File:X rays and crystal structure (1915) (14591513467).jpg

Identifier: xrayscrystalstru00braguoft (find matches)
Title: X rays and crystal structure
Year: 1915 (1910s)
Authors: Bragg, William Henry, Sir, 1862-1942 Bragg, William Lawrence, Sir, 1890-1971
Subjects: Crystallography X-rays
Publisher: London : G. Bell
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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g generally determined bypressing the face to be used against a metal templatewhich is afterwards removed. The reflected pencil of X-rays passes into anionisation chamber mounted so as to be capable ofrevolving about the same vertical axis as the crystaltable. An adjustable slit D stands in front of theionisation chamber. The chamber consists of aclosed brass cylinder 15 cm. long and 5 cm. in dia-meter, made of stout brass tube and faced at the endwhere the rays enter with a lead plate. A hole inthe centre of the plate is covered by a thin sheet ofaluminium which transmits the reflected ray withoutmuch loss, The opening is large enough to take ina pencil i cm. wide ; but the width is often limitedto very small dimensions by the slit at D. The chamber is filled with a gas which absorbsthe X-rays strongly, and so yields a large ionisationcurrent. We have generally used SO.,, whichabsorbs most rays about ten times as much as air.For the more penetrating X-rays methyl bromide is Plate II.
Text Appearing After Image:
X-RAV SPECTROMETER. LLL. Lead box. A, B. D, Slits. C, Crystal. /, lonisatioii chamber. V, \ernier oi crystal table. V , Nernier of ionisation chamber. K, Earthing key. E, Elect roscooe. M, Microscope. Facing /><igf 24. THE X-RAY SPECTROMETER 25 more effective than SOo. The chamber is insulatedfrom the earth and raised to a high potential by abattery of storage cells. The electrode is mountedin the cylinder, just out of the way of the streamof rays which enter, and is connected through amounting in a sulphur plug of the usual kind with afine wire which leads to a Wilson tilted electroscope. The wire is connected to the electroscope at apoint immediately below and on the continuation ofthe axis of the instrument. The photograph(Plate II.) will make this clear. The object of thisarrangement is to make it possible to turn theionisation chamber about the axis without strainino-the connection with the electroscope. The connect-ing wire of the electroscope is electrically shieldedby st

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