Abstract
Trapping technologies of positrons, the antimatter counterpart of electrons, are indispensable for various atomic, molecular, and optical experiments and for material analyses that use ...positron swarms. Efficient trapping of high-intensity positron beams generated by electron linear accelerators (LINACs) will improve the quality and throughput rate of experiments but have yet to be practically realized. In the present work, we demonstrate the efficient trapping and extraction of a LINAC-based positron beam by using a silicon carbide (SiC) remoderator with a center hole. The positron beam was remoderated by 4H-SiC wafers in the back-reflection geometry followed by accumulation in an electromagnetic trap with CF
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cooling gas. A rotating electric field was driven to spatially compress the accumulated positrons, enabling the lossless extraction of the positrons through the SiC hole. A trapping efficiency in the higher 20% range was achieved. The proposed trapping scheme employing a center-hole SiC remoderator is thus a practical technique to accumulate and cool positron beams generated by LINACs.
A buncher and a magnetic lens were introduced to improve the beam flux density of a pulsed positron beam extracted from the low energy positron accumulator at National Institute of Advanced ...Industrial Science and Technology (AIST). The buncher made the pulse width ~ 1/4 and the magnetic lens reduced the beam cross section ~ 1/9, which resulted in about 36 times increase in the beam flux density. Possible applications for electron-positron plasma experiments are also discussed.
A detailed experimental study has been conducted to demonstrate the efficient confinement of ions in the popular four-rod configuration of a linear Paul trap without exciting the transverse ...radio-frequency (rf) quadrupole field. The three-dimensional (3D) ion confinement is achieved with an identical rf voltage applied to the end electrodes. The optimum operating region is visualized in the stability tune diagram, which indicates that a large number of ions can be stored by adjusting a few fundamental parameters. The lifetime of an ion cloud in the present linear trap is over a second (corresponding to a million rf cycles), long enough for various practical applications. It is also shown through 3D numerical simulations that one can easily extract ions from the trap at a low loss rate below 10%.
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