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1.2 MW klystron for Asymmetric Storage Ring B Factory
A cw klystron operating at 476 MHz has been developed jointly by SLAC and Varian Associates. The unique set of characteristics of this tube were strongly guided by requirements of the fast feedback necessary to prevent oscillations of the storage ring beams caused by the detuned accelerating cavity. This requires a combination of bandwidth and short group delay within the klystron. The RF feedback stabilization scheme also requires amplitude modulation making it necessary to operate the klystron about 10% below saturation. Performance specifications and initial operating results are presented.
Date:
March 1995
Creator:
Fowkes, W. R.; Caryotakis, G. & Doyle, E.
System:
The UNT Digital Library
1.3 GHz superconducting RF cavity program at Fermilab
At Fermilab, 9-cell 1.3 GHz superconducting RF (SRF) cavities are prepared, qualified, and assembled into cryomodules (CMs) for Project X, an International Linear Collider (ILC), or other future projects. The 1.3 GHz SRF cavity program includes targeted R&D on 1-cell 1.3 GHz cavities for cavity performance improvement. Production cavity qualification includes cavity inspection, surface processing, clean assembly, and one or more cryogenic low-power CW qualification tests which typically include performance diagnostics. Qualified cavities are welded into helium vessels and are cryogenically tested with pulsed high-power. Well performing cavities are assembled into cryomodules for pulsed high-power testing in a cryomodule test facility, and possible installation into a beamline. The overall goals of the 1.3 GHz SRF cavity program, supporting facilities, and accomplishments are described.
Date:
March 1, 2011
Creator:
Ginsburg, C. M.; Arkan, T.; Barbanotti, S.; Carter, H.; Champion, M.; Cooley, L. et al.
System:
The UNT Digital Library
1-D Van der Waals Foams Heated by Ion Beam Energy Deposition
One dimensional simulations of various initial average density aluminum foams (modeled as slabs of solid metal separated by low density regions) heated by volumetric energy deposition are conducted with a Lagrangian hydrodynamics code using a van der Waals equation of state (EOS). The resulting behavior is studied to facilitate the design of future warm dense matter (WDM) experiments at LBNL. In the simulations the energy deposition ranges from 10 to 30 kJ/g and from 0.075 to 4.0 ns total pulse length, resulting in temperatures from approximately 1 to 4 eV. We study peak pressures and temperatures in the foams, expansion velocity, and the phase evolution. Five relevant time scales in the problem are identified. Additionally, we present a method for characterizing the level of inhomogeneity in a foam target as it is heated and the time it takes for a foam to homogenize.
Date:
March 19, 2010
Creator:
Zylstra, A; Barnard, J J & More, R M
System:
The UNT Digital Library
O(1/M{sup 3}) effects for heavy-light mesons in lattice NRQCD
The masses of spin-singlet and spin-triplet S-wave mesons containing a single heavy quark are computed in the quenched approximation. The light quark action and gauge field action are both classically-improved and tadpole-improved, and the couplings to the heavy quark are organized by the 1/M expansion of tadpole-improved NRQCD. At each of two lattice spacings, near 0.22fm and 0.26fm, meson masses are obtained for heavy quarks spanning the region between charmed and bottom mesons. Results up to O(1/M), O(1/M{sup 2})and O(1/M{sup 3}) are displayed separately, so that the convergence of the heavy quark expansion can be discussed. Also, the effect of each term in the O(1/M{sup 3}) contribution is computed individually. For bottom mesons the 1/M-expansion appears to be satisfactory, but the situation for charmed mesons is less clear.
Date:
March 1998
Creator:
Lewis, Randy & Woloshyn, R. M.
System:
The UNT Digital Library
2-1/2-dimensional numerical solution for the electromagnetic scattering using a hybrid technique
The use of the electromagnetic method for geothermal reservoir exploration and delineation was studied. A number of techniques were developed to provide high quality field data. The remaining problem of interpreting these data in regions of complex geologic structure was overcome by the development of a numerical solution based on the hybrid technique, making use of both the finite element and the integral equation techniques. The major improvement is in the computing speed. (ACR)
Date:
March 1, 1983
Creator:
Lee, K. H. & Morrison, H. F.
System:
The UNT Digital Library
A 2.53 NEF 8-bit 10 kS/s 0.5 µm CMOS Neural Recording Read-Out Circuit with High Linearity for Neuromodulation Implants
This article presents a power-efficient complementary metal-oxide-semiconductor (CMOS) neural signal-recording read-out circuit for multichannel neuromodulation implants.
Date:
March 3, 2021
Creator:
Tasneem, Nishat Tarannum & Mahbub, Ifana
System:
The UNT Digital Library
A 3.3 MJ, Rb + 1 driver design based on an integrated systems analysis
A computer model for systems analysis of heavy ion drivers has been developed and used to evaluate driver designs for inertial fusion energy (IFE). The present work examines a driver for a close-coupled target design that requires less total beam energy but also smaller beam spots sizes than previous target designs. Design parameters and a cost estimate for a 160 beam, 3.3 MJ driver using rubidium ions (A = 85) are reported, and the sensitivity of the results to variations in selected design parameters is given.
Date:
March 7, 2000
Creator:
Meier, W. R.; Barnard, J. J. & Bangerter, R. O.
System:
The UNT Digital Library
3-d finite element model development for biomechanics: a software demonstration
Finite element analysis is becoming an increasingly important part of biomechanics and orthopedic research, as computational resources become more powerful, and data handling algorithms become more sophisticated. Until recently, tools with sufficient power did not exist or were not accessible to adequately model complicated, three-dimensional, nonlinear biomechanical systems. In the past, finite element analyses in biomechanics have often been limited to two-dimensional approaches, linear analyses, or simulations of single tissue types. Today, we have the resources to model fully three-dimensional, nonlinear, multi-tissue, and even multi-joint systems. The authors will present the process of developing these kinds of finite element models, using human hand and knee examples, and will demonstrate their software tools.
Date:
March 1, 1997
Creator:
Hollerbach, K.; Hollister, A.M. & Ashby, E.
System:
The UNT Digital Library
A 3-D SAR approach to IFSAR processing
Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super-resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.
Date:
March 1, 2000
Creator:
Doerry, Armin W. & Bickel, Doug L.
System:
The UNT Digital Library
3-dimensional beam scanning system for particle radiation therapy
In radiation therapy treatment volumes up to several liters have to be irradiated. Today's charged particle programs use ridge filters, scattering foils, occluding rings collimators and boluses to shape the dose distribution. An alternative approach, scanning of a small diameter beam, is analyzed and tentative systems specifications are derived. Critical components are scheduled for fabrication and testing at LBL.
Date:
March 1977
Creator:
Leemann, C.; Alonso, J.; Grunder, H.; Hoyer, E.; Kalnins, G.; Rondeau, D. et al.
System:
The UNT Digital Library
4-D conformal field theories and strings on orbifolds
None
Date:
March 16, 1998
Creator:
Kachru, Shamit & Silverstein, Eva
System:
The UNT Digital Library
4. pi. physics. [/sup 40/Ar + KCl, 0. 4 to 1. 8 GeV/A]
Exclusive ..pi../sup -/ and charged-particle production in collisions of /sup 40/Ar on KCl are studied at incident energies from 0.4 to 1.8 GeV/A. The correlation between the ..pi../sup -/ and the total charged particle multiplicity confines the reaction along a narrow ridge with no exotic islands of pion production. For high multiplicities the system reaches the total disintegration of target and projectile into singly charged fragments and pions. Every 200 MeV/A datum was taken with a central and inelastic trigger. For central collisions the mean ..pi../sup -/ multiplicity increases linearly with the bombarding energy with no marked discontinuities due to the ..delta..(3,3) resonance. At 1.8 GeV/A evidence for nonthermal ..pi../sup -/ production in central collisions is found. The total c.m. energy in ..pi../sup -/ shows linear dependence on the ..pi../sup -/ multiplicity with a slope of epsilon = 300 MeV/..pi../sup -/. Strange particle production in the central collision of 1.8 GeV/A Ar on KCl is seen. 8 figures.
Date:
March 1, 1980
Creator:
Sandoval, A.
System:
The UNT Digital Library
9. 1-T iron-free Nb-Ti dipole magnet with pancake windings
An eight-pancake Nb-Ti dipole magnet, with bent up ends, called D-108B has been built and tested. This magnet is a Nb-Ti version of a Nb/sub 3/Sn magnet designed to produce a 10-tesla dipole field in a 40 mm diameter aperture. The pancack design is used for the heavy 12,000 ampere Nb/sub 3/Sn cable because of the mechanical difficulty in winding such a heavy cable into the conventional nested cylindrical shell configuration with a 2'' inner winding diameter. The Nb-Ti version operates at 1.8K, in He II, has superconducting cable half as thick as the Nb/sub 3/Sn cable, and operates at half the operating current: 6000 A rather than 12,000 A at 10 tesla. Both magnets are approximately one meter long. D-10B was tested from January 26 to February 2, 1983 and reached short-sample performance in both He I and He II after moderate training. The central field at 4.3K is 7.0 (+- 0.1) tesla, and at 1.8K is 9.1 (+- 0.2) tesla. Ramp rate sensitivity and cyclic heating data were also measured.
Date:
March 1, 1983
Creator:
Gilbert, W.; Caspi, S.; Hassenzahl, W.; Meuser, R.; Peters, C.; Rechen, J. et al.
System:
The UNT Digital Library
The 50 GeV program at SLAC
SLAC has undertaken a modes programs to upgrade the beam energy for fixed target experiments to 50 GeV. This upgrade is possible due to the previous extensive development work on the linac accelerating gradient for the SLC, which has been operational for over five years. The SLC can deliver a beam of energy up to 60 GeV using a pulse compression technique in the rf system which trades pulse length for a higher pulse amplitude. This mode of operation has been reliable and routine for the SLC. However the beam line transport which takes electrons or positrons from the end of the linac to the target in End Station A has not been upgraded from the original design energy of 25 GeV. The 50 GeV upgrade for the fixed target experiments consists in modifying and increasing the number of beam line dipole magnets to reach 50 GeV, plus modernization of the beam line instrumentation and controls. The plans for spin structure experiments using electron beams at energies up to 50 GeV are described.
Date:
March 1, 1994
Creator:
Prescott, C. Y.
System:
The UNT Digital Library
50 MW X-BAND RF SYSTEM FOR A PHOTOINJECTOR TEST STATION AT LLNL
In support of X-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. Timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.
Date:
March 11, 2011
Creator:
Marsh, R A; Anderson, S G; Barty, C J; Beer, G K; Cross, R R; Ebbers, C A et al.
System:
The UNT Digital Library
53 Per, slow, and Be star pulsations. Lecture 8
Spectral variations of the class of variable stars that seems to have no radial pulsations at all are discussed. Models of the rotation of these stars are considered. (GHT)
Date:
March 14, 1983
Creator:
Cox, A. N.
System:
The UNT Digital Library
100-Picometer Interferometry for EUVL
Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.
Date:
March 18, 2002
Creator:
Sommargren, G. E.; Phillion, D. W.; Johnson, M. A.; Nguyen, N. O.; Barty, A.; Snell, F. J. et al.
System:
The UNT Digital Library
>100 watt average power at 0.53 {mu}m with 25 ns, 2.5 kHz repetition rate pulses from a single power oscillator
We have generated approximately 100 watts of frequency doubled light from the output of an electro-optically Q-switched, diode-pumped Nd:YAG slab laser oscillator operating at an average power of 200 watts (2.5 kHz repetition rate, 80 mJ/pulse, 25 ns pulsewidth). The Q-switch was a compensated z-axis propagation LiNbO{sub 3} electro-optic modulator, and the frequency conversion crystal was a thin slab of KTP. In addition, Q-switched operation at an average power of approximately 250 watts with 26 ns pulsewidths has been demonstrated.
Date:
March 1, 1994
Creator:
Velsko, S. P.; Comaskey, B.; Albrecht, G. F. & Beach, R. J.
System:
The UNT Digital Library
120-GeV proton transport for antiproton production in the Fermilab Tevatron I project
Short bunches of 120 GeV protons will be used for the production of 8 GeV antiprotons. Protons will be extracted vertically from the Main Ring using two high field Lambertson type magnets at location F17. The beam transport is made of three sections: horozintol dispersion cancellation, vertical dispersion cancellation and final focusing. The final focusing section is composed of two quadrupole doublets and allows for variation in ..beta..* values at the target from 1.5 m to 20.0 m.
Date:
March 1, 1983
Creator:
Colton, E.; Hojvat, C. & Oleksiuk, L.
System:
The UNT Digital Library
184-Inch Synchrocyclotron decommissioning
None
Date:
March 1, 1989
Creator:
Reimers, D.; Haley, J. & Hampton, G.
System:
The UNT Digital Library
400 MeV upgrade for the Fermilab linac
Fermilab has plans for a comprehensive accelerator upgrade to open new possibilities for both the fixed target and collider experimental programs. An early step in this program is to increase the energy of the linac from 200 to 400 MeV by replacing the last four of its nine 201 MHz Alvarez tanks with twenty-eight 805 MHz side-coupled cavity chains operating at about 8 MV/m average axial field. The principal purpose is to reduce the incoherent spacecharge tuneshift at injection into the Booster which currently limits both the brightness of the beam, an important determinant of collider luminosity, and total intensity to produce both the antiprotons for the collider and the beams to fixed target experimental areas. Other consequences of higher Booster injection energy expected to contribute to some degree of higher intensity limits and improved operational characteristics include improved quality of the guide field at injection, reduced frequency swing for the rf systems, and smaller emittance for the injected beam. The linac upgrade project has moved from a 1986 study through a development project including structure models and numerical studies to a full-feature module prototyping starting this year.
Date:
March 24, 1989
Creator:
MacLachlan, J.A.
System:
The UNT Digital Library
810 Future plans
It is believed that a good bet for finding the Quark-Gluon Plasma at AGS energies is with the heaviest projectiles on the heaviest target, i.e. Au on Au. One of the likely signatures of the plasma is strangeness enhancement. Al Saulys has shown what it's like to find {Delta} and K{degree} with Si projectiles. Our Monte Carlo simulations show track densities 4 times higher for Au projectiles. In addition, the Au beam itself produces 30 times more ionization. Thus the present TPC's will be limited to only a few hundred ions per sec. This paper discusses plans for these experiments and modification to TPC. 9 figs.
Date:
March 27, 1990
Creator:
Etkin, A.; Foley, K. J.; Hackenburg, R. W.; Longacre, R. S.; Love, W. A.; Morris, T. W. et al.
System:
The UNT Digital Library
1300-nm gain obtained with dysprosium-doped chloride crystals
Dy{sup 3+} - doped chloride crystals have high 1300-nm emission quantum yields. Pump - probe experiments on La Cl{sub 3}:Dy{sup 3+} demonstrate optical gain consistent with predictions based on spectroscopic cross sections and lifetimes.
Date:
March 1, 1996
Creator:
Page, R. H.; Schaffers, K. I.; Beach, R. J.; Payne, S. A. & Krupke, W. F.
System:
The UNT Digital Library