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[en] Methods for non-contact tests with ultrasonics produced by lasers on glowing or radioactive components are dealt with here. In particular, a heterodyne interferometer is described for the wide band testing of normal ultrasonic deflections and is compared with other types of interferometers. Applications such as the determination of grain size in thin sheets and the absolute determination of the ultrasonic deflections achieved are demonstrated. By means of reconstruction of the signal beam by the application of optical phase conjugation, the 'etendue' (ability to collect light) was improved from 2.6x10-7 to about 1x10-2, so that the use of this type of interferometry is possible, even on rough surfaces. A capacitative sensor was used for the quantitative measurement of the characteristics of the ultrasonic field produced by a laser, as the sound deflection in these experiments lay below the sensitivity threshold of the interferometer. A simple optical process for testing acoustic surface waves is described. (orig./HP)
[de]Behandelt werden Methoden zum beruehrungslosen Nachweis von lasererzeugtem Schall an gluehenden oder radioaktiven Komponenten. Insbesondere wird ein Heterodyneinterferometer zum breitbandigen Nachweis von normalen Ultraschallauslenkungen beschrieben und mit anderen Interferometertypen verglichen. Anwendungen wie die Korngroessenbestimmung in duennen Blechen, sowie die absolute Bestimmung der erreichten Ultraschallauslenkungen werden demonstriert. Mittels Rekonstruktion des Signalstrahls durch Anwendung der optischen Phasenkonjugation konnte die Etendue (Lichtsammelvermoegen) von 2.6x10-7 auf ca. 10-2 verbessert werden, so dass der Einsatz dieser Art von Interferometrie auch an rauhen Oberflaechen moeglich ist. Zur quantitativen Vermessung der Richtcharakteristik des lasererzeugten Schallfeldes wurde ein kapazitiver Aufnehmer benutzt, da die Schallauslenkungen in diesen Experimenten unterhalb der Nachweisempfindlichkeit des Interferometers lagen. Ein einfaches optisches Verfahren zum Nachweis von akustischen Oberflaechenwellen wird beschrieben. (orig./HP)
[en] Virginia Power has developed a methodology for use in reload designs that predicts the count rate at the source-range detector from spontaneous fission neutrons generated by burned fuel assemblies. This has enabled Virginia Power to eliminate the use of secondary sources and significantly improve core reload designs. Secondary source elimination allows burnable poisons (BPs) in locations otherwise needed for secondary sources and reduces the number of fuel assembly shuffles during a refueling. An essential part of this methodology is the COUNT computer program, which was developed by Virginia Power to predict source-range detector count rates with or without secondary sources present. To date, COUNT has consistently provided adequate predictions of the source-range detector count rate for six sourceless fuel offloads and seven sourceless fuel onloads. In stark contrast to the Monte Carlo or discrete ordinates methods usually employed to model neutron flux outside the reactor vessel, COUNT predicts the source-range detector count rate for a typical refueling in 1 or 2 CPUs on a mainframe computer
[en] A high-intensity neutron source based on a Liquid-Lithium Target (LiLiT) and the 7Li(p,n) reaction was developed at SARAF (Soreq Applied Research Accelerator Facility, Israel) and is used for nuclear astrophysics experiments. The setup was commissioned with a 1.3 mA proton beam at 1.91 MeV, producing a neutron yield of ~ 2 ×1010 n/s, more than one order of magnitude larger than conventional 7Li(p,n)-based neutron sources and peaked at ~25 keV. The LiLiT device consists of a high-velocity (> 4 m/s) vertical jet of liquid lithium (~200 °C) whose free surface is bombarded by the proton beam. The lithium jet acts both as the neutron-producing target and as a power beam dump. The target dissipates a peak power areal density of 2.5 kW/cm2 and peak volume density of 0.5 MW/cm3 with no change of temperature or vacuum regime in the vacuum chamber. Preliminary results of Maxwellian-averaged cross section measurements for stable isotopes of Zr and Ce, performed by activation in the neutron flux of LiLiT, and nuclear-astrophysics experiments in planning will be described. (author)
[en] OAK-B135 The goal of the Caltech program is to determine how helicity injection works by investigating the actual dynamics and topological evolution associated with magnetic relaxation. A new coaxial helicity injection source has been constructed and brought into operation. The key feature of this source is that it has maximum geometric simplicity. Besides being important for fusion research, this work also has astrophysical implications. Photos obtained using high-speed cameras show a clear sequence of events in the formation process. In particular, they show initial merging/reconnection processes, jet-like expansion, kinking, and separation of the plasma from the source. Various diagnostics have been developed, including laser induced fluorescence and soft x-ray detection using high speed diodes. Gas valves have been improved and a patent disclosure relating to puffed gas valves has been filed. Presentations on this work have been given in the form of invited talks at several university physics departments that were previously unfamiliar with laboratory plasma experiments
[en] The design of the D0 single sided 3 chip ladder is shown in figures 1-3. The SVX II chips are mounted directly opposite the cooling channel so that they are most efficiently cooled. Outboard of the cooling channel on the ladder top side is mounted a flex hybrid of copper/kapton. which is adhered to a beryllium substrate using a two part epoxy. The beryllium substrate. aside from providing a solid mounting structure for the flex circuit. provides a thermal conduction path between the components on the hybrid which dissipate heat and the cooling channel. The thickness of the top and bottom beryllium substrates is selected based on the (expected) channel temperature. the power dissipation of the SVX II chips, the power dissipation of the hybrid passive components, and the maximum acceptable silicon temperature within the ladder. The thermal conductivity of the various materials within the ladder must be known to a fair degree of confidence in order to accurately simulate the ladder steady state cooling performance. The thermal conductivity of a number of ladder epoxy candidates was measured using a device at Lab D at Fermilab. Preliminary measurements at Lab D, using a similar setup. have been performed in order to measure the thermal conductivity of beryllium. silicon, aluminum, and other ladder materials. In order to simulate the cooling performance with confidence. prototype ladders were constructed using aluminum substrates (in place of beryllium), blank silicon, and nonfunctional prototype flex hybrid circuits. SVX II heat loads were simulated using 350 ohm strain gages which were adhered to the flex hybrid using a thin layer of epoxy. Temperatures were measured on the prototype ladders using a hand-held IR temperature probe, which has a laser focusing beam enabling simple optical focal length determination. The IR probe allows a correction to account for the surface emissivity of the material being measured. Preliminary measurements at Lab D indicate that the alloy used to construct the ladder models has a conductivity of 237 W/m-K. The assumed conductivity of the blank silicon is 149 W/m-K. Ladder prototypes with aluminum substrates were constructed using the prototype 3 chip assembly fixture at Lab D. A two dimensional cooling simulation program was written using a simultaneous equation solver. The simulation is written by dividing the 2D model into small dx and dy elements and performing an energy balance on each element based on the thermal resistance between the individual elements and their neighbors. It is otherwise known as the finite difference method. The steady state solution is obtained by solving the array of energy balance equations as a DC circuit Convective boundaries can be added on exposed elements using appropriate equations. Following is a schematic which shows the energy balance terms in each element.
[en] Readout cables extend from the ladder end to the outer barrel radius in the region where the F-disks are mounted. In this region it is difficult to know what the gas temperature will be due to the power dissipating components on the F-disks and power from all the cables. This region is convectively cooled by the barrel bulkhead and the F-disk cooling channel. Power dissipated in the cable will not only warm the surrounding gas but will warm the hybrid to which it is attached on the ladders and disks. Just how much power goes into the hybrid will be estimated here. Physically, the cable is composed of two layers of copper which are separated and encased by 3 layers of kapton. The central kapton layer is 0.001-inch thick, the outer two kapton layers are 0.0005-inch thick, and the two copper layers are 0.0006-inch thick. Mike Matulik estimated the power dissipation of the cables for the 3. 6, and 9 chip ladders. These estimates are based on the assumed cross-sectional area of copper in the cable and the current these cables will carry, for a 12-inch cable length. The assumed powers are 14, 49, and 114 mW, respectively. The cable power dissipation is modeled using the finite difference technique. To determine the allowable node size for this simulation a 5-inch cable was simulated, with the same cross-sectional area and nominal power dissipation approximately equal to the power dissipated in the 6 chip ladder cable. Node sizes of 25, 50, and 100 mils are considered. Considering Figures 1 and 2,100 mil nodes will be used for future simulations, considered adequately small to simulate the cable.
[en] Purpose/Objective: This refresher course reviews current research activity and treatment results in the field of radiation therapy fractionation. The presentation emphasizes worldwide studies of altered fractionation, highlighting head and neck cancer as the primary teaching model. Basic radiobiological principles guiding the development of altered fractionation regimens, and advancing the understanding of fractionation effects on normal and tumor tissue are reviewed. A 'standard' prescription of 2 Gy x 35 fractions = 70 Gy may not provide the optimal balance between primary tumor control and late normal tissue effects for all patients with squamous cell carcinoma of the head and neck. The last decade has witnessed the treatment of thousands of head and neck cancer patients with curative radiotherapy using altered fractination schedules designed to improve overall treatment results. Although the number of different fractionation regimens currently being investigated continues to increase, the common guiding principles behind their design are relatively simple. Common fractionation terminology (i.e., accelerated hyperfractionation) will be reviewed, as well as a brief summary of radiobiological concepts pertaining to tumor potential doubling time, tumor proliferation kinetics, overall treatment time and fraction size-dependence of acute and late tissue effects. Several well known head and neck fractionation schedules from around the world (Manchester Christie Hospital-United Kingdom, Princess Margaret Hospital-Canada, Massachusetts General Hospital-USA, MD Anderson Hospital-USA, University of Florida-USA, Mount Vernon Hospital CHART-United Kingdom, RTOG and EORTC trials-USA and Europe) will be summarized with regard to design-rationale, treatment technique and results. The design of several current cooperative group trials investigating altered head and neck fractionation will be presented, as well as concepts prompting the pilot evaluation of several brand new treatment regimens
[en] Laboratory experiments simulating many of the dynamical features of solar coronal loops have been carried out. These experiments manifest collimation, kinking, jet flows, and S-shapes. Diagnostics include high-speed photography and x-ray detectors. Two loops having opposite or the same magnetic helicity polarities have been merged and it is found that counter-helicity merging provides much greater x-ray emission. A non-MHD particle orbit instability has been discovered whereby ions going in the opposite direction of the current flow direction can be ejected from a magnetic flux tube.
[en] This research program involved direct observation of the complicated plasma dynamics underlying spheromak formation. Spheromaks are self-organizing magnetically dominated plasma configurations which potentially offer a simple, low-cost means for confining the plasma in a controlled thermonuclear fusion reactor. The spheromak source used in these studies was a coaxial co-planar magnetized plasma gun which was specifically designed to have the simplest relevant geometry. The simplicity of the geometry facilitated understanding of the basic physics and minimized confusion that would otherwise have resulted from complexities due to the experimental geometry. The coaxial plasma gun was mounted on one end of a large vacuum tank that had excellent optical access so the spheromak formation process could be tracked in detail using ultra-high speed cameras. The main accomplishments of this research program were (1) obtaining experimental data characterizing the detailed physics underlying spheromak formation and the development of new theoretical models motivated by these observations, (2) determining the relationship between spheromak physics and astrophysical jets, (3) developing a new high-speed camera diagnostic for the SSPX spheromak at the Lawrence Livermore National Lab, and (4) training graduate students and postdoctoral fellows
[en] Purpose/Objective: To provide a detailed understanding of the anatomy of the larynx, hypopharynx and regional lymphatics; the clinical pattern of spread of squamous cell carcinomas arising in these sites; the utility of radiographic staging; techniques of radiation delivery; and anticipated therapeutic outcome. Although confined to a relatively small anatomic volume, the larynx and hypopharynx are complex structures with distinct subsites each with it's own staging system, pattern of spread and risk of involvement of regional lymphatics. Diagrams and clinical photographs will be used to illustrate this as an appreciation of the anatomy is essential to the design of a course of radiation therapy. In addition to the physical examination, radiographic imaging with MRI, CT, Barium swallow, etc. can facilitate a more complete appreciation of the extent of disease. Representative treatment fields will be presented for selected disease sites and stages; patient set-up, target volumes, standard and alternative fractionation doses will be discussed. Clinical data on disease control will be reviewed, specifically, historical data on once-daily fractionation as well as data on alternative fractionation regimens. The role of induction therapy for laryngeal preservation will be addressed