Accelerator Schematic

News from Jefferson Lab

Scott Schwahn
A couple months ago, we formally tested the production ability of the Free Electron Laser (FEL) by irradiating several batches of solid ammonia and deuterated ammonia in a liquid argon dewer (to produced polarized centers in the ammonia). This was our first real chance to empirically verify the dump shielding and integral shielding which makes up the structure of the accelerator vault and above-ground user laboratory. The experiment required some analysis for radionuclide production in the liquid, releases to the air, direct radiation from the dewer (both prompt and induced), as well as full mockups for handling.

We (meaning the RadCon Group) made sure to insert ourselves into the process in the very early planning stages (even during the theory stages, where we found an error in the PC distribution of EGS4!). This effort paid off in the end and saved us a lot of trouble, as a short 4-hour run produced approximately 2E10 Bq (0.5 Ci) of Cl-39 from the (gamma,p) reaction from Ar-40. The successful cooperation of our group with the experimenters helped to reduce the time for all the planned irradiations to half of the alloted time and was a big feather in the cap of the FEL team. The targets produced will be used for an entire year's worth of experiments in Hall C.

Thanks mostly to the efforts of the Jefferson Lab User Liaison Office, Keith Welch, our Training Manager, and Becky Nevarez, our records custodian, we have a web site now. Take a look when you get a chance. We're pretty please with it, at least in concept, and are working to improve it. It includes commonly used forms, training guides, and will eventually have on-site online testing. You can find it at <http://www.jlab.org/accel/RadCon/>.

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