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Determining the optical quality of focusing collectors without laser ray tracing

Description: This paper describes a novel alternative to the laser ray trace technique for evaluating the optical quality of focusing solar collectors. The new method does not require any equipment beyond what is used for measuring collector efficiency; it could therefore become part of routine collector testing. The total optical errors resulting from imperfect specularity and from inaccuracies in reflector position or slope are characterized by an angular standard deviation sigma/sub optical/, the rms deviation of the reflected rays from the design direction. The method is based on the fact that the off-axis performance of a concentrator depends on sigma/sub optical/. An angular scan is performed, i.e., the collector output is measured as a function of misalignment angle over the entire range of angles for which there is measurable output (typically a few degrees). This test should be carried out on a very clear day, with receiver close to ambient temperature (if the latter conditions cannot be satisfied, appropriate corrections are necessary). The parameter sigma/sub optical/ is then determined by a least-squares fit between the measured and the calculated angular scan. We tested the method on a parabolic trough collector manufactured by Hexcel, but it is suitable for parabolic dishes as well. The method appears to be accurate enough to determine sigma/sub optical/ within about 10%.
Date: February 1, 1980
Creator: Bendt, P.; Gaul, H. & Rabl, A.
Partner: UNT Libraries Government Documents Department

Lowering the beam in the SLC arcs

Description: It has been decided, at least tentatively, to mount the arc magnets on pedestals, the motivation being to provide the most rigid support possible. In the same spirit the pedestals should be as short as possible. It has been proposed to shorten the pedestals by about 10 inches by either raising the floor of the tunnels or lowering the beams. A relatively simple means for lowering the beams is considered here.
Date: December 16, 1983
Creator: Murray, J.J. & Servranckx, R.V.
Partner: UNT Libraries Government Documents Department

LAMPF transition-region mechanical fabrication

Description: The new Transition Region (TR-II) optimizes phase matching of H/sup +/ and H/sup -/ beams during simultaneous transport between the drift-tube linac and side-coupled linac at LAMPF. Improvements include, larger aperture, a straight beam track, greater beam path length adjustments, and better utility routing. Hardware density required innovative designs for magnets, mounting, vacuum, and utilities. Dipoles are powered by one constant current and one variable current supply which cause the fields to add or buck providing +-20 mm path length variation for phase matching. Alignment was done using two digital theodolites coupled to a computer to give real-time three-dimensional data. Production beams up to 950 ..mu..A at 100 MeV have been routinely transported since September 1983.
Date: January 1, 1985
Creator: Bush, E.D. Jr.; Gallegos, J.D.F.; Harrison, R.; Hart, V.E.; Hunter, W.T.; Rislove, S.E. et al.
Partner: UNT Libraries Government Documents Department

Beam-based alignment and tuning procedures for e sup + e sup minus collider final focus systems

Description: For future linear colliders, with very small emittances and beam sizes and demanding tolerances on final focus system alignment and magnet errors, it becomes increasingly important to use the beam as a diagnostic tool. We report here procedures we have identified and will be implemented in the Final Focus Test Beam at SLAC incorporating (1) quadrupole strength changes, (2) central orbit modifications, (3) spot size measurements, and (4) beam stability monitoring. 3 refs., 4 figs., 3 tabs.
Date: May 1, 1991
Creator: Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Odian, A.; Roy, G. et al.
Partner: UNT Libraries Government Documents Department

Misalignment study of NLC bunch compressor

Description: Results of computer simulations of the misalignments in the 180{degree}-bend angle second-stage bunch compressor for the NLC are described. The aim of this study was to evaluate alignment and production error tolerances. Three versions of the second stage, differing in their minimum obtainable bunch length (44 {mu}, 60 {mu}, and 86 {mu}) were studied. Simulations included orbit correction produced by errors and misalignments of the compressor elements. The orbit correction itself was done within some error margins. The effects of misalignments on transverse emittance growth were found. Recommendations for alleviating alignment tolerances are discussed. 5 refs., 6 figs., 1 tab.
Date: May 1, 1991
Creator: Rogers, R.P. & Kheifets, S.A.
Partner: UNT Libraries Government Documents Department

Linear colliders

Description: This report discusses the following topics: SLC performance and fundamental limits; obtaining the energy in an NLC; obtaining the luminosity in an NLC; and example designs and future potential.
Date: July 1, 1991
Creator: Ruth, R.D. (ed.)
Partner: UNT Libraries Government Documents Department

A technique for aligning sextupole systems using beam optics

Description: A technique for beam based alignment of sextupole system is developed exploiting the enhancement effect of orbit differences by the sextupoles. This technique can in principle be applied to sextupole or sextupole strings with controlled orbit pattern and BPM configurations. This paper will discuss the theoretical basis, special optimization considerations and expected accuracy. Application to the SLC final focus is also discussed.
Date: March 1, 1992
Creator: Chao, Yu-Chiu.
Partner: UNT Libraries Government Documents Department

Calculations of emittance and damping time effects in the SLC damping rings

Description: In a recent NDR machine experiment the transverse emittance was studied as a function of store time and tune. To explain the observed transverse emittance damping time constants, the magnetic measurement data of the longitudinal field of the bending magnets had to be taken into account. The variation of the transverse emittances with tune due to misalignments and the associated anomalous dispersion is studied as well as the effect of synchrobetatron coupling due to dispersion in the RF cavities.
Date: March 1, 1992
Creator: Limberg, T.; Moshammer, H.; Raubenheimer, T.; Spencer, J. & Siemann, R.
Partner: UNT Libraries Government Documents Department

The D[O] upgrade silicon tracker

Description: A large silicon strip tracking detector is planned for the upgrade of the D0 experiment at Fermilab. This detector is designed to gag secondary vertices, to measure the momenta of charged particles and to operate in the high rate environment of the upgraded Tevatron. Details of the detector design are presented here.
Date: November 1, 1992
Creator: Heinson, A.P.
Partner: UNT Libraries Government Documents Department

Consequences of expansion joint bellows rupture

Description: Expansion joints are used in piping systems to accommodate pipe deflections during service and to facilitate fitup. Typically, the expansion joint bellows is the thinnest part of the pressure boundary, bellows rupture frequencies are typically several orders of magnitude higher than pipe rupture frequencies. This paper reviews an effort to estimate the flow rates associated with bellows rupture. The Level I PRA (probabilistic risk assessment) for the Savannah River Site production reactors made the bounding assumption that bellows rupture would produce the maximum possible leakage - that of a double-ended guillotine break (DEGB). This assumption resulted in predictions of flooding of the reactor building with a high conditional probability that a Loss of Pumping Accident and core melting would follow. This paper describes analyses that were performed to develop a realistic break area and leak rate resulting from bellows rupture and therefore reduce the impact that bellows rupture can have on the estimated total core melt frequency. In the event of a 360 degree circumferential break of the bellows the resulting two sections will separate to the point where the force from the internal pressure acting to push the bellows open is just balanced by the spring force of the bellows itself. For the bellows addressed in this analysis, the equilibrium separation distance is 0.7 inches with normal pump lineup. The opening area is influenced by any initial compression or extension due to installation alignment, and by any operational displacements such as thermal expansion of the adjoining pipe. The influence of such factors is considered and the impact on the flooding rate and, hence, core melt frequency is reviewed.
Date: January 1, 1992
Creator: Daugherty, W.L.; Miller, R.F. & Cramer, D.S.
Partner: UNT Libraries Government Documents Department

Development of distributed ion pumps for g-2 beam vacuum system

Description: Distributed ion pumps (DIPs) will be used for the beam vacuum system of the g-2 muon storage ring. The magnetic field intensity and alignment angle at the DIP locations are not uniform. The pumping behavior of several different ion pump elements under this non-uniform magnetic field has been studied. The results are compared with the theoretical predictions. Based on these results, the optimum design of the g-2 DIPs has been developed.
Date: January 1, 1993
Creator: Hseuh, H.C.; Mapes, M. & Snydstrup, L.
Partner: UNT Libraries Government Documents Department

Incorporation of the KERN ECDS-PC software into a project oriented software environment

Description: The Stanford Linear Accelerator Center (SLAC) is in the process of building a new particle collider, the Stanford Linear Collider (SLC). The tunnel which houses the SLC is about 3 km long and contains approximately 1000 magnets. Besides a very precise absolute positioning of these magnets, the alignment of adjacent magnet ends is of particular importance to the success of the whole project. Because of this and the limited time frame, a survey method which was not only reliable and self-checking but also fast had to be developed. Therefore, the concept of MAS (Magnet Alignment System) was developed. This system utilizes the on-line data collection and the rigorous least-squares bundle adjustment of the KERN ECDS-PC system to fulfill these requirements. The ECDS software is embedded in a project tailored software system with modules which take care of: fixture and magnet calibration corrections, the calculation of ideal coordinates and their comparison to measured coordinates, the translation of detected misalignments into the coordinate system of the mechanical adjustments and the control of the adjustments with on-line electronic dial-gauges. This paper gives a brief introduction to the SLC project and some of the survey problems which are unique to this machine. The basic ideas of the KERN ECDS-PC system are explained and a discussion of the practical aspects, such as targeting and set-ups, are given. MAS and its modules are explained in detail.
Date: November 1, 1986
Creator: Oren, W.; Pushor, R. & Ruland, R.
Partner: UNT Libraries Government Documents Department

SSC collider dipole magnets field angle data

Description: In the fabrication of both 40 and 50 mm collider dipole superconducting magnets, surveys of the direction of the magnetic field along their length have been taken. This data besides being used for certifying compliance with the specifications for the finished magnet, yields interesting information on the straightness and rigidity of the coil placement between some stages in their manufacture and testing. A discussion on the measuring equipment and procedures is given. All of the 40 mm magnets that were built or cryostat at Fermilab have at least one of these surveys, and a summary of the data on them is presented. Most of the 50 mm magnets built and cold tested at Fermilab have been surveyed before and after insertion in the cryostat and before and after being cold tested. A summary of this data is also presented.
Date: September 1, 1992
Creator: Kuchnir, M.; Bleadon, M.; Schmidt, E.; Bossert, R.; Carson, J.; Delchamps, S.W. et al.
Partner: UNT Libraries Government Documents Department

Omnium-G parabolic dish optical efficiency: a comparison of two independent measurement techniques

Description: Measurements made at SERI of the optical efficiency of the Omnium-G parabolic dish concentrator are described. Two independent techniques were used: the cold-water calorimeter method and the heat of fusion method. Results from both techniques agree quite well and indicate that the optical efficiency for a 10-cm receiver aperture is 25%. Optical efficiency measured in early 1979 was 37%, and in mid 1979 it had degraded to 21%. An optical alignment procedure is described that resulted in the increase in optical efficiency from 21% to the current value of 25%.
Date: October 1, 1980
Creator: Bohn, M. & Gaul, H.
Partner: UNT Libraries Government Documents Department

Tandem mirror experiment upgrade (TMX-U) throttle, mechanical design, construction, installation, and alignment

Description: We will soon add a high-field axisymmetric throttle region to the central cell of the TMX-U. Field amplitude will be adjusted between 2.25 and 6.0 T. This field is produced by adding a high-field solenoid and a cee coil to each end of the central cell. We describe these coils as well as the additions to the restraint structure. We analyzed the stresses within the solenoid using the STANSOL code. In addition, we performed a finite-element structural analysis of the complete magnet set with the SAP4 code. Particular attention was paid to the transition section where the new magnets were added and where the currents in the existing magnets were increased. The peak temperature rise in the throttle coil was calculated to be 41/sup 0/C above ambient.
Date: December 2, 1983
Creator: Pedrotti, L.R. & Wong, R.L.
Partner: UNT Libraries Government Documents Department

Beam determination of quadrupole misalignments and beam position monitor biases in the SLC linac

Description: Misalignments of magnetic quadrupoles and biases in beam position monitors (BPMs) in the Stanford Linear Collider (SLC) linac can lead to a situation in which the beam is off-center in the disk-loaded waveguide accelerator structure. The off-center beam produces wakefields which can limit SLC performance by causing unacceptably large emittance growth. We present a general method for determining quadrupole misalignments and BPM biases in the SLC linac by using beam trajectory measurements. The method utilizes both electron and positron beams on opposite rf cycles in the same linac lattice to determine simultaneously magnetic quadrupole misalignments and BPM biases. The two-beam trajectory data may be acquired without interrupting SLC colliding beam operations. 2 refs., 5 figs.
Date: September 1, 1988
Creator: Lavine, T.L.; Seeman, J.T.; Atwood, W.B.; Himel, T.M.; Petersen, A. & Adolphsen, C.E.
Partner: UNT Libraries Government Documents Department

Annual report for the High Energy Physics Program at The University of Alabama

Description: The High Energy Physics group at University of Alabama is a member of the L3 collaboration studying e{sup +}e{sup {minus}} collisions near the Z{degree} pole at the LEP accelerator at CERN. About 2 million Z{degree} events have been accumulated and the experiment has been prolific in publishing results on the Z resonance parameters, the Z couplings to all leptons and quarks with mass less than half the Z mass, searches for new particles and interactions, and studies of strong interactions and/or weak charged current decays of quarks and leptons abundantly produced in Z decays. They are contributing to data analysis as well as to detector hardware. In particular, they are involved in a major hardware upgrade for the experiment, namely the design, construction and commissioning of a Silicon Microvertex Detector (SMD) which has successfully been installed for operation during the present grant period. A report is presented on their recent L3 activities and their plans for the next grant period of twelve months (April 1, 1994--March 31, 1995). Their main interests in data analysis are in the study of single photon final states and the physics made more accessible by the SMD, such as heavy flavor physics. Their hardware efforts continue to be concentrated on the high precision capacitive and optical alignment monitoring systems for the SMD and also includes gas monitoring for the muon system. They are also planning to participate in the coming upgrade of the L3 detector.
Date: October 1, 1993
Creator: Baksay, L. & Busenitz, J. K.
Partner: UNT Libraries Government Documents Department

Operation of the CDF Silicon Vertex Detector with colliding beams at Fermilab

Description: In this paper we briefly describe the main features of the CDF Silicon Vertex Detector (SVX) and discuss its performance during actual colliding beam operation at the Fermilab Tevatron. Details on S/N ratio, alignment, resolution and efficiency are given.
Date: October 1, 1992
Creator: Bedeschi, F.; Bolognesi, V.; Dell'Agnello, S.; Galeotti, S.; Grieco, G.; Mariotti, M. et al.
Partner: UNT Libraries Government Documents Department

Damping ring designs for a TeV Linear Collider

Description: In this paper we present a damping ring design for the TLC (TeV Linear Collider). The ring operates at 1.8 GeV. It has normalized emittances of elepsilon/sub x/ = 2.8 mrad and elepsilon/sub y/ = 25.4 nmrad. The damping times are /tau//sub x/ = 2.5 ms and /tau//sub y/ = 4.0 ms. To achieve these extremely low emittances and fast damping times, the ring contains 22 m of wigglers. 30 refs., 7 figs., 7 tabs.
Date: December 1, 1988
Creator: Raubenheimer, T.O.; Rivkin, L.Z. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department

Solar Central Receiver Prototype Heliostat. Volume I. Final technical report

Description: The objective of this project was to support the Solar Central Receiver Power Plant research, development and demonstration effort by: (1) Establishment of a heliostat design, with associated manufacturing, assembly, installation and maintenance approaches, that, in quantity production will yield significant reductions in capital and operating costs over an assumed 30 year plant lifetime as compared with existing designs; and (2) Identification of needs for near term and future research and development in heliostat concept, materials, manufacture, installation, maintenance, and other areas, where successful accomplishment and application would offer significant payoffs in the further reduction of the cost of electrical energy from solar central receiver power plants. The prototype heliostat design is presented in detail; and manufacturing, installation, and maintenance procedures described. (WHK)
Date: June 1, 1979
Partner: UNT Libraries Government Documents Department

Nova control system: goals, architecture, and system design

Description: The control system for the Nova laser must operate reliably in a harsh pulse power environment and satisfy requirements of technical functionality, flexibility, maintainability and operability. It is composed of four fundamental subsystems: Power Conditioning, Alignment, Laser Diagnostics, and Target Diagnostics, together with a fifth, unifying subsystem called Central Controls. The system architecture utilizes a collection of distributed microcomputers, minicomputers, and components interconnected through high speed fiber optic communications systems. The design objectives, development strategy and architecture of the overall control system and each of its four fundamental subsystems are discussed. Specific hardware and software developments in several areas are also covered.
Date: May 19, 1982
Creator: Suski, G.J.; Duffy, J.M.; Gritton, D.G.; Holloway, F.W.; Krammen, J.R.; Ozarski, R.G. et al.
Partner: UNT Libraries Government Documents Department

Silicon ingot casting: heat exchanger method (HEM). Multi-wire slicing: fixed abrasive slicing technique (FAST). Phase IV. Silicon sheet growth development for the large area sheet task of the low-cost solar array project. Quarterly progress report No. 3, July 1, 1980-September 30, 1980

Description: The size of ingots cast by HEM has been increased to 45 kg with 34 cm x 34 cm and 32 cm x 32 cm cross-sections. A new crucible has been developed which has a better shape factor. It has shown considerable improvement in yields of square ingots. A 45 kg ingot was solidified in this crucible. Optimization of the solidification cycle has shown that as the height of the ingot is increased, the gradients at the bottom, as well as instrumentation control, have to be very precise for efficient solidification. A new cutting head has been fabricated and assembled with the present drive unit of the FAST slicer. In addition to the salient features of rigidity and accurate alignment, the bladehead is lighter and larger to accommodate a 30 cm wide wirepack. Surface speeds of 500 ft/min were achieved with minimum vibration. Encouraging results have been achieved with the new cutting heat cutting head. High cutting rates and yields, 5.1 mils/min and 96%, respectively, have been seen from electroplated bladepacks. Electroplated wires with diamonds in cutting edge only have been used during the present reporting period with good slicing performance. The impregnated wirepacks have also demonstrated cutting effectiveness with the new bladehead.
Date: October 1, 1980
Creator: Schmid, F; Khattak, C P & Basaran, M
Partner: UNT Libraries Government Documents Department

Laser-beam-alignment system

Description: A plurality of pivotal reflectors direct a high-power laser beam onto a workpiece, and a rotatable reflector is movable to a position wherein it intercepts the beam and deflects a major portion thereof away from its normal path, the remainder of the beam passing to the pivotal reflectors through an aperture in the rotating reflector. A plurality of targets are movable to positions intercepting the path of light traveling to the pivotal reflectors, and a preliminary adjustment of the latter is made by use of a low-power laser beam reflected from the rotating reflector, after which the same targets are used to make a final adjustment of the pivotal reflectors with the portion of the high-power laser beam passed through the rotating reflector. The system was developed to cut the casings of spent nuclear fuel elements into segments as the initial step in recovering usable fuel. (WHK)
Date: February 26, 1982
Creator: Kasner, W.H.; Racki, D.J. & Swenson, C.E.
Partner: UNT Libraries Government Documents Department

Design and fabrication of a Transverse Field Focussing (TFF) 180 keV negative ion accelerator

Description: The 180 keV Transverse Field Focussing (TFF) negative ion accelerator described is the final component of a negative ion based neutral beam acceleration system which is being developed as proof-of-principle demonstration of a radiation hardened neutral beamline. The 180 keV beamline consists of: a surface conversion negative ion source, a 80 keV pre-accelerator, a TFF pumping, matching, and transport section, and the 180 keV TFF accelerator presented. This beamline is expected to provide 1 A of H/sup -/ at 180 keV. In the design of the accelerator, particular importance was given to the rigidity of the accelerator electrode mounting structures and to the electrical isolation of the electrodes along with their related cooling lines. An optical alignment scheme was developed to assemble and to insure precision alignment of the electrodes. (LEW)
Date: November 1, 1985
Creator: Matuk, C.A.; Anderson, O.A.; Owren, H.M.; Paterson, J.A. & Purgalis, P.
Partner: UNT Libraries Government Documents Department