摘要:

A method is described for continuously measuring the polarization and other parameters of radio pulse echoes reflected from the ionosphere in very compact form. Time‐varied intensity modulation is employed to resolve split echoes with respect to height of reflection.

ISSN:0034-6748    

DOI:10.1063/1.1771289

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A time‐of‐flight mass spectrometer based on principles previously described has been constructed with two major modifications to facilitate appearance potential measurements. These modifications are (1) an axial electron beam is pulsed through an ionization chamber utilizing techniques of Fox,et al., and (2) a gated ion detector is employed to allow for integration of the resolved ion current from successive cycles. The instrument has been constructed of stainless steel to allow for measurements on chemically active gases. Theoretical resolution, limited by thermal energies of the ions, appears to be well over mass 200. Preliminary experimental work has verified this up to the region of mass 100. Ionization potentials, using the difference method, have been obtained from various gases that are in agreement with the spectroscopic data to within 0.05 volts.

ISSN:0034-6748    

DOI:10.1063/1.1771290

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An apparatus is described which compares the signals developed by two detectors. An application is the measurement and plotting of the distribution of radiation energy produced by x‐ray generators. Measurement of the radiation energy is made with ionization chambers or scintillation counters as detectors, the signals of which are amplified with dc amplifiers. The noise level of the amplifiers is equivalent to a current of about 5×10−15amperes when used with an input resistor of 1011ohms. The ratio of the outputs of the two detectors is obtained directly, using a servo system which compares a fraction of the larger signal with the smaller one. The accuracy and reproducibility of the balancing circuit is better than 0.2 percent. The minimum detectable signal is less than 0.1 millivolt. The same servo system is also employed to control the motion in space of one of the detectors (a probe) so as to seek a position such that its signal is any preselected portion of the other detector's (monitor) signal. Thus, a path of constant energy is traversed by driving the probe perpendicularly to the direction of the x‐ray beam and controlling the position parallel to the beam through the servo system. The trace of the path of the probe is simultaneously duplicated and recorded on a chart. The mechanical reproducibility of the detector position and plotting mechanism in any direction is better than one millimeter. The application of the apparatus for the automatic determination and recording of isodose contours produced in water by the absorption of x‐ray beams of widely different energies is outlined.

ISSN:0034-6748    

DOI:10.1063/1.1771291

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The resultant force of electrostatic attraction between two concentric hemispherical electrodes can be determined rigorously, and it is a suitable arrangement for an absolute electrostatic voltmeter.The curved electrodes have great mechanical rigidity and constancy of form.Stability of balance between the electrostatic and mechanical forces, elimination of the error introduced by the width of separation between the moving electrode and the guard electrode, and other unexpected advantages were obtained by their use.

ISSN:0034-6748    

DOI:10.1063/1.1771292

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A microbalance assembly is described, suitable for the measurement of adsorption isotherms at liquid helium temperatures by the gravimetric method. The design leaves the balance readily accessible and overcomes the two principal difficulties which are spurious mechanical disturbances and buoyancy effects.

ISSN:0034-6748    

DOI:10.1063/1.1771293

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Extensive studies have been made of the starting potentials and plateau characteristics of chlorine‐quenched neon and argon counters with titanium and zirconium metal cathodes, using a previously described optical absorption method to measure the concentration of the halogen in the presence of the rare gases. An equation of the type first formulated by Lauterjung for the starting potentials of organic‐quenched counters, has been found to hold for chlorine‐quenched counters. The constants in this equation have been determined for the counter fillings and cathodes used. A nomograph has been drawn which enables the starting potentials of neon‐chlorine counters to be determined for various counter dimensions, total gas pressures and percentage of chlorine. From the deviations of the experimental data from straight lines at highE/p, an estimate has been made of the behavior of &agr;/p(&agr; is Townsend's first coefficient), for neon and argon at higherE/pvalues than those which are given in the literature. The consideration of secondary Townsend processes gives a new interpretation of the Lauterjung constants. The plateau length of counters filled to a constant total pressure was found to increase linearly with an increase in chlorine concentration. Plateau slopes have been found to decrease initially with increasing chlorine concentration, then to remain constant. Normally, it has been found to be of no advantage to add argon to a neon‐chlorine counter.

ISSN:0034-6748    

DOI:10.1063/1.1771294

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Various zinc sulfide phosphor mixtures for neutron scintillation counting have been compared. Selected compounds of hydrogen, lithium, boron, and fissionable elements were mixed in varying proportions with ZnS(Ag), and the corresponding neutron and gamma counting efficiencies measured as functions of energy. The low sensitivity of these mixtures to gammas (10−5−10−4percent) and the measured short time decay constant (&tgr;=0.04 &mgr;sec) offer distinct advantages for fast neutron counting.

ISSN:0034-6748    

DOI:10.1063/1.1771295

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An apparatus is described for the measurement of the low‐frequency (0.0003 to 2 cps) dynamic properties of solid and liquid polymers. It is basically a torsion pendulum driven in forced vibration by a low‐frequency sinusoidal current. The current generator, which is a mechanically‐driven potentiometer arrangement, is also briefly described. The treatment of data, calibration, and areas of usefulness of the instrument are discussed, and an example of the results of its application to a concentrated polymer solution is given.

ISSN:0034-6748    

DOI:10.1063/1.1771296

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A torsional magnetic susceptibility balance suitable for studying the de Haas‐van Alphen effect has been developed in which the torque and magnetic field are recorded continuously while the magnet current is reduced automatically. The torque is recorded as a bucking current to a galvanometer suspension supporting the sample, and the magnetic field is obtained from a recording of the magnet current. A circuit for stabilizing the magnet current is also described.

ISSN:0034-6748    

DOI:10.1063/1.1771297

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

To facilitate heats of wetting measurements, a metal calorimeter has been designed and constructed which employs a platinum resistance thermometer for temperature measurement and an evacuated dead space to minimize heat losses. Auxiliary circuits for the temperature bridge, and bath temperature control are shown. Initial measurements of the heats of solution of NaCl, both coarse and finely divided samples, indicate a precision of measurement of 0.08 percent. The surface energy of NaCl, calculated from these data, is 366 ergs/cm2.

ISSN:0034-6748    

DOI:10.1063/1.1771298

出版商:AIP    

年代:1955

数据来源: AIP