The Cosmic-Ray Observations of December 4, 1957
A RECENT communication from Legrand and Helary1 reports an increase in the total component of cosmic radiation at Paris on December 4, 1957. The increase amounted to about 18 per cent and extended over three hours with the maximum occurring at 2245 U.T. A small increase in the nucleonic component at Thule preceded the Paris event by about three hours. Optical and radio data indicate a flare of importance 1 on the western hemisphere of the Sun at 1657 U.T. (ref. 2).
Ionospheric Disturbance at the Time of Cosmic Ray Increases
IN a recent communication Legrand and Helary1 have reported the occurrence of an anomalous increase in the intensity of the total cosmic ray component at the Paris Cosmic Ray Survey Station on December 4, 1957. At about the same time an increase was also observed in the intensity of the nucleonic component at Thule, Greenland. This cosmic ray event was further described as being analogous to one which was observed at Paris on January 21, 1957 (ref. 2). It has been suggested that these events are manifestations of the precipitation into the Earth's atmosphere of high-energy protons which emanate from the disturbed Sun.
THE CONCEPTUAL DESIGN OF THE 4GLS XUV-FEL
The Conceptual Design Report for the 4th Generation Light Source (4GLS) at Daresbury Laboratory in the UK was published in Spring 2006 [1]. A key component of the proposal is an XUV-FEL amplifier directly seeded by a High Harmonic source and operating in the photon energy range 8-100eV. Numerical modelling shows the FEL may generate 50fs (FWHM) pulses of variablypolarised, temporally-coherent radiation with peak powers in the range 2-8 GW.