Positrons!

We now have our 22Na source installed in the chamber.

This photograph shows the source on the far left-hand side (encased in lead bricks). The emitted positrons are moderated in solid neon and are then magnetically guided through the vacuum chamber towards the trap (toward the right of the image, next to the gas cylinder).

DSC_0275

This plot shows how the moderator is grown by injecting neon gas in the source chamber up to a pressure of around 10^-4 mbar (red, dashed). The 22Na source is housed on the top of a cold head, maintained at around 7 K (blue). This is cold enough for the neon to freeze, which it does inside an aperture directly in front of the source. This solid block of neon forms the moderator which slows down the emitted positrons to speeds where we can easily guide and trap them. mod_3 The black curve shows the growth in detected slow positrons as the moderator is formed. The positrons are measured downstream of the source, directly in front of the trap.

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