| Article | |
| Report number | CERN-PPE-95-162 |
| Title | Isotope Effects on Delayed Annihilation Time Spectra of Antiprotonic Helium Atoms in Low-Temperature Gas |
| Author(s) |
Ketzer, B (Phys. Dep., Technische Univ. München, Germany) ; Hartmann, F J (Phys. Dep., Technische Univ. München, Germany) ; Daniel, H (Phys. Dep., Technische Univ. München, Germany) ; Von Egidy, T (Phys. Dep., Technische Univ. München, Germany) ; Niestroj, A (Phys. Dep., Technische Univ. München, Germany) ; Schmid, S (Phys. Dep., Technische Univ. München, Germany) ; Schmid, W (Phys. Dep., Technische Univ. München, Germany) ; Yamazaki, T (Inst. for Nuclear Study, Univ. of Tokyo, Japan) ; Sugai, I (Inst. for Nuclear Study, Univ. of Tokyo, Japan) ; Nakayoshi, K (Inst. for Nuclear Study, Univ. of Tokyo, Japan) ; Hayano, R S (Dep. of Phys., Univ. of Tokyo, Japan) ; Maas, F E (Dep. of Phys., Univ. of Tokyo, Japa) ; Torii, H A (Dep. of Phys., Univ. of Tokyo, Japa) ; Ishikawa, T (Dep. of Phys., Univ. of Tokyo, Japa) ; Tamura, H (Dep. of Phys., Univ. of Tokyo, Japa) ; Morita, N (Inst. for Molecular Science, Myodaiji, Japan) ; Horváth, D (KFKI Research Inst. for Particle and Nuclear Phys., Budapest, Hungary) ; Eades, John (CERN) ; Widmann, E (CERN) |
| Publication | 1996 |
| Imprint | 16 Nov 1995 |
| Number of pages | 19 |
| In: | Phys. Rev. A 53 (1996) 2108-2117 |
| DOI | 10.1103/PhysRevA.53.2108 |
| Subject category | Other Fields of Physics |
| Accelerator/Facility, Experiment | CERN LEAR ; PS205 |
| Abstract | The delayed annihilation time spectra (DATS) of antiprotonic helium atoms have been studied in isotopically pure low temperature ^3He and ^4He gas at various densities. The DATS taken at 5.8 K and 400 mbar are very similar in shape except for i) a small difference in the time scale and ii) the presence of a distinct fast decay component in the case of ^3He. The ratio of overall trapping times (mean lifetimes against annihilation), R = T_{\mathrm{trap}}(\mbox{^{4}He})/T_{\mathrm{trap}}(\mbox{^{3}He}), has been determined to be 1.144 \pm 0.009, which is in good agreement with a theoretical estimate yielding R = [(M^*(\mbox{\overline{\mathrm{p}}}\mbox{^{4}He})/ M^*(\mbox{\overline{ \mathrm{p}}}\mbox{^{3}He})]^2=1.14, where M^* denotes the reduced mass of the \mbox{\overline{\mathrm{p}}}\mbox{He^{++}}\ system. The presence of a short-lived component with a lifetime of (0.154\pm 0.007)\ \mbox{\mus} in the case of \mbox{^{3}He}\ suggests that the \mbox{\overline{\mathrm{p}}}\mbox{^{3}He^{+}}\ atom has a state of intermediate lifetime on the border between a metastable zone and an Auger-dominated short-lived zone. The fraction of antiprotons trapped in metastable states at 5.8 K and 400 mbar is lower by 22.2(4)\% for \mbox{^{3}He}\ than for \mbox{^{4}He}. All the data can be fitted fair |
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Zapis kreiran 1995-11-30, zadnja izmjena 2018-09-24
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