BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:0 UID:UW-Physics-Event-2350 DTSTART:20120217T213000Z DURATION:PT1H0M0S DTSTAMP:20260420T062822Z LAST-MODIFIED:20111206T223055Z LOCATION:2241 Chamberlin Hall (coffee at 4:30 pm) SUMMARY:Plasma Techniques Used to Trap Antihydrogen[1]\, Physics Depar tment Colloquium\, Joel Fajans\, University of California\, Berkeley DESCRIPTION:

Recently\, the ALPHA collaboration at CERN trapped anti hydrogen atoms.[2] To date\, over three hundred antiatoms have been co nfined\, some for as long as 1000s.[3] This was the first time that an ti-atoms had ever been trapped. The ultimate goal of the ALPHA collabo ration is to test CPT invariance by comparing the spectra of hydrogen and antihydrogen\, and to measure the gravitational attraction between matter and antimatter. Such studies might resolve the baryogenesis pr oblem: why is there very little antimatter in the Universe? The ALPHA experiment brought together techniques from many different fields of p hysics\, but the crucial breakthroughs were in plasma physics. The ess ential problem is this: How does one combine two Malmberg-Penning trap ped plasmas\, one made from antiprotons\, and the other positrons\, wh ich have opposite electrostatic potentials of nearly one volt\, in suc h a manner that the antiprotons traverse the positrons with kinetic en ergies of less than 40μeV\, this latter being the depth of the superi mposed neutral antihydrogen trap? The plasma techniques ALPHA develope d to accomplish this include: \n

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  • Minimizing the effects of the neutral trap multipole fields on the positron and anti proton plasma confinement.
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  • Compressing antiprotons down to less than 0.5mm.
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  • Using autoresonance to inject antiprotons into the positrons with very little excess energy.
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  • Evaporat ive cooling of the electrons and antiprotons to record low temperature s.
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  • Development of charge\, radial profile\, temperature\, a nd antiproton loss location diagnostics.
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  • Careful and length y manipulations to finesse the plasmas into the best states for optima l antihydrogen production and trapping.
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    \nThe plasma techn iques necessary to trap antihydrogen will be reviewed in this talk.

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    \n[1] This work was supported by DOE and NSF\, and is repo rted on behalf of the ALPHA collaboration. \n
    \n[2] Trapped antih ydrogen\, Nature\, 468\, 673\, 2010. \n
    \n[3] Confinement of antih ydrogen for 1000 seconds\, Nature Physics\, 7\, 558\, 2011. \n

    URL:https://www.physics.wisc.edu/events/?id=2350 END:VEVENT END:VCALENDAR