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20.10.2014 09:40

Prof. Keran O'Brien repräsentiert IASON auf Kongress in Japan

Professor Keran O’Brien und IASON arbeiten seit Jahren höchst erfolgreich zusammen. Prof. O’Brien ist der wissenschaftliche Berater von IASONs F.R.E.E. Abteilung, die sich mit der Berechnung der Strahlungsexposition des Bordpersonals von Linienflügen befasst. Kürzlich hat Professor O’Brien nun am “9th International Symposium on the Natural Radiation Environment“, das von 22.-26. September in Hirosaki, Japan, stattgefunden hat, teilgenommen. Im Zuge dieses Kongresses hat Prof. O’Brien IASONs Ansehen in der wissenschaftlichen Community durch seinen interessanten Vortrag gemehrt. Hier sein Bericht über die spannende Reise ins „Land des Lächelns“:

After an overnight stay in Tokyo, Dorothy and I arrived at the New Castle Hotel in Hirosaki on September 23rd, two hours before the Cosmic-ray Keynote lecture which I was scheduled to chair. We were met by Dr. Masahiro Hosoda, a member of the local organizing committee and a faculty member of Hirosaki University. Dr. Hosoda was responsible for appointing me chair of the keynote lecture.

The Cosmic-ray Keynote lecture was presented by Dr. Eric Benton of Oklahoma State University. The subject was the radiation exposure of humans during long-duration space missions. The presentation was excellent. He also presented a paper on the initiation of lightning that depended on electron production by cosmic rays at high altitudes. He told me that the cosmic-ray code he used to calculate electron production gave nonsense results at these high altitudes. I offered to do such calculations with my own code for which I have experimental confirmation up to about 27 km elevation.

I gave my own paper on the afternoon of the 25th. The subject was the mechanism by which high-energy processes such as Type II supernovae transfer their energy to cosmic rays. This mechanism is known as first-order Fermi diffusive shock acceleration. High-energy processes can produce supersonic shock waves that accelerate “down stream” particles through interaction with the shock front. This mechanism can explain the interstellar cosmic-ray spectrum.

Aside from the keynote presentations, the sessions were divided into 11 categories, heavily weighted toward radon and thoron. There was only one half session devoted to cosmic rays, a total of 5 presentations including Dr. Benton’s keynote presentation. There were 5 sessions and 31 presentations devoted to radon and thoron, which I think is excessive.

An interesting paper by S. Akiba from Kagoshima University in Japan suggested that the excess relative risk of cancer per gray of exposure, (ERR/Gy) as measured in high natural background areas such as Kerala in India or Yangjiang in China, is significantly less for chronic, low-dose exposure than it is for acute exposure such as that suffered by atomic-bomb survivors. Radiation exposure limits are partly based on the data from atomic-bomb survivors. This may have some relevance for aircrews, since they are chronically exposed to low doses of cosmic radiation.

Two colleagues came up to Hirosaki to visit: Susumu Minato, from Nagoya (an old and close friend) and Masaharu Okano, from Kamakura. Dr. Okano, 90 years of age, had a gift for Dorothy, a beautiful pair of chopsticks, Dr. Minato, gave us a plaque inscribed in Japanese, “Cosmic-ray Laboratory.”

 

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