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BEGIN:VEVENT
DTSTAMP:20260816T114617Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20070227T201500Z
DTEND:20070227T220000Z
UID:event66@bu.edu
URL:http://physics.bu.edu/internal/events/show/66
SUMMARY:New Measurement of the Electron Magnetic Moment and the Fine Struct
	ure Constant
DESCRIPTION:Featuring Gerald Gabrielse\, Harvard University\nHosted by: Lee
	 Roberts\n\nPart of the Physics Department Colloquia Series.\n\nRemarkably\
	, the famous UW measurement of the electron magnetic moment has stood since
	 1987. With QED theory\, this measurement has determined the accepted value
	 of the fine structure constant. This colloquium is about a new Harvard mea
	surement of these fundamental constants. The new measurement has an uncerta
	inty that is about six times smaller\, and it shifts the values by 1.7 stan
	dard deviations.  One electron suspended in a Penning trap is used for the 
	new measurement\, like in the old measurement.  What is different is that t
	he lowest quantum levels of the spin and cyclotron motion are resolved\, an
	d the cyclotron as well as spin frequencies are determined using quantum ju
	mp spectroscopy.  In addition\, a 0.1 K Penning trap that is also a cylindr
	ical microwave cavity is used to control the radiation field\, to suppress 
	spontaneous emission by more than a factor of 100\, to control cavity shift
	s\, and to eliminate the blackbody photons that otherwise stimulate excitat
	ions from the cyclotron ground state.  Finally\, great signal-to-noise for 
	one-quantum transitions is obtained using electronic feedback to realize th
	e first one-particle self-excited oscillator.  The new methods may also all
	ow a million times improved measurement of the 500 times smaller antiproton
	 magnetic moment.
LOCATION: \, \, 
STATUS:CONFIRMED
CLASS:PUBLIC
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