12360. Gebbie, K. B., Thomas, R. N., The temperature control bracket, Astrophys. J. 168, No. 3, 461-479 (Sept. 15, 1971). Key words: Boundary temperature; coliisional-control; non- The factors determining the temperature distribution in a stellar atmosphere are divided into transfer effects and population effects. As a measure of the latter, we introduce the Temperature Control Bracket [TCB], which, in radiative equilibrium, describes the control of T, by the quantity and spectral distribution of the radiation field. Algebraic expressions for the [TCB] are given in terms of the microscopic rate processes for a pure hydrogen atmosphere. A caricatured computation is presented to demonstrate the influence of the various physical effects on the distribution of T, in radiative equilibrium. 12361. Gravatt, C. C., The application of light scattering, Appl. Spectry. 25, No. 5, 509-516 (Sept.-Oct. 1971). Key words: Air pollution; Brillouin spectroscopy; lasers; light scattering; macromolecules; optical mixing spectroscopy; review. Light scattering provides information concerning the size, shape, number, and time dependence of the physical nonuniformities of a system. Measurements of the scattered intensity as a function of both scattering angle and wavelength describe static properties, whereas the spectral distribution of the scattered radiation is related to time dependent phenomena. The applications of light scattering are discussed, including critical phenomena, molecular weight determination, air pollution analysis, and diffusion phenomena. 12362. Grimes, D. N., Linear microdensitometry, J. Opt. Soc. Am. 61, No. 9, 1263 (Sept. 1971). Key words: Diffuse density measurement; linear microdensitometer; microdensitometry. A linear microdensitometer is proposed whose operation is independent of the coherence of the source used and which measures diffuse density. A theoretical analysis is given. 12363. Grundl, J. A., Fission-neutron spectra: macroscopic and integral results, Proc. Neutron Standards and Flux Normalization, Symp. Argonne National Laboratory, Argonne, Ill., Oct. 21-23, 1970, sponsored by the European American Nuclear Data Committee, pp. 417-451 (Aug. 1971). Key words: Fission cross sections; fission neutron spectra; integral measurements. Certain integral measurements performed with pure fission neutrons, and also with macroscopic systems that are dominated by the fission spectrum, locate an important area of difficulty for differential microscopic data. The classic measured value for the 238U average fission cross section for 235 U thermal-neutron-induced fission neutrons, σX25, 238U)=310±4 mb, is in serious disagreement with predicted values which fall between 270 and 282 mb depending upon the choice of 238U fission cross section and fission spectrum shape. Critical consideration is given to direct absolute determinations of σX25, 238U), and to indirect values obtained from fission ratio measurements with activation detectors. The latter substantiate the classic value and also provide a new value for the 239Pu fission spectrum. Equivalent disagreements with prediction occur in the interpretation fission ratio measurements performed in 235U and 239Pu metal critical spheres, and the discrepancy between calculated and measured age-to-indium-resonance of fission neutrons in water is in a direction consistent with the fission spectrum discrepancy. The growing importance of integral measurements for the technology of nuclear energy, and the consequent need for fast-neutron standardization to serve it, is assumed to emphasize the difficulties summarized in this review. 12364. Hall, J. T., Dixon, R. G., Getting it all together the cybernetic way, Management Rev. pp. 16-22 (American Management Association, Inc., New York, N.Y., July 1971). Key words: Brainstorming; cybernetic technique; data collection; group dynamics; interpersonal relationships; management research; opinion survey. This paper describes a number of management research experiments with a technique for generating and gathering ideas, quickly and effectively, from people in moderate to large size groups. The experiments were conducted by the Management and Organization Division of the National Bureau of Standards. The paper also describes applications of this technique by Bureau staff members to various community related situations. The mechanics by which this technique works involve the collection of inputs and feedbacks from individuals arrayed in a variety of configurations. As the collection process proceeds, a process of synthesis and a process of evaluation also occur. The primary value of the technique, again, is the ease with which it allows us to comprehend and capture complex ideas from groups of people. Through the dynamics of capture, feedback, and recapture of thoughts in a changing interpersonal environment, users get much closer to the reality or at least to the shape of group opinions and ideas; closer than any survey or questionnaire techniques we have used or seen used in the management field. 12365. Hellwig, H., Barnes, J. A., Glaze, D. J., Frequency biases in a beam tube caused by Ramsey excitation phase differences, Proc. 25th Annual Symp. on Frequency Control, Atlantic City, N. J., April 26-28, 1971, pp. 309-312 (Electronic Industries Association, Washington, D.C., April 1971). Key words: Cavity phase shift; cesium beam tube; frequency accuracy; frequency modulation; frequency standard; power shift; resonance line shape. A phase difference between the two interaction regions of a Ramsey excitation resonance structure results in a frequency bias in the measured beam resonance. A simple mathematical model is discussed which describes the dependence of this bias on the phase difference, the microwave power level, the modulation amplitude, and the resonance linewidth. This dependence results from the interaction of the modulated microwave excitation frequency with the asymmetric shape of the slightly shifted resonance line. In a first order approximation, no dependency on the frequency modulation amplitude is expected. Near-linear dependencies on the linewidth and microwave power level which are quite pronounced even at relatively small cavity phase differences are predicted. The theoretical results are compared with one set of experimental data on the microwave power dependence as measured in 1969 with the primary cesium beam standard NBS-III. After a correction is applied to remove the power dependence due to spectral impurity of the microwave excitation, the remaining measured power dependence agrees quantitatively with that calculated using a cavity phase difference of about 3 milliradians. 12366. Kulin, G., Discussion of the paper "Triangular broadcrested weir," by C. D. Smith and W. S. Liang, Proc. Am. Soc. Civil Engrs., Irrigation Drainage Div. 96, IR4, 494-497 (Dec. 1970). Key words: Flow measurement; weirs, broad-crested. Published data on discharge coefficients for triangular broadcrested weirs are analyzed using a boundary layer model. Effects of changing the critical Reynolds number for boundary layer transition and possible scale effects are pointed out. 12367. Laufer, A. H., Okabe, H., Heat of formation and bond dissociation energy of diazomethane by a photodissociation method, J. Am. Chem. Soc. 93, 4137-4140 (1971). Key words: Bond dissociation energy; diazomethane; heat of formation; vacuum ultraviolet. A lower limit for the heat of formation of diazomethane has been obtained from measurement of the minimum energy required to produce the A2A state of CH in the low-intensity vacuum-ultraviolet photolysis of diazomethane. The value obtained is AH, %(CH2N2) ≥ 51.3 kcal/mol (2.22 eV). In conjunction with AH% (CH2)=93.0 kcal/mol, the dissociation energy of the C=N bond in diazomethane is < 41.7 kcal/mol (1.81 eV). Reasonable upper limits for AHƒ°%(CH2N2) are discussed. 12368. Lawless, W. N., Radebaugh, R., Soulen, R. J., Studies of a glass-ceramic capacitance thermometer btween 0.025 and 2.4 K, Rev. Sci. Instr. 42, No. 5, 567-570 (May 1971). Key words: Capacitor; depolarization; dielectric; dilution refrigerator; glass ceramic; phase transition; strontium titanate; thermometer. Capacitance measurements from 0.025 to 2.4 K are reported for capacitance thermometers (made from an SrTiO3 glassceramic crystallized at 1100 and 1203 °C), two of which were the ones reported in the previous article. It was found that the 1200-type thermometer has a useful thermometric range down to 0.06 K and a linear C-T region down to 0.5 K. The 1100-type thermometer has a useful range down to 0.110 K and a linear region down to 1.1 K. The measured data do not appear to be influenced by self-heating or adiabatic correction effects. Both thermometers display an unexpected increase in capacitance with decreasing temperature below their monotonically decreasing ranges. The 1100-type thermometer displays the more pronounced increase, with C T-1 from 0.100 to 0.025 K. It is argued that this T-1 behavior is due to the onset of an ultralow temperature phase transition in the glass crystallized SrTiO3, and the possibility of using this effect to achieve adiabatic depolarization cooling is discussed. 12369. Milligan, D. E., Jacox, M. E., Infrared spectrum of the BrHBr ion isolated in an argon matrix, J. Chem. Phys. 55, No. 5, 2550-2560 (Sept. 1, 1971). Key words: Alkali metal reactions; BrHBr-; charge transfer; CIHCI-; electron attachment; infrared spectrum; matrix isolation; molecular rotation; vacuum-ultraviolet photolysis; vibrational potential function. Infrared absorptions assigned to vз,(v3+v1), and (v3+2v1) of BrHBr have been observed in samples of HBr in an argon matrix which have been subjected to 1216-Å photolysis or which have been co-deposited with an alkali metal atomic beam and then subjected to mercury-arc radiation. The corresponding experiments on deuterium-enriched samples support this identification. Mechanisms by which BrHBr is produced in these experiments are considered in detail. An atomic mechanism leading to the stabilization of the uncharged species is shown to be inadequate. However, several ionic processes may contribute to the observed production of the anion. As previously postulated, dissociative electron attachment to (HBr), may occur. In addition, it is necessary to postulate the production of Br- by various charge-transfer processes, followed by the reaction of Br- with HBr. Analysis of the infrared spectra of BrHBr- and of BrDBrindicates that the vibrational potential function must include significant contributions from both cubic and quartic terms. 12370. Mountain, R. D., Raveché, H. J., Entropy and molecular correlation functions in open systems. II. Two- and three-body correlations, J. Chem. Phys. 55, No. 5, 2250-2255 (Sept. 1, 1971). Key words: Configuration entropy; correlation function; entropy; hard sphere; liquid state; neon; Percus-Yevick equation. We consider the contributions from the correlation of pairs and triples of molecules to the configurational entropy per molecule of a simple fluid system. Using numerical values of the pair function and only certain moments of the triplet function, we have computed the first few terms in an expression for the entropy in terms of the correlation functions. The results, which compare favorably with experimental values over a range of densities including that of the liquid, indicate that the contributions from the correlations of triples of molecules can be appreciable. The computations are done for a fluid of hard spheres and liquid neon and the results are discussed in terms of the molecular correlations in a simple fluid. 12371. Page, C. H., External field of an ideal toroid, Am. J. Phys. 39, No. 9, 1039-1043 (Sept. 1971). Key words: Leakage flux; magnetic field; toroid; transformer; vector potential. The external magnetic field of an ideal toroid vanishes for dc excitation but not for an ac excitation. The external static field has a nonvanishing vector potential; the emf in a transformer winding is due to the time variation of this vector potential. An expression for the external magnetic field is derived, and it is shown that the external flux density is a negligible fraction of the flux density in the core. 12372. Page, C. H., On the external magnetic field of a closed-loop core, Am. J. Phys. 39, No. 10, 1206-1209 (Oct. 1971). Key words: Magnetic field; solenoid; toroid; transformer; vector potential. An infinite solenoid, or a toroidal coil, has no external magnetic field for de excitation but has a nonvanishing vector potential field. The development of the steady-state condition from the transient response to step excitation is discussed. Under ac excitation, an external magnetic field must be present, but in practical cases its magnitude is negligible. 12373. Raveché, H. J., Entropy and molecular correlation functions in open systems. I. Derivation, J. Chem. Phys. 55, No. 5, 2242-2250 (Sept. 1, 1971). Key words: Activity derivatives; closed system; correlation functions; entropy; open system; potentials of mean force. A method is presented for obtaining an expression for the entropy in terms of molecular correlation functions defined in the grand canonical ensemble. The procedure is for a system of a single molecular species whose dynamics are determined by classical equations of motion. The entropy is obtained as a sum of two different classes of functions each involving the correlations between n-tuples of molecules. One class contains logarithmic terms similar to those obtained for the closed system; the other class involves isothermal activity derivatives of potentials of mean force. The latter terms, which are moments of the correlations between disjoint sets of molecules, can make appreciable contributions to the entropy. The method leads to results similar to those obtained from a different procedure by Nettleton and Green. The expression for the entropy is obtained and properties of the results are discussed for a simple fluid system. 12374. Rubin, R. J., Comment on "Conformation of adsorbed polymeric chain. II," J. Chem. Phys. 51, No. 10, 4681 (Nov. 15, 1969). Key words: Adsorption; chain polymer; lattice model; partition function; random walk. There is an error in one of the results in a recent paper by Motomura and Matuura [K. Motomura and R. Matuura, Mem. Fac. Sci., Kyushu University 6, 97 (1968)]. The result in question, which concerns the mean square end-to-end separation of an adsorbed polymer chain, is quoted in a subsequent paper [K. Motomura and R. Matuura, J. Chem. Phys. 50, 1281 (1969)]. In this Comment, the origin of the error is identified and the form of the correct result is indicated. 12375. Rubin, R. J., Transmission properties of an isotopically disordered one-dimensional harmonic crystal. II. Solution of a functional equation, J. Math. Phys. 11, No. 6, 1857-1867 (June 1970). Key words: Defects in harmonic crystal; functional equation; many-body problem; multiple scattering; statistical physics; transmission coefficient. ω The amplitude of a wave of frequency w which is transmitted by a disordered array of N isotopic defects in a 1-dimensional harmonic crystal is investigated in the limit N→ ∞. In particular, the ratio (w) of the amplitude of the Nth defect to the amplitude of the first defect is represented as exp [- Nâx(w, Q, {a})], where {an}, n=2, ··, N, is the sequence of nearestneighbor spacings and Q=(M — m)/m. It is known from earlier work that a(w, Q, {an}) is the logarithm of the Nth root of the magnitude of a continuant determinant of order N. The value of the continuant is expressed formally as a product of N factors ĝn which are recursively related. In the present case, the ĝ, happen to lie on a circle Ko in the complex g plane. Assuming that the spacings between defects are independent identically distributed random variables with the mean value c-1 and going to the limit N→∞, a functional equation for the limiting distribution function of the gn on Ko is derived. The limiting value a(w, Q, c)=lim âx(w, Q, {a,}), as N→ ∞, can be determined from the limiting distribution function of the ĝn. We determine the solution of the functional equation in three different ways for three different cases: (a) In the case of the special frequency of Matsuda, w = 2-1/2 and Q = 1, we obtain exact values of the integral of the ĝ distribution function which are in excellent agreement with Monte Carlo estimates; (b) in the physically interesting case where the mean spacing between defects is small compared to the incident wavelength, i.e., c-1w < 1, we obtain the solution of the functional equation correct to first order in c-1w and we calculate the lowest-order nonzero value of a(w, Q, c); (c) for the general case of moderate values of w, Q, and c, we develop a numerical method for solving the functional equation and present the results of the numerical calculations in several representative cases. These numerical results are in good agreement with Monte Carlo estimates. One of the principal results, obtained by solving the functional equation, is that a(w, Q, c) > 0 for w <c< 1 and w(Q+c-1) < 1 with Q # 0. 12376. Rubin, R. J., Greer, W. L., Abnormal lattice thermal conductivity of a one-dimensional, harmonic, isotopically disordered crystal, J. Math Phys. 12, No. 8, 1686-1701 (Aug. 1971). Key words: Disordered one-dimensional crystal; multiple scattering; statistical physics; thermal conductivity; transport properties. Energy transport is investigated in a model system for which exact analytic results can be obtained. The system is an infinite, one-dimensional harmonic crystal which is perfect everywhere except in a finite segment which contains N isotopic defects. Initially, the momenta and displacements of all atoms to the left of the defect region are canonically distributed at a temperature T, and the right half of the crystal is at a lower temperature. This initial nonequilibrium state evolves according to the equations of motion, and ultimately a steady state is established in the vicinity of the region containing the defects. The thermal conductivity is calculated from exact expressions for the steady state energy flux and thermal gradient. For a crystal in which the N isotopic defects are distributed at random but in which the overall defect concentration is fixed, we demonstrate that the thermal conduc tivity approaches infinity as least as fast as N1/2. A Monte Carlo evaluation of the thermal conductivity for a given defect-to-host mass ratio and concentration is carried out for a series of random configurations of N defects for N in the range, 25 ≤ N ≤ 600. The thermal conductivity is proportional to No1/2 within the statistical uncertainty except for slight deviations at the smallest values of N. 12377. Saylor, C. P., Return of the prodigal, Capital Chem. 21, No. 6, 95-99 (Sept. 1971). Key words: Cathedral; deformation; lead; roof; Washington The Washington Cathedral, built in the English style, was given a lead roof. Under the hot Washington sun, it crept. This caused it to leak. E. W. Washburn, Chief Chemist of NBS, diagnosed the difficulty and suggested correction. The events recounted in this article took place shortly after 1921. 12378. Shoup, R. R., VanderHart, D. L., Effect of CH scalar coupling on 13C transverse relaxation times, J. Am. Chem. Soc. 93, 2053-2054 (1971). Key words: Fourier transform; nmr; relaxation; scalar coupling; sensitivity; 13C. Experimental 13C NMR relaxation rates are reported for 60 percent enriched 13CH3I, 13CH3COOCD3, and 13CS2. Except for CS2 transverse relaxation rates, Rec's, are found to be substantially higher than the corresponding longitudinal relaxation rates. This effect is shown, on the basis of the variation of R2c with Carr-Purcell pulse repetition rate, to arise from scalar coupling of 13C with relaxing protons. Implications for 13C spectroscopy, particularly Fourier transform techniques, are discussed. 12379. Smith, J. C., Kermish, G. A., Fenstermaker, C. A., Separation of filler particles from the matrix in a particulateloaded composite subjected to tensile stress, Proc. 162nd Meeting American Chemical Society, Organic Coatings and Plastics Chemistry, Washington, D.C., Sept. 13-15, 1971, 31, No. 2, 149-155 (Sept. 1971). Key words: Composite materials; coupling agents; epoxy polymer; parting agents; poisson's ratio; release agents; stress-strain curve; volume dilation. Simultaneous measurements of tensile stress, longitudinal strain, and transverse strain were obtained on particulate-filled composites. The matrix was a flexible epoxy polymer. Small glass spheres were used as filler in various volume ratios up to .35. The spheres were pretreated as follows: clean, coated with a parting agent, coated with either of two silane coupling agents. The volume expansion behavior of composites containing parting agent treated spheres could readily be distinguished from that of composites containing clean glass spheres, but differences caused by coating the spheres with coupling agents could not be distinguished. Stress-strain behaviors for the various composite systems also showed differences. These differences in both kinds of data are taken as indicative of matrix-filler separation and subsequent vacuole formation. 12380. Tech, J. L., Ward, J. F., Accurate wavelength measurement of the 1s2p3P° -2p2 3P transition in 'He I, Phys. Rev. Letters 27, No. 7, 367-370 (Aug. 16, 1971). Key words: Atomic energy levels; atomic theory; autoionization; helium; wavelength measurement. An accurate spectroscopic measurement has yielded 320.2926 +0.0010 Å for the wavelength of the 1s2p 3P° - 2p2 3P transition in 'He I. Combining this wavelength with the well-known position of the 1s2p term gives an experimental value of 481301.5 ± 1.2 cm-1 for the position of the doubly excited 2p2 3 P term relative to the ground 1s2 1S. The new measurement is in excellent agreement with Aashamar's theoretical calculation of 481301.6 cm-1 for the energy of the term. |