Abstract
AbstractIn order to progress positron and antimatter related research, it is highly desirable to develop options for intense sources of positrons capable of fueling positron beams with >107 positrons/sec. At the Center for Materials Research at Washington State University, we are investigating 13N as a positron source based on the nuclear reaction 12C(d,n)13N. Based on cross section data and earlier tests a source activity of about 11 mCi per μA of 3 MeV deuterons can be achieved. At 300 μA a 3 (4) MeV Van de Graaff accelerator will generate 1.2 (2.0) × 1011 positrons/sec in a graphite target. Several methods of utilizing this production rate for moderated positron beams have been tried. These include single crystal CVD diamond, high and low density graphite, frozen source gases, tungsten foil moderation and solid gas moderation. To date, the most successful approach yielded ∼105 moderated positrons per second – efficient moderation of the source flux has not been accomplished. We will present the current status and discuss possible reasons for the poor performance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Published Version
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