The Scotsman James Clerk Maxwell (1831-1879), in the century XIX, he/she/you foresaw the existence and the nature of the waves eletromagnéticas, that include until the visible light
In 1887, German Heinrich Rudolf Hertz (1857-1894), it produced the first waves artificial eletromagnéticas (waves of radio), using advices of Hermann von Helmholtz (1821-1894). Among other things, Helmholtz suggested that a radiation eletromagnética of high frequency should interact faintly with the matter, to the likeness of the sound waves in an instrument of strings. He/she/you also suggested that these waves could be very penetrating.
Helmholtz got to indicate the appropriate instrument to produce those penetrating waves: the flask of Crookes, called tube of Crookes at that time, where they were generated the mysterious rays catódicos.
Many cientists in Europe began to seek that radiation type. Among them, the largest specialist in rays catódicos of Germany, Philipp Lenard (1862-1947).
The difficulty at that time, is that would not happen to anybody a detection method that was shown such radiations in fact they existed
.The discovery was Wilhelm Conrad Röntgen (1845-1923) who discovered and he/she baptized the Raios X, besides doing the first x-ray of the history . This happened when Röntgen studied the phenomenon of the luminescência produced by rays catódicos in a tube of Crookes .This device, it was involved by a box of black cardboard and kept in a darkroom. Close to the box, there was a paper piece covered of barium platinocianeto.
Conrad Röntgen noticed that, when it supplied electric current to the elétrons of the tube, this, emitted a radiation that veiled the photographic foil, bestirred, it decided to insert between the device and the photographic paper, opaque bodies to the visible light. This way he/she obtained proofs that several opaque materials to the light decreased, but they didn't eliminate the emission of this it finds strange irradiation induced by the ray of invisible light, then unknown.
This indicated that the energy crossed the objects easily, and he/she behaved as the visible light. After exhausting experiences with inanimate objects, Röntgen decided to ask for your wife to put the hand between the device and the photographic paper. The picture revealed the structure bony intern of the human hand, with all your bony formations, it was the first foil of rays X, name given by the cientist to your discovery on November 8, 1895.
Raios X'S discovery would take later many other cientists to receive her/it the prize physics Nobel with researches on the subject.
Characteristics THE device that generates Raios X it is called tube of Coolidge. In the same way that a valve termiônica, this component is a hollow tube and evacuated, it still possesses an incandescent cathode that generates a flow of elétrons of high energy. These are accelerated for a great potential difference and they reach to the anode or plate.
The anode is hollow and made in tungsten. The reason of this construction type is the generation of heat for the process of creation of the rays X. Para not to melt, the device needs resfriamento through the oil circulation.
When being accelerated, the elétrons win energy and they are addressed against an objective, when reaching him/it they are braked losing a part of the acquired energy during the acceleration abruptly. The result of the collisions and of the frenagem it is the transferred energy of the elétrons for the atoms of the white element. This he/she becomes warm abruptly, because around 99% of the energy of the electronic bunch it is dissipated in him.
The abrupt desaceleração of an electronic load generates the emission of a pulse of radiation eletromagnética. To this effect he/she feels the name of Bremsstrahlung, that means brake radiation.
The forms of collision of the electronic bunch in the objective feel in different energy levels due to the variations of the happened collisions. As several possible forms of collision owed path angulação exist, the electron doesn't get to lose the totality of the acquired energy in an only shock, the generation of a wide radiation spectrum whose range of frequencies is quite wide happening then, or with several wavelengths. These depend on the initial energy of the incident electronic bunch. This is the reason for which the need of thousands of volts of potential of acceleration exists for Raios X.'S production
Detection
The detection of the rays X can be made in several ways, to principal it is the impression photographic foils that allows the medicinal and industrial use through the x-rays. Other detection forms are for the heating of elements the lead base, that they generate images termográficas, the heating of lead sheets to measure your intensity, besides elements that possess gases in your interior to example of the valve Geiger-Müller used for the detection of radiation ionizante and radiation non ionizante.
Uses of the Medicine
In the medicine the rays X are used in the analyses of the conditions of the internal organs, researches of fractures, treatment of tumors, cancer, bony diseases, etc.
With therapeutic purposes the rays X are used with an approximate irradiation of five thousand röntgens, on small areas of the body, for small space of time.
Exhibition
The tolerance of the human organism to the exhibition to the rays X is of 0,1 röntgen a day in the maximum in the whole corporal surface. The radiation of a röntgen produces in 1,938x10 - 3 grams of air, the liberation for ionization, of an electric charge of 3,33x10 - 3C.
In the human being the slow exhibition to the rays X can cause redness of the skin, ulcerations and empolamento. In more serious cases of exhibition it can cause serious cancerous lesions, death of the cells and leukemia.
He/she/you researches of materials
In the industry, the rays X are used in the exam of fractures of pieces, foundry conditions, besides other employments correlatos. In the laboratories of analyses physicist chemistries the Raios X have I release use spectrum.
Nature eletromagnética
The rays X spread to the speed of the light, as any radiation eletromagnética they are subject to the refraction phenomena, difração, reflection, polarization, interference and attenuation. Your penetrância in the materials is important, because all the substances are transparent to the Raios X in adult or smaller degree.
In some substances as composed of calcium and barium platinocianeto, the rays X generate luminescência. This radiation ionizes the gases through where it passes. To example of the visible light, it is not diverted by the action of fields electric or magnetic. He/she/you moves in straight line, candle photographic foils, besides to discharge the loaded objects electrically, any that is the polarity.