摘要:

A hot uranium purifier for hydrogen (or deuterium) has been constructed which will remove relatively large amounts of negative ion forming impurities such as O2, Cl2, H2O, thus permitting electron pulse collection without any elaborate outgassing procedure. The method has been tested at 6 atmospheres hydrogen pressure by observing the pulse distribution from a Pu239&agr;‐source in the chamber and plotting the ``most‐probable‐pulse‐amplitude'' against purifying time. A ``purifying time constant'' of about two days was obtained.

ISSN:0034-6748    

DOI:10.1063/1.1746013

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The requirements that must be met by a satisfactory dee biasing system are outlined. A successful and simple means of meeting these requirements is described.

ISSN:0034-6748    

DOI:10.1063/1.1746014

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The Knorr‐Albers microphotometer has been modified to permit the application of the trapezoidal rule to the measurement of the true areas of photographically recorded figures of irregular shape. These modifications include a vertical plate‐elevating mechanism and a timer controlled by a cam and roller microswitch.

ISSN:0034-6748    

DOI:10.1063/1.1746015

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

Stacks of photographic plates have been used to analyze the continuous spectrum of high energy protons emitted by a carbon target bombarded with &ggr;‐rays from an electron synchrotron. The planes of successive plates in a stack lay at 30° to a line through plate and target centers, and the plates were interleaved with aluminum absorbers. The numbers of proton tracks per square cm in the emulsions of successive plates yield an integral spectrum of the protons. Protons with energies up to more than 120 Mev were present when the synchrotron was operated at 195 Mev. The effects of multiple scattering of the protons in the stacks are discussed, and it is shown how the tracks of protons originating from the target can be distinguished clearly from a background of randomly oriented tracks.

ISSN:0034-6748    

DOI:10.1063/1.1746016

出版商:AIP    

年代:1951

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1746017

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The design and performance of a feedback amplifier for the precision control of the current through a 40‐kw magnet is described. The system uses the difference between theIRdrop in a standard resistor and a preset potentiometer voltage to control the current. The principal components are a high gain vibrator amplifier and a stabilized power amplifier incorporating a commercial motor‐generator set. Current fluctuations are kept below one part in a million.

ISSN:0034-6748    

DOI:10.1063/1.1746018

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The present form of the accelerated and stopped flow methods for the measurement of the reaction kinetics and spectra of intermediate compounds in biochemical reactions is described. This apparatus gives satisfactory records with only a few tenths of a cubic centimeter of 2×10−7M iron enzyme solution and covers a time range from a few milliseconds to several minutes. The wavelength range is 370 to 600 m&mgr;, and the spectral interval is 7.5 m&mgr;. The error in optical density measurement is about 1×10−5corresponding to a signal‐to‐noise ratio of 5×104for a response time of 1 sec over the wavelength range of 380–580 m&mgr;. The present performance and range of usefulness considerably exceed that reported previously.

ISSN:0034-6748    

DOI:10.1063/1.1746019

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

The stabilization of the light sources and the photocell circuits of a quartz spectrophotometer and the design of suitable stopped flow apparatuses are described. The latter have been designed for 1.6‐ and 10‐mm optical paths and have been shown to give rapid mixing (<0.1 sec). Errors of optical density measurement are diminished by rectangular observation tubes, and errors of extinction coefficients are minimized by a narrow spectral interval (less than 2 m&mgr; from 230–600 m&mgr;). The error of optical density caused by the photoelectric circuits is about 1×10−4for a response time (10–90 percent) of 1 sec. The application of this apparatus to the measurement of rapid chemical reactions in the visible and ultraviolet regions is described.

ISSN:0034-6748    

DOI:10.1063/1.1746020

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

An apparatus for accurately timing the sequence of spectroscopic events in turbid suspensions of the cytochrome oxidase system has been developed. This apparatus measures simultaneously small optical density changes occurring at two wavelengths in the visible region with a small spectral interval in spite of the large scattering of light by the heart muscle suspensions. The cross talk between the two channels corresponds to an optical density change of less than 5×10−4. Transients arising from the modulation and demodulation processes cause no difficulty. The error of optical measurements caused by the noise level in the photocurrent is 2×10−4for a rise time (10–90 percent) of 1 sec. Some typical experimental results are included.

ISSN:0034-6748    

DOI:10.1063/1.1746021

出版商:AIP    

年代:1951

数据来源: AIP

摘要:

A radiation detection instrument, employing a large naphthalene‐anthracene crystal and a concentric conical collimator, for the localization of radioactive concentrations at a distance is described. A simplified method of obtaining the general outline of volumetric distributions of radioiodine is presented.

ISSN:0034-6748    

DOI:10.1063/1.1746022

出版商:AIP    

年代:1951

数据来源: AIP