Stark-PerturbedLαDecay in Flight

Abstract

The ${\mathrm{L}}_{\alpha }$ decay in flight of a 150-keV beam of single-foil-excited hydrogen atoms was tracked with a Geiger-Muller counter transversely viewing successive cylindrical segments of the beam as the counter was moved downstream. An adjustable transverse magnetic field encompassing both the foil and viewing regions produced Stark-induced ${\mathrm{L}}_{\alpha }$ intensity oscillations. The experimental fluctuation frequency disagrees with a previously published measurement of Bickel but agrees well with the usual Bethe-Lamb theory of Stark quenching. No frequency doubling effect is found. New information about foil collision dynamics emerges from studying the phase of the fluctuation patterns and the decay rates of the observed radiation. Our conclusion concerning relative $s_{\frac{1}{2}}$- and $p_{\frac{1}{2}}$- state populations is also in disagreement with the earlier work.