Generation of High Intensity Thermal Positron Beams Using a 20 MeV Electron Linac

We present an update on the development of a positron-facility at Argonne National Laboratory. We discuss the advantages of using a low energy electron accelerator, present our latest results on slow positron production simulations, and describe our plans for further development of the facility. We have installed a new converter/moderator assembly thai is appropriate for our electron energy and increases the yield about an order of magnitude. We have obtained a Penning trap and buncher from Lawrence Livermore National Laboratory (LLNL) that we plan to install. We have simulated the relative yields of thermalized positrons as a function of incident positron energy on the moderator. We use these data to calculate positron yields that we compare with our experimental data as well as with available literature data. We will discuss the new design of the next generation positron front end utilizing reflection moderation geometry.