摘要:

The two point boundary value problem of ordinary differential equations is reduced to two initial value problems, each of which can be easily solved by analog equipment. The computer can judiciously combine these results to yield a solution of the boundary value problem. The methods involved are described analytically and an example solved on the REAC is provided. A complete diagram of the electronic mechanization is provided.

ISSN:0034-6748    

DOI:10.1063/1.1715797

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Crystal monochromators can provide the exceptionally fine collimation requisite for the study of small‐angle diffraction phenomena. To obtain sufficient intensity and contrast it is necessary not only to bend the crystal but also to use two crystals in tandem with their focal circles mutually orthogonal.The apparatus described uses the x‐ray ``weak window'' line source to illuminate the (200) planes of mica in transmission and the (101¯1) planes of a cylindrically ground, polished, and etched quartz crystal in reflection. Symmetrical couple mounts were used to minimize aberrations. The camera essentially isolates theK&agr;1component and consequently reduces diffuse background and general radiation artifacts as shown by pertinent applications to collagen and feather keratin. Although operating in air and using exposure times comparable (50–250 hr) to those encountered with aperture‐collimated systems, the camera has resolved the central first order of the 640‐A macroperiod of collagen fibers and is capable of resolving consecutive orders of spacings as high asca3800 A.The Johansson, Johann, and Cauchois geometries are illustrated in a new manner to show the importance of weak and large sources of x‐rays, to demonstrate the focal pattern characteristic of two‐crystal point‐focusing arrangements, and to show why mosaic crystals are incapable of the fine focus required.

ISSN:0034-6748    

DOI:10.1063/1.1715798

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A rapid, convenient, and reproducible method has been developed for the radioassay of volatile materials labeled with beta emitters of more than 0.15‐Mev energy. The sensitive detection element is a thin‐walled aluminum G. M. tube sealed into an annular jacket and attached directly to a high‐vacuum manifold. Analysis data for SiCl436is presented, and application of the method to several tracer problems is suggested.

ISSN:0034-6748    

DOI:10.1063/1.1715799

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

By designing an ionization gauge such that the electron paths are short and well‐defined and that the collection efficiency of the ion collector is near unity, one can extend the range of ionization gauges to pressures of the order of a millimeter of mercury. Several specific tube constructions are proposed and the characteristics of the gauges are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715800

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A laboratory technique for the quantitative environmental testing and comparison of various types of subsurface transducers is described. Such transducers are currently in use to determine the transient surface temperature response to intense surface heating of a metal slab that is a good heat conductor. The simulator provides surface heating whose uniformity is estimated to be within about 3% of the heating rate over an area of 1 in.2with flux capability exceeding 1500 w/cm2. (Surface melting of a semi‐infinite slab of pure copper occurs in less than 10 sec at this rate.) Because the method of heating is electric, a shaped surface heat pulse may be produced by programing an input Variac. An important feature of the device is its symmetry which permits identical heating of two opposing surfaces simultaneously.

ISSN:0034-6748    

DOI:10.1063/1.1715801

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

This note discusses the use of ``armored'' O‐ring seals for the pressure range to 10 000 atmospheres. In addition, a simple high‐pressure pump piston seal and a proprietary surface treatment to reduce liability of galling of steel parts are described.

ISSN:0034-6748    

DOI:10.1063/1.1715802

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A cryostat is described for temperature control from 300° to − 150°C. Novel features of this apparatus include a combined heating‐cooling thermal exchange coil, good temperature homogeneity over the experimental volume combined with simplicity in design and ease of demountability and maintenance. By using other bath liquids the range of the cryostat can be extended to higher and lower temperatures.

ISSN:0034-6748    

DOI:10.1063/1.1715803

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A system for the generation, amplification, and detection of extremely short, monochromatic pulses in the 5–6 mm region is briefly described. The pulses are 3 m&mgr;sec wide at the base, with a peak power of a few milliwatts at 55 kMc/sec; they may be viewed on a commercially available oscilloscope.

ISSN:0034-6748    

DOI:10.1063/1.1715804

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A controlled pressure mass spectrometer for the study of ion‐molecule collision processes is described. A pressure ratio of 200 to 1 can be maintained between the ion chamber and the analyzer tube by means of differential pumping. Ion beams of the sample gas undergo collision reactions with molecules of the same or other gases in the analyzer tube.

ISSN:0034-6748    

DOI:10.1063/1.1715805

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

In connection with a precision adiabatic calorimeter used for heat‐capacity measurements up to 500°C, there is described apparatus for automatically controlling and recording the temperature difference between the calorimeter and its surroundings and for evaluation of the heat leak by electronic integration of the time‐temperature difference function.

ISSN:0034-6748    

DOI:10.1063/1.1715806

出版商:AIP    

年代:1957

数据来源: AIP