ATRAP Antihydrogen Experiments

  AIP Physics Story of the Year


Long Term Goal: Precise laser or microwave spectroscopy of trapped antihydrogen
               to make the most stringent lepton and baryon CPT tests


``When antihydrogen is formed in an ion trap, the neutral atoms will no longer be confined and will thus quickly strike the trap electrodes. Resulting annihilations of the positron and antiproton could be monitored. ..."


"... it is clear that the very low [antihydrogen production rate] will make ... experiments with antihydrogen to be very ... difficult. For me, the most attractive way ... would be to capture the antihydrogen in a neutral particle trap ... The objective would be to then study the properties of a small number of [antihydrogen] atoms confined in the neutral trap for a long time."



Gerald Gabrielse, 1986 Erice Lecture (shortly after first trapping of antiprotons), in Fundamental Symmetries, ed. by P. Bloch, et al., p. 59 (Plenum, NY, 1987)


ATRAP Simultaneously Loads Positrons and Antiprotons During a 100 Second Cycle

tick marks: 1 meter
Positron accumulator
Cold positrons and
accumulates positrons
cold antiprotons are accumulated
from a 22Na source
in Penning traps located
within a 1-3 Tesla solenoid
  (below left)
  Antiprotons come from
  the CERN Antiproton
time axis
Decelerator (AD)
storage ring
0 seconds
antiprotons load
30 seconds
positrons load
70 seconds
more positrons load
100 seconds
cycle starts over



Anihydrogen is produced
within a Ioffe trap
by either of two methods
that ATRAP developed
(method 1, method 2,
traps for antihydrogen)

Solenoid and vacuum container for the traps

Inside view of Penning traps and Ioffe trap
rotated 90 degrees clockwise


Gabrielse Group Participation in ATRAP

  • Professor Gabrielse is the ATRAP spokesperson and coordinator
  • Gabrielse group is responsible for the integration of the experiment
  • Gabrielse group is responsible for the Penning traps, particle trapping, hbar formation
  • Group is responsible for trapping, damping and detection charged particles
  • Group was responsible for conceptual design of the first generation Ioffe trap
  • Group is responsible for the second generation Ioffe trap
  • Juelich collaborators - responsible for the scintillating detectors and first generation Ioffe trap production
  • York collaborators - responsible for the positron accumulator
  • Mainz collaborators - responsible for spectroscopy lasers
  • MPQ collaborators - joining in for antihydrogen spectroscopy
  • Rowland at Harvard collaborators - laser de-excitation of antihydrogen
Note: everyone at ATRAP helps out as needed on whatever part of the project needs help, so these divisions are often blurred

Dr. Jonathan Wrubel supervises much of the Harvard activity at CERN. He designed and operated our new 1.2 K system. Philippe Larochelle is writing his thesis after demonstrating that we can non-destructively detect a single antiproton, and thus (we hope) an single antihydrogen ion. Robert McConnell is leading our efforts to see if we can trap antihydrogen atoms produced by laser-controlled charge exchange. Steve Kolthammer is building a new apparatus which includes our second generation Ioffe trap. Philip Richerme is helping with this and investigating methods of manipulating antihydrogen atoms.

Return to Gabrielse group home page
Printable narrative of Gabrielse group results (pdf, doc)
See ATRAP's latest apparatus and progress