Discovery of X-rays X-rays were discovered in 1895 by the German physicist Wilhelm Roentgen. Roentgen knew how to observe, he knew how to notice something new where many scientists before him had not discovered anything remarkable. This special gift helped him make a remarkable discovery. At the end of the 19th century, gas discharge at low pressure attracted the attention of physicists. Under these conditions, flows of very fast electrons were created in the gas-discharge tube. At that time they were called cathode rays. The nature of these rays has not yet been established with certainty. All that was known was that these rays originated at the cathode of the tube. Having started studying cathode rays, Roentgen soon noticed that the photographic plate near the discharge tube was overexposed even when it was wrapped in black paper. After this, he was able to observe another phenomenon that really amazed him. A paper screen moistened with a solution of barium platinum oxide began to glow if it was wrapped around the discharge tube. Moreover, when Roentgen held his hand between the tube and the screen, the dark shadows of the bones were visible on the screen against the background of the lighter outlines of the entire hand.
Discovery of X-rays The scientist realized that when the discharge tube operates, some previously unknown, highly penetrating radiation appears. He called them X-rays. Subsequently, the term “X-rays” became firmly established behind this radiation. X-ray discovered that new radiation appeared in the place where the cathode rays (streams of fast electrons) collided with the glass wall of the tube. In this place the glass glowed with a greenish light. Subsequent experiments showed that X-rays arise when fast electrons are slowed down by any obstacle, in particular metal electrodes.
Properties of X-rays The rays discovered by X-rays acted on a photographic plate, caused ionization of the air, but were not noticeably reflected from any substances and did not experience refraction. The electromagnetic field had no effect on the direction of their propagation.
Properties of X-rays The assumption immediately arose that X-rays are electromagnetic waves that are emitted when electrons are sharply decelerated. Unlike visible light and ultraviolet rays, X-rays have a much shorter wavelength. Their wavelength is shorter, the greater the energy of the electrons colliding with the obstacle. The high penetrating power of X-rays and their other features were associated precisely with the short wavelength. But this hypothesis needed evidence, and evidence was obtained 15 years after Roentgen’s death.
X-Ray Diffraction If X-rays are electromagnetic waves, then they should exhibit diffraction, a phenomenon common to all types of waves. First, X-rays were passed through very narrow slits in lead plates, but nothing resembling diffraction could be detected. German physicist Max Laue suggested that the wavelength of X-rays was too short to detect diffraction of these waves by artificially created obstacles. After all, it is impossible to make slits measuring 10 -8 cm, since this is the size of the atoms themselves. What if the X-rays are about the same full length? Then the only option left is to use crystals. They are ordered structures in which the distances between individual atoms are equal in order of magnitude to the size of the atoms themselves, i.e. 10 -8 cm. A crystal with its periodic structure is that natural device that should inevitably cause noticeable wave diffraction if the length they are close to the size of atoms.
Diffraction of X-rays And so a narrow beam of X-rays was directed at the crystal, behind which a photographic plate was located. The result was completely consistent with the most optimistic expectations. Along with the large central spot, which was produced by rays propagating in a straight line, regularly spaced small spots appeared around the central spot (Fig. 50). The appearance of these spots could only be explained by the diffraction of X-rays on the ordered structure of the crystal. The study of the diffraction pattern made it possible to determine the wavelength of the X-rays. It turned out to be less than the wavelength of ultraviolet radiation and in order of magnitude was equal to the size of an atom (10 -8 cm).
Applications of X-rays X-rays have found many very important practical applications. In medicine, they are used to make the correct diagnosis of a disease, as well as to treat cancer. The applications of X-rays in scientific research are very extensive. From the diffraction pattern produced by X-rays when they pass through crystals, it is possible to establish the order of arrangement of atoms in space - the structure of the crystals. It turned out to be not very difficult to do this for inorganic crystalline substances. But with the help of X-ray diffraction analysis it is possible to decipher the structure of complex organic compounds, including proteins. In particular, the structure of the hemoglobin molecule, containing tens of thousands of atoms, was determined.
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Presentation on the topic: Wilhelm Conrad Roentgen
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German physicist Wilhelm Conrad Röntgen was born in Lennep, a small town near Remscheid in Prussia, the only child in the family of a successful textile merchant, Friedrich Conrad Röntgen and Charlotte Constance (nee Frowein) Röntgen. In 1848, the family moved to the Dutch city of Apeldoorn - the homeland of Charlotte's parents. The expeditions made by Röntgen in his childhood in the dense forests in the vicinity of Apeldoorn instilled in him a lifelong love of wildlife.
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Röntgen entered the Utrecht Technical School in 1862, but was expelled for refusing to name a friend who had drawn an irreverent caricature of an unloved teacher. Without an official certificate of completion of a secondary educational institution, he formally could not enter a higher educational institution, but as an volunteer he took several courses at Utrecht University. After passing the entrance exam, Röntgen was enrolled as a student at the Federal Institute of Technology in Zurich in 1865, intending to become a mechanical engineer, and received a diploma in 1868. August Kundt, an outstanding German physicist and professor of physics at this institute, drew attention to Röntgen’s brilliant abilities and strongly advised him to take up physics. He followed Kundt's advice and a year later defended his doctoral dissertation at the University of Zurich, after which he was immediately appointed by Kundt as first assistant in the laboratory. Röntgen entered the Utrecht Technical School in 1862, but was expelled for refusing to name a friend who had drawn an irreverent caricature of an unloved teacher. Without an official certificate of completion of a secondary educational institution, he formally could not enter a higher educational institution, but as an volunteer he took several courses at Utrecht University. After passing the entrance exam, Röntgen was enrolled as a student at the Federal Institute of Technology in Zurich in 1865, intending to become a mechanical engineer, and received a diploma in 1868. August Kundt, an outstanding German physicist and professor of physics at this institute, drew attention to Röntgen’s brilliant abilities and strongly advised him to take up physics. He followed Kundt's advice and a year later defended his doctoral dissertation at the University of Zurich, after which Kundt was immediately appointed first assistant in the laboratory.
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The experimental research carried out by Röntgen in Strasbourg concerned various areas of physics, such as the thermal conductivity of crystals and the electromagnetic rotation of the plane of polarization of light in gases, and, according to his biographer Otto Glaser, earned Röntgen a reputation as a "subtle classical experimental physicist". In 1879, Röntgen was appointed professor of physics at the University of Hesse, where he remained until 1888, refusing offers to occupy the chair of physics successively at the universities of Jena and Utrecht. In 1888, he returned to the University of Würzburg as professor of physics and director of the Physical Institute, where he continued to conduct experimental research on a wide range of problems, incl. compressibility of water and electrical properties of quartz. In 1894, when Röntgen was elected rector of the university, he began experimental studies of electric discharge in glass vacuum tubes. Much has already been done in this area by others. In 1853, French physicist Antoine Philibert Masson noticed that a high-voltage discharge between electrodes in a glass tube containing gas at very low pressure produced a reddish glow (such tubes were the first predecessors of modern neon tubes). When other experimenters began pumping the gas out of the tube to greater rarefaction, the glow began to disintegrate into a complex sequence of individual luminous layers, the color of which depended on the gas. The experimental research carried out by Röntgen in Strasbourg concerned various areas of physics, such as the thermal conductivity of crystals and the electromagnetic rotation of the plane of polarization of light in gases, and, according to his biographer Otto Glaser, earned Röntgen a reputation as a "subtle classical experimental physicist". In 1879, Röntgen was appointed professor of physics at the University of Hesse, where he remained until 1888, refusing offers to occupy the chair of physics successively at the universities of Jena and Utrecht. In 1888, he returned to the University of Würzburg as professor of physics and director of the Physical Institute, where he continued to conduct experimental research on a wide range of problems, incl. compressibility of water and electrical properties of quartz. In 1894, when Röntgen was elected rector of the university, he began experimental studies of electric discharge in glass vacuum tubes. Much has already been done in this area by others. In 1853, French physicist Antoine Philibert Masson noticed that a high-voltage discharge between electrodes in a glass tube containing gas at very low pressure produced a reddish glow (such tubes were the first predecessors of modern neon tubes). When other experimenters began pumping the gas out of the tube to greater rarefaction, the glow began to disintegrate into a complex sequence of individual luminous layers, the color of which depended on the gas.
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Roentgen repeated some of the earlier experiments, in particular showing that cathode rays emanating from the Lenard window (then unknown) caused fluorescence of a screen coated with barium cyanoplatinite. One day (this happened on November 8, 1895), to facilitate observations, Roentgen darkened the room and wrapped the Crookes tube (without Lenard's window) in thick, opaque black paper. To his surprise, he saw a fluorescent band on a nearby screen coated with barium cyanoplatinite. After carefully analyzing and eliminating possible causes of errors, he established that fluorescence appeared every time he turned on the tube, that the source of radiation was the tube and not some other part of the circuit, and that the screen fluoresced even at a distance of almost two meters from the tube , which far exceeded the capabilities of short-range cathode rays. Roentgen repeated some of the earlier experiments, in particular showing that cathode rays emanating from the Lenard window (then unknown) caused fluorescence of a screen coated with barium cyanoplatinite. One day (this happened on November 8, 1895), to facilitate observations, Roentgen darkened the room and wrapped the Crookes tube (without Lenard's window) in thick, opaque black paper. To his surprise, he saw a fluorescent band on a nearby screen coated with barium cyanoplatinite. After carefully analyzing and eliminating possible causes of errors, he established that fluorescence appeared every time he turned on the tube, that the source of radiation was the tube and not some other part of the circuit, and that the screen fluoresced even at a distance of almost two meters from the tube , which far exceeded the capabilities of short-range cathode rays.
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He spent the next seven weeks investigating a phenomenon he called X-rays (i.e., unknown rays). The shadow cast on the fluorescent screen by the conductor from the induction coil, which created the high voltage necessary for the discharge, gave Roentgen the idea of studying the penetrating ability of X-rays in various materials. He discovered that X-rays can penetrate almost all objects to varying depths, depending on the thickness of the object and the density of the substance. Holding a small lead disk between the discharge tube and the screen, Roentgen noticed that lead was impenetrable to X-rays, and then made a startling discovery: the bones of his hand cast a darker shadow on the screen, surrounded by a lighter shadow from soft tissue. He spent the next seven weeks investigating a phenomenon he called X-rays (i.e., unknown rays). The shadow cast on the fluorescent screen by the conductor from the induction coil, which created the high voltage necessary for the discharge, gave Roentgen the idea of studying the penetrating ability of X-rays in various materials. He discovered that X-rays can penetrate almost all objects to varying depths, depending on the thickness of the object and the density of the substance. Holding a small lead disk between the discharge tube and the screen, Roentgen noticed that lead was impenetrable to X-rays, and then made a startling discovery: the bones of his hand cast a darker shadow on the screen, surrounded by a lighter shadow from soft tissue.
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He soon discovered that X-rays caused not only the glow of the screen coated with barium cyanoplatinite, but also the darkening of photographic plates (after development) in those places where the X-rays hit the photographic emulsion. So Roentgen became the world's first radiologist. In honor of him, X-rays began to be called X-rays. Roentgen's X-ray photograph (x-ray) of his wife's hand became widely known. On it, bones are clearly visible (white, since denser bone tissue retains X-rays, preventing them from reaching the photographic plate) against the background of a darker image of soft tissue (retaining X-rays to a lesser extent) and white stripes from rings on the fingers . He soon discovered that X-rays caused not only the glow of the screen coated with barium cyanoplatinite, but also the darkening of photographic plates (after development) in those places where the X-rays hit the photographic emulsion. So Roentgen became the world's first radiologist. In honor of him, X-rays began to be called X-rays. Roentgen's X-ray photograph (x-ray) of his wife's hand became widely known. On it, bones are clearly visible (white, since denser bone tissue retains X-rays, preventing them from reaching the photographic plate) against the background of a darker image of soft tissue (retaining X-rays to a lesser extent) and white stripes from rings on the fingers .
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Roentgen's first report of his research, published in a local scientific journal at the end of 1895, aroused great interest both in scientific circles and among the general public. “We soon discovered,” wrote Roentgen, “that all bodies are transparent to these rays, although to very different degrees.” Roentgen's experiments were immediately confirmed by other scientists. Röntgen published two more papers on X-rays in 1896 and 1897, but then his interests moved to other areas. Roentgen's first report of his research, published in a local scientific journal at the end of 1895, aroused great interest both in scientific circles and among the general public. “We soon discovered,” wrote Roentgen, “that all bodies are transparent to these rays, although to very different degrees.” Roentgen's experiments were immediately confirmed by other scientists. Röntgen published two more papers on X-rays in 1896 and 1897, but then his interests moved to other areas.
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Doctors immediately realized the importance of X-rays for diagnosis. At the same time, the X-rays became a sensation, which was trumpeted throughout the world by newspapers and magazines, often presenting materials on a hysterical note or with a comic overtone. Roentgen was irritated by the sudden fame that fell on him, taking away his precious time and interfering with further experimental research. For this reason, he began to rarely publish articles, although he did not stop doing so completely: during his life, Roentgen wrote 58 articles. In 1921, when he was 76 years old, he published a paper on the electrical conductivity of crystals. Doctors immediately realized the importance of X-rays for diagnosis. At the same time, the X-rays became a sensation, which was trumpeted throughout the world by newspapers and magazines, often presenting materials on a hysterical note or with a comic overtone. Roentgen was irritated by the sudden fame that fell on him, taking away his precious time and interfering with further experimental research. For this reason, he began to rarely publish articles, although he did not stop doing so completely: during his life, Roentgen wrote 58 articles. In 1921, when he was 76 years old, he published a paper on the electrical conductivity of crystals.
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In 1899, shortly after the closure of the physics department at the University of Leipzig, Röntgen became professor of physics and director of the Institute of Physics at the University of Munich. While in Munich, Röntgen learned that he had become the first (1901) Nobel Prize laureate in physics “in recognition of his extraordinary services to science, expressed in the discovery of the remarkable rays subsequently named in his honor.” At the presentation of the laureate, K. T. Odhner, a member of the Royal Swedish Academy of Sciences, said: “There is no doubt how much progress physical science will achieve when this hitherto unknown form of energy is sufficiently explored.” Odhner then reminded the audience that X-rays have already found numerous practical applications in medicine. In 1899, shortly after the closure of the physics department at the University of Leipzig, Röntgen became professor of physics and director of the Institute of Physics at the University of Munich. While in Munich, Röntgen learned that he had become the first (1901) Nobel Prize laureate in physics “in recognition of his extraordinary services to science, expressed in the discovery of the remarkable rays subsequently named in his honor.” At the presentation of the laureate, K. T. Odhner, a member of the Royal Swedish Academy of Sciences, said: “There is no doubt how much progress physical science will achieve when this hitherto unknown form of energy is sufficiently explored.” Odhner then reminded the audience that X-rays have already found numerous practical applications in medicine.
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The modest, shy Roentgen was deeply disgusted by the very idea that his person could attract everyone's attention. He loved the outdoors and visited Weilheim many times during his holidays, where he climbed the neighboring Bavarian Alps and hunted with friends. He resigned from his posts in Munich in 1920, shortly after the death of his wife. He died three years later from internal organ cancer. The modest, shy Roentgen was deeply disgusted by the very idea that his person could attract everyone's attention. He loved the outdoors and visited Weilheim many times during his holidays, where he climbed the neighboring Bavarian Alps and hunted with friends. He resigned from his posts in Munich in 1920, shortly after the death of his wife. He died three years later from internal organ cancer.
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Although Roentgen was quite satisfied with the knowledge that his discovery was of such great importance for medicine, he never thought about either a patent or financial reward. He was the recipient of many awards in addition to the Nobel Prize, including the Rumford Medal of the Royal Society of London, the Barnard Gold Medal for Distinguished Service to Science of Columbia University, and was an honorary and corresponding member of scientific societies in many countries. Although Roentgen was quite satisfied with the knowledge that his discovery was of such great importance for medicine, he never thought about either a patent or financial reward. He was the recipient of many awards in addition to the Nobel Prize, including the Rumford Medal of the Royal Society of London, the Barnard Gold Medal for Distinguished Service to Science of Columbia University, and was an honorary and corresponding member of scientific societies in many countries.
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Historical events: it was 110 years since the discovery of X-rays (1895-2005), 100 years ago it became known about characteristic X-rays (1906-2006). The significance of the discovery of X-rays for the development of science and understanding of the structure of the world cannot be overestimated. Wilhelm Conrad Roentgen, German physicist.
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Discovery of X-rays by Wilhelm Roentgen Properties of X-rays Diffraction of X-rays Design of an X-ray tube Application of X-rays: Medicine Scientific research X-ray structural analysis Defectoscopy
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Discovery of X-rays
In 1895, Wilhelm Roentgen experimented with one of the vacuum tubes (Crookes). He suddenly noticed that some nearby crystals glowed brightly. Since Roentgen knew that previously discovered rays could not penetrate glass to produce this effect, he suggested that it must be a new type of ray, which he called X-rays, thereby emphasizing the unusual nature of their properties.
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In fact, rays invisible to the eye easily penetrated through opaque fabric, paper, wood and even metals, exposing carefully packed photographic film. The famous photograph of his wife’s hand, which he published in his article, also contributed to Roentgen’s fame. For the discovery of the rays that bear his name, V. Roentgen received the FIRST ever Nobel Prize in Physics (1901)
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Properties of X-rays
The rays discovered by X-ray acted on the photographic plate, caused ionization of the air, were not reflected, not refracted, but were not deflected in the magnetic field. X-rays had enormous penetrating power, which was incomparable to anything else. The assumption immediately arose that these were electromagnetic waves that were emitted when electrons suddenly slowed down. Evidence of this was obtained only 15 years after Roentgen’s death. The first page of V. Roentgen's article on X-rays
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X-ray diffraction
A narrow beam of X-rays was directed at the crystal, behind which a photographic plate was located. Regularly spaced small spots appeared around the central spot on the plate. Their appearance can only be explained by diffraction, which is inherent in all types of electromagnetic waves. This means that X-ray radiation is electromagnetic.
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X-RAY TUBE – ...an electric vacuum device for producing x-rays. The simplest X-ray tube consists of a glass cylinder with soldered electrodes - a cathode and an anode. Electrons emitted by the cathode are accelerated by a strong electric field in the space between the electrodes and bombard the anode. When electrons strike the anode, their kinetic energy is partially converted into X-ray energy.
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Schematic illustration of an X-ray tube.
X - X-rays, K - cathode, A - anode, C - heat sink, Uh - cathode filament voltage, Ua - accelerating voltage, Win - water cooling inlet, Wout - water cooling outlet Previous slide
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General view of X-ray tubes for structural analysis (a), flaw detection (b) and medical (c) X-ray diagnostics
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Biological effects
X-ray radiation is ionizing. It affects living organisms and can cause radiation sickness and cancer. For this reason, protective measures must be taken when working with X-rays. Damage to hereditary DNA information leads to cancer. It is believed that the damage is directly proportional to the absorbed dose of radiation. X-ray radiation is a mutagenic factor.
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Applications of X-rays
In medicine In scientific research: X-ray structural analysis Materials science Crystallography Chemistry Biology Defectoscopy
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Medicine
X-rays can be used to illuminate the human body, resulting in images of bones and internal organs. Also used to treat cancer.
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X-ray diffraction analysis
From the diffraction pattern produced by X-rays as they pass through crystals, it is possible to establish the order of arrangement of atoms in space—the structure of the crystals.
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In materials science, crystallography, chemistry and biochemistry, X-rays are used to elucidate the structure of substances at the atomic level using X-ray diffraction scattering (XRD). A well-known example is the determination of the structure of DNA.
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In addition, the chemical composition of a substance can be determined using X-rays. In an electron beam microscope, the analyte is irradiated with electrons or X-rays, causing the atoms to ionize and emit characteristic X-rays. This analytical method is called X-ray fluorescence analysis.
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X-ray flaw detection
A method for detecting cavities in castings, cracks in rails, checking the quality of welds, etc. It is based on a change in the absorption of X-rays in a product if there is a cavity or foreign inclusions in it. X-ray flaw detector
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Presentation on the topic “X-rays” teachers of MAOU Lyceum No. 14 Ermakova T.V.
- Opening x-rays
- X-ray tube device
- Literature
- X-rays were discovered in 1895 by the German physicist Wilhelm Roentgen.
- He knew how to observe, he knew how to notice something new where many scientists before him had not discovered anything remarkable. This special gift helped him make a remarkable discovery.
- At the end of the 19th century, gas discharge at low pressure attracted the attention of physicists. Under these conditions, flows of very fast electrons were created in the gas-discharge tube. At that time they were called cathode rays. The nature of these rays has not yet been established with certainty. All that was known was that these rays originated at the cathode of the tube.
- Having started studying cathode rays, Roentgen soon noticed that the photographic plate near the discharge tube was overexposed even when it was wrapped in black paper. After this, he was able to observe another phenomenon that really amazed him. A paper screen moistened with a solution of barium platinum oxide began to glow if it was wrapped around the discharge tube. Moreover, when Roentgen held his hand between the tube and the screen, the dark shadows of the bones were visible on the screen against the background of the lighter outlines of the entire hand.
- The scientist realized that when the discharge tube was operating, some previously unknown, highly penetrating radiation was generated. He called him X-rays. Subsequently, the term “X-rays” became firmly established behind this radiation.
- X-ray discovered that new radiation appeared in the place where the cathode rays (streams of fast electrons) collided with the glass wall of the tube. In this place the glass glowed with a greenish light.
- Subsequent experiments showed that X-rays arise when fast electrons are decelerated by any obstacle, in particular metal electrodes.
- The rays discovered by X-ray acted on the photographic plate, causing ionization of the air, but were not noticeably reflected from any substances and did not experience refraction. The electromagnetic field had no effect on the direction of their propagation.
- The assumption immediately arose that X-rays are electromagnetic waves that are emitted when electrons are suddenly slowed down. Unlike visible light and ultraviolet rays, X-rays have a much shorter wavelength. Their wavelength is shorter, the greater the energy of the electrons colliding with the obstacle. The high penetrating power of X-rays and their other features were associated precisely with the short wavelength. But this hypothesis needed evidence, and evidence was obtained 15 years after Roentgen’s death.
If X-rays are electromagnetic waves, then they should exhibit diffraction, a phenomenon common to all types of waves. First, X-rays were passed through very narrow slits in lead plates, but nothing resembling diffraction could be detected. German physicist Max Laue suggested that the wavelength of X-rays was too short to detect diffraction of these waves by artificially created obstacles. After all, it is impossible to make slits measuring 10 -8 cm, since this is the size of the atoms themselves. What if X-rays have approximately the same wavelength? Then the only option left is to use crystals. They are ordered structures in which the distances between individual atoms are equal in order of magnitude to the size of the atoms themselves, i.e. 10 -8 cm. A crystal with its periodic structure is that natural device that should inevitably cause noticeable wave diffraction if the length they are close to the size of atoms.
- And so a narrow beam of X-rays was directed at the crystal, behind which a photographic plate was located. The result was completely consistent with the most optimistic expectations. Along with the large central spot, which was produced by rays propagating in a straight line, regularly spaced small spots appeared around the central spot (Fig. 50). The appearance of these spots could only be explained by the diffraction of X-rays on the ordered structure of the crystal.
- The study of the diffraction pattern made it possible to determine the wavelength of the X-rays. It turned out to be less than the wavelength of ultraviolet radiation and in order of magnitude was equal to the size of an atom (10 -8 cm).
X-rays have found many very important practical applications.
In medicine, they are used to make the correct diagnosis of a disease, as well as to treat cancer.
The applications of X-rays in scientific research are very extensive. From the diffraction pattern produced by X-rays when they pass through crystals, it is possible to establish the order of arrangement of atoms in space - the structure of the crystals. It turned out to be not very difficult to do this for inorganic crystalline substances. But with the help of X-ray diffraction analysis it is possible to decipher the structure of complex organic compounds, including proteins. In particular, the structure of the hemoglobin molecule, containing tens of thousands of atoms, was determined.
- X-rays have wavelengths ranging from 10 -9 to 10 -10 m. They have great penetrating power and are used in medicine, as well as for studying the structure of crystals and complex organic molecules.
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Topic: “X-ray radiation” The work was completed by a student of class 11 “A” of the Municipal Educational Institution “Secondary School No. 95 named after. N. Shchukina p. Arhara” Gogulova Kristina Valerievna.
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Objectives: 1. Find out what X-ray radiation is. 2. Find out why bones stop x-rays. 3. Using knowledge about X-ray radiation, we can find out its application in medicine.
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X-ray Wilhelm Conrad. Born - March 27, 1845, Lennep, near Düsseldorf. The largest German experimental physicist, member of the Berlin Academy of Sciences. He discovered X-rays in 1895 and studied their properties.
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“Send me some rays in an envelope.” A year after the discovery of x-rays, Roentgen received a letter from an English sailor: “Sir, since the war I have had a bullet stuck in my chest, but they can’t remove it because it is not visible. And so I heard that you found rays through which my bullet can be seen. If possible, send me some rays in an envelope, the doctors will find the bullet, and I will send you the rays back.” Roentgen’s answer was as follows: “At the moment I do not have that many rays. But if it’s not difficult for you, send me your chest, and I’ll find the bullet and send your chest back.”
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What are X-rays? Electrons emitted from the hot cathode filament are accelerated by the electric field and collide with the surface of the anode. An electron colliding with the anode surface can be deflected due to interaction with the nucleus, or knock out one of the electrons in the inner shell of the atom, i.e. ionize it. In the first case, it results in the emission of an x-ray photon, the wavelength can be in the range of 0.01-10 nm (continuous spectrum)
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The intensity of such radiation is proportional to the charge Z from which the anode is made. The greater the voltage applied between the cathode and anode of the X-ray tube, the greater the power of the X-rays. In the second case, the place of the knocked-out electron is taken by an electron with a “higher” shell, and the difference in their potential energy is released in the form of an X-ray photon of the corresponding frequency.
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What is X-ray spectroscopy? Each chemical element absorbs X-ray radiation particularly strongly at a strictly defined, characteristic wavelength. In this case, the atom transitions from a normal state to an ionized one, with one electron removed. Therefore, by measuring the frequencies of X-ray radiation at which the radiation is especially strong, we can draw a conclusion about what elements are included in the composition of the substance. This is the basis of X-ray spectroscopy.
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Why do bones stop X-rays? The penetrating ability of X-rays, in other words, their hardness, depends on the energy of their photons. It is customary to call radiation with a wavelength greater than 0.1 nm soft, and the rest - hard. To diagnose a target, hard radiation of no more than 0.01 nm should be used, otherwise the X-rays will not pass through the body. It turned out that a substance absorbs X-ray radiation more, the higher the density of the material. The more atoms X-rays encounter on their path and the more electrons there are in the shells of these atoms, the greater the likelihood of photon absorption.
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In the human body, X-rays are most strongly absorbed in bones, which are relatively dense and contain many calcium atoms. When rays pass through bones, the intensity of radiation decreases by half every 1.2 cm. Blood, muscles, fat and the gastrointestinal tract absorb x-rays much less (a 3.5 cm thick layer is halved) The air in the lungs retains the least amount of radiation ( twice with a layer thickness of 192 m.) Therefore, in X-rays, the bones cast a shadow on the photographic film, and in these places it remains transparent. Where the rays managed to illuminate the film, it becomes dark, and doctors see the patient “through and through”
