Trapping low-energy antiprotons in an ion trap
A fraction of antiprotons from the Low Energy Antiproton Ring (LEAR) of CERN are slowed from 5.9 MeV to below 3 keV as they pass through thin foils. Transmitted particle energy distribution and low energy antiproton yield are measured by a time-of-flight technique. The difference in the range of protons and antiprotons (known as the Barkas effect) is observed. While still in flight, up to 1.3 {times} 10{sup 5} antiprotons with energies between 0 eV to 3 keV are stored in an ion trap from a single pulse of 5.9 MeV antiprotons leaving LEAR, thus a trapping efficiency exceeding of 4 {times} 10{sup {minus}4} is established. Trapped antiprotons maintain their initial energy distribution unless allowed to collide with a cloud of trapped electrons, whereupon they slow and cool below 1 meV in 10 s, and fall into a harmonic potential well suited for precision mass measurements. The slowing, trapping and cooling of antiprotons are the main focus of this thesis. The stored antiprotons are in thermal equilibrium at 4.2 K. In this ion trap, the antiproton cyclotron frequency is measured and compared with the proton (or electron) cyclotron frequency. The new measured ratio of the antiproton and proton inertial masses, with its 4 {times} 10{sup {minus}8} uncertainty, is more than three orders of magnitude more accurate than previous measurements using exotic atoms. This is a most precise test of CPT invariance with baryons. The antiproton lifetime in an ion trap was measured to be more than 103 days by trapping a cloud of antiprotons for 59 days. The indicates the number density of atoms is less than 100/cm{sup 3} which corresponds to the pressure in the vacuum chamber being less than 5 {times} 10{sup {minus}17} Torr at 4.2 K if we apply the ideal gas law.
- Research Organization:
- Harvard Univ., Cambridge, MA (United States)
- OSTI ID:
- 5658999
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
74 ATOMIC AND MOLECULAR PHYSICS
ANTIPROTONS
MASS
TRAPPING
BARYONS
CPT THEOREM
COMPARATIVE EVALUATIONS
COOLING
CYCLOTRON FREQUENCY
ENERGY SPECTRA
FOILS
LIFETIME
PROTONS
TESTING
TIME-OF-FLIGHT METHOD
ANTIBARYONS
ANTIMATTER
ANTINUCLEI
ANTINUCLEONS
ANTIPARTICLES
ELEMENTARY PARTICLES
EVALUATION
FERMIONS
HADRONS
INVARIANCE PRINCIPLES
MATTER
NUCLEI
NUCLEONS
SPECTRA
662410* - Properties of Baryons & Baryon Resonances- (1992-)
662120 - General Theory of Particles & Fields- Symmetry
Conservation Laws
Currents & Their Properties- (1992-)
664000 - Atomic & Molecular Physics- (1992-)