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objective of further experiments is to apply the technique to thc mcasurement of the gyromagnetic ratio of the proton (yp) to an accuracy near | part in 108, using a precision solenoid whose departures from ideal are small.

of the role of statistics in relation to specifications. It briefly considers the questions of what specification requirements are, what they apply to, how they are arrived at, how they are interpreted, and how statistics can help in the various stages of this process. 18441. Dick, C. E., Soares, C. G., Motz, J. W., X-ray scatter data for diagnostic radiology, Phys. Med. Biol. 23, No. 6, 1076-1085 (1978).

Key words: diagnostic radiology; scatterer thickness; scatterer to image plane separation; tissue equivalent phantoms; x-ray beam diameter; x-ray energies of 30 to 70 keV; X-ray scatter.

18438. Miller, E. B., Eitzen, D. G., Ultrasonic transducer

characterization at the NBS, IEEE Trans. Sonics Ultrason. SU. 26, No. 1, 28-37, 63-64 (Jan. 1979).

Key words: acoustic theory; calorimetry; electroacoustic method; medical applications; metrology; NDE; radiation

force; transducer characterization; ultrasonics. Four methods for characterizing ultrasonic transducers are reviewed. These methods have been or are being developed at the National Bureau of Standards (NBS) for characterizing the performance of ultrasonic devices operating into a water load. The nominal frequency range for the methods considered here is 0.5 to 30 MHz, which corresponds to devices used in nondestructive testing, medicine, and animal science. The principles upon which these methods are based are electrical measurements related to the equivalent circuit of a quartz transducer, a thermal equivalent calorimetric method, a measurement of total radiation force, and an electroacoustic method involving sampling the acoustic field of a directive device. It is helpful to thoroughly understand the physical theory which applies to each measurement method so that appropriate methods can be developed and analyzed for errors or uncertainties. Studies of errors and their basis constitute an important part of measurement science or "metrology," and metrology is a principal interest of the National Bureau of Standards. Consistent with this interest, and to provide continuity among the measured quantities, linear and second-order acoustic relationships are tabulated in terms of the pressure and particle-velocity variables for lossless fluids. This provides an outline which interrelates measured quantities and suggests other derived quantities, or measurements, that may also be of interest. A formally economical method for obtaining such nonlinear acoustic relationships is outlined briefly in the Appendix. This provides the basis for the brief analyses which pertain to the radiation force method and to the scanning technique in the body of the paper. Aspects of the treatment of radiation force appear to be novel. References are given which relate to more fundamental theory and to more extensive intercomparison of methods and consideration of errors.

The ratio of the scattered to the total x-ray fluence (scatter fraction) at the centre of the image plane for x-rays transmitted through polystyrene phantoms has been measured for x-ray energies of 32 and 69 keV, X-ray beam diameters from 4 to 40 cm, phantom thicknesses from 5 to 30 cm and phantom-toimage-plane separations from 0.3 to 40 cm. The experimental values for this ratio have less than a 10% variation for these two x-ray energies and the experimental data show good agreement with Monte Carlo calculations and available exnerimental results for low atomic number materials. Based on these results, simple curves are generated which give estimates (+ 10%) of the scatter fraction for all combinations of the geometric parameters encountered in diagnostic radiology.

18442. MacDonald, W. M., Dressler, E. T., O'Connell, J. S.,

Photopion production in the Fermi-gas model, Phys. Rev. C 19, No. 2, 455-464 (Feb. 1979).

Key words: beryllium; differential cross section; Fermi gas;

lithium; optical potentials; photopion; pion. Differential and total cross sections for (7,4) reactions in nuclear matter are calculated using the single particle yNo amplitudes recently proposed for nuclear calculations. The effect of the Pauli principle on the pion spectrum and angular distribution is examined. Optical potentials for the nucleons and pions are introduced to investigate the influence of the nuclear medium on photopion production. The total photoabsorption cross section is computed and compared with recent data on lithium and beryllium.

18439. Ackerhalt, J. R., Eberly, J. H., Shore, B. W., Statistical

broadening and population loss in strongly excited three-level systems, Phys. Rev. A 19, No. 1, 248-263 (Jan. 1979).

Key words: coherent excitation; dressed atoms; inhomogeneous broadening; intense laser; multiphoton dissociation; multiphoton ionization; Rabi frequency; statisti

cal broadening; three-level system. We study the effects of statistical broadening and population loss on the dynamics of strongly excited three-level quantum systems. The results of both analytic and numerical treatments of the three-level Schrödinger.equation are displayed. In order to allow for statistical broadening, solutions are required for arbitrary detuning of the two very intense monochromatic lasers. The most efficient statistically averaged population depletion occurs when the Rabi frequency of the second transition is greater than that of the first.

18443. Laufer, A. H., Bass, A. M., Photochemistry of acetylene.

Biomolecular rate constant for the formation of butadiyne and reactions of ethynyl radicals, J. Phys. Chem. 83, No. 3, 310313 (1979).

Key words: acetylene; butadiyne; ethynyl; hydrogen;

mechanism; photochemistry; radicals; rate constant. The vacuum-ultraviolet flash photolysis of acetylene has been investigated and the mechanisms and rate constant for butadiyne production have been measured. The major photolytic decomposition path deduced is C,H, + hv C,H + H. A minor channel corresponding to C,H, C(:P) + CH,(X-,-) (6) was also suggested. Evidence suggests that butadiyne is formed in a first-order process: C2H + C,H, → C,H, + H (2). The rate of (2) was determined by monitoring butadiyne concentration spectroscopically and a rate constant, kg = 3.1 +0.2 x 10-'1 cm molecule-s', determined. Addition of H, reduces the yield of C,H, by the reaction C2H + H2 → C,H, + H (8) and a ratio kalk, = 4.9 10% was obtained. The photolysis of CF, C,H was briefly investigated.

18440. Natrella, M. G., Statistics in specifications, ASTM Stand. News 7, No. 1, 10-11, 40 (Jan. 1979).

Key words: conformance; sampling; specifications; statisti

cal methods; statistics. This article, one of a series in ASTM Standardization News describing the work of ASTM Committee E-11, is a discussion

18444. November, L. J., Toomre, J., Gebbie, K. B., Simon, G.

W., The height variation of supergranular velocity fields determined from simultaneous OSO 8 satellite and groundbased observations, Astrophys. J. 227, No. 2, 600-613 (Jan. 15, 1979).

polymethyl-methacrylate, polystyrene and polyurethane polymers. The activation energies obtained are measured to 0.2 kcal mole-, in favorable cases. This is adequate for diagnosis of changes in mechanism but may sometimes be inadequate for scaling temperature accelerated tests to room temperature.

Key words: convection; solar; solar atmospheric motions;

supergranules. Simultaneous satellite and ground-based observations of supergranular velocities in the Sun were made using the University of Colorado UV Spectrometer on OSO 8 and the Sacramento Peak Observatory diode array instrument. We compare our observations of the steady Doppler velocities seen toward the limb in the middle chromosphere and the photosphere: the observed Si u ^ 1817 and Fe 1 15576 spectral lines differ in height of formation by about 1400 km.

The striking results of these observations are that supergranular motions are able to penetrate at least 11 density scale heights and that, in doing so, the motion increases from about 800 m s' in the photosphere to at least 3000 m s' in the middle chromosphere. Further, a distinct change appears to occur in the flow structure: whereas the horizontal component of the velocity predominates in the low photosnhere, suggesting strong braking of vertical momentum, the motions higher in the atmosphere are more isotropic. These observations imply that supergranular velocities should be evident in the transition region.

The strong horizontal shear layers in supergranulation must produce turbulence and internal gravity waves. These smaller scale motions have bearing on chromospheric heating and nonthermal line broadening. 18445. Dickens, B., Computer program to implement automated factor-jump thermogravimetry, Thermochim. Acta 29, 57-85 (1979).

Key words: activation energy; computer automation; computerized thermogravimetry; computer program; polymer

degradation; polymer oxidation; thermogravimetry. The paper describes a computer program written to implement the factor-jump method on a thermogravimetry apnaratus automated with an in-laboratory minicomputer. The nrogram is written almost entirely in FORTRAN and constitutes a system of seven overlays. It determines activation energies during the course of the experiment and provides active feedback to pursue desired precision in experimental quantities and in the activation energy. The program is modular and can probably adapt to situations other than the apnaratus and technique for which it was originally designed.

18448. Schroeder, L. W., Mathew, M., Cation ordering in Carlos(SiO..Oz, J. Solid State Chem. 26, 383-387 (1978).

Key words: cation distribution; cation ordering; inipurities;

oxyapatite. The distribution of Lad+ and Cas+ over the cation sites in Cap Lay(SiO,EO, was determined by single-crystal x-ray diffraction. Ca Lag(SiO.).O, has the apatite structure, and all available evidence indicates that the space group is P6z/m, thus precluding a completely ordered structure. The 6h lattice sites are occupied by Last: In contrast, the 4f sites are occupied equally by Ladt and Cas+ ions. Consideration of the properties of the Ladand Cast ions suggests that this distribution is thermodynamically favored for this composition. A simple Ising model suggests ordered columns. These would not be precluded by space group P6z/m, if the correlation between adjacent columns were random.

18449. Smyth, K. C., Bentz, B. L., Bruhn, C. G., Harrison, W.

W., The role of penning lonization of the minor species in a noon hollow cathode dlecharge, J. Am. Chem. Soc. 101, No. 4, 797-799 (Feb. 14, 1979).

Key words: carbon; copper; hollow cathodes; mass spec

trometry; neon; nitrogen; Penning effect. Using a tunable dye laser, a neon hollow cathode discharge was irradiated at wavelengths corresponding to Isn + 2p, neon transitions, and thereby the neon metastable atom population was perturbed. At these wavelengths, changes were detected in both the voltage across the discharge and in the ion signals for the various neon species, as well as for minor (including sputtered) species in the discharge. Attention is focused on the several possible ionization mechanisms for the minor species. Our results suggest that Penning ionization by metastable neon atoms plays the most important role at low discharge currents, but only a minor role at high currents.

18446. McCann, K. J., Flannery, M. R., Multistate semiclassical

orbital treatment of Li+-H, and H+-H, collisions, Chem. Phys. Lett. 60, No. 3, 523-527 (Jan. 15, 1979).

Key words: elastic scattering; ion-molecule collisions; rota

tional excitation; semiclassical orbital; theory. A semiclassical orbital description of elastic scattering and of rotational excitation in ion-molecule collisions is presented. Specific account is taken of interference effects between the classical trajectories that contribute to a given scattering angle, and of rainbow scattering. Excellent agreement with full quantal differential cross sections is obtained.

18ASO. Dickens, B., Automation of factor-jump ther

mogravimetry for active computer control, Thermochim. Acta 29, 41-56 (1979).

Key words: activation energy; degradation apparatus; factor-jump thermogravimetry; polymer degradation; polymer oxidation; programmed temperature control; ther

mogravimetry. A scheme of automation of a thermogravimetry apparatus is described which was developed with the factor-jump method in mind. Temperature, pressure and flow rates of two gases are controlled; all components except the furnace are commercially available. This paper describes the details of the automation scheme and provides data on the quality of its performance. The scheme includes a mini-computer; if no feedback is required, a recording computer terminal can be used instead.

18447. Dickens, B., Experiences in developing an automated

factor-jump method of thermogravimetry, Thermochim. Acta 29, 87-113 (1979).

Key words: activation energy; automated thermogravimetry; computer automated thermogravimeter; factor-jump thermogravimetry; polymer degradation; ther.

mogravimetry. We have recently provided details of an anparatus and computer programs to implement the factor-jump method of thermogravimetry. This paper describes the refinement of the technique to the present status of quasi-automatic routine operation. The procedure was worked out using samples of

18451. Galloway, K. F., VLSI processing, radiation, and

hardening, IEEE Trans. Nucl. Sci. NS-25, No. 6, 1469-1472 (Dec. 1978).

Key words: E-bcam lithography; integrated circuits; ion implantation; plasma etching; radiation damage; radiation

hardening: VLSI processing: x-ray lithogranhy. Process-induced radiation damage to silicon dioxide films is expected to be commonplace for VLSI circuit fabrication. This might be expected to be most serious for the production of radiation-hardened VLSI. In this paper, the oxide damage due to ion processing is reviewed and the radiation levels associated with advanced lithographic techniques are estimated. Implications for radiation-hardened VLSI circuits are considered.

18452. Cutkosky, R. D., A new switching technique for binary

resistive dividers, IEEE Trans. Instrum. Meas. IM-27, No. 4, 421-422 (Dec. 1978).

Key words: binary divider; divider network; guarded divider; resistive divider; self calibration; voltage divider.

A binary resistive divider network has been found which utilizes N cascaded DPDT reversing switches plus one SPDT switch for an N-bit divider. The network features a simple and accurate method for internal calibration. With a fixed divider input voltage the power dissipated in each resistive element is independent of switch setting.

In molecular dynamics, the pressure in a homogeneous system in equilibrium may be calculated by two different methods. The first is based on the virial theorem of Clausius and gives the pressure at the boundary of the system. The second is based on the notion of stress, which is the sum of the appropriate components of the interatomic forces intercepted by an area, and of the components of momentum flux across the area, averaged over the area and over time. We show by means of a detailed comparison of the forces involved that the two methods are equivalent in the thermodynamic limit. In a small system with arbitrary boundary conditions, the neglect of a part of the interactions between the system and the wall results in some error in the pressure calculated by the virial method. In the special case of a system with periodic boundaries, there is no external “wall," and the internal pressures calculated by the two methods are the same. However, with com parable effort in computation, the stress method makes more efficient use of the data and yields a result of greater precision than does the virial method. In a system not in equilibrium or not homogeneous, the stress method remains valid but the virial method leads to ambiguous results. These considerations indicate that the method of stress calculation is more general than the virial method.

18453. Cutkosky, R. D., A programmable phase-sensitive detec

tor for automatic bridge applications, IEEE Trans. Instrum. Meas. IM-27, No. 4, 401-402 (Dec. 1978).

Key words: a-c detector; automatic bridge; detector; high resolution detector; phase sensitive detector; programma. ble detector.

A phase-sensitive detector is described which features programmable gain, digital output, and a resolution of 0.02 kV. The instrument suppresses harmonic sensitivity through the use of analog circuitry which multiplies the signal by constant amplitude sine and cosine waves derived from an external reference of arbitrary voltage and frequency.

18457. Sengers, J. V., Moldover, M. R., Critical phenomena ex

periments in space?, Z. Flugwiss. Weltraumforsch 2, 371-379 (1978).

Key words: critical phenomena; critical-point universality;

fluids; gravity effects; materials science; spacelab. Earth-bound experiments near the critical point of fluids are severely affected by the presence of the earth's gravitational field. Some estimates of the gravitational limitations are presented and it is indicated how these limitations could be reduced by performing critical phenomena experiments in an orbiting laboratory. Because of the “universal" features of critical phenomena, such experiments will contribute to our understanding of the nature of critical-point phase transitions in a large number of systems, including solids as well as fluids.

18454. Shields, J. Q., Absolute measurement of loss angle using

a toroidal cross capacitor, IEEE Trans. Instrum. Meas. IM-27, No. 4, 464-466 (Dec. 1978).

Key words: capacitor; cross capacitor; dielectric; dissipation factor; loss angle; microphonic coupling; phase angle; surface films.

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An absolute measurement of loss angle has recently been completed at NBS. The measurement utilized a special toroidal cross capacitor in which the effects of dielectric films are greatly attenuated. The resulting unit of loss angle has an estimated uncertainty of 0.02 urad at an optimum frequency of 1592 Hz.

18455. Field, B. F., A fast response low-frequency voltmeter,

IEEE Trans. Instrum. Meas. IM-27, No. 4, 368-372 (Dec. 1978).

18458. Koyama, R. Y., Phillips, W. E., Myers, D. R., Liu, Y.

M., Dietrich, H. B., The energy levels and the defect signature of sulfur-implanted silicon by thermally stimulated measurements, Solid-State Electron. 21, No. 7, 953-955 (July 1978).

Key words: deep level measurements; defect center characterization; defect density; ion implantation; silicon; sulfur; sulfur energy level in silicon; thermally stimulated

capacitance; thermally stimulated current. Two energy levels of sulfur in the upper half of the energy gap of silicon

obtained by isothermal transient capacitance and thermally stimulated current measurements on samples prepared by sulfur implantation and high-temperature annealing. The measured energy levels are in good agreement with two levels for sulfur introduced by a closed-tube diffusion but disagree with one of two levels measured for implanted sulfur after low-temperature annealing.

were

Key words: ac voltage measurement; low frequency;

microcomputer. A sampling voltmeter implemented with a microprocessor has been developed to perform as a true rms voltmeter and waveform analyzer. The instrument measures to 0.1 percent accuracy the true rms voltage of approximately sinusoidal inputs at voltages from 2 mV to 10 V and frequencies from 0.1 to 120 Hz. The major feature of the instrument is fast response time, with a total autoranging, settling, and measurement time of two signal periods for frequencies below 10 Hz.

18456. Tsai, D. H., The virial theorem and stress calculation in

molecular dynamics, J. Chem. Phys. 70, No. 3, 1375-1382 (Feb. 1, 1979).

18459. Bender, P. L., Faller, J. E., Levine, J., Moody, S., Pearl

man, M. R., Silverberg, E. C., Possible high-mobility LAGEOS ranging station, (Proc. 1977 Symp. on Recent Crustal Movements, Trieste, Italy, June 20-24, 1977), Paper in Tectonophysics, C. A. Whitten, R. Green, and B. K. Meade, Eds., 52, 69-73 (Elsevier Scientific Publ. Co., Amsterdam, The Netherlands, 1979).

Key words: continental drift; distortion-of-plate;

geophysics; ranging; tectonic motions. A relatively low-cost system for determining both the vertical and horizontal coordinates of several dozen points per year

Key words: equilibrium; homogeneous system; hydrostatic pressure; internal stress; internal virial; molecular dynamics; Monte Carlo method; periodic boundaries; pressure; stress calculation; virial theorem of Clausius.

ing will be required to determine if it meets the criteria for improving adhesion by a chemical mechanism.

18462. Bowman, C. D., Eisenhauer, C. M., Gilliam, D. M.,

Photofission effects in reactor pressure vessel dosimetry, Prox.
Second ASTM-EURATOM Symp. on Reactor Dosimetry, Palo
Alto, CA, Oct. 3-7, 1977, pp. 575-582 (Available as
NUREG/CP-0004 from National Technical Information Ser.
vice, Springfield, VA 22161, 1978).
Key

words: dosimetry; fast neutrons; photofission; photoneutrons; pressure vessel; reactor; threshold detectors.

with an accuracy of about 2 cm appears feasible. One approach considered is to use a subnanosecond pulse length laser with a few millijoules per pulse output energy and to employ single photoelectron detection of the returned signal. The single photoelectron approach has been thoroughly tested in the Lunar Laser Ranging Experiment. With a laser average power of about 50 mW, a 30-cm diameter transmit-receive aperture, 10 arc sec pointing accuracy and a beam divergence of 20 arc sec, the expected returned signal level is about 70 pulses in a 3-min interval. If the differences between the observed ranges and those calculated from a reasonably good LAGEOS ephemeris over a 3-min interval are considered, the expected standard deviation of the mean is < 0.7 cm.

The calibration procedure used in lunar ranging appears capable of reducing any bias due to the photomultiplier or timing system to 0.5 cm. The other main error source we have considered for the measured optical transit time is a possible difference in arrival time in different parts of the far field pattern because of laser mode structure. This effect needs to be checked experimentally, but we expect it to be 0.5 cm or less for a laser pulse length of about 200 psec. Based on these error estimates, simulations for one week of observations from the high-mobility station have been carried out for us at the National Geodetic Survey. When a refraction model error of 0.15% was used, the uncertainty of the high-mobility station position with respect to a reference station 500 km away was found to be 2.4 cm or less in each coordinate. After the gravity-field uncertainties have been reduced, the station location accuracy will be improved further and the limitation of measuring with respect to a regional reference station can be relaxed.

Experiments and calculations both suggest that serious backgrounds from photofission are present when threshold fission foils are used as spectral indices for fast neutron intensity and spectrum measurements in pressure vessel dosimetry. The problem might be resolved by a measurement of the higher energy y-ray spectrum and intensity by means of induced activity from (y,n) reactions.

18463. Buehler, M. G., Microelectronic test patterns for use in

procuring LSICs, Proc. Industry/Joint Services Automatic Test Conf. and Workshop on Advanced Test Technology Management Acquisition Suppori, San Diego, CA, Apr. 5, 1978, pp. 233-235 (American Electronics Association, Palo Alto, CA, Apr. 1978).

Key words: integrated circuit; process validation wafer

(PVW); reliability; silicon; test pattern; transistor gain. The complexity of today's integrated circuits requires new procedures for evaluating the performance of emerging fabrication processes and for insuring that reliability is built into mature components. One approach, currently being developed at NBS, involves the Process Validation Wafer (PVW) concept which is useful in assessing the merits of a new technology and in establishing the base-line performance of an existing process. One key to built-in reliability is parameter uniformity. This is illustrated by a wafer map showing the variability in bipolar transistor gain across a silicon wafer.

18460. Blackburn, D. L., Larrabee, R. D., Automated photovol

taic technique for nondestructively measuring resistivity variations of high resistivity silicon slices, (Proc. Topical Conf. on Characterization Techniques for Semiconductor Materials and Devices, Seattle, WA, May 21-26, 1978), Chapter in Electrochemical Society, P. A. Barnes and G. A. Rozgonyi, Eds., 78-3, 168-179 (Electrochemical Society, Princeton, NJ, 1978).

Key words: electrical measurements; resistivity; semicon

ductors; silicon. An automated, nondestructive photovoltaic technique for measuring the resistivity variation of high resistivity slices is described. The physics of the bulk photovoltaic effect is reviewed, an improved mathematical analysis of the bulk photovoltaic effect due to a small light spot on a large circular slice is discussed, the computer-controlled measurement system is described, and comparisons between photovoltaic and fourprobe resistivity profiles on float-zoned silicon slices with average resistivity between 10 and 150 N.cm are given.

18464. Burnett, E. D., NBS hearing aid test procedures and test

results of FY 78 hearing aids, Paper in Handbook of Hearing Aid Measurement 1979, IB 11-68, 324 pages (Veterans Administration, Washington, DC, Mar. 1979).

Key words: anthropometric manikin; free-field measurements; hearing aids; hearing aid tests; orthotelephonic

response. This report discusses the current test procedures used by NBS to evaluate the electro-acoustic properties of hearing aids. It includes the technical and practical reasons for performing the various tests in the manner described and in certain cases presents ideas and preliminary test methods for the evaluation of special-purpose hearing aids. However, the specific details of the electronic equipment used to perform the tests are not described.

Data for hearing aid testing for the Veterans Administration for their use in Fiscal Year 1978 are presented. The methods used are those previously agreed upon with the Veterans Administration.

18461. Bowen, R. L., Adhesive bonding of various materials to

hard tooth tissues XVIII: Synthesis of a polyfunctional surface-active comonomer, J. Deni. Res. 58, No. 3, 1101-1107 (Mar. 1979).

Key words: acrylates; adhesion, dental; bonding; coupling agent; dental; monomers; resins; surface-active comonomers.

A facile synthesis regimen was developed for the preparation of a resin that, apparently, has the characteristics of a polyfunctional surface-active comonomer. The first reaction involves the addition of acrylic acid to half of the epoxy groups of a commercial diglycidyl ether of bisphenol A oligomer. The product is then reacted stoichiometrically with the amino groups of lithium o-aminobenzoate in a protic, mixed solvent containing stabilizers and catalysts. Preliminary qualitative tests of the product were favorable. Further analytical procedures and test

18465. Calvano, N. J., Wakamiya, S., Dobbyn, R. C., Technical

Coordinators, The ballistic resistance of police body armor, NILECJ-STD-0101.01, 17 pages (U.S. Department of Justice, Law Enforcement Assistance Administration, National Institute of Law Enforcement and Criminal Justice, Washington, DC, Dec. 1978).

Key words: armor, body; ballistic deformation; ballistic penetration; body armor; bullet proof vests.

This standard is for personnel armor intended to protect the torso against gunfire. It establishes methods of test for ballistic penetration and deformation of body armor. The standard provides for five levels of protection, designated as 22 LR-38 Spec., lower velocity 357 Mag.-9 mm, higher velocity 357 Mag.-9 mm, high velocity rifle, and armor-piercing rifle.

18466. Colwell, J. H., A solid-dielectric capacitive pressure

transducer, (Proc. 6th AIRAPT Conf., Boulder, CO, July 2529, 1977), Paper R-8 in High-Pressure Science and Technolosy, K. D. Timmerhaus and M. S. Barber, Eds., 1, 798-804 (Plenum Press, New York, NY, 1979).

Key words: adiabatic heating; As Sz; automatic bridge; Bi, GeOzoi CaCO,; CaFz; capacitance measurement; evaporated electrodes; pressure transducer; temperature

dependence. We are developing a direct-reading pressure transducer that uses the change in capacitance with hydrostatic pressure of solid-dielectric capacitors. The transducer should be capable of reproducing the accuracy and long-term stability of the piston gauge at pressures of 14-700 MPa (2,000-100,000 psi). The large temperature dependence of earlier devices based on this principle have been largely overcome by using two selected capacitors of different materials in opposite arms of the measuring bridge.

Key words: energy levels; exotic atoms; interferometry, a

rays. An improved connection chain has been established between the hydrogen Rydberg (i.e., H Balmer a) and y-ray lines to whichi mesic x-ray transitions are compared. This new y-ray scale, together with improved comparisons between muonic spectra and the y-ray lines, appears to have resolved the longstanding problem of vacuum polarization in high 2 muonic atoms. It now becomes of interest to turn to high 2 electronic spectra where accurate relativistic calculations are recently available. Direct re-measurement of these spectra is underway; meanwhile, however, there are already some results available. This report describes the H Balmer a to y-ray comparisons and summarizes the results of initial comparisons between re-evaluated x-ray transition energies and those which follow from recent relaxed-orbital relativistic Hartree-Fock-Slater calcula. tions.

18470. Durst, R. A., Reference materials for pH and blood

gases, (Proc. Workshop on Blood pH and gases, Utrecht, The Netherlands, June 5-6, 1978), Paper in Blood pH and Gases, A. H. J. Maas, Ed., Session III, pp. 81-87 (University Press, Utrecht, The Netherlands, Mar. 1979).

Key words: acid-base status of blood; blood gases; blood

PH; carbon dioxide; oxygen; pH. This paper is an extended abstract of a talk presented at the Workshop on pH and Blood Gases in Utrecht, The Netherlands on June 6, 1978. The full publication will eventually appear as an IFCC Recommendation on Quantities related to pH and Blood Gases, Part 3. Reference Materials.

18467. Crissman, J. M., Internal friction study of polycrystalline

n-paraffins, J. Appl. Phys. 45, No. 10, 4190-4203 (Oct. 1974).

Key words: audio frequencies; impurities; internal friction; isomers; low temperatures; n-paraffins; polycrystals; relaxa

tion process; Young's modulus. Recent measurements have shown that mechanical relaxation peaks commonly observed in n-paraffins are absent in single crystals of n-eicosane (C20H.2). This work has now been extended to include polycrystalline samples of several highly pure long-chain hydrocarbons. Internal friction data obtained for a variety of n-paraffins, pure or otherwise, have revealed no lowtemperature y relaxation. Moreover, the a relaxation peak is suppressed completely by purification. In attempts to induce an a or y loss peak, several dilute mixtures of other n-paraffins in pure CzH., have been examined. Only the addition of odd. numbered shorter chains induced loss peaks. On the other hand, the presence of a branched impurity, in this case the CzHaz isomers 2-methylnonadecane and 10-methylnonadecane, did induce loss peaks, one of which correlates very well to the a process found in as-received CxHaz. It is proposed here that isomer impurities are an important factor in the mechanics of many of the loss processes in long-chain hydrocarbons observed both mechanically and dielectrically.

18471. Eisenhart, C., Contribution to invited discussion of

“Francis Ysidro Edgeworth, Statistician", by Stephen M. Stigler, J. Roy. Stat. Soc. Ser. A (General) 141, Pt. 3, 317-318 (1978).

Key words: binomial test; chi-squared test; Francis Ysidro
Edgeworth (1845-1926); goodness of fit; Sir Francis Beau-

fort (1774-1857). It is pointed out that Sir Francis Beaufort (1774-1857), Hydrographer of the Admiralty and originator of the Beaufort Wind Scale, was both grand-uncle and uncle of F. Y. Edgeworth, and it would be interesting to know to what extent the former influenced the latter's development. It is noted also that the latter's test of goodness-of-fit to a particular hypothetical distribution, Ho, can be arranged so as to be the best possible binomial test in small samples, or chi-squared test in large samples, relative to a single completely specified alternative distribution, H,, when He is also completely specified.

18468. Crissman, J. M., Zapas, L. J., Dynamic mechanical

behavior of polyethylene during creep to failure in uniaxial extension, J. Appl. Phys. 48, No. 10, 4049-4051 (Oct. 1977).

Key words: failure criteria; loss factor; nonlinear creen;

polyethylene. Dynamic mechanical measurements in torsion superposed on large uniaxial creep strains have been obtained on two types of polyethylene resins. At creep strains of about 10% it is observed that tand goes through a minimum and rises sharply thereafter.

18472. Faller, J. E., Rinker, R. L., Zumberge, M. A., Plans for

the development of a portable absolute gravimeter with a few parts in 10% accuracy, (Proc. 1977 Symp. on Recent Crustal Movements, Trieste, Italy, June 20-24, 1977), Paper in Tectonophysics, C. A. Whitten, R. Green, and B. K. Meade, Eds., 52, 107-116 (Elsevier Scientific Publ. Co., Amsterdam, The Netherlands, 1979).

Key words: earthquake; fundamental “constant":

geophysics precision measurement; gravity. Successful development of a few parts in 109 portable g apparatus (which corresponds to a height sensitivity of about 1 cm) would have an impact on large areas of geodynamics as well as having possible application to earthquake prediction. Furthermore, the use of such an instrument in combination with classical leveling or extraterrestrially determined height data would yield information on internal mass motions. The plans for the development of such an instrument at JILA using

18469. Deslattes, R. D., Rydberg values for x. and y-rays,

(Proc. Int. Conf. on X-ray and XUV Spectroscopy, Sendai, Japan, Aug. 28-Sept. 1, 1978), Jap. J. Appl. Phys. Suppl. 17, Part 2, 1-6 (1978).

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