High pressure hydrogen magnet Wilson Cloud Chamber, approximately 480mm high and 520mm diameter, weight approximately 300Kg. Used by Basil Rose to show that Spectrum of Neutrons from the Zero Energy Thermonuclear Assembly (Zeta) was not consistent with neutrons from a thermonuclear reaction, c. 1957-1958. (Note: ZETA is sometimes incorrectly expanded as Zero Energy Thermal Apparatus). High pressure hydrogen magnet Wilson Cloud Chamber 1955-1960