Electroscope

Poland, native country of Mme. Curie) Polonium, also called Radium F, was the first element discovered by Mme. Curie in 1898 while seeking the cause of radioactivity of pitchblend from Joachimsthal, Bohemia. The electroscope showed it separating with bismuth. 

Evans, R. D. and R. W. Raitt, The Radioactivity of the Earth s Crust and Its Influence on Cosmic-Ray Electroscope Observations Made Near Ground Level. Phvs. Rev. 48(3)1171-176 (1935). 

The gold-leaf electroscope has been widely used in the past to study ionizing radiation. 

The gold-leaf electroscope has been widely used in the past to study ionizing radiation. The first measurement of the properties of ionizing radiation was accomplished with this instrument. A microscope containing a graduated scale in the eyepiece is used to observe the gold leaf. 

The newest electroscope utilizes a quartz fiber and has many advantages over the gold-leaf type. It is portable, less dependent on position, much smaller in size, and more sensitive. The capacity of the quartz fiber electroscope is about 0.2 pico-farads, and its voltage sensitivity is about one volt per division on the scale. The sensitive element is a fine gold plated quartz fiber mounted on a parallel metal support. Figure 22 illustrates a quartz fiber electroscope. 

The operation of an electroscope ionization chamber is summarized below. 

The electroscope ionization chamber is charged using a battery. 

USP 2421778 (1947), p 5 8t CA41, 5724 (1947) [El ectrostatic charges were detd by means of an electroscope for pure LA (Lead Azide), DLA (dextrinated LA), and PVA-LA (polyvinyl.alcbhoI LA), before and after tumbling. Before starting the experiment each sample was allowed to stand for 16 hours before its electrostatic charge, prior to tumbling, was measured. 

Electroscope. An apparatus for detecting electrical charges consists in its simplest form of two strips of gold-leaf attached to an insulated conductor suspended from the stopper of a glass container (See Fig on p 300 of Ref 1), When desired to determine the potential of an electrostatic charge, a so-called measuring electroscope" is used. 

POLONIUM. [CAS 7440-02-06], Chemical element, symbol Po, at. no. 84, at. wt. 210 (mass number of the most stable isotope), mp 252,JC. bp 960°C, sp gr 9.4. The element was first identified as an ingredient of pitchblende by Mane Curie in 1898. The element occurs in nature only as a decay product of thorium and uranium, Because of limited availability and high cost, relatively few practical uses for the element have been found, Meteorological instruments for measuring the electrical potential of air have used small quantities of the metal, It is interesting to note that when Mme. Curie first identified polonium, she found that an electroscope was... 

Charge Taken by Particles—Since 1909 several investigations have been made on the nature of dust electrification. Knoblauch (1901) determined the charge on particles of many different materials placed on plates of platinum, sulfur, glass, and paraffin. This dust was then dropped on a grounded copper plate and the charge noted with an electroscope connected to the different plates. Knoblauch s experiments were carefully made. He found that platinum and paraffin... 

This radiation can be detected and its intensity measured by means of the electrical conductivity which it produces in air and other gases. An electroscope suitable for measuring such conductivity is shown in Fig. 22. 

It is found that there is a small amount of conductivity in the electroscope when it is anywhere at about sea level. Part of this can be got rid of by taking the electroscope in a boat... 

Part of the remaining conductivity can be eliminated by sinking the electroscope deep in the lake so that it is surrounded on all sides by a large thickness of water. The remaining conductivity is believed to be due to radiation emitted by the electroscope itself. 

Instead of sinking the electroscope in deep water it may be surrounded by thick walls of lead or iron. 

Experiments like these were first done by McLennan and Burton about 1903. Hess in 1911 and 1912 took such an electroscope up in a balloon. He found that the conductivity decreased at first up to a-height of about 3300 feet, but then began to increase, and at 16,500 feet was two or three times that on the ground. 

It is found that the decrease in intensity of the radiation due to sinking the electroscope in water is very nearly the same as that due to sinking it through an equal weight of air. Water... 

In 1929 Regener reported very exact measurements with an electroscope in Lake Constance in Switzerland. He was able to detect the radiation even at a depth of seven hundred and fifty feet below the surface of the water. 

The following table gives the relative intensities of the radiation at different depths below the top of the atmosphere, reckoned in feet of water. The whole atmosphere is equivalent to about thirty-four feet of water. The depths given in the table are the thickness of water above the electroscope, plus the water equivalent of the air above it. 

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