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Memorial Tributes Volume 21 (2017) / Chapter Skim
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ROBERT L. FLEISCHER
Pages 118-125

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From page 119...
... These etched tracks not only served as a new and useful method of detecting nuclear radiation, but found widespread applications in a host of fields, including nuclear physics, cosmic ray physics, dating of ­minerals and archaeological artifacts, lunar science, radon dosimetry, and filtration. Bob was born in Columbus, Ohio, on July 8, 1930, the second son of Rosalie Kahn and Leopold Fleischer.
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From page 120...
... The plastic deformation of metals and alloys occurs by the motion of linear crystal defects called dislocations, and one source of strengthening in pure metals is the interaction of dislocations with the boundaries between adjacent crystals, commonly called grain boundaries. Bob's thesis involved the growth by directional solidification of aluminum ­ icrystals, b samples that contained only one grain boundary.
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From page 121...
... Differences in size and compressibility between alloying atoms and the dominant atoms of the metal produce localized internal stresses in the crystal lattice that interact with the stress fields of dislocations, interfering with dislocation motion and thus producing hardening. His research gained recognition in the field, and the term "Fleischer hardening" is still used to refer to some of his specific contributions.
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From page 122...
... Sheets of plastic detectors were sent aloft in high-­ altitude balloons, and the varying speed of the nuclei through the plastic led to variations in the length and shape of the etched tracks that produced information on the charge and energy of each nucleus, allowing identification of each. Most cosmic rays observed in these experiments originated outside the solar system, but plastic and glass track detectors sent to the moon with Apollo 16 generated considerable information
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From page 123...
... Tracks produced by cosmic rays have also been studied in numerous minerals, ­ meteorites, moon rocks, and glass from a Surveyor moon lander brought back by Apollo 12. At a NASA meeting in Houston, Bob was fascinated to learn that the space helmets worn by the Apollo astronauts were made of Lexan polycarbonate, which had been established as a well-calibrated detector of cosmic rays.
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From page 124...
... In addition to over 350 published papers, Bob had 19 patents and received three IR-100 awards from Industrial Research Magazine for his technological contributions. His work led to two spinoff companies, Nuclepore, which utilized etched particle tracks to produce filters, and Terradex, which used etched particle tracks to detect radon.
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From page 125...
... Those many lunchtime swims had made him a very strong swimmer. Bob is survived by his brother Richard, his wife Barbara, daughters Cathy and Elizabeth (Betsy)
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Key Terms

  • etched particle
  • track detectors
  • particle tracks
  • cosmic rays
  • etched nuclear

  • nuclear track
  • nuclear particles
  • etched tracks
  • nuclear physics
  • including nuclear

  • track etching
  • particles produce
  • alpha particles
  • cloud chambers
  • wife barbara

  • mechanical properties
  • american nuclear
  • lexan polycarbonate
  • produce filters
  • radioactive daughter

  • staff physicist
  • peak temperatures
  • western ontario
  • track detection
  • helmets worn

  • ticle tracks
  • generated widespread
  • atmospheric research
  • archaeological artifacts
  • extremely wide


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