Patent Number: 047524324
Section: summary

DESCRIPTION 1. Technical Field This invention relates to a device and process for the direct production of nitrogen-13 ammonium ion in an aqueous or other fluid solution from a carbon-13 fluid slurry target. 2. Background Art Nitrogen-13 is commonly used in scanning operations where it is introduced into the body and monitored by state-of-the-art techiques. It is desirable to produce nitrogen-13 by a relatively simple process. Known prior art methods teach the use of natural water in a batch or recirculating mode to produce predominantly nitrogen-13 oxides. These oxides must be chemically reduced in a basic solution to ammonia which is then distilled and collected. Prior devices and methods employing this approach produce added complexity, chemical losses, and processing time with concomitant, crucial radioactive decay loss. In addition, the p,.alpha. nuclear reaction on natural water has a much lower probability of occurrence for low energy protons than the p,n reaction on carbon-13 in the target original employed in the present invention. Accordingly, it is an object of the present invention to provide a slurry target capable of generating a high yield of nitrogen-13, and the direct production of the desired chemical form in a simple continuous flow collection which precludes complex chemical processing and radioactive decay losses. It is another object of the invention, with the utilization of 10.2 MeV protons entering the target at a beam current of 20 .mu.A, to produce about 175 mCi of nitrogen-13 ammonium ion in a time period of 10 minutes. In the prior art, a typical larger cyclotron (16 MeV) produces nitrogen-13 using 20 .mu.A of protons on natural water; and after chemical reduction, about 175 mCi of ammonium ion is available in a time period of about 25 minutes after the initiation of bombardment. Therefore, the slurry target of the present invention produces in one embodiment about the same activity in about half the time using two-thirds of the proton energy. It is a further advantage of the present invention that the enriched carbon-13 inventory employed as a constitutent part of the fluid slurry target is not expended since it remains fixed in the target for subsequent production runs.