Antiproton Capture

In order to give you an idea of how antihydrogen is actually made and trapped, we have made a small game that takes you through some key steps. You must succeed at each step to progress to the next.

In the first part you need to capture antiprotons from the AD. The animation shows how the antiprotons pass through a foil to slow them down (through collisions with the foil atoms). Once they are in the trap, the ones with low energy energy (few keV) can be captured. This is done by using a pre-erected electric potential to reflect (some of) the antiprotons back towards the entrance, and, before they all return to annihilate on the entrance foil, erect a second barrier at the entrance such that they are captured. In order to do this you need to adjust the thickness of the foil. This determines how many antiprotons pass through and have low energy and you need to adjust the timing of the gate to close after most antiprotons have passed, but before the low energy ones have reflected back.

Once enough antiprotons have been captured you pass to the second stage where you need to merge them with positrons. There are many parameters critical to this process, but in particular it depends on the number of positrons and their density. To adjust those you can adjust the radial size of the positron cloud and the number of positrons in it. The reason this process is delicate (as you will notice when you try) is that you need to make the antihydrogen at low enough kinetic energy that it’s trapped by the magnetic fields that will only hold antihydrogen colder than about 0.5 Kelvin (~50 micro eV). Once successful you’ll be shown how we can use these to do spectroscopy on antihydrogen.

Try it yourself!

Antihydrogen Trapping Game
ALPHA Trap Game