factory. We fully reconstruct the hadronic decay of one of the B mesons in {Upsilon}(4S) {yields} B{sup +}B{sup -} and then search for evidence of the signal decay within the rest of the event. This method provides clean kinematic information on the signal's missing energy and high momentum photon and lepton, and allows for a model-independent analysis of this decay. Using a data sample of 465 million B-meson pairs, we obtain sensitivity to branching fractions of the same order as predicted by the Standard Model. We report a model-independent branching fraction upper limit of {Beta}(B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma}) < 15.6 x 10{sup -6} ({ell} = e or {mu}) at the 90% confidence level.
Date: April 9, 2012
Creator: Lindemann, D. M.
System: The UNT Digital Library
Cavity Beam Position Monitor System for ATF2 (open access)

Cavity Beam Position Monitor System for ATF2

The Accelerator Test Facility 2 (ATF2) in KEK, Japan, is a prototype scaled demonstrator system for the final focus required for a future high energy lepton linear collider. The ATF2 beam-line is instrumented with a total of 38 C and S band resonant cavity beam position monitors (CBPM) with associated mixer electronics and digitizers. The current status of the BPM system is described, with a focus on operational techniques and performance. The ATF2 C-band system is performing well, with individual CBPM resolution approaching or at the design resolution of 50 nm. The changes in the CBPM calibration observed over three weeks can probably be attributed to thermal effects on the mixer electronics systems. The CW calibration tone power will be upgraded to monitor changes in the electronics gain and phase. The four S-band CBPMs are still to be investigated, the main problem associated with these cavities is a large cross coupling between the x and y ports. This combined with the large design dispersion in that degion makes the digital signal processing difficult, although various techniques exist to determine the cavity parameters and use these coupled signals for beam position determination.
Date: July 9, 2012
Creator: Boogert, Stewart; /Oxford U., JAI; Boorman, Gary; /Oxford U., JAI; Swinson, Christina; /Oxford U., JAI et al.
System: The UNT Digital Library
Lepton-Flavor-Violating Tau Decays at BaBar (open access)

Lepton-Flavor-Violating Tau Decays at BaBar

We present the most recent searches for lepton-flavor-violating (LFV) {tau} decays in BABAR. We find no evidence of {tau} decaying to three charged leptons or to a charged lepton and a neutral meson (K{sub S}{sup 0}, {rho}, {phi}, K*{sup 0}, {bar K}*{sup 0}), and set upper limits on the corresponding branching fractions (BF) between 1.8 and 19 x 10{sup -8} at 90% confidence level (CL).
Date: April 9, 2012
Creator: Marchiori, G. & /Paris, LPTHE
System: The UNT Digital Library
Developing of superconducting RF guns at BNL (open access)

Developing of superconducting RF guns at BNL

N/A
Date: September 9, 2012
Creator: Belomestnykh, S.; Altinbas, Z.; Ben-Zvi, Ilan; Boulware, C. H.; Brutus, J. C.; Burrill, A. et al.
System: The UNT Digital Library
Performance Modeling of Algebraic Multigrid on Blue Gene/Q: Lessons Learned (open access)

Performance Modeling of Algebraic Multigrid on Blue Gene/Q: Lessons Learned

None
Date: September 9, 2012
Creator: Gahvari, H.; Gropp, W.; Jordan, K. E.; Schulz, M. & Yang, U. M.
System: The UNT Digital Library
Future Synchrotron Light Sources Based on Ultimate Storage Rings (open access)

Future Synchrotron Light Sources Based on Ultimate Storage Rings

The main purpose of this talk is to describe how far one might push the state of the art in storage ring design. The talk will start with an overview of the latest developments and advances in the design of synchrotron light sources based on the concept of an 'ultimate' storage ring. The review will establish how bright a ring based light source might be, where the frontier of technological challenges are, and what the limits of accelerator physics are. Emphasis will be given to possible improvements in accelerator design and developments in technology toward the goal of achieving an ultimate storage ring. An ultimate storage ring (USR), defined as an electron ring-based light source having an emittance in both transverse planes at the diffraction limit for the range of X-ray wavelengths of interest for a scientific community, would provide very high brightness photons having high transverse coherence that would extend the capabilities of X-ray imaging and probe techniques beyond today's performance. It would be a cost-effective, high-coherence 4th generation light source, competitive with one based on energy recovery linac (ERL) technology, serving a large number of users studying material, chemical, and biological sciences. Furthermore, because of the experience accumulated …
Date: April 9, 2012
Creator: Cai, Yunhai
System: The UNT Digital Library
Efficient Laser-Induced 6 - 8 KeV X-Ray Production From Iron Oxide Aerogel and Foil-Lined Cavity Targets (open access)

Efficient Laser-Induced 6 - 8 KeV X-Ray Production From Iron Oxide Aerogel and Foil-Lined Cavity Targets

None
Date: May 9, 2012
Creator: Perez, F.; Kay, J. J.; Patterson, R.; Kane, J.; Villette, B.; Girard, F. et al.
System: The UNT Digital Library
Characterization of Slow Orbit Motion in the SPEAR3 (open access)

Characterization of Slow Orbit Motion in the SPEAR3

SPEAR3 is a third-generation synchrotron light source storage ring. The beam stability requirements are {approx}10% of the beam size, which is about 1 micron in the vertical plane. Hydrostatic level system (HLS) measurements show that the height of the SPEAR3 tunnel floor varies by tens of microns daily. We present analysis of the HLS data, including accounting for common-mode tidal motion. We discuss the results of experiments done to determine the primary driving source of ground motion. We painted the accelerator tunnel walls white; we temporarily installed Mylar over the asphalt in the center of the accelerator; and we put Mylar over a section of the tunnel walls.
Date: July 9, 2012
Creator: Sunilkumar, Nikita; Gassner, Georg; Safranek, James & Yan, Yiton
System: The UNT Digital Library
Improvements at the BNL 200 MeV LINAC (open access)

Improvements at the BNL 200 MeV LINAC

N/A
Date: September 9, 2012
Creator: Raparia, D.; Alessi, J.; Briscoe, B.; Fite, J.; Gould, O.; LoDestro, V. et al.
System: The UNT Digital Library
Novel Perspectives for Hadron Physics (open access)

Novel Perspectives for Hadron Physics

I discuss several novel and unexpected aspects of quantum chromodynamics. These include: (a) the nonperturbative origin of intrinsic strange, charm and bottom quarks in the nucleon at large x; the breakdown of pQCD factorization theorems due to the lensing effects of initial- and final-state interactions; (b) important corrections to pQCD scaling for inclusive reactions due to processes in which hadrons are created at high transverse momentum directly in the hard processes and their relation to the baryon anomaly in high-centrality heavy-ion collisions; and (c) the nonuniversality of quark distributions in nuclei. I also discuss some novel theoretical perspectives in QCD: (a) light-front holography - a relativistic color-confining first approximation to QCD based on the AdS/CFT correspondence principle; (b) the principle of maximum conformality - a method which determines the renormalization scale at finite order in perturbation theory yielding scheme independent results; (c) the replacement of quark and gluon vacuum condensates by 'in-hadron condensates' and how this helps to resolve the conflict between QCD vacuum and the cosmological constant.
Date: March 9, 2012
Creator: Brodsky, Stanley J.
System: The UNT Digital Library
Beam Measurements at LCLS (open access)

Beam Measurements at LCLS

None
Date: May 9, 2012
Creator: Frisch, J.; Akre, R.; Decker, F. J.; Ding, Y.; Dowell, D.; Emma, P. et al.
System: The UNT Digital Library
120-Channel, Chronically Implantable, Wireless, Polymer Neural Interface (open access)

120-Channel, Chronically Implantable, Wireless, Polymer Neural Interface

None
Date: May 9, 2012
Creator: Tooker, A; Shah, K; Tolosa, V; Sheth, H; Felix, S; Delima, T et al.
System: The UNT Digital Library
High Energy Electron Signals from Dark Matter Annihilation in the Sun (open access)

High Energy Electron Signals from Dark Matter Annihilation in the Sun

In this paper we discuss two mechanisms by which high energy electrons resulting from dark matter annihilations in or near the Sun can arrive at the Earth. Specifically, electrons can escape the sun if DM annihilates into long-lived states, or if dark matter scatters inelastically, which would leave a halo of dark matter outside of the sun. Such a localized source of electrons may affect the spectra observed by experiments with narrower fields of view oriented towards the sun, such as ATIC, differently from those with larger fields of view such as Fermi. We suggest a simple test of these possibilities with existing Fermi data that is more sensitive than limits from final state radiation. If observed, such a signal will constitute an unequivocal signature of dark matter.
Date: April 9, 2012
Creator: Schuster, Philip; Toro, Natalia; Weiner, Neal & Yavin, Itay
System: The UNT Digital Library
Optimization of the Configuration of Pixilated Detectors Based on the Sgabbib-Nyquist Theory for the X-ray Spectroscopy of Hot Tokamak Plasmas (open access)

Optimization of the Configuration of Pixilated Detectors Based on the Sgabbib-Nyquist Theory for the X-ray Spectroscopy of Hot Tokamak Plasmas

This paper describes an optimization of the detector configuration, based on the Shannon-Nyquist theory, for two major x-ray diagnostic systems on tokamaks and stellarators: x-ray imaging crystal spectrometers and x-ray pinhole cameras. Typically, the spectral data recorded with pixilated detectors are oversampled, meaning that the same spectral information could be obtained using fewer pixels. Using experimental data from Alcator C-Mod, we quantify the degree of oversampling and propose alternate uses for the redundant pixels for additional diagnostic applications.
Date: August 9, 2012
Creator: : E. Wang, P. Beiersdorfer, M. Bitter, L.F. Delgado-Apricio, K.W. Hill and N. Pablant
System: The UNT Digital Library
The high-current ERL at BNL (open access)

The high-current ERL at BNL

N/A
Date: September 9, 2012
Creator: Ben-Zvi, Ilan
System: The UNT Digital Library
Studies of Charmonium-Like States at BaBar (open access)

Studies of Charmonium-Like States at BaBar

Several charmonium-like states above D{bar D} threshold have been discovered at the Belle and BABAR B-factories. Some of these states are produced via Initial State Radiation (e.g. Y(4260) and Y(4350)), and some are observed in B-meson decays (e.g. X(3872), and Y(3940)). The Belle observations of the enhancements in the {Psi}(2S){pi}{sup -} and {chi}{sub cl}{pi}{sup -}, i.e. the Z(4430){sup -}, Z{sub 1}(4050){sup -}, and Z{sub 2}(4250){sup -}, have generated a great deal of interest, because such states must have minimum quark content (c{bar c}d{bar u}), i.e. these are four-quark states. The BABAR Collaboration does not confirm the existence of the Z(4430){sup -}.
Date: April 9, 2012
Creator: Mokhtar, Arafat Gabareen
System: The UNT Digital Library
DETERMINATION OF THE DISTRIBUTION AND INVENTORY OF RADIONUCLIDES WITHIN A SAVANNAH RIVER SITE WATERWAY (open access)

DETERMINATION OF THE DISTRIBUTION AND INVENTORY OF RADIONUCLIDES WITHIN A SAVANNAH RIVER SITE WATERWAY

An investigation was conducted to evaluate the radionuclide inventory within the Lower Three Runs (LTR) Integrator Operable Unit (IOU) at the U.S. Department of Energy’s (DOE’s) Savannah River Site (SRS). The scope of this effort included the analysis of previously existing sampling and analysis data as well as additional streambed and floodplain sampling and analysis data acquired to delineate horizontal and vertical distributions of the radionuclide as part of the ongoing SRS environmental restoration program, and specifically for the LTR IOU program. While cesium-137 (Cs-137) is the most significant and abundant radionuclide associated with the LTR IOU it is not the only radionuclide, hence the scope included evaluating all radionuclides present and includes an evaluation of inventory uncertainty for use in sensitivity and uncertainty analyses. The scope involved evaluation of the radionuclide inventory in the P-Reactor and RReactor cooling water effluent canal systems, PAR Pond (including Pond C) and the floodplain and stream sediment sections of LTR between the PAR Pond Dam and the Savannah River. The approach taken was to examine all of the available Sediment and Sediment/Soil analysis data available along the P- and R-Reactor cooling water re-circulation canal system, the ponds situated along those canal reaches and …
Date: November 9, 2012
Creator: Hiergesell, R. & Phifer, M.
System: The UNT Digital Library
Project X RFQ EM Design (open access)

Project X RFQ EM Design

Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H- ion source, a low-energy beam transport (LEBT), a CW 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the CW 162.5 MHz RFQ that provides bunching of the 1-10 mA H- beam with acceleration from 30 keV to 2.1 MeV.
Date: May 9, 2012
Creator: Romanov, Gennady; Hoff, Matthew; Li, Derun; Staples, John & Virostek, Steve
System: The UNT Digital Library
A Model-Independent Search for the decay B->l nu gamma (open access)

A Model-Independent Search for the decay B->l nu gamma

The authors present a search for the radiative leptonic decay B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma}, where {ell} = e, {mu}, using a data sample of 465 million B{bar B} pairs collected by the BABAR experiment. In this analysis, they fully reconstruct the hadronic decay of one of the B mesons in {Upsilon}(4S) {yields} B{sup +}B{sup -} decays, then search for evidence of B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma} in the rest of the event. They observe no significant evidence of signal decays and report model-independent branching fraction upper limits of {Beta}(B{sup +} {yields} e{sup +}{nu}{sub e}{gamma}) < 17 x 10{sup -6}, {Beta}(B{sup +} {yields} {mu}{sup +}{nu}{sub {mu}}{gamma}) < 24 x 10{sup -6}, and {Beta}(B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma}) < 15.6 x 10{sup -6} ({ell} = e or {mu}), all at the 90% confidence level.
Date: October 9, 2012
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
INTERCOMPARISON OF 14C ANALYSIS OF CARBONACEOUS AEROSOLS: EXERCISE 2009 (open access)

INTERCOMPARISON OF 14C ANALYSIS OF CARBONACEOUS AEROSOLS: EXERCISE 2009

None
Date: November 9, 2012
Creator: Bench, G
System: The UNT Digital Library
Modeling Multi-Bunch X-band Photoinjector Challenges (open access)

Modeling Multi-Bunch X-band Photoinjector Challenges

An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray technology at LLNL. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Of critical import to the functioning of the LLNL X-band system with multiple electron bunches is the performance of the photoinjector. In depth modeling of the Mark 1 LLNL/SLAC X-band rf photoinjector performance will be presented addressing important challenges that must be addressed in order to fabricate a multi-bunch Mark 2 photoinjector. Emittance performance is evaluated under different nominal electron bunch parameters using electrostatic codes such as PARMELA. Wake potential is analyzed using electromagnetic time domain simulations using the ACE3P code T3P. Plans for multi-bunch experiments and implementation of photoinjector advances for the Mark 2 design will also be discussed.
Date: May 9, 2012
Creator: Marsh, R A; Anderson, S G; Gibson, D J & Barty, C J
System: The UNT Digital Library
Superconducting RF linac for eRHIC (open access)

Superconducting RF linac for eRHIC

N/A
Date: September 9, 2012
Creator: Belomestnykh, S.; Ben-Zvi, Ilan; Brutus, J. C.; Hahn, H.; Kayran, D.; Litvinenko, V. et al.
System: The UNT Digital Library