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 Technology, K. D. Timmerhaus and M. S. Barber, Eds., 1, 798-804 (Plenum Press, New York, NY, 1979).

Key words: adiabatic heating; As2S3; automatic bridge; Bi2GeO20 CaCO3; CaF2; 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.

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; relaxation 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 (C2H42). 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 C20H42 have been examined. Only the addition of oddnumbered shorter chains induced loss peaks. On the other hand, the presence of a branched impurity, in this case the C20H42 isomers 2-methylnonadecane and 10-methylnonadecane, did induce loss peaks, one of which correlates very well to the a process found in as-received C2H42. 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.

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.

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).

Key words: energy levels; exotic atoms; interferometry; x rays.

An improved connection chain has been established between the hydrogen Rydberg (i.e., H Balmer a) and y-ray lines to which 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 Z muonic atoms. It now becomes of interest to turn to high Z 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 calculations.

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.

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 Beaufort (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 H, is also completely specified.

18472. Faller, J. E., Rinker, R. L., Zumberge, M. A., Plans for the development of a portable absolute gravimeter with a few parts in 109 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. Meaɗe, Eds., 52, 107-116 (Elsevier Scientific Publ. Co., Amsterdam, The Netherlands, 1979).

Key words: earthquake; fundamental
geophysics precision measurement; gravity.

"constant";

Successful development of a few parts in 10o 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

the method of free fall will be given. The proposed interferometric method uses one element of an optical interferometer as the dropped object. Recent work has resulted in substantial progress towards the development of a new type of longperiod (T> 60 sec) suspension for isolating the reference mirror (corner cube) in the interferometer. Improvements here over the isolation methods previously available, together with state-of-the-art timing and interferometric techniques, are expected to make it possible to achieve a few parts in 10o accuracy with a field-type instrument.

18473. Flannery, M. R., McCann, K. J., Systematic trends in the inelastic cross sections and form factors for_nl → n'l' direct collisional transitions, J. Phys. B 12, No. 3, 427-445 (1979).

Key words: collisional transitions; highly excited Rydberg states; population of angular momentum states.

mar

Certain theoretical predictions are presented for the preferential population of final states with angular momentum I in collisions involving an initially excited atom. Varying l', we find that the maxima of both the inelastic form factors and cross sections for the nl→ n'l' transitions in hydrogen, induced by collision with electrons and heavy particles, in general oscillate on a background which rises as l' is increased, until they both attain a pronounced peak at a unique value l', which is strongly dependent on only the inital principal quantum number n and which is fairly insensitive to changes in / and n'. An expression for l'maz is derived. For l'> l'mar, the form factors and associated cross sections exhibit a dramatic decline, resulting in negligible population of those states. The predictions differ from those suggested by the Bethe high-energy asymptotic limit which favours dipole transitions, and assume significance in situations where excited states are important as in laser modelling, astrophysical and fusion plasmas, and in laboratory studies of excited Rydberg states. For heavy-particle (nl→ n'l') collisional transitions the additional undulations which appear in the cross sections over a wide energy range are predicted and explained.

18474. Gallagher, A., Far-wing line broadening, Acta Phys. Pol. A54, No. 6, 761-765 (1978).

Key words: line broadening; line shapes.

Some of the history and applications of the quasi-static theory of line broadening are discussed, as is its relationship to molecular radiation theory. Interaction potentials of alkalinoble gas diatomic pairs in the ground and first excited state, obtained from application of this theory, are given.

18475. Garvey, R. M., Hellwig, H. W., Jarvis, S., Jr., Wineland, D. J., Two-frequency separated oscillating fields technique for atomic and molecular beam spectroscopy, IEEE Trans. Instrum. Meas. IM-27, No. 4, 349-354 (Dec. 1978).

Key words: atomic beams; atomic frequency standards; cavity phase shift; Ramsey envelope; Ramsey separated oscillating fields; two frequency separated oscillating fields. We report on a novel method to reduce the effects of cavity phase shift upon atomic beam interrogation in Ramsey cavity configurations. Two distinct cavities driven at different frequencies are employed to produce a cavity phase shift which advances (or recedes) at a constant rate.

18476. Geist, J., Applications of absolute radiometers, Proc. 10th Annual Electro-Optics Laser 78 Conf., Boston, MA, Sept. 19-21, 1978, pp. 277-284 (Industrial and Scientific Conference Management, Inc., Chicago, IL, 1978).

Key words: absolute radiometers; blackbody measurements; chemical actinometry; second harmonic generation; solar radiation measurements.

The history of the application of absolute radiometers in science and technology is reviewed. The current growth of applications is described, and a possible role as the primary standard for all radiometric measurements is investigated.

18477. Geist, J., Quantum efficiency of the p-n junction in silicon as an absolute radiometric standard, Appl. Opt. 18, No. 6, 760-762 (Mar. 15, 1979).

Key words: absolute detector; absorption coefficient; dead layer model; external; internal quantum efficiency; silicon. An investigation has been performed which shows that the absolute external quantum efficiency of a silicon detector can be accurately predicted by a simple model over a broad region of the spectrum. In the visible beyond 600 nm the accuracy of this calculation exceeds that of direct radiometric measurement of the external quantum efficiency, hence it should be possible to use silicon as an absolute detector in this spectral region. Using a good thermal detector, one can then "bootstrap" a silicon based calibration down into the blue or ultraviolet region of the spectrum.

18478. Greenberg, R. R., Gallorini, M., Gills, T. E., Cadmium analysis by radiochemical neutron activation analysis, Environ. Health Perspec. 28, 1-4 (Feb. 1979).

Key words: cadmium; neutron activation; radiochemistry, Radiochemical neutron activation analysis (RNAA) has been routinely used at the National Bureau of Standards to analyze Cd in a variety of environmentally important matrices. The method used to separate Cd from other neutron-activated products is solvent extraction. Zinc diethyldithiocarbamate [Zn(DDC),] in chloroform will quantitatively extract Cd from an aqueous solution over a pH range from 1 to 12. In addition to the extraction of Cd, Zn(DDC), will also extract Cu, which can interfere with the Cd analysis by producing a high background level of radiation. This can be avoided by first extracting with Bi(DDC), in chloroform which removes Cu, but not Cd. Copper concentrations can, therefore, be determined in addition to Cd.

This two extraction radiochemical separation procedure is very versatile and is often used as part of a larger multi-element analysis scheme. One such scheme involves the use of an inorganic-ion exchanger, Hydrated Manganese Dioxide (HMD), to retain As, Sb, Se, and Cr prior to extraction. The eluted fraction is then extracted with Bi(DDC), to remove Cu, and then with Zn(DDC), to remove Cd.

18479. Greenspan, M., Piston radiator: Some extensions of the theory, J. Acoust. Soc. Am. 65, No. 3, 608-621 (Mar. 1979).

Key words: baffled piston radiator; piston radiator; radiation of sound; ultrasonic radiator.

Those results of the theory of the baffled, uniform-piston radiator that can be calculated exactly are extended to some other cases, especially the simplest case of a simply supported radiator, the simplest case of a clamped-edge radiator and a Gaussian radiator. It is also shown that from the solution to a problem with boundary conditions framed in terms of velocity, the solution to a corresponding problem, having boundary conditions framed in terms of pressure, can be obtained very easily.

18480. Han, C. C., Concentration dependence of the diffusion coefficient of polystyrene at theta-condition, Polymer Notes 20, 259-261 (Feb. 1979).

Key words: polymers; polystyrene at theta-condition; theta temperature.

Despite many experimental and theoretical studies, the concentration dependence of diffusion coefficient, kn, of polymers at their theta-conditions still remain an unsettled problem. Many investigators found experimentally that k, has a negative value; furthermore, Cantow found that the diffusion coefficient D is independent of the concentration at theta temperature. Meanwhile, theoretical investigations have been carried out by Yamakawa and Imai and also by Pyun and Fixman. The Pyun and Fixman (P-F) approach uses a spherical model instead of the more realistic beads and spring model which was employed by Yamakawa and Imai (Y-I). But it has been pointed out by Pyun and Fixman that Yamakawa's earlier approach is incorrect due to the approximation made by assuming independent inter- and intra-molecular distributions and consequently resulting in the neglect of correlations due to the intermolecular interactions. In the later work of Yamakawa, a negative concentration dependence of D was introduced through the change of coordinate system from actual polymer velocity to the drift velocity. Even though this model leads to a different magnitude for the kp than the one obtained from P-F model, nonetheless both theories predict a negative and molecular weight independent ko at the theta condition.

18481. Hardy, S. C., The motion of bubbles in a vertical temperature gradient, J. Colloid Interface Sci. 69, No. 1, 157-162 (Mar. 15, 1979).

Key words: air bubbles; bubbles, air; viscous silicon oil. The motions of air bubbles in a viscous silicone oil in response to buoyancy and Marangoni forces have been studied. The Marangoni forces are produced by establishing a temperature gradient in the oil which generates a surface tension gradient over the bubbles. From the thermal gradients required to balance the buoyancy and Marangoni forces, the temperature dependence of the surface tension, y', is found to be -0.055 mJ/m2s. This is in agreement with an independent measurement of y' using the pendant drop technique.

18482. Hudson, R. P., The 1978 Nobel Prize in Physics, Science 202, 960-962 (Dec. 1, 1978).

Key words: low temperature physics; Nobel Prize.

The career of P. L. Kapitsa, 1978 Nobel Laureate in Physics, is summarized.

A closed system of six stellar hydrodynamic equations is derived for describing the dynamics of perturbed motions of thin disk galaxies in which the motion is primarily circular. These hydrodynamic equations can be solved exactly in the special case of the uniformly rotating Maclaurin disk. This solution is consistent with Kalnajs's exact solution of the collisionless Boltzmann equation for this disk, and describes the important barlike modes exactly. More generally, the stellar hydrodynamic equations provide a feasible method for calculating large-scale modes of oscillation of disk galaxies, and help elucidate the differences between stellar and gaseous disks. 18484. Jewett, K. L., Brinckman, F. E., Bellama, J. M., Influence of environmental parameters on transmethylation between aquated metal ions, Chapter 11 in Organometals and Organometalloids. Occurrence and Fate in the Environment, ACS Symposium Series No. 82, pp. 158-187 (SIS/ACS, Washington, DC, 1978).

Key words: activation parameters; aqueous transmethylation; chloride complexes; environment; formation constants; ionic mechanisms; kinetics; methylmercury; methyltin; NMR; primary salt effect; speciation.

The transmethylation reaction between trimethyltin and mercury (II) species in water, was examined under varying conditions of temperature, ionic strength, and chloride ion concentrations to establish the influence of environmental parameters on the rate and pathways for the reaction. A computer program, CHEMSPECIES, was developed to apply available formation constants in calculating net and relative concentrations of reactant methyltin and Hg2+ species, as well as product ions and molecules formed, during course of kinetic runs. Input data included observed pH, [CH], and [methylmetal species] observable by proton NMR. Bimolecular total reaction rates k (obs) were observed for all runs. Direct extension of BrønstedDebye-Hückel concepts for ion-molecule reactions in water, provided a coherent estimation of concurrent individual reaction rates for six biomolecular pathways all contributing to k2 (obs). These individual rate constants could be applied to transmethylation at diverse ion strengths using simple correction factors consistent with modern theory and reasonable views on the nature of principal reaction pairs. Prospects for encountering such reactions mechanisms in natural waters are briefly discussed.

18485. Kaufman, V., Hagan, L., Spectrum and energy levels of singly ionized aluminum (Al 11), J. Opt. Soc. Am. 69, No. 2, 232-238 (Feb. 1979).

Key words: aluminum; energy levels; ionization energy; wavelengths.

New wavelength measurements in the spectrum of singly ionized aluminum (8640-683 Å) have been combined with some previous observations to re-evaluate all of the known energy levels of that ion. The designations of the previously known 3p3 D° and 3P terms have been changed and newly found terms have been identified as 3p3ďD° and 3p11S. The ionization energy is 151 862.7(4) cm21 or 18.828 73(5) eV. 18486. Kautz, R. L., Attenuation in superconducting striplines, IEEE Trans. Magn. 15, No. 1, 566-569 (Jan. 1979).

Key words: dielectric losses; superconducting losses; superconducting microcircuit; superconducting striplines. Measurements of the Q of stripline resonators yield values for the attenuation of Nb-Nb2O-Pb striplines typical of those used in superconducting microcircuits. At 4 K the attenuation between 50 and 500 MHz is proportional to frequency and probably results from dielectric losses. Near the transition temperature of Pb, the attenuation begins to show the frequencysquared dependence associated with superconducting losses.

18487. Kessler, E. G., Jr., Deslattes, R. D., Henins, A., Wavelength of the W Ka, x-ray line, Phys. Rev. A 19, No. 1, 215-218 (Jan. 1979).

Key words: gamma rays; precision wavelength; silicon lattice spacing; tungsten x rays; x-ray wavelength ratios.

The wavelength of the Ka, line from an electron-bombarded natural W anode has been measured in terms of that of an I stabilized HeNe laser. This visible laser is a reference point for current Rydberg determinations and for the present-day definition of length. The resulting wavelength value, namely 0.20901349 Å (0.90 ppm) (energy = 59.319233 keV) appears to resolve historical inconsistencies in the x-ray route to y wavelengths.

18488. Kimbleton, S. R., Data sharing protocols: Structure, requirements and interrelationships, Proc. COMPSAC 78, IEEE Computer Society's Second Int. Computer Software and Application Conf., Chicago, IL, Nov. 13-16, 1978, pp. 270276 (IEEE Service Center, Piscataway, NJ, Nov. 1978).

Key words: communications; computers; data bases; networks; operating systems; protocols.

Computer networks provide the basic mechanism for accessing programs and data. Effective use of networks requires appropriate protocols to preserve the meaning of data being transmitted between heterogeneous systems. Currently existing protocols were developed to support the requirements of scientists and engineers. Information processing support, for example remote database access, requires substantially more sophisticated protocols. This paper describes a spectrum of data sharing protocols, identifies the need for a Structure Transport Protocol (STP), describes the nature of an STP, and discusses its utilization in the context of remote database access. 18489. Kraft, R., Finite difference techniques for diffusion and redistribution problems with segregation-type boundary conditions, (Proc. AICA Int. Symp. on Computer Methods for Partial Differential Equations, Lehigh University, Bethlehem, PA, June 17-19, 1975), Paper in Advances in Computer Methods for Partial Differential Equations, R. Vichnevetsky, Ed., pp. 328-333 (AIC, Department of Computer Science, Rutgers University, New Brunswick, NJ, 1975).

Key words: algorithm, finite-difference; finite-difference; integral form, conservation of mass principle; mass principle.

Finite-difference techniques and a particular finite-difference algorithm, derived from the integral form of the conservation of mass principle, are given for a one-dimensional diffusion problem in a composite domain with segregation-type boundary conditions specified at a moving interfacial boundary.

18490. Lindstrom, R. M., Harrison, S. H., Harris, J. M., Accurate calibration of gold film standards by neutron activation and gravimetry, J. Appl. Phys. 49, No. 12, 5903-5908 (Dec. 1978).

Key words: accuracy and precision; gold films; gravimetry; neutron activation analysis; Rutherford backscattering; standards.

A set of evaporated gold films on silicon substrates has been prepared for use as standards in the measurement of film thickness by Rutherford backscattering. The mass of gold in the films was determined independently by gravimetry and by instrumental neutron activation. The area was measured with an optical comparator; film uniformity was assayed by backscattering. Systematic errors in the single-element comparator method of activation analysis have been assessed and either eliminated or compensated, with the result that the single-sample agreement in mass between the two methods was 0.3% and the mean relative bias was below the random errors, also 0.3%.

18491. Mathew, M., Schroeder, L. W., Crystal structure of a struvite analogue, MgKPO, 6H2O, Acta. Cryst. B35, 11-13 (1979).

Key words: crystal structure; magnesium phosphate; potassium phosphate; struvite analogue.

The struvite analogue, MgKPO, 6H2O, crystallizes in the orthorhombic space group Pmn2, with Z = 2. The cell of a = 6.873 (2), b = 6.160 (2) and c = 11.087 (3) Å, obtained in this study by a least-squares fit of thirty± 20 values, is in good agreement with that reported on JCPDS powder diffraction file

card 20-685. Our structure determination shows that MgKPO, 6H2O is isostructural with struvite, MgNH,PO1·6H2O, and that the substitution of NH, by the smaller K✶ produces only minor structural changes. The K+ ion is loosely coordinated to four water molecules at the base and more tightly to a PO, oxygen at the apex of a tetragonal pyramid. The packing of the Mg2+, K+ and PO, ions occurs in planes approximately parallel to the (101) and (011) planes, which provides a structural basis for the observation that crystals grown in aqueous solutions occur as irregular tetrahedra bounded by the (101), (T01), (011) and (OTI) planes.

18492. Mills, R., Velapoldi, R. A., Technical Coordinators, Chemical spot test kits for preliminary identification of drugs of abuse, NILECJ-STD-0604.00, 19 pages (U.S. Department of Justice, Law Enforcement Assistance Administration, National Institute of Law Enforcement and Criminal Justice, Washington, DC, Dec. 1978).

Key words: chemical spot tests; color tests; drugs of abuse; field test kits; sensitivity; specificity.

This is a performance standard for field testing kits that use chemical spot tests for the preliminary identification of drugs of abuse. Performance requirements and methods of test are given for such attributes as specificity, sensitivity, color development, and labeling.

18493. Milton, H. J., Our metric future. An analysis of metrication's impact upon construction specifications, Constr. Specifier 32, No. 2, 36-47 (Feb. 1979).

Key words: construction specifications; conversion approaches; dimensional coordination; metrication; SI; stages in metrication.

The paper examines some of the background considerations in metrication for the construction community, highlights some of the changes that will need to be made, examines different approaches to conversion, and suggests adaptive strategies for the construction specifications sector during the transitional period.

18494. Misakian, M., Kotter, F. R., Discussion of F 78 169-5, “Analysis of the proximity effects in electric field measurements", IEEE Trans. Power Appar. Syst. PAS-97, No. 6, 2175-2176 (Nov./Dec. 1978).

Key words: electric field measurements; instrumentation; measurement procedures; observer proximity effects; power transmission lines; Russian measurement technique. 18495. O'Connell, J. S., Electroproduction and decay of giant resonances, Comments Nucl. Part. Phys. 8, No. 5, 151-156 (1979).

Key words: alpha particle; dipole giant resonance; electroproduction; nickel; photon; photoproduction; quadrupole giant resonance.

The experimental technique of comparing electro and photoproduction of nuclear reactions to determine the multipolarity of the absorbed electromagnetic quanta is reviewed. The results for three isotopes of nickel (A = 58, 60, 62) show the isoscalar electric quadrupole giant resonance decays predominantly by alpha particle emission.

18496. O'Connell, J. S., MacDonald, W. M., Dressler, E. T., Photopion production in the Fermi gas model, (Proc. Int. Symp. on Photopion Nuclear Physics, Rensselaer Polytechnic Inst., Troy, NY, Aug. 10-12, 1978), Paper in Photopion Nuclear Physics, P. Stoler, Ed., pp. 381-384 (Plenum Publishing Corp., New York, NY, 1979).

Key words: beryllium; differential cross section; Fermi gas; lithium; optical potentials; photopion; pion.

Differential and total cross sections for (y,) reactions in nuclear matter are calculated using the single particle уNπ amplitudes recently proposed for nuclear calculations. 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. 18497. Paffenbarger, G. C., The contributions to dental science of Robert J. Nelsen (Introductory remarks), (Callahan Memorial Award of the Ohio Dental Association, Columbus, Ohio, Sept. 23, 1978), J. Am. Coll. Dent. 46, No. 1, 57-59 (Jan. 1979).

Key words: Callahan Memorial Award; dental handpiece; dental materials; dental radiography; dental research; Nelsen, Robert J.

Dr. Robert J. Nelsen, the present Executive Officer of the American College of Dentists, was the recipient of the Callahan Memorial Award in 1978. The presentation of the Award inIcluded the benefit/cost ratio (27,000) of his invention of the turbine contra-angle dental handpiece in 1953 while he was a Research Associate of the American Dental Association at the National Bureau of Standards. The money saved by the use of the turbine contra-angle handpiece for the year 1978 would educate and set up in practice the equivalent of over 9,000 dentists. As it costs about $100,000 to educate a dentist beyond high school, and to set up a practice, approximately 1 billion dollars would be saved. Dr. Nelsen's research work in dental radiography and in dental materials, together with his administrative positions, are reflected in the introduction.

18498. Raymer, M. G., Carlsten, J. L., Pichler, G., Comparison of collisional redistribution and emission line shapes, J. Phys. B Lett. to Ed. 12, No. 4, L119-L124 (1979).

Key words: collisional line broadening; collisional redistribution; resonance fluorescence.

We have studied collisional redistribution of near-resonance radiation in thallium vapour caused by collisions with argon buffer gas. We spectrally resolved electronic Raman scattering and collision-induced fluorescence, both to the weakly populated metastable 62P3/2 level in thallium. Thus we partially avoided the problem with radiative trapping encountered in previous experiments. By measuring the total collision-induced fluorescence as a function of the incident laser frequency, we obtained the absolute collisional redistribution line shape. We have compared this line shape with the emission line shape measured by Cheron, Scheps and Gallagher.

18499. Reader, J., Acquista, N., Spectrum and energy levels of four-times ionized zirconium (Zr V), J. Opt. Soc. Am. 69, No. 2, 239-253 (Feb. 1979).

Key words: spectra; ultraviolet; wavelengths; zirconium. The spectrum of zirconium was observed in the region from 200 to 2670 Å with a sliding-spark discharge on the 10.7-m normal- and grazing-incidence spectrographs at NBS. About 580 lines were assigned to Zr V. From these observations the energy level system of Zr V (Kr I isoelectronic sequence, ground state 4s2 4p 1S.) has been extended to the complete 4s24p 5s, 6s, 7s, 5p, 4d, 5d, 4f, 5g, and 4s4p 4d configurations and the nearly complete 4s24p36d and 6g configurations. About 330 lines have been classified. All observed configurations have been theoretically interpreted. The energy parameters determined by least-squares fits to the observed levels are compared with Hartree-Fock calculations. The ionization energy derived

from the 4p3ng, n = 5,6 levels is 648 050 ± 60 cm1 (80.349 ± 0.007 eV).

18500. Reader, J., Luther, G., Acquista, N., Spectrum and energy levels of thirteen-times ionized molybdenum (Mo XIV), J. Opt. Soc. Am. 69, No. 1, 144-149 (Jan. 1979).

Key words: energy levels; ions; molybdenum; pulsed laser; spectra; wavelengths.

The spectrum of Mo XIV was observed with a low-inductance spark and a laser-produced plasma in the region from 70 to 630 Å on the 10.7-m grazing-incidence spectrograph at NBS. From the identification of 35 lines, a system of 22 energy levels was determined. The level system (Cu I isoelectronic sequence, 3d1o nl) includes the series ns (n = 4-6), np(n = 46), nd(n = 4,5), nf(n = 4-6), and ng(n = 5-7). The observed energy levels are compared with Hartree-Fock calculations. The ionization energy is determined from the ng series (n = 57) to be 2 440 600 ± 300 cm3 (302.60 ± 0.04 eV).

18501. Richmond, J. C., Evaluation of solar absorbers, reflectors and transmitters-Physical reflectance standards, Proc. 1979 Conf. of the 25th Annual Tech. Meeting Learning to Use Our Environment, Seattle, WA, Apr. 30-May 2, 1979, pp. 26 (Institute of Environmental Sciences, Mt. Prospect, IL, 1979).

Key words: diffuse reflectance standards; solar absorptance; solar optical properties; solar reflectance; solar transmittance; spectral reflectance standards; terrestrial solar irradiance.

The classical method of evaluating solar optical properties of materials (reflectance, absorptance and transmittance) is to measure the spectral property of interest (absorptance is taken as one minus reflectance) under conditions of directional irradiation and hemispherical collection, and compute the solar property as the weighted average spectral property, with the solar spectral irradiance as the weighting function. Integrating sphere reflectometers are almost universally used for measuring spectral directional-hemispherical reflectance. Such instruments defined, for accuracy, on the use of calibrated reference standards of absolute directional-hemispherical reflectance. Terrestrial solar spectral irradiance varies widely with changes in the path length of the sun's rays through the atmosphere. There is no generally accepted terrestrial solar spectral irradiance distribution. This paper briefly describes the work now in progress by the Solar Optical Materials Program Planning Committee of the Department of Energy to recommend for adoption a standard terrestrial solar spectral distribution and to make available, through the Office of Standard Reference Materials of the National Bureau of Standards, calibrated reference standards of spectral directional-hemispherical reflectance and of specular spectral reflectance.

18502. Rowan, W: L., Roberts, J. R., Electron-impact ionization-rate coefficients for lithiumlike nitrogen and oxygen, Phys. Rev. A 19, No. 1, 90-98 (Jan. 1979).

Key words: electron impact ionization; ionization cross section; ionization rate coefficient; lithiumlike ions, ionization of; N+4; O+5; rate coefficient.

The electron-impact ionization-rate coefficients for lithiumlike nitrogen and oxygen are obtained from the time evolution of spectral lines emitted by a hot plasma. The plasma is produced in a 37-kJ theta pinch. Laser scattering diagnostics indicate that N, 4 x 10'5 cm3 and kT,≈ 80 eV during the time of principal interest. Under these conditions, the ionization-rate for lithiumlike nitrogen is (7.4 ± 2.2) × 10-10 cm3 s ̄', and that for lithiumlike oxygen is (4.1 ± 1.2) × 10-10 cm3 s1. The rate coefficients measured here and all other measure