Abstract
Systematic studies of the phase and density dependence of the delayed annihilation time spectra of antiprotons (DATS) in gaseous, liquid, and solid helium have been performed using the low energy antiproton ring at CERN. The results show a small but significant dependence of DATS on the phase and density of the helium medium. The average lifetime of antiprotons ([ital T][sub [ital a][ital v]]) in gas at 10--30 K was found to be 4.03[plus minus]0.02 [mu]s. In liquid helium [ital T][sub [ital a][ital v]] decreases with density from 3.0 [mu]s at 1 bar to 2.5 [mu]s at 60 bars, while in solid helium its value is 2.14[plus minus]0.03 [mu]s, 20% shorter than that in liquid helium of the same density. There is no change of DATS betweeen normal 1-bar liquid and superfluid helium. An isotope effect between [sup 4]He and [sup 3]He similar to the one previously observed in the gas phase has also been found for liquid helium. All the data can be fitted fairly well with a simple three-level chain decay model with describes the general structure of DATS, characterized by downaward curving behavior on a logarithmic scale at later times and by the presence of a short-lived component.more » No delayed annihilation was observed in lithium.« less
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Physical review. A, Atomic, molecular, and optical physics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.