Positron beam

We have built a dc beam of positrons. After moderation in solid neon the positrons are magnetically guided away from the source,  through what will be our buffer gas trap, and onto a phosphor screen, located in front of a CCD camera.

Below is a typical image we have recorded of our positron beam.


The beam has a roughly doughnut-shape, which is determined by the shape of the neon moderator (the moderator has a hollow centre, and so there are fewer of the slow positrons that we detect in the centre of the beam). This beam structure is highlighted in the following figure which shows the recorded beam intensity along a line (shown in the above figure).


In this experiment we are recording around 2 million positrons per second, several metres downstream of the source.

This is an important step forward in our experiment. The next step will be to accumulate positrons in our trap, and then accelerate them onto a target for Ps production.

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