On a diffuse reflection of the α-particles

Abstract

495one employed in these experiments. The number of ions produced by a single a-particle under the special conditions of the experiment is easily found from the curve given in fig. 3. The determination of the ionisation current in the bulb then gives at once the total number of a-particles. Care has to be taken to obtain saturation and to avoid ionisation by collision, which occurs when too large a voltage is applied. I wish to acknowledge the assistance which Mr. E. Marsden has given me in some of these observations.In conclusion, I desire to express my gratitude to Prof. Rutherford for his valuable suggestions and his kind interest in the experiments.On a Diffuse Reflection o f the a.-Particles. When /3-particles fall on a plate, a strong radiation emerges from the same side of the plate as that on which the /3-particles fall. This radiation is regarded by many observers as a secondary radiation, but more recent experi ments seem to show that it consists mainly of primary ^-particles, which have 'been scattered inside the material to such an extent that they emerge again at the same side of the plate* For a-particles a similar effect has not previously been observed, and is perhaps not to be expected on account of the relatively small scattering which a-particles suffer in penetrating matter.f On a Diffuse Reflection of theIn the following experiments, however, conclusive evidence was found of the existence of a diffuse reflection of the a-particles. A. small fraction of the a-particles falling upon a metal plate have their directions changed to such an extent that they emerge again at the side of incidence. To form an idea of the way in which this effect takes place, the following three points were investigated:-

Núcleos exóticos e síntese dos elementos químicos

“…O modelo atômico hoje vigente, com elétrons envolvendo um pequeno núcleo pesado e positivamente carregado, foi evidenciado experimentalmente por E. Rutherford em 1911, no célebre trabalho onde discutiu os dados experimentais de espalhamentos de partículas alfa obtidos por G. Geiger e E. Marsden. 1,2 Este modelo do átomo nuclear está completando 100 anos, colocado como uma ideia inovadora, necessitou de novas teorias para fundamentá-lo, estabelecendo desafios que conduziram à formulação da mecânica quântica, que ainda dava os primeiros passos. Apesar de demonstrada a existência do núcleo atômico, a sua composição só ficou determinada em 1932, com a descoberta do nêutron por J. Chadwick.…”

Ernest Rutherford his genius shaped our modern world

“…Rutherford published his model of the atom [1] in 1911 as an interpretation of the α-scattering work carried out by Geiger and Marsden [3] two years earlier. e puzzle centred on finding a convincing explanation for the small fraction of α particles (around 1 in 20,000) which were deflected through large angles, aer passing through gold foil only 0.00004 cm thick.…”

Measurement of the nucleon structure function in iron using 215- and 93-GeV muons

“…v=:p·q/MN=E-E', (1) where E, E', and 9 are the initial and final muon energies and the muon scattering angle as measured in the laboratory frame (the target rest frame). Terms containing the lepton mass have been neglected.…”