摘要:

Two linear accelerators have been built for the acceleration of ions in the mass region from helium to argon. The linear accelerators consist of two 70‐Mc cavity resonators of the Alvarez design. Ions with a charge to mass ratioe/m≥0.15 times thee/mof a proton are injected into the first cavity of the linear accelerator with a Cockcroft‐Walton accelerator. In the first cavity the ions are accelerated from the injection energy of 0.07 Mev/nucleon to 1.0 Mev/nucleon. They are then stripped to ane/m≥0.3 and accelerated to the final energy of 10 Mev/nucleon in the second linac cavity.

ISSN:0034-6748    

DOI:10.1063/1.1717456

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A method for the rapid measurement of magnetic anisotropy is described. The instrument consists of a self‐exciting torsion pendulum containing the magnetic sample, which is suspended in a magnetic field in a furnace. The resonance frequency of the pendulum, which depends on the anisotropy energy in a known way, lies between 10 and 100 cps so that the time required for a measurement is shorter than in other methods. The instrument is therefore capable of following a rapidly changing anisotropy, e.g., during the magnetic annealing of the sample. The measurement of the anisotropy of a single crystal of Ticonal G magnet steel during cooling from 900° to 400°C in a magnetic field is described as an example.

ISSN:0034-6748    

DOI:10.1063/1.1717457

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A convenient labor‐saving method of introducing up to eight (and more, if necessary) electrical leads into a one‐half inch diameter pressure chamber (which is applicable with liquid media to pressures in excess of 30 kilobars) is described.

ISSN:0034-6748    

DOI:10.1063/1.1717458

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The study of thin metal films, used as passive components in microelectronic circuitry, led to the development of a multiple cathode sputtering system. The major advantage of a sputtering system is that highly refractory materials can be sputtered quite readily, but they cannot be evaporated without elaborate equipment. Thus, a sputtering system permits studies of thin metal films to be extended from those with low melting points into the range of metals with high melting points. This paper describes a versatile sputtering system which incorporates several cathodes and a rotating anode, making it possible to sputter one metal after another without breaking the vacuum and to deposit films of various thicknesses under identical conditions.

ISSN:0034-6748    

DOI:10.1063/1.1717459

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

An improved magnetically supported equilibrium ultracentrifuge is described for the determination of molecular weights and molecular weight averages. The rotor is magnetically suspended in a vacuum. The rotor is driven to operating speed by an electric motor or by an air turbine. The rotor is allowed to ``coast'' freely during the course of the sedimentation and loses about 1 rps per day. An improved Jamin interferometer is used to measure the concentration in the ultracentrifuge cell both before and after equilibrium has been established. A precision of the order of 0.1% is obtained for monodisperse substances over a very wide molecular weight range.

ISSN:0034-6748    

DOI:10.1063/1.1717460

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A technique described previously by Hettinger and Starfelt for the reduction of iodineKx‐ray escape when measuring narrow collimated beams of continuous x rays with a NaI(Tl) scintillation spectrometer consisted of confining the photon beam to a small well in the crystal to reduce the solid angle through which iodieKx‐ray escape is possible. This technique was evaluated for tungsten characteristic radiation (∼60 kev) and was reported to provide a very substantial reduction in the escape peak. The present paper describes an investigation of this technique at lower photon energies (10 to 60 kev). A tail was observed to appear on the low energy side of the photopeak of magnitude showing inverse dependence on photon energy. This distortion of pulse‐height response is large enough to indicate that the well crystal technique is unsatisfactory when making measurements of continuous x‐ray spectra in the energy region where the escape of iodineKx rays is an important factor. The likely explanation is that light losses associated with the well itself are responsible for the observed tails since reflecting liners were not present. Introduction of a reflecting liner into the well was found to reduce the tail effect considerably.

ISSN:0034-6748    

DOI:10.1063/1.1717461

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The combination of a Si (111) monochromator and a quartz ``single‐crystal'' filter proves effective for the elimination of higher‐order contamination from the monochromatic beam of a neutron crystal spectrometer in the energy range from ∼0.02–0.10 ev. This system greatly enhances the usefulness of crystal spectrometers for obtaining cross section data in the thermal range. The properties of the quartz filter have been studied at room temperature and 77°K, and it is shown that the filter is more efficient in this application at room temperature. The higher‐order contaminations from Si (111) and NaCl (200) reflections are compared, and it is clearly demonstrated that Si (111) is a superior monochromator in the thermal region.

ISSN:0034-6748    

DOI:10.1063/1.1717462

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

This paper describes the usefulness of a variable coupling resonant cavity for microwave spectroscopy. The variable coupling scheme achieves slightly greater sensitivity than does the usual microwave bridge circuit. It can single out either the absorption or dispersion component of a resonance signal without using bridge techniques. It is considerably less sensitive to microphonic noise than is the bridge. It is recommended for use in reflection‐type cavity spectrometers.

ISSN:0034-6748    

DOI:10.1063/1.1717463

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The focusing properties of a three‐element quadrupole lens system have been studied, and the results of thicklens calculations are presented in the form of graphs showing the field‐strength parameters and magnifications, as functions of object and image distances.

ISSN:0034-6748    

DOI:10.1063/1.1717464

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A simple, sensitive pulse shape discriminator is described, which was designed to permit detection of low energy neutrons in the presence of a very high &ggr;‐ray background, and at high counting rates. An improvement relative to discrimination circuits published so far was obtained by incorporating a fast crystal diode switch for the separation of the fast and slow parts of the scintillator de‐excitation pulse. This device greatly reduces interference effects of nearly coincident detector pulses and also permits better pulse matching and comparison. The best discrimination was obtained for moderate sensitivity and counting rates, where out of 105detected &ggr; rays about one was erroneously admitted. A detailed description of the circuit and accessories is given, and results of test runs at a 20 Mev FM cyclotron are presented.

ISSN:0034-6748    

DOI:10.1063/1.1717465

出版商:AIP    

年代:1961

数据来源: AIP