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A Study of Band Edge Distortion in Heavily Doped Germanium
Details of the energy band structure of degenerate n-type germanium were determined by analysis of fine structure in the 4.2K volt-ampere characteristic of germanium tunnel diodes. No shift in the relative energy of the conduction band minima was observed. The band edge is found to be exponentially distributed with 1/e energies of the order of 10 MeV. There appears to be an ordering mechanism among the group V impurity atoms used as substrate dopants. (Author).
Theory of Continuous Zone Refining Via the Zone-transport Method
This paper explains the differences and the reasons for the differences which exist between the theory of the zone-transport system of continuous zone refining as presented by W. G. Pfann and T. Abe. The identity between the mathematical model used to describe the zone-transport system and one of the models used to describe the recently reported matter-transport system is noted. Nondimensional equations for the zone-transport system are presented and the difference between the limit of alpha in the zone-void and zonetransport systems, when L sub e = 0, is correlated. (Author).
Ion Dissociation in the Drift Tube of a Time-of-flight Mass Spectrometer
Spurious fragment peaks that simulate fragment-ion products of ion dissociation reactions occurring in the reaction region can arise from processes that occur after the reactant ion has passed through the reaction region and entered the potential barrier used to separate normal products and reactants. Analytic expressions for the flighttime shifts characteristics of peaks arising in this way are derived. These flight-time shifts depend on the distance from the ion source to the potential barrier, whereas flight-time shifts for true fragments formed in the reaction zone are independent of this distance. (Author).
Directivity and Beamwidth Approximations for Large Scanning Dolph-Chebyshev Arrays
Directivity and beamwidth for radiation patterns corresponding to the optimum Dolph-Chebyshev design have heretofore been determined by means of formulas that, although exact, are intractable to computation and not particularly open to physical interpretation. Approximate but accurate formulas are presented here in closed form, for the purpose of easy examination and computation of directivity and beamwidth for large scannable Dolph-Chebyshev arrays. Array length, number of array elements, the spacing of these elements, and the sidelobe level desired are parameters in this study. The maximum achievable directivity for Chebyshev arrays is in principle limited, regardless of how large the array becomes. Data is given to establish the array length required to obtain a value of directivity at some prescribed level below the maximum value. Comparisons between exact and approximate theory are presented in graphical form in such a way as to illustrate the lower limits of array size for which the approximations are valid. Element spacings less than a half-wavelength are included in this study. (Author).
Measurement of Noise Figure of a X-Band Waveguide Mixer with Tunnel Diode
Noise-figure measurements of an X-band tunnel diode mixer must be carried out with extreme care, since spurious responses can often produce incorrect results. At microwave frequencies, a waveguide system with a plunger at one side of the diode is used and it is important that one terminal of the diode be isolated from the waveguide wall when the bias voltage is applied. The output of the mixer containing the difference frequency is connected to the input of an amplifier with a series combination of bias components. This series combination contains additional inductance and capacitance other than that of the 30 Mcps amplifier and can produce resonance effects when the tunnel diode is operated in the positive region close to the peak current, thereby leading to an error in the noisefigure measurement. Correct and incorrect noise figures are compared. A noise figure of 3 db, free of spurious responses, has been measured for a tunnel diode (D4168D) operated at a pump frequency of 9.205 Gc and a difference frequency of 30 Mcps in an X-band waveguide mixer. (Author).
Apparent Sky Temperatures at Millimeter-wave Frequencies
Measurements of apparent sky temperatures taken over a one-year period at 15, 17 and 35 Gc are summarized. Sky temperature profiles for various meteorological conditions are presented as well as curves showing the percentage time distributions for various zenith angles. Such factors as absorption and radiation by oxygen and water vapor, extrapolation of the data to other geographical areas, and the relation between total attenuation of the atmosphere and sky temperature are discussed. A description of the radiometers and the calibration techniques are included. (Author).
