A high efficiency photoionization detector using tetraaminoethylenes in a gaseous state having a low ionization potential and a relative photoionization cross section which closely matches the emission spectrum of xenon gas. Imaging proportional counters are also disclosed using the novel photoionization detector of the invention. The compound of greatest interest is TMAE which comprises tetrakis(dimethylamino)ethylene which has a measured ionization potential of 5.36 +- 0.02 eV, and a vapor pressure of 0.35 torr at 20/sup 0/C.

A nuclear fuel processing solution containing: (1) hydrocarbon diluent; (2) tri-n-butyl phosphate or tri-2-ethylhexyl phosphate; and (3) monobutyl phosphate, dibutyl phosphate, mono-2-ethylhexyl phosphate, di-2-ethylhexyl phosphate, or a complex formed by plutonium, uranium, or a fission product thereof with monobutyl phosphate, dibutyl phosphate, mono-2-ethylhexyl phosphate, or di-2-ethylhexyl phosphate is contacted with silica gel having alkali ions absorbed thereon to remove any degradation products from said solution. The principal impurities removed from TBP solvent by the process of this invention are monobutyl phosphate, dibutyl phosphate, UO/sub 2//sup 2 +/, Pu/sup 4 +/, and fission products of plutonium and uranium complexed with monobutyl phosphate or dibutyl phosphate. Nitric acid is also removed from the TBP solution by the treated silica gel. Conventional adsorption column techniques are applicable for the process of the invention.

A conductor and method of making the conductor are provided for use in winding electrical coils which are cooled by a fluid communicating with the conductor. The conductor is cold worked through twisting and reshaping steps to form a generally rectangular cross section conductor having a plurality of helical cooling grooves extending axially of the conductor. The conductor configuration makes it suitable for a wide variety of winding applications and permits the use of simple strip insulation between turns and perforated sheet insulation between layers of the winding.