Alpha scattering

Table 1. Results of the instrumental analysis of the lunar surface by the unmanned space probes Surveyor V, VI, and VII via the alpha-scattering technique (Turkevich et al.1 ). The data obtained on Apollo 11 soil sample 10084 are given for comparison2)...

Rutherford described his new model of the atom during a lecture he gave in Cambridge in the fall of 1911. J. J. Thomson listened to the lecture, hut while the alpha-scattering data presented by Rutherford supported a nuclear model, Thomson did not. It may have heen that another physicist, Niels Bohr, also heard this... 

Surveyor 6 (USA) Landed in Sinus Medii November 10, 1967 Studied surface composition with alpha-scattering equipment... 

Surveyor 7 crater Tycho with alpha-scattering equipment ... 

Kusko, B., Cahill, T. A., Eldred, R. A., Matsuda, Y., and Miyabe, H. (1989) Nondestructive analysis of total nonvolatile carbon by forward alpha scattering technique (FAST), Aerosol Sci. Technol. 10, 390-396. 

Alpha particle A helium nucleus He2+ ion, 30 emission, 513 scattering experiment, 26... 

Fig. 14-9. Rutherford s apparatus for observing the scattering of alpha particles by a metal foil. (The entire apparatus is enclosed in a vacuum chamber.)...

Fig. 14-10. The scattering of alpha particles by a metal foil made of Thomson atoms.

Platinum and zinc have the same number of atoms per cubic centimeter. Would thin sheets of these elements differ in the way they scatter alpha particles Explain. 

Alpha carbon atoms, 348 Alpha decay, 417, 443 Alpha particle, 417 scattering, 245 Aluminum boiling point, 365 compounds, 102 heat of vaporization, 365 hydration energy, 368 hydroxide, 371 ionization energies, 269, 374 metallic solid, 365 occurrence, 373 properties, 101 preparation, 238. 373 reducing agent, 367 Alums, 403 Americium... 

Luminescent screen to detect scattered alpha particles... 

The use of nuclear techniques allows the determination of C, N, H, O, and heavier contaminants relative fractions with great accuracy, and of the elements depth profile with moderate resolution (typically 10 nm). Rutherford backscattering spectroscopy (RBS) of light ions (like alpha particles) is used for the determination of carbon and heavier elements. Hydrogen contents are measured by forward scattering of protons by incident alpha particles (ERDA) elastic recoil detection analysis [44,47]. 

Since the nuclear and electronic scattering cross sections for alpha particles are well known, the relative concentrations of the elements and their depth profiles can be easily obtained. The relative element concentrations are determined by the relative scattering intensities. The depth profile is obtained from the energy spread of the scattered particles, which lose energy before and after the nuclear collision, by inelastic scattering with electrons. The knowledge of the elements areal density and of the film thickness allows the determination of film density. 

Sir Ernest Rutherford (1871-1937 Nobel Prize for chemistry 1908, which as a physicist he puzzled over) was a brilliant experimentalist endowed with an equal genius of being able to interpret the results. He recognized three types of radiation (alpha, beta, and gamma). He used scattering experiments with alpha radiation, which consists of helium nuclei, to prove that the atom is almost empty. The diameter of the atomic nucleus is about 10 000 times smaller than the atom itself. Furthermore, he proved that atoms are not indivisible and that in addition to protons, there must also be neutrons present in their nucleus. With Niels Bohr he developed the core-shell model of the atom. 

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