Die absolute Intensität der durch Elektronenstoß in einer dicken Wolfram-Antikathode erzeugtenLα-Strahlung
AbstractThe number
$$N_{L_\alpha  }^{dir} $$
 (produced) ofLα-photons produced by electron-bombardment in a thick target of tungsten per incident electron has been measured absolutely with the Ross-filter method and relatively with the crystal-spectrometer method in the energyregion up to the 3.6 times theLIII-ionization energy
$$E_{L_{III} } $$
. The result can be presented in the following empirical form:
$$N_{L_\alpha  }^{dir} $$
 (produced)=4π·ŧ·(U0−1)n with ŧ=0.52·10−4±5% andn=1.44±0.02
$$(U_0  = E_0 /E_{L_{III} }< 3.6)$$
. Out of this the number
$$n_{L_{III} } $$
 ofLIII-ionizations per electron which is slowed down to the energy
$$E_{L_{III} } $$
 within the target, has been evaluated. The computation of
$$n_{L_{III} } $$
 out of the elementary process by usingBethe's non-relativistic formulae for totalLIII-ionization cross sectionQL and energy loss-dE/ds is in full agreement with experiment in the region 2<U0<3.6, if the constants in
$$Q_{L_{III} } $$
 are chosen as follows:
$$B = 4E_{L_{III} } , b_{L_{III} }  = 0.25 \cdot 5.89$$
. By comparison of this result for
$$b_{L_{III} } $$
 with the corresponding value ofbK in the totalK-ionization cross-sectionQK for copper (bK=0.35·2.26) it is concluded that
$$Q_{L_{III} } $$
 is considerably higher than predicted by theory.The necessary correction factors as e.g. loss ofLIII-ionizations by rediffusion of electrons and portion of indirectly producedLα-radiation-radiation are determined for tungsten quantitatively.