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New Measurements on the Absolute Cosmic Ray Ionization from Sea Level to 1540 Kilometers Altitude


George, Michael James (1969) New Measurements on the Absolute Cosmic Ray Ionization from Sea Level to 1540 Kilometers Altitude. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/8VR3-1083.


An air filled ionization chamber has been constructed with a volume of 552 liters and a wall consisting of 12.7 mg/cm2 of plastic wrapped over a rigid, lightweight aluminum frame. A calibration in absolute units, independent of previous Caltech ion chamber calibrations, was applied to a sealed Neher electrometer for use in this chamber. The new chamber was flown along with an older, argon filled, balloon type chamber in a C-135 aircraft from 1,000 to 40,000 feet altitude, and other measurements of sea level cosmic ray ionization were made, resulting in the value of 2.60 ± .03 ion pairs/cm3 sec atm) at sea level. The calibrations of the two instruments were found to agree within 1 percent, and the airplane data were consistent with previous balloon measurements in the upper atmosphere. Ionization due to radon gas in the atmosphere was investigated. Absolute ionization data in the lower atmosphere have been compared with results of other observers, and discrepancies have been discussed.

Data from a polar orbiting ion chamber on the OGO-II, IV spacecraft have been analyzed. The problem of radioactivity produced on the spacecraft during passes through high fluxes of trapped protons has been investigated, and some corrections determined. Quiet time ionization averages over the polar regions have been plotted as function of altitude, and an analytical fit is made to the data that gives a value of 10.4 ± 2.3 percent for the fractional part of the ionization at the top of the atmosphere due to splash albedo particles, although this result is shown to depend on an assumed angular distribution for the albedo particles. Comparisons with other albedo measurements are made. The data are shown to be consistent with balloon and interplanetary ionization measurements. The position of the cosmic ray knee is found to exhibit an altitude dependence, a North-South effect, and a small local time variation.

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):
  • Neher, Henry Victor
Thesis Committee:
  • Unknown, Unknown
Defense Date:25 April 1969
Funding AgencyGrant Number
Office of Naval ResearchNonr-220(53)
NASANGL 05-002-007
NASANAS 5-3095
NASANAS 5-9317
Record Number:CaltechTHESIS:02222016-131300841
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9576
Deposited On:23 Feb 2016 17:21
Last Modified:29 Apr 2024 20:59

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