Possible Use of Stonehenge
HAWKINS1,2 has suggested that the Aubrey holes at Stonehenge were used to count the years of a 56-year cycle, important in the motion of the Moon and the occurrence of eclipses. Hoyle3 and Colton and Martin4 have suggested other ways that Stonehenge could have been used to predict eclipses. Here we suggest a use of Stonehenge that has nothing to do with eclipses. We suggest also that the Aubrey holes, if they were used as counters at all, were used to count intervals of 56 months rather than 56 years.
Eclipse Cycles and Eclipses at Stonehenge
Was Stonehenge used to predict eclipses? Previous claims have assumed a high degree of sophistication on the part of the builders of Stonehenge, and that the number of Aubrey holes (56) is particularly significant. It may be that neither assumption is justified or necessary, and that if the builders of Stonehenge did predict eclipses, they did it in much simpler ways.
DESIGN CONSIDERATION TO PPM KLYSTRONS FOR INDUSTRIAL LINAC
Toshiba has been developing the C-band and X-band Periodic Permanent Magnet (PPM) focused klystron in collaboration with KEK and manufactured prototypes for the JLC project. [1] The PPM klystron has an advantage to enhance the total efficiency as a result of eliminating the electric power for the focusing magnet. From experience on the development the PPM focused klystrons for the JLC project, we plan to apply the PPM focused klystron to the medical and industrial linac. The periodic magnet focusing scheme has some technical difficulties such as stop band voltage. To design the PPM klystron for the medical and industrial linac, it is necessary to give heed to electron beam instability; so that the tube parameters of the PPM focused klystrons have some constraints. The size of the accelerator system is substantially reduced if a PPM focused klystron is used. The majority of medical and industrial linacs use frequencies of S-band range. We discuss the availability of the S-band PPM focused klystron in this paper.