The possibility of utilizing the high inherent sensitivity of the FP-54 Pliotron in nuclear disintegration-studies, particularly in connection with the problem presented by the discrepancies in present experimental results on resonance-disintegration of aluminum, has been investigated. The usable sensitivity of the tube is found to be limited only by a residual fluctuation of about ±3×${10}^{-5\mathrm{}}$ root-mean square volt. A theoretical consideration shows that this fluctuation is of the order of magnitude to be expected from shot-effects and thermal effects in the grid-circuit.

Disintegration-Experiments on Aluminum.—Preliminary observations on the disintegration of aluminum when using a thick target gave the following results. The yield was about 20 protons, of ranges between 30 and 50 cm per ${10}^8$ $\alpha$-particles, in good agreement with the results of Pose. Groups with ranges of about 30 cm and 60 cm were found to show the abrupt drop in the absorption-curve characteristic of Pose's results. (The present series of observations failed for purely technical reasons to give a conclusive result in the range 45 to 50 cm.) A "differential" curve neglecting the smallest deflections gave a maximum in the region 45 to 50 cm, suggesting the presence of a strong group of about this range. A discussion of other discrepancies in experimental data on the basis of FP-54 results must await further observations with a more suitable $\alpha$-particle source.

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