Alpha particles early experiments

Also in the early 1900s Ernest Rutherford performed his famous Gold Foil Experiment. Rutherford set up an experiment in which a radioactive substance released alpha particles. These particles were aimed at a thin sheet of gold foil. A screen coated with zinc sulfide was set up around the gold foil to detect the alpha particles when they hit the screen. Rutherford s experiment... 

Please also excuse errors in summarizing the earlier experiments. Information about these was obtained by reading the literature and by reading review articles by the relevant authors, as I was not in the field yet. In particular, I will be making use of the information in Early Developments in Radiation Chemistry edited by Jerzy Kroh, a book that collected the personal accounts of many of the most prominent radiation chemists of the middle of the 20th century, and The Chemieal Effects of Alpha Particles and Electrons by Samuel C. Lind, which discussed much of the radiation chemistry up to 1928. 

The discussion in this section is primarily based on Lind s book. Much of the early work in radiation chemistry was done either with radium sources and/or radon sources. These sources produced primarily alpha rays and weak beta rays. The lack of penetrating power of these particles made early experiments very difficult. 

As early as 1903, Ramsay demonstrated that helium was a product of the radioactive disintegration of radium. His experiment was an early example of the transmutation of one element into another. Today, helium is used as a source of bombarding particles in modern atom smashers. The helium nucleus—stripped of the atom s two electrons—is a common product of radioactivity and is known also as an "alpha particle. ... 

Most metals except the alkalis and alkaline earths can be electroplated at the cathode with suitable applied voltage from acid solutions. Relatively early experience with electrodeposition of various metals is summarized in Fig. 3.9. The process typically is applied for carrier-free or low-concentration samples to prepare sources for alpha-particle spectral analysis. It is also useful for depositing thin sources for counting radionuclides that emit beta-particles with low maximum energy. 

As usual, Fermi hewed the neutron experiments by hand. In February and early March he personally assembled crude Geiger counters from aluminum cylinders acquired by cutting the bottoms off tubes of medicinal tablets. Wired, filled with gas, their ends sealed and leads attached, the counters were slightly smaller than rolls of breath mints and a hundred times less efficient than modern commercial units, but with Fermi to operate them they served. While he built Geiger counters he asked Rasetti to prepare a neutron source in the form of polonium evaporated onto beryllium. Since polonium emits relatively low-energy alpha particles, the resulting source emitted relatively few neutrons per second, and Fermi and Rasetti irradiated several samples without success. 

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