Direct Measurement of the Effect of Polarization on Energy Loss

The energy losses suffered by 15.7-Mev electrons in traversing samples of about one gram per ${\mathrm{cm}}^2$ of absorber in gas and solid form have been measured. Two pairs of absorbers have been used; perfluorocyclobutane gas and its polymer, tetrafluoroethylene resin, "Teflon," and chlorotrifluoroethylene gas and its polymer, "Kel-F" plastic. The losses measured were of the order of one Mev and the resolution of the apparatus made possible an accuracy of 20 kev. The measured losses compared with theoretical predictions are as follows: Teflon—gas 1.33 Mev by experiment and 1.33 Mev by theory, solid 1.27 Mev by experiment and 1.24 Mev by theory; Kel-F—gas 1.29 Mev by experiment and 1.33 Mev by theory, solid 1.09 Mev by experiment and 1.11 Mev by theory.