Abstract
We present measurements of the capture cross section for the negative ion by vortex lines in pure 4He and a 0.94 % solution of 3He in 4He. A measurable capture of positive ions was not observed in either system. In pure 4He the departure of the experimental data from the predictions of stochastic theory at lower temperatures is explained in terms of a simple breakdown in that theory, and lifetime effects are shown to be of only secondary importance. The decrease in cross section with decreasing temperature, due essentially to a reduced number density of rotons, is predicted by the results of a Monte Carlo calculation. The cross section in the solution follows stochastic theory to significantly lower temperatures, but at about 1 K there again occurs a marked discrepancy. Measurements of the ion trapping lifetime at low temperatures indicate that it is the finite lifetime that accounts for this discrepancy. Elimination of lifetime effects results in fair agreement between the cross section data in the solution and the predictions of stochastic theory.
Original language | English |
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Pages (from-to) | 159-179 |
Number of pages | 21 |
Journal | Journal of Low Temperature Physics |
Volume | 20 |
Issue number | 1-2 |
DOIs | |
State | Published - Jul 1975 |
Externally published | Yes |