A repeatable technique for preparation of thin, self-supporting copper films has been developed at the Lawrence Radiation Laboratory in Livermore, California. The process, done in a vacuum chamber, involves evaporation of copper by electron bombardment, and deposition of the copper on a detergent-coast glass substrate. The copper film is later removed from the substrate by immersion in water.

This paper reports the chemical and physical properties of the NTA film packet. It correlates with these properties the response of this packet to neutrons of various energies. In this correlation the concept of the track unit is introduced as a basic unit for reporting film-packet response.

The guiding center motion and the adiabatic invariants of charged particle trajectories in electromagnetic fields are treated in this review. General and specific theories of charged particle motion are also reviewed.

Figures 1 and 2 summarize total decay energies for the four radioactive series. The alpha-decay energy obtained by measuring the energy of the alpha particle leading to the ground state includes the energy of the recoil nucleus. The curve shown in figure 3 defines in broad outline the conditions and regions of alpha instability. A great deal more is to be learned from a more detailed examination of the region where alpha radioactivity is prominent. Of great value to the experimentalist is that he is able to predict alpha energies, and the agreement between predicted and measured values often serves as a criterion for isotopic assignment. A number of systems for correlating alpha decay energies have been employed, and that perhaps most widely used is illustrated in figure 4. Here the isotopes of each element on a mass number vs. energy plot are joined, resulting in a family of curves which over a wide region comprise a series of nearly parallel lines.

An easy experiment for undergraduate students to measure the mass and diameter of a copper atom can be performed with inexpensive apparatus normally available any college physics laboratory. By measuring the density and by copperplating, one can obtain results which are accurate to better than 5%.