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SOME MONTE CARLO CALCULATIONS FOR CYLINDRICAL AND CRUCIFORM CONTROL RODS

Description: A limited investigation of neutron absorption was conducted to examine the relative effectiveness of crucfform and cylindrical control rods. If such data could be firmly established, reactors using cruciform rods could be readily analyzed by transforming the rods to their cylindrical equivalent then applying traditional theories. Conversely, the number of rods required in a reactor and their lceation could be determined for cylindrical rods then transformed to equivalent cruciform rods. In the present context, only the cruciform rods are of engineering interest; the eylindrical rods are namely an analytical device. The Monte Carlo method was selected for this study to minimize the number of approximations required. The asane with which it can handle complex geometries makes this method particularly attractive for the control rod problems, but it often becomes very expensive to follow a sufficient number of neutrons to achieve satisfactory statistics. The project was, in part, an experiment to determine if this tyce of problem could be solved with reasomable accuracy at a reasonable cost with Monte Carlo. (auth)
Date: June 30, 1958
Creator: McCampbell, J.M. & Chow, K.T.
Partner: UNT Libraries Government Documents Department

Automating Pro/Engineer Using Trail Files and External Programs

Description: Keyboard macros provide shortcuts to many repetitive command sequences in Pro/Engineer. They map any number of frequently used command sequences to user-selected keyboard keys. They may be nested within each other and may also include user keyboard entry within the macro. Another powerful feature of Pro/Engineer is adding menu options. Menu options may be added to any Pro/Engineer menu and is an effective way to graphically display keyboard macros to make them more accessible. Command sequences are mapped to a single user-defined menu option added to the bottom of any Pro/Engineer window. The '{at}setbutton' command added to the 'menu{_}def.pro' file specifies the commands to associate with added menu options. Menu options may also be used to execute non-Pro/Engineer commands. The associated command is linked to a menu option within Pro/Engineer's Utilities menu (in the Misc menu) and is issued whenever the menu option is selected. Such a feature is useful for adding menu options to start the Pro/Engineer User Guide utility, start a text editor from within Pro/Engineer, or perform system level actions. The '{at}setbutton{_}exec' command is used in the 'menu{_}def.pro' file for non-Pro/Engineer commands. A more detailed description of adding menu options can be found in the Pro/Engineer Fundamentals Guide. Another useful component of Pro/Engineer is the trail file functionality. Trail files are automatically created every time a new working Pro/Engineer session begins. Although they are typically used to reconstruct a previous working session, they can also be used to automate a series of commands. By specifying all the commands in a trail file, a user can issue the commands quickly and repetitively using the command sequence 'Misc-Trail' and specifying the trail file name. All actions, including keyboard entries and mouse click locations, may be included in a trail file. Although adding menu options and using trial files provide ...
Date: May 21, 1996
Creator: Chow, K.
Partner: UNT Libraries Government Documents Department

PLUTONIUM RECYCLE IN THE CALDER HALL TYPE REACTOR

Description: The economiics and physics of four schemes of pIutonium recycle in the Calder Hall type reactor are considered. The four possible schemes are: (I) to blend the Pu produced In a run with fresh naturaI U for a subsequeut run; (2) to alloy the Pu with somie diIuent metal and fabricate the alloy Into high heat- transfer elements morc like MIR or PWR-sced type elements and"spike' a subsequent load of fresh natural U elemients with these Pu elemicnts; (3) to recycle half the spent U as well as the Pu; and (4) to thke advantage of the extra reactivity gained fromi the recyeIed Pu to deerease the Iattice spacIng, thereby increasing the conversion ratio with the hope of increasirg the attaInabIe exposure. It was concluded that schcme (1) is the miost economiical. (W.D.M.)
Date: January 1, 1958
Creator: Barbieri, L.J.; Webster, J.W. & Chow, K.T.
Partner: UNT Libraries Government Documents Department

Measurements of Modulus of Elasticity and Thermal Contraction of Epoxy Impregnated Niobium-Tin and Niobium-Titanium Composites

Description: In the high field magnet program at Lawrence Berkeley National Laboratory, accelerator magnet prototypes are designed with epoxy impregnated niobium-tin and niobium-titanium superconductor. Accurate mechanical property values are essential for magnet mechanical design and prediction of conductor performance. Two key mean property values are measured on coil samples: modulus of elasticity (Young's modulus) and mean thermal contraction. Measurements are made in compression and are conducted in three orthogonal directions. Modulus of elasticity measurements are currently conducted at room temperature and the mean thermal contraction is measured from room temperature to liquid nitrogen temperature. Room temperature values are compared with values estimated using the individual coil components.
Date: September 1, 1998
Creator: Chow, K.P. & Millos, G.A.
Partner: UNT Libraries Government Documents Department

Fully confined photonic band gap and guided modes in a two-dimensional photonic crystal slab

Description: A new two-dimensional photonic crystal (2D PC) slab structure was created with a full three-dimensional light confinement. Guided modes with broad bandwidth and high transmission within the band gap are also observed. As an optical analog to electronic crystals, PC promises a revolution in the photonic world similar to the electronic revolution created by the electronic band gap engineering in semiconductor. 2D PC has an advantage of being easier to fabricate at optical wavelength ({lambda}) comparing with 3D PC. However, the light leakage in the vertical direction has been the main problem for using 2D PC in opto-electronic application. In this study, the authors solve this problem by combining traditional 2D PC with strong vertical index guiding between the waveguide layer (GaAs) and the cladding layer (Al{sub x}O{sub y}). A set of triangular lattice holes 2D PC's were fabricated with lattice constant a=460nm, hole diameter (d=0.6a) and waveguide layer thickness (t = 0.5a). Those parameters were chosen to maximize the TE photonic band gap (PBG) around {lambda} = 1.55{micro}m. The depth of etched holes is {approximately}0.6{micro}m and the 2{micro}m thick Al{sub x}O{sub y} cladding layer is obtained by thermal oxidation of Al{sub 0.9}Ga{sub 0.1}As. PC waveguides were also created by introducing line defects along {Gamma}K direction. The authors perform transmission measurement by coupling light to PC with 3{micro}m wide waveguides which extends {approximately}0.6mm on both sides of PC. An aspheric lens with NA = 0.4 is used to focus the collimated light from tunable diode laser into the input waveguide. Another identical lens is used to collect the transmitted light and focus to an infrared (IR) camera and a calibrated photo-detector with a beamsplitter. The Gaussian waveguide mode indicates that the signal detected by the photodetector comes only from the light interacting with PC and propagating along the waveguide. The ...
Date: December 15, 1999
Creator: Chow, K.C.; Lin, S.Y.; Johnson, S.G.; Villeneuve, P.R. & Joannopoulos, J.D.
Partner: UNT Libraries Government Documents Department

A High Field Magnet Design for A Future Hadron Collider

Description: US high energy physics community is exploring the possibilities of building a Very Large Hadron Collider (VLHC) after the completion of LHC. This paper presents a high field magnet design option based on Nb{sub 3}Sn technology. A preliminary magnetic and mechanical design of a 14-16 T, 2-in-1 dipole based on the 'common coil design' approach is presented. The computer code ROXIE has been upgraded to perform the field quality optimization of magnets based on the racetrack coil geometry. A magnet R&D program to investigate the issues related to high field magnet designs is also outlined.
Date: September 1, 1998
Creator: Gupta, R.; Chow, K.; Dietderich, D.; Gourlay, S.; Millos, G.; McInturff, A. et al.
Partner: UNT Libraries Government Documents Department

Mechanical design of a high field common coil magnet

Description: A common coil design for high field 2-in-1 accelerator magnets has been previously presented as a 'conductor-friendly' option for high field magnets applicable for a Very Large Hadron Collider. This paper presents the mechanical design for a 14 tesla 2-in-1 dipole based on the common coil design approach. The magnet will use a high current density Nb{sub 3}Sn conductor. The design addresses mechanical issues particular to the common coil geometry: horizontal support against coil edges, vertical preload on coil faces, end loading and support, and coil stresses and strains. The magnet is the second in a series of racetrack coil magnets that will provide experimental verification of the common coil design approach.
Date: March 18, 1999
Creator: Caspi, S.; Chow, K.; Dietderich, D.; Gourlay, S.; Gupta, R.; McInturff, A. et al.
Partner: UNT Libraries Government Documents Department

Spreader Design for FERMI@Elettra Free Electron Laser

Description: In this note we describe a conceptual design of a part ofthe electron beam delivery system for FERMI@Elettra free electron laser(FEL) located between the end of the linac and the entrance to the FEL.This part includes the emittance diagnostic section, the electron beamswitchyard for two FELs called spreader and matching sections. The designmeets various constrains imposed by the existing and planned buildingboundaries, desire for utilization of existing equipment and demands forvarious diagnostic instruments.
Date: January 18, 2007
Creator: Zholents, A.; Bacescu, D.; Chow, K.; Diviacco, B.; Ferianis, M.; Di Mitri, S. et al.
Partner: UNT Libraries Government Documents Department

EVALUATION OF AN ADVANCED ENGINEERING TEST REACTOR DESIGN

Description: The scope of the study was primarily concerned with optimization of the geometrical and core-composition variables to achieve maximum flux in the loop region per unit core power without exceeding heat transfer and other engineering limitations. Centain other design questions are to be investigated. (A.C.)
Date: July 15, 1958
Creator: McVey, M.; Bradfute, J.O.; Buck, K.E.; Chow, K.T.; Jaffee, R.J.; Quilici, R.f Richardson, I. et al.
Partner: UNT Libraries Government Documents Department

Operational Characteristics, parameters, and history of a 13T Nb3Sn dipole

Description: The early design and test results have been previously reported. During the subsequent operation of 'D20' the accelerator prototype dipole has provided both additional and more detailed data as to its characteristics and performance. D20's use as a test facility for high field critical current measurements has provided operational experience and history pertammg to accelerator required characteristics. There has been recently obtained data related to field quality, operational reproducibility and reliability, which will be presented. This prototype 'D20' has attained the highest magnetic field of any accelerator prototype dipole constructed and tested to date. The magnet has continued to operate routinely.
Date: March 18, 1999
Creator: Benjegerdes, R.; Bish, P.; Caspi, S.; Chow, K.; Dietderich, D.; Hannaford, R. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and Test Results of a Nb3Sn Superconducting Racetrack Dipole Magnet

Description: A 'proof-of-principle' Nb{sub 3}Sn superconducting dual-bore dipole magnet was built from racetrack coils, as a first step in a program to develop an economical, 15 Tesla, accelerator-quality magnet. The mechanical design and magnet fabrication procedures are discussed. No training was required to achieve temperature-dependent plateau currents, despite several thermal cycles that involved partial magnet disassembly and substantial pre-load variations. Subsequent magnets are expected to approach 15 Tesla with substantially improved conductor.
Date: February 6, 2000
Creator: Chow, K.; Dietderich, D.R.; Gourlay, S.A.; Gupta, R.; Harnden, W.; Lietzke, A. F. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and Test Results of a Nb3Sn Superconducting Racetrack Dipole Magnet

Description: A 'proof-of-principle' Nb{sub 3}Sn superconducting dual-bore dipole magnet was built from racetrack coils, as a first step in a program to develop an economical, 15 Tesla, accelerator-quality magnet. The mechanical design and magnet fabrication procedures are discussed. No training was required to achieve temperature-dependent plateau currents, despite several thermal cycles that involved partial magnet disassembly and substantial pre-load variations. Subsequent magnets are expected to approach 15 Tesla with substantially improved conductor.
Date: March 22, 1999
Creator: Chow, K.; Dietderich, D.R.; Gourlay, S.A.; Gupta, R.; Harnden, W.; Lietzke, A.F. et al.
Partner: UNT Libraries Government Documents Department

Fabrication and Test Results of a Prototype, Nb3Sn Superconducting Racetrack Dipole Magnet

Description: A prototype, Nb{sub 3}Sn superconducting magnet, utilizing a racetrack coil design has been built and tested. This magnet represents the first step in a recently implemented program to develop a high field, accelerator quality magnet. This magnet was constructed with coils wound from conductor developed for the ITER project, limiting the magnet to a field of 6-7 Tesla. Subsequent magnets in the program will utilize improved conductor, culminating in a magnet design capable of producing fields approaching 15 Tesla. The simple geometry is more suitable for the use of brittle superconductors necessary to eventually reach high field levels. In addition, fewer and simpler parts are used in fabricating these coils compared with the more conventional cosine theta cross section coils. The general fabrication steps, mechanical design and quench performance are discussed.
Date: September 1, 1998
Creator: Gourlay, S. A.; Chow, K.; Dietderich, D.R.; Gupta, R.; Hannaford, R.; Harnden, W. et al.
Partner: UNT Libraries Government Documents Department

Design and Fabrication of Racetrack Coil Accelerator Magnets

Description: Most accelerator magnets for applications in the field range up to 9 T utilize NbTi superconductor and a cosine theta coil design. For fields above 9 T, it is necessary to use Nb{sub 3}Sn or other strain sensitive materials, and other coil geometries that are more compatible with these materials must be considered. This paper describes their recent efforts to design a series of racetrack coil magnets that will provide experimental verification of this alternative magnet design for a dual aperture dipole magnet with the goal of reaching a field level of 15 T, will be described. The experimental program, which consists of a series of steps leading to a high field accelerator quality magnet, will be presented. Fabrication of a racetrack dipole magnet utilizing Nb{sub 3}Sn superconductor and a wind and react approach will be presented.
Date: November 11, 1998
Creator: Chow, K.; Dietderich, D.R.; Gourlay, S.A.; Gupta, R.; Harnden, W.; Lietzke, A. et al.
Partner: UNT Libraries Government Documents Department

A superconducting quadrupole magnet array for a heavy ion fusion driver

Description: A multi-channel quadrupole array has been proposed to increase beam intensity and reduce space charge effects in a Heavy Ion Fusion Driver. A single array unit composed of several quadrupole magnets, each with its own beam line, will be placed within a ferromagnetic accelerating core whose cost is directly affected by the array size. A large number of focusing arrays will be needed along the accelerating path. The use of a superconducting quadrupole magnet array will increase the field and reduce overall cost. We report here on the design of a compact 3 x 3 superconducting quadrupole magnet array. The overall array diameter and length including the cryostat is 900 x 700 mm. Each of the 9 quadrupole magnets has a 78 mm warm bore and an operating gradient of 50 T/m over an effective magnetic length of 320 mm.
Date: June 27, 2000
Creator: Caspi, S.; Bangerter, r.; Chow, K.; Faltens, A.; Gourley, S.; Hinkins, R. et al.
Partner: UNT Libraries Government Documents Department

Rad-hard Luminosity Monitoring for the LHC

Description: Luminosity measurements at the high luminosity points of the LHC are very challenging due to the extremely high radiation levels in the order of 180 MGy/yr. They have designed an ionization chamber that uses a flowing inorganic gas mixture and a combination of metals and ceramics. With such a choice, an additional challenge is achieving the necessary speed to be able to resolve bunch-by-bunch luminosity data. They present the design, analysis and experimental results of the early demonstration tests of this device.
Date: June 24, 2007
Creator: Beche, J.F.; Byrd, J.M.; Chow, K.; Denes, P.; Ghiorso, W.; Matis,H.S. et al.
Partner: UNT Libraries Government Documents Department

Test Results for a High Field (13T) Nb3Sn Dipole

Description: A Nb{sub 3}Sn dipole magnet (D20) has been designed, constructed, and tested at LBNL. Previously, they had reported test results from a hybrid design dipole which contained a similar inner Nb{sub 3}Sn and outer NbTi winding. This paper presents the final assembly characteristics and parameters which will be compared with those of the original magnet design. The actual winding size was determined and a secondary calibration of the assembly pre-load was done by pressure sensitive film. The actual azimuthal and radial D20 pre-loading was accomplished by a very controllable novel stretched wire technique. D20 reached 12.8T(4.4K) and 13.5T(1.8K) the highest dipole magnetic fields obtained to date in the world.
Date: December 1, 1996
Creator: McInturff, A.D.; Benjegerdes, R.; Bish, P.; Caspi, S.; Chow, K.; Ell'Orco, D. et al.
Partner: UNT Libraries Government Documents Department

Design and Fabrication of a 14 T, Nb3Sn Superconducting Racetrack Dipole Magnet

Description: Most accelerator magnets for applications in the field range up to 10 T utilize NbTi superconductor and a cosine theta coil design. For fields above 10 T, it is necessary to use Nb{sub 3}Sn or other strain sensitive superconductors land other coil geometries that are more compatible with these materials. This paper describes our recent efforts to design a series of racetrack coil magnets that will provide experimental verification of an alternative magnet design philosophy, with the near-term goal of reaching a field level of approximately 14 T. The conductor and fabrication issues relevant to building high field, racetrack dipoles utilizing Nb{sub 3}Sn superconductor and a wind and react approach will also be discussed.
Date: September 1, 1999
Creator: Gourlay, S.A.; Bish, P.; Caspi, S.; Chow, K.; Dietderich, D.R.; Gupta, R. et al.
Partner: UNT Libraries Government Documents Department

The XMM-SERVS survey: new XMM–Newton point-source catalogue for the XMM-LSS field

Description: This article presents an X-ray point-source catalogue from the XMM-Large Scale Structure (XMMLSS) survey region, one of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields.
Date: April 25, 2018
Creator: Chen, C. -T. J.; Brandt, William Nielsen; Luo, Bin; Ranalli, P.; Yang, G.; Alexander, David M. et al.
Partner: UNT College of Arts and Sciences