Zur Energieabhängigkeit der Wirkungsquerschnitte für die Anregung von Singulett-Zuständen des Heliums durch schnelle Protonen

Abstract

The energy dependence of then ¹ S (n=3, 4, 5),n ¹ D-(n=3, 4, 5) andn ¹ P (n=3, 4) levels of helium excited by protons has been determined in the energy range from 100 keV to 1 MeV. The measurements are compared with the other experiments in the same energy range and with the results of calculations using the first Born approximation.

This comparison shows that the first Born approximation is not valid below 1 MeV proton energy, except perhaps below 500 keV for then ¹ P-levels. It demonstrates the necessity for more accurate absolute measurements in the 100 keV-region and above 1 MeV proton energy.