Beam detectors negative surface ionization

Fig. 18. Total cross sections Q for the production of negative ions in collisions of K, Na and Li on Br2 and Cl2, divided by the unknown energy dependent surface ionization detector efficiency / , vs. the CM-energy. The thresholds are indicated by arrows. The insets show enlargements of the thresholds. Notice the small structure at about 4eV in the Na-Cl2 cross section. The constant signal below threshold is due to the presence of dimers in the alkali beam (Baede and Los, 1971).

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