摘要:

A high precision adiabatic gamma‐ray calorimeter is described. For most gamma‐ray sources, the calorimeter walls are thick enough to absorb more than 99% of the gamma rays emitted by the source being measured. The standard deviation of the mean in the measurement of a half‐curie Co60source was 0.2%; that of a half‐curie radium source was 0.03%.

ISSN:0034-6748    

DOI:10.1063/1.1717601

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The bipolar output of the rf phase detector of the receiver in a nuclear magnetic resonance pulse experiment is fed through a 4‐diode sampling switch to an RC integrator, whose output is read by a recording electrometer. The switch (a ``transmission gate'') includes two type 7266 ceramic thermionic diodes, whose back resistance is extremely high (> 1012&OHgr; at −50 v). The Mylar integrating capacitor, therefore, discharges so slowly between successive sampling gates that the typical holding time with a 0.01‐&mgr;f capacitor is ∼10 min. A simple method is given for using the ``boxcar'' as a sampling oscillograph for slowly and automatically plotting the entire boxcar input signal as it is seen on a cathode ray oscilloscope, but with the noise integrated out. There is a detailed discussion of circuitry, components, and performance.

ISSN:0034-6748    

DOI:10.1063/1.1717602

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A high vacuum device has been designed and constructed for the investigation of luminescence from powdered or single luminophor samples when excited by several means. In the present design, many samples can be investigated at temperatures both above and below that of ambient without the necessity of breaking the vacuum of the system. The samples may be excited either by an electron beam, a beam of electromagnetic radiation, or co‐excited by both.

ISSN:0034-6748    

DOI:10.1063/1.1717603

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A device has been built which, without requiring intra‐arterial puncture, automatically constructs a calibrated upstroke of the arterial pulse wave as well as the durations and intensities of the arterial sounds. The horizontal sweep of a cathode‐ray oscilloscope is triggered by the electrocardiogram. The vertical axis is determined by the height of the mercury column in the sphygmomanometer. The vibration amplitude and duration of the acoustic signal are recorded as the brightness and duration of the trace during each cycle.

ISSN:0034-6748    

DOI:10.1063/1.1717604

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A total absorption NaI(Tl) gamma‐ray spectrometer has been assembled and has been tested over the range 0–10 Mev with thermal neutron capture gamma rays. It employs an 8‐in. diam by 12‐in. NaI(Tl) anticoincidence mantel. The measured width at 8.5 Mev is 3% (full width at half‐maximum). Typical spectra are presented. Measurements of efficiency, line shape, and resolution are analyzed. The usefulness of this spectrometer for analysis of complex spectra at high efficiency is demonstrated.

ISSN:0034-6748    

DOI:10.1063/1.1717605

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Although the volume charge distribution in a homogeneous substance decays exponentially with time, in general this will not be true of the electric field above a free surface of the substance, due to the formation of surface charge. This must be taken into account in using the electric field or the surface potential as a measure of the electrification, or the decrease of these quantities as a measure of the time constant of a charged sample. The formation of surface charge during charge relaxation is considered in a simple one‐dimensional case. The contribution made by surface charge to the surface potential and electric field above the surface may be large if a grounded object, such as a probe or field meter, is near the surface.

ISSN:0034-6748    

DOI:10.1063/1.1717606

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The thermal equations for a bridgewire or equivalent electroexplosive device are presented. When sinusoidal current passes through such a thermally sensitive resistance, it is capable of generating a third harmonic voltage which is a measure of the ability to follow the instantaneous cycling power fluctuations. By measuring the variation of this third harmonic with frequency it is possible to determine the thermal time constant.

ISSN:0034-6748    

DOI:10.1063/1.1717607

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A scattering chamber, consisting of a fixed cylinder upon which a cylindrical sleeve slides in helical motion, has been designed and constructed. This chamber allows continuous rotation under vacuum over an angular range from −5° to +165°. With a moderate increase in dimensions it would be practical to extend the angular range to ±175°.

ISSN:0034-6748    

DOI:10.1063/1.1717608

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A Cosslett‐Nixon type microfocus x‐ray tube has been modified for use as an electron probe microanalysis unit, producing an electron beam of adequate intensity approximately one micron in diameter. The design of the unit is discussed, and a description of the electron optical design and the associated electronic power supplies is included.

ISSN:0034-6748    

DOI:10.1063/1.1717609

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A new method for the measurement of the time dependence of the light intensity from scintillators is described. An important aspect of the method is the ease with which it can be applied to all modes of excitation. The results of measurements on the time dependence of the scintillators for several modes of excitation are presented.

ISSN:0034-6748    

DOI:10.1063/1.1717610

出版商:AIP    

年代:1961

数据来源: AIP