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A Balloon Measurement of the Isotopic Composition of Galactic Cosmic Ray Boron, Carbon, and Nitrogen


Zumberge, James Frederick (1981) A Balloon Measurement of the Isotopic Composition of Galactic Cosmic Ray Boron, Carbon, and Nitrogen. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/22yw-v483.


The isotopic compositions of galactic cosmic ray boron, carbon, and nitrogen have been measured at energies near 300 MeV amu-1, using a balloon-borne instrument at an atmospheric depth of ~ 5 g cm-2. The calibrations of the detectors comprising the instrument are described. The saturation properties of the cesium iodide scintilla tors used for measurement of particle energy are studied in the context of analyzing the data for mass. The achieved rms mass resolution varies from ~ 0.3 amu at boron to ~ 0.5 amu at nitrogen, consistent with a theoretical analysis of the contributing factors. Corrected for detector interactions and the effects of the residual atmosphere, the results are 10B/B = 0.33+0.17-0.11, 13C/C = 0.06+0.13-0.01, and 15N/N = 0.42+0.19-0.17. A model of galactic propagation and solar modulation is described. Assuming a cosmic ray source composition of solar-like isotopic abundances, the model predicts abundances near earth consistent with the measurements.

Item Type:Thesis (Dissertation (Ph.D.))
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):
  • Stone, Edward C.
Group:Space Radiation Laboratory
Thesis Committee:
  • Stone, Edward C. (chair)
  • Tombrello, Thomas A.
  • Blandford, Roger D.
  • Burnett, Donald S.
Defense Date:25 February 1981
Funding AgencyGrant Number
NASANGR 05-002-160
Record Number:CaltechTHESIS:10092014-153207228
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8689
Deposited By: Ignis Nguyen
Deposited On:09 Oct 2014 23:14
Last Modified:16 Apr 2021 22:58

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