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Antihydrogen -- it's really cool at CERN!

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 Antiproton production and deceleration:

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Production and detection of antihydrogen in ATHENA:

Antiprotons from the AD enter the ATHENA apparatus and are slowed down by an entrance counter. As they hit the entrance counter, half are annihilated. Those with energy less than 5000eV (red second ring) will be reflected. The entrance counter goes up in voltage before the reflected antiprotons can get out again. 10'000 are trapped out of 2x107. Positrons from a sodium-22 source come from the right, they are slowed down and captured. 200 million in 5 minutes.

They are then transferred into the mixing trap.

In the mixing trap antiprotons and positrons interact and produce an antihydrogen atom. Being neutral, it is not held in the trap. It escapes and annihilates with normal matter of the trap walls. The annihilation produces two photons (red) and several charged particles (orange, mostly pions) which traverse the detector. The intersection points of the particles are then used to reconstruct their trajectories. This allows antihydrogen annihilations to be unambiguously identified.
640x480 sized QuickTime version (6.9MB) Download Quicktime

Antihydrogen production in ATRAP

Antiprotons (yellow particles) enter the trap through a degrader foil (the thin green disk) where most of the antiprotons annihilate (thus the flash when the antiprotons enter). Some fraction come out with an energy that is low enough to trap. These oscillate within the trap and eventually cool into a small well. At the same time positrons (green particles) enter from the opposite end behind the rotating electrode (gold ball). The rotating electrode is needed to allow the positrons to load without interference from the antiproton loading. When both the positrons and antiprotons have loaded, the rotatable electrode is opened and the positrons moved to the trap with the antiprotons. Once the antiprotons and positrons are in place, the antiprotons are launched into the positron cloud. The antiprotons pass through the positron cloud many times, all the time colliding with the positrons and losing energy. When the antiprotons have a low enough energy compared to the positrons there is a chance that a positrons can become bound to the antiproton forming antihydrogen.The antihydrogen is shown as a blue ball.
240x180 sized QuickTime version (18.0MB) - 160x120 sized AVI version (1.0MB) - 320x240 sized AVI version (6.0MB)
640x480 sized AVI version (7.2MB)

 

 

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