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Electromagnetic Lifetimes of Nuclear Levels by Doppler-Shift and Recoil Methods


Gordon, David Marshall (1973) Electromagnetic Lifetimes of Nuclear Levels by Doppler-Shift and Recoil Methods. Senior thesis (Major), California Institute of Technology. doi:10.7907/RJAY-BF26.


The Doppler-shift-attenuation (DSAM) and recoil-distance methods have been used to measure electromagnetic lifetimes of nuclear levels in 16O, 26Al, 30P, 32P, 33S, 35Cl, 37Ar, 38K and 40K, and the electromagnetic transition strengths deduced from the measured lifetimes have been compared with recent nuclear-model calculations. In addition, measurements have been performed to investigate the existence and magnitude of possible systematic errors in nuclear lifetimes obtained using the gas- stopper version of the DSA technique due to localized heating of the stopping gas by the incident particle beam.

Parameters describing the rate of energy loss of heavy ions in Xe, Ar and He stopping gases have been extracted from DSAM measurements of the γ rays from the decay of the 418-keV level of 26Al, whose lifetime is well known from electronic-timing measurements. In addition, the electronic stopping cross sections for 12C and 27Al ions slowing in He and Xe gases were measured for ion energies in the range 560 ≤ E ≤ 2320 keV. Deviations from recent theoretical calculations of electronic stopping power as large as a factor of two have been observed.

Item Type:Thesis (Senior thesis (Major))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kavanagh, Ralph William
Thesis Committee:
  • Unknown, Unknown
Defense Date:9 August 1972
Funding AgencyGrant Number
Record Number:CaltechTHESIS:07112018-114139360
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11113
Deposited On:11 Jul 2018 23:33
Last Modified:21 Dec 2019 02:06

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