Metastable lifetime measurements on levels of highly charged ions /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1992.
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| Subjects: | |
| Online Access: | Link to ProQuest copy Link to OAKTrust copy |
| Abstract: | Measurements of the mean lives of selected metastable levels of multiply-charged ions have been completed by observing the corresponding magnetic dipole (M1) or electric quadrupole (E2) transitions. The ions were certain charge states of 3.5q keV Ar[^q+] (2 < q < 13) ions extracted from the Electron Cyclotron Resonance (ECR) ion source at the Texas A&M University Cyclotron Institute. The ions were produced in metastable states in the source and injected into an electrostatic ion trap (Kingdon Trap). The visible or UV photon emission from the forbidden decays was detected by a photomultiplier while the ions were confined in the trap. A fraction of the ions ejected from the trap at various storage times was detected by a microchannel plate located approximately 1 inch away from the trap to provide a measure of ion storage time, which was used to correct the measured metastable lifetimes. The corrected metastable lifetime τ[0]=159.7 [plus or minus] 9.7 ms for the Ar[^2+] 1S[0] level was in good agreement with theoretical predictions and previous measurements. Systematic tests showed no dependence of the measured lifetime on the number of stored ions or electric field strength inside the ion trap. Metastable lifetime measurements of Ar[q+] ions were made possible for charge states q > 2 for the first time. The final results obtained for the Ar[9+] 2P[1/2] level and the Ar[^10+] 3P[1] level radiative lifetimes were 8.53 [plus or minus 0.24 ms and 14.8 [plus or minus] 1.1 ms respectively, which were also in good agreement with theoretical calculations. Linear dependence of the reciprocal metastable lifetimes vs. background gas (Ar or N2 pressure yielded total metastable loss rates for the metastable levels investigated. Results are presented in Sections V.2 and V.3. Metastable radiations were also observed from the Ar[^3+] 2P[3/2,1/2] and Ar[4+] 1S[0] levels at wavelengths near 2860A and 4625A respectively. However specific experimental complications require further measurements in order to obtain the decay lifetimes of these levels with comparable precision. |
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| Item Description: | "Major subject: Physics." Vita. |
| Physical Description: | xii, 108 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |