摘要:

An instrument for time‐resolved spectroscopy with an effective time resolution capability of 2×10−7sec has been built using a pulsed photomultiplier and the stroboscopic time resolution technique. Because of the higher voltages allowable in pulsed operation, the photomultiplier gain is found to be increased by more than two orders of magnitude and the dark current is reduced by a factor of about five. Therefore, the apparatus is very useful for analyzing weak fluorescence and absorption spectra of microsecond duration. Fluorescence rise and decay times of fractions of a microsecond have also been measured. The instrument was found to be very suitable for analyzing the fluorescence properties of rare‐earth chelate laser materials.

ISSN:0034-6748    

DOI:10.1063/1.1719320

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

H3+ions gave an abnormally high cross section for dissociation to H2+and a high secondary‐electron yield on copper‐beryllium. These ions were produced by a hydrogen ion source which is excited by a radio frequency voltage and is aperture extracted. To produce these ions this source was operated at low pressure and in a high magnetic field. It is assumed that such ions are vibrationally excited. Production of the various ions was studied as a function of source magnet field, rf voltage, and geometry. In addition to H+, H2+, and H3+, H5+was detected. The secondary‐electron yield of H2+from H3+on H2was measured for different source conditions.

ISSN:0034-6748    

DOI:10.1063/1.1719321

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A military surplus ``Snooperscope'' has been converted into a stroboscopic shutter for the study of plasma oscillations. Some modification of the surplus item plus the adaptation of commercially available electronic gear has given a device with which periodic fluctuations in the light output of a plasma in the frequency range 103to 106cps can be stroboscopically ``stopped'' and studied. The electric circuits permit a ``lock on'' to a reference signal obtained from the plasma. In this fashion, the stroboscopic shutter will operate even though the plasma oscillations have a frequency jitter greater than 10%. An example of how the device has been used in an investigation of moving striations is given. Other possible uses in the study of plasmas are suggested.

ISSN:0034-6748    

DOI:10.1063/1.1719322

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The total neutron cross sections of representative, single‐crystal samples of bismuth and quartz have been measured at room and liquid nitrogen temperatures over the neutron energy range of 0.0007 to 2.0 eV to obtain data for the design of single‐crystal filters for attenuating fast neutrons and gamma rays in reactor beams. The epithermal neutron and gamma‐ray transmissions of these crystals, calculated from cross sections given in various compilations, are also presented graphically. From this information, filters composed of one or both crystals may be constructed to optimize beam characteristics for low energy neutron experiments. The design and performance of the 32‐cm bismuth, single‐crystal filter at the Danish DR‐3 reactor are described. The average thermal transmission of a typical reactor beam through this filter is 16%. In the wavelength region from 5 to 15 Å, the transmission is 72%. Neutron intensity in the resonant energy region is attenuated by a factor of 5000, and gamma rays of all energies by more than 5×105. The filter improved the Cd ratio of the reactor beam by a factor of 800.

ISSN:0034-6748    

DOI:10.1063/1.1719323

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The ion bombardment camera, designed specifically for orientation determinations, is machined from clear acrylic plastic and incorporates an ion source of the glow discharge type. A plastic orienting sphere, illuminated from within, has engraved on it the low index directions of cubic crystals. Hemispherical collectors, bearing ejection patterns, are positioned on the sphere and the orientation of the crystals may then be immediately observed.

ISSN:0034-6748    

DOI:10.1063/1.1719324

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A multiple molecular beam technique is described in which a series of beams are used in parallel in a single apparatus to increase total beam intensity while retaining a high sensitivity to small deflections. The particular arrangement used had a single source slit and multiple collimator and detector slits arranged such that 19 beams transversed the three meter machine, each 0.012 mm wide at the collimator and spaced 0.032 mm apart.

ISSN:0034-6748    

DOI:10.1063/1.1719325

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Two devices are described which permit sensitive circular dichroism measurements to 185 m&mgr; in a Beckman DK‐2A recording spectrophotometer. One device consists of a special cell holder which fits into the sample compartment of the spectrophotometer; the other device is an adaptation of the electro‐optic technique of Grosjean and Legrand to the DK. Both devices are readily detached from the spectrophotometer.

ISSN:0034-6748    

DOI:10.1063/1.1719326

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

This report covers a new method of displaying the signal from a beam‐induction electrode signal in a synchrotron. A dual‐axis time display is produced by using a ramp and a series of trigger pulses, generated from the rf, to produce a raster on an oscilloscope. The results give a picture that retains the details of a fast sweep and at the same time covers a relatively long time period.

ISSN:0034-6748    

DOI:10.1063/1.1719327

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A chemisorption detector for hydrogen has been developed. The device depends upon the change in work function of a palladium filament when it is exposed to hydrogen. The detector is effective over the pressure range of 10−5to 10−8Torr. The system has been checked for sensitivity to other gases, i.e., O2and N2; it responds strongly to O2and weakly to N2.

ISSN:0034-6748    

DOI:10.1063/1.1719328

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

We describe a 4‐kMc waveguide load which radiates an effective noise temperature (approximately 5°K) known to within a small fraction of a degree Kelvin. The absorber is immersed in liquid helium and the temperature distribution along the guide is measured by means of an array of germanium diode thermometers.

ISSN:0034-6748    

DOI:10.1063/1.1719329

出版商:AIP    

年代:1965

数据来源: AIP