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A 1.8 Mev K+ injector for the high current beam transport experiment fusion (open access)

A 1.8 Mev K+ injector for the high current beam transport experiment fusion

For the High Current Beam Transport Experiment (HCX) at LBNL, an injector is required to deliver up to 1.8 MV of 0.6 A K{sup +} beam with an emittance of {approx}1 p-mm-mrad. We have successfully operated a 10-cm diameter surface ionization source together with an electrostatic quadrupole (ESQ) accelerator to meet these requirements. The pulse length is {approx}4 {micro}s, firing at once every 10-15 seconds. By optimizing the extraction diode and the ESQ voltages, we have obtained an output beam with good current density uniformity, except for a small increase near the beam edge. Characterization of the beam emerging from the injector included measurements of the intensity profile, beam imaging, and transverse phase space. These data along with comparison to computer simulations provide the knowledge base for designing and understanding future HCX experiments.
Date: May 20, 2002
Creator: Kwan, J. W.; Bieniosek, F. M.; Henestroza, E.; Prost, L. & Seidl, P.
System: The UNT Digital Library
1 GeV CW nonscaling FFAG for ADS, and magnet parameters (open access)

1 GeV CW nonscaling FFAG for ADS, and magnet parameters

Multi-MW proton driver capability remains a challenging, critical technology for many core HEP programs, particularly the neutrino ones such as the Muon Collider and Neutrino factory, and for high-profile energy applications such as Accelerator Driven Subcritical Reactors (ADS) and Accelerator Transmutation of Waste for nuclear power and waste management. Work is focused almost exclusively on an SRF linac, as, to date, no re-circulating accelerator can attain the 10-20 MW capability necessary for the nuclear applications. Recently, the concept of isochronous orbits has been explored and developed for nonscaling FFAGs using powerful new methodologies in FFAG accelerator design. Work is progressing on a stable, high-intensity, 1 GeV isochronous FFAG. Initial specifications of novel magnets with the nonlinear radial fields required to support isochronous operation are also reported here.
Date: May 20, 2012
Creator: Johnstone, C.; Meot, F.; Snopok, P. & Weng, W.
System: The UNT Digital Library
18th U.S. Department of Energy Low-Level Radioactive Waste Management Conference. Program (open access)

18th U.S. Department of Energy Low-Level Radioactive Waste Management Conference. Program

This conference explored the latest developments in low-level radioactive waste management through presentations from professionals in both the public and the private sectors and special guests. The conference included two continuing education seminars, a workshop, exhibits, and a tour of Envirocare of Utah, Inc., one of America's three commercial low-level radioactive waste depositories.
Date: May 20, 1997
Creator: unknown
System: The UNT Digital Library
3D simulations of multipacting in the 56 MHz SRF cavity (open access)

3D simulations of multipacting in the 56 MHz SRF cavity

The 56 MHz SRF Quarter-Wave Resonator (QWR) is designed for RHIC as a storage cavity to improve the collider performance. 2D multipacting simulation has been done for the cavity alone. Ripples were added to the outer body of the cavity for multipacting suppression based on the simulation findings. During operation, there will be four higher order mode (HOM) couplers. All of these components will be exposed to high RF fields. In this paper we compare 2D and 3D codes simulation results for multipacting in the cavity. We also report 3D simulation results for multipacting simulation at the couplers.
Date: May 20, 2012
Creator: Q., Wu; Belomestnykh, S.; Ge, L.; Ko, K.; Li, Z.; Ng, C. et al.
System: The UNT Digital Library
Abstracts of adhesive colloquim at LLL, April 24--25, 1974 (open access)

Abstracts of adhesive colloquim at LLL, April 24--25, 1974

None
Date: May 20, 1974
Creator: Peck, L. E.
System: The UNT Digital Library
Advances in Tandem Mirror fusion power reactors (open access)

Advances in Tandem Mirror fusion power reactors

The Tandem Mirror exhibits several distinctive features which make the reactor embodiment of the principle very attractive: Simple low-technology linear central cell; steady-state operation; high-..beta.. operation; no driven current or disruptions; divertorless operation; direction conversion of end-loss power; low-surface heat loads; and advanced fusion fuel capability. In this paper, we examine these features in connection with two tandem mirror reactor designs, MARS and MINIMARS, and several advanced reactor concepts including the wall-stabilized reactor and the field-reversed mirror. With a novel compact end plug scheme employing octopole stabilization, MINIMARS is expressly designed for short construction times, factory-built modules, and a small (600 MWe) but economic reactor size. We have also configured the design for low radioactive afterheat and inherent/passive safety under LOCA/LOFA conditions, thereby obviating the need for expensive engineered safety systems. In contrast to the complex and expensive double-quadrupole end-cell of the MARS reactor, the compact octopole end-cell of MINIMARS enables ignition to be achieved with much shorter central cell lengths and considerably improves the economy of scale for small (approx.250 to 600 MWe) tandem mirror reactors. Finally, we examine the prospects for realizing the ultimate potential of the tandem mirror with regard to both innovative configurations and novel neutron …
Date: May 20, 1986
Creator: Perkins, L. J. & Logan, B. G.
System: The UNT Digital Library
Aftershock Characteristics as a Means of Discriminating Explosions from Earthquakes (open access)

Aftershock Characteristics as a Means of Discriminating Explosions from Earthquakes

The behavior of aftershock sequences around the Nevada Test Site in the southern Great Basin is characterized as a potential discriminant between explosions and earthquakes. The aftershock model designed by Reasenberg and Jones (1989, 1994) allows for a probabilistic statement of earthquake-like aftershock behavior at any time after the mainshock. We use this model to define two types of aftershock discriminants. The first defines M{sub X}, or the minimum magnitude of an aftershock expected within a given duration after the mainshock with probability X. Of the 67 earthquakes with M > 4 in the study region, 63 of them produce an aftershock greater than M{sub 99} within the first seven days after a mainshock. This is contrasted with only six of 93 explosions with M > 4 that produce an aftershock greater than M{sub 99} for the same period. If the aftershock magnitude threshold is lowered and the M{sub 90} criteria is used, then no explosions produce an aftershock greater than M{sub 90} for durations that end more than 17 days after the mainshock. The other discriminant defines N{sub X}, or the minimum cumulative number of aftershocks expected for given time after the mainshock with probability X. Similar to the …
Date: May 20, 2009
Creator: Ford, S R & Walter, W R
System: The UNT Digital Library
The AGS synchrotron with four helical magnets (open access)

The AGS synchrotron with four helical magnets

The idea of using two partial helical magnets was applied successfully to the AGS synchrotron to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. The placement of four helical magnets in the AGS ring provides many advantages over the present setup of the AGS which uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides for a larger 'spin tune gap', which allows the vertical and horizontal tunes to be placed, and prevent the horizontal and vertical intrinsic spin resonances of the AGS to occur during the acceleration cycle. Although the same spin gap can be obtained with a single or two partial helices, the required high field strength of a single helix makes its use impractical, and that of the double helix rather difficult. In this paper we will provide results on the spin tune and on the optics of …
Date: May 20, 2012
Creator: Tsoupas, N.; Huang, H.; Roser, T.; MacKay, W. W. & Trbojevic, D.
System: The UNT Digital Library
Amplitudes and Ultraviolet Behavior of N = 8 Supergravity (open access)

Amplitudes and Ultraviolet Behavior of N = 8 Supergravity

In this contribution we describe computational tools that permit the evaluation of multi-loop scattering amplitudes in N = 8 supergravity, in terms of amplitudes in N = 4 super-Yang-Mills theory. We also discuss the remarkable ultraviolet behavior of N = 8 supergravity, which follows from these amplitudes, and is as good as that of N = 4 super-Yang-Mills theory through at least four loops.
Date: May 20, 2011
Creator: Bern, Zvi; Carrasco, John Joseph; Dixon, Lance J.; Johansson, Henrik & Roiban, Radu
System: The UNT Digital Library
Analysis of beam loss induced abort kicker instability (open access)

Analysis of beam loss induced abort kicker instability

Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.
Date: May 20, 2012
Creator: Zhang, W.; Sandberg, J.; Ahrens, L.; Fischer, W.; Hahn, H.; Mi, J. et al.
System: The UNT Digital Library
Analysis of kicker noise induced beam emittance growth (open access)

Analysis of kicker noise induced beam emittance growth

Over the last few years, physicists have occasionally observed the presence of noise acting on the RHIC beams leading to emittance growth at high beam energies. While the noise was sporadic in the past, it became persistent during the Run-11 setup period. An investigation diagnosed the source as originating from the RHIC dump kicker system. Once identified the issue was quickly resolved. We report in this paper the investigation result, circuit analysis, measured and simulated waveforms, solutions, and future plans.
Date: May 20, 2012
Creator: Zhang, W.; Sandberg, J.; Ahrens, L.; Blacker, I. M.; Brennan, M.; Blaskiewicz, M. et al.
System: The UNT Digital Library
ASCI terascale simulation environmental implementation (open access)

ASCI terascale simulation environmental implementation

The ASCI Blue-Pacific Sustained Stewardship TeraOp/s computer demonstrated 1.2 TeraOP/s in September 1998. Two thirds of the system was delivered to the Lawrence Livermore National Laboratory in early October 1999 and the remainder in December 1998. Since that time ASCI scientists have been performing ''full-system'' runs of remarkable scientific value in Quantum Chemistry, Biology, Molecular Dynamics, Turbulence, Neutron Transport and Astrophysics. In addition, there has been an intensive ASCI 3D physics simulation development effort. The SST also supports a large production workload. This paper focuses on the architecture of the Blue-Pacific SST, the integration of this platform into a full simulation environment, full-system science runs and a discussion of the operational model for the SST.
Date: May 20, 1999
Creator: Seager, M K
System: The UNT Digital Library
Barriers to Pain Management: Caregiver Perceptions and Pain Talk by Hospice Interdisciplinary Teams (open access)

Barriers to Pain Management: Caregiver Perceptions and Pain Talk by Hospice Interdisciplinary Teams

Article on caregiver perceptions, pain talk by hospice interdisciplinary teams, and barriers to pain management.
Date: May 20, 2008
Creator: Oliver, Debra Parker; Wittenberg-Lyles, Elaine; Demiris, George; Washington, Karla T.; Porock, Davina, Ph. D. & Day, Michele L.
System: The UNT Digital Library
Beam dynamics studies of four-gap low-beta superconducting resonators (open access)

Beam dynamics studies of four-gap low-beta superconducting resonators

The four-gap superconducting resonators which have been developed at Argonne for use in the low-beta positive ion-injector for ATLAS have potential applications for ions with velocities less than 0.007c and q/m less than 0.1. It was previously observed that at low velocities these structures can be focusing in both longitudinal and transverse phase spaces due to an inherent alternating-phase-focusing property. Studies are underway to determine the optimum combination of multi-gap structures and solenoids at low velocity and low q/m. In this paper the authors present the results of acceptance studies for the first three resonators at the front of the positive-ion injection linac, with and without the focusing solenoids. These studies include the effects of higher-order distortions in longitudinal and transverse phase spaces since minimizing such aberrations is very important for most nuclear physics applications of such accelerators.
Date: May 20, 1993
Creator: Nolen, J. A. & Joh, K.
System: The UNT Digital Library
Beam Experiments Towards High-Intensity Beams in RHIC (open access)

Beam Experiments Towards High-Intensity Beams in RHIC

Proton bunch intensities in RHIC are planned to be increased from 2 {center_dot} 10{sup 11} to 3 {center_dot} 10{sup 11} protons per bunch to increase the luminosity, together with head-on beam-beam compensation using electron lenses. To study the feasibility of the intensity increase, beam experiments are being performed. Recent experimental results are presented.
Date: May 20, 2012
Creator: Montag, C.; Ahrens, L.; Brennan, J. M.; Blaskiewicz, M.; Drees, A.; Fischer, W. et al.
System: The UNT Digital Library
Beam optics and the pp2pp experiment at RHIC (open access)

Beam optics and the pp2pp experiment at RHIC

The newly installed forward detector system at the STAR experiment at RHIC measures small angle elastic and inelastic scattering of polarized protons on polarized protons. The detector system makes use of a pair of Roman Pot (RP) detectors, instrumented with silicon detectors, and located on either side of the STAR intersection region downstream of the DX and D0 dipoles and quadrupole triplets. The parallel to point optics is designed so that scattering angles are determined from position measurements at the RP's with small error. The RP setup allows measurement of position and angle for a subset of the scattered protons. With this position/angle correlations at the RP's can be compared with optics model predictions to get a measure of the accuracy of the quadrupole triplet current settings. The current in each quadrupole in the triplets is comprised of sums and differences of up to six power supplies and an overall 1% error in the triplet field strengths results in a 4% error in four-momentum transfer squared. This technique is also useful to check the polarity of the skew elements located in each quadrupole triplet. Results of the analysis will be presented.
Date: May 20, 2012
Creator: H., Pile P.; Guryn, W.; Lee, J. H.; Tepikian, S. & Yip, K.
System: The UNT Digital Library
Biofunctionalization of metallic implants by calcium phosphate coatings (open access)

Biofunctionalization of metallic implants by calcium phosphate coatings

Article provides a brief summary of state-of-art of surface biofunctionalization on implantable metals by CaP coatings.
Date: May 20, 2019
Creator: Su, Yingchao; Cockerill, Irsalan; Zheng, Yufeng; Tang, Liping; Qin, Yi‐Xian & Zhu, Donghui
System: The UNT Digital Library
Bonding, Backbonding, and Spin-Polarized Molecular Orbitals:Basis for Magnetism and Semiconducting Transport in V[TCNE]x~;;2 (open access)

Bonding, Backbonding, and Spin-Polarized Molecular Orbitals:Basis for Magnetism and Semiconducting Transport in V[TCNE]x~;;2

X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (MCD) at the V L2,3 and C and N K edges reveal bonding/backbonding interactions in films of the 400 K magnetic semiconductor V[TCNE]x~;;2. In V spectra, dxy-like orbitals are modeled assuming V2+ in an octahedral ligand field, while dz2 and dx2-y2 orbitals involved in strong covalent bonding cannot be modeled by atomic calculations. C and N MCD, and differences in XAS from neutral TCNE molecules, reveal spin-polarized molecular orbitals in V[TCNE]x~;;2 associated with backbonding interactions that yield its novel properties.
Date: May 20, 2008
Creator: Kortright, Jeffrey B.; Lincoln, Derek M.; Edelstein, Ruth Shima & Epstein, Arthur J.
System: The UNT Digital Library
Bounds on Unparticles from the Higgs Sector (open access)

Bounds on Unparticles from the Higgs Sector

We study supersymmetric QCD in the conformal window as a laboratory for unparticle physics, and analyze couplings between the unparticle sector and the Higgs sector. These couplings can lead to the unparticle sector being pushed away from its scale invariant fixed point. We show that this implies that low energy experiments will not be able to see unparticle physics, and the best hope of seeing unparticles is in high energy collider experiments such as the Tevatron and the LHC. We also demonstrate how the breaking of scale invariance could be observed at these experiments.
Date: May 20, 2007
Creator: Fox, Patrick J.; Rajaraman, Arvind & Shirman, Yuri
System: The UNT Digital Library
Bunch compressor design for potential FEL operation at eRHIC (open access)

Bunch compressor design for potential FEL operation at eRHIC

N/A
Date: May 20, 2012
Creator: Y., Jing; Hao, Y. & Litvinenko, V.
System: The UNT Digital Library
Calculation of synchrotron radiation from high intensity electron beam at eRHIC (open access)

Calculation of synchrotron radiation from high intensity electron beam at eRHIC

The Electron-Relativistic Heavy Ion Collider (eRHIC) at Brookhaven National Lab is an upgrade project for the existing RHIC. A 30 GeV energy recovery linac (ERL) will provide a high charge and high quality electron beam to collide with proton and ion beams. This will improve the luminosity by at least 2 orders of magnitude. The synchrotron radiation (SR) from the bending magnets and strong quadrupoles for such an intense beam could be penetrating the vacuum chamber and producing hazards to electronic devices and undesired background for detectors. In this paper, we calculate the SR spectral intensity, power density distributions and heat load on the chamber wall. We suggest the wall thickness required to stop the SR and estimate spectral characteristics of the residual and scattered background radiation outside the chamber.
Date: May 20, 2012
Creator: Y., Jing; Chubar, O. & Litvinenko, V.
System: The UNT Digital Library
Calculation of the Surface Tension of Ordinary Organic and Ionic Liquids by Means of a Generally Applicable Computer Algorithm Based on the Group-Additivity Method (open access)

Calculation of the Surface Tension of Ordinary Organic and Ionic Liquids by Means of a Generally Applicable Computer Algorithm Based on the Group-Additivity Method

This article presents the calculation of the surface tension of ordinary organic and ionic liquids, based on a computer algorithm applying a refined group-additivity method.
Date: April 16, 2018
Creator: Naef, Rudolf
System: The UNT Digital Library
Cascade ICF power reactor (open access)

Cascade ICF power reactor

The double-cone-shaped Cascade reaction chamber rotates at 50 rpm to keep a blanket of ceramic granules in place against the wall as they slide from the poles to the exit slots at the equator. The 1 m-thick blanket consists of layers of carbon, beryllium oxide, and lithium aluminate granules about 1 mm in diameter. The x rays and debris are stopped in the carbon granules; the neutrons are multiplied and moderated in the BeO and breed tritium in the LiAlO/sub 2/. The chamber wall is made up of SiO tiles held in compression by a network of composite SiC/Al tendons. Cascade operates at a 5 Hz pulse rate with 300 MJ in each pulse. The temperature in the blanket reaches 1600 K on the inner surface and 1350 K at the outer edge. The granules are automatically thrown into three separate vacuum heat exchangers where they give up their energy to high pressure helium. The helium is used in a Brayton cycle to obtain a thermal-to-electric conversion efficiency of 55%. Studies have been done on neutron activation, debris recovery, vaporization and recondensation of blanket material, tritium control and recovery, fire safety, and cost. These studies indicate that Cascade appears to …
Date: May 20, 1986
Creator: Hogan, W.J. & Pitts, J.H.
System: The UNT Digital Library
Changing the PEP-II Center-of-Mass Energy Down to 10 GeV and up to 11 GeV (open access)

Changing the PEP-II Center-of-Mass Energy Down to 10 GeV and up to 11 GeV

PEP-II, the SLAC, LBNL, LLNL B-Factory was designed and optimized to run at the Upsilon 4S resonance (10.580 GeV with an 8.973 GeV e- beam and a 3.119 GeV e+ beam). The interaction region (IR) used permanent magnet dipoles to bring the beams into a head-on collision. The first focusing element for both beams was also a permanent magnet. The IR geometry, masking, beam orbits and beam pipe apertures were designed for 4S running. Even though PEP-II was optimized for the 4S, we successfully changed the center-of-mass energy (E{sub cm}) down to the Upsilon 2S resonance and completed an E{sub cm} scan from the 4S resonance up to 11.2 GeV. The luminosity throughout most of these changes remained near 1 x 10{sup 34} cm{sup -2}s{sup -1}. The E{sub cm} was changed by moving the energy of the high-energy beam (HEB). The beam energy differed by more than 20% which produced significantly different running conditions for the RF system. The energy loss per turn changed 2.5 times over this range. We describe how the beam energy was changed and discuss some of the consequences for the beam orbit in the interaction region. We also describe some of the RF issues that …
Date: May 20, 2009
Creator: Sullivan, M; Bertsche, K.; Novokhatski, A.; Seeman, J. & Wienands, U.
System: The UNT Digital Library