Download the presentation on X-rays. Presentation for the lesson "X-ray radiation"

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X-rays are electromagnetic waves, the energy of photons of which lies on the scale of electromagnetic waves between ultraviolet radiation and gamma radiation. The energy ranges of X-rays and gamma radiation overlap in a wide energy range. Both types of radiation are electromagnetic radiation and, with the same photon energy, are equivalent. The terminological difference lies in the method of occurrence - X-rays are emitted with the participation of electrons, while gamma radiation is emitted in the processes of de-excitation of atomic nuclei

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X-ray tubes X-rays arise from the strong acceleration of charged particles, or from high-energy transitions in the electronic shells of atoms or molecules. Both effects are used in X-ray tubes

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The main structural elements of such tubes are a metal cathode and anode. In X-ray tubes, electrons emitted by the cathode are accelerated by the difference in electrical potential between the anode and the cathode and strike the anode, where they are sharply decelerated. In this case, due to bremsstrahlung, X-ray radiation is generated, and at the same time electrons are knocked out from the internal electron shells of the anode atoms. The empty spaces in the shells are occupied by other electrons of the atom. Currently, anodes are made mainly of ceramics, and the part where the electrons strike is made of molybdenum or copper. During the acceleration-deceleration process, only about 1% of the kinetic energy of the electron goes into x-ray radiation, 99% of the energy is converted into heat.

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Particle accelerators X-ray radiation can also be produced at charged particle accelerators. So-called synchrotron radiation occurs when a beam of particles is deflected in a magnetic field, causing them to experience acceleration in a direction perpendicular to their motion. Synchrotron radiation has a continuous spectrum with an upper limit. With appropriately selected parameters, X-rays can also be obtained in the spectrum of synchrotron radiation

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Interaction with matter The wavelength of X-rays is comparable to the size of atoms, so there is no material from which an X-ray lens can be made. In addition, when perpendicularly incident on a surface, X-rays are almost not reflected. Despite this, methods have been found in X-ray optics to construct optical elements for X-rays. In particular, it turned out that diamond reflects them well

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X-rays can penetrate matter, and different substances absorb them differently. Absorption of X-rays is their most important property in X-ray photography. The intensity of X-rays decreases exponentially depending on the path traveled in the absorbing layer (I = I0e-kd, where d is the thickness of the layer, coefficient k is proportional to Z³λ³, Z is the atomic number of the element, λ is the wavelength).

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Absorption occurs as a result of photoabsorption (photoeffect) and Compton scattering:

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X-ray radiation is ionizing. It affects the tissues of living organisms and can cause radiation sickness, radiation burns and malignant tumors. For this reason, protective measures must be taken when working with X-rays. It is believed that the damage is directly proportional to the absorbed dose of radiation. X-ray radiation is a mutagenic factor. Biological effects

Discovery of X-ray. In 1894, when Roentgen was elected rector of the university, he began experimental studies of electric discharge in glass vacuum tubes. On the evening of November 8, 1895, Roentgen, as usual, was working in his laboratory, studying cathode rays. Around midnight, feeling tired, he got ready to leave. Looking around the laboratory, he turned off the light and was about to close the door, when he suddenly noticed some luminous spot in the darkness. It turns out that a screen made of barium bluehydride was glowing. Why is it glowing? The sun had long set, electric light could not cause a glow, the cathode tube was turned off, and in addition it was covered with a black cardboard cover. X-ray looked at the cathode tube again and reproached himself: it turns out that he forgot to turn it off. Having felt the switch, the scientist turned off the receiver. The glow of the screen also disappeared; turned on the handset again - and the glow appeared again. This means that the glow is caused by the cathode tube! But how? After all, the cathode rays are delayed by the cover, and the meter-long air gap between the tube and the screen is armor for them. Thus began the birth of the discovery.

Slide 5 from the presentation “X-ray physics” for physics lessons on the topic “Ionizing radiation”

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Ionizing radiation

“X-Ray Physicist” - January, 1896... But how? Head: Baeva Valentina Mikhailovna. Thus began the birth of the discovery. X-rays have the same properties as light rays. Discovery of X-rays. X-rays. The glow of the screen also disappeared; turned on the handset again - and the glow appeared again. In 1862, Wilhelm entered the Utrecht Technical School.

"Ultraviolet radiation" - Ultraviolet radiation. Radiation receivers. Biological action. High temperature plasma. Properties. The sun, stars, nebulae and other space objects. Ultraviolet radiation is divided into: For wavelengths less than 105 nm, there are practically no transparent materials. History of discovery. Photoelectric receivers are used.

"Infrared radiation" - Application. The warmer an object is, the faster it emits. Large doses may cause eye damage and skin burns. You can take photographs in ultraviolet rays (see Fig. 1). The earth emits infrared (thermal) radiation into the surrounding space. 50% of the solar radiation energy comes from infrared rays.

“Types of radiation physics” - During beta decay, an electron flies out of the nucleus. Chernobyl accident. The time it takes for half of the atoms to decay is called the half-life. Modern views on radioactivity. There are many different explanations for the causes of the Chernobyl accident. It turned out that the radiation is not uniform, but is a mixture of “rays”.

Lecture 11 for 1st year students studying in the specialty of Pediatrics, Ph.D., Associate Professor Shilina N.G. Krasnoyarsk, 2012 X-ray radiation. Radioactivity Topic: X-ray radiation. Radioactivity Department of Medical and Biological Physics

X-ray radiation X-ray radiation is electromagnetic waves with a length from 80 to nm.

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Application of X-ray radiation X-ray diagnostics (up to 120 keV) Radiography Image on photographic film Fluoroscopy Image on an X-ray luminescent screen X-ray therapy keV

Linear ionization density is the ratio of ions of the same sign dn formed by a charged ionizing particle on an elementary path dL to the length of this path. I = dn/dL Linear stopping power is the ratio of the energy dE lost by a charged ionizing particle when passing an elementary path dL to the length of this path. S = dE/dL

Characteristics α- radiation - radiation Speed, cm/s2 Energy, MeV70.01 3 Range (air)2 9 cm cm Range (fabric) 0.01 cm1 1.5 cm Ionization density (ion pairs/cm) 50 Interaction with substance

Elements of dosimetry Radiation dose (absorbed dose) - the ratio of the energy transferred to a substance to its mass. 1 rad = Gr

Elements of dosimetry Exposure dose X - a measure of air ionization by X-ray or gamma radiation 1 roentgen - exposure dose of X-ray or gamma radiation, at which, as a result of complete ionization of 1 cm 3 of dry air at no. ions are formed that carry a charge equal to 1 CGS unit of each sign. 1Р = 2.58·10 -4 C/kg; D = fX

Equivalent dose Allows you to compare the biological effects caused by various radioactive radiations. K - quality factor (RBE) shows how many times the effectiveness of the biological effect of a given type of radiation is greater than that of x-ray or gamma radiation. Н = КD [Н] = Sievert (Sv) 1rem = 0.01 Sv

Dose SIV non-systemic Absorbed J/kg = Gy 1 Gy = 100 rad rad 1 rad = 0.01 Gy Absorbed power W/kg = Gy/srad/s Exposure C/kg C/kg = 3876 R R (roentgen) · 1 R = 2.58 · C/kg Exposure power C/(kg s) = A/kg (amps per kg) R/sR/s Equivalent J/kg=Sv 1Sv = 100 rem rem 1 rem = 0.01 Sv Equivalent power Sv/c=J /(kg s)rem/s Relationships between dose units

RECOMMENDED READING Mandatory: Remizov A.N. Medical and biological physics: textbook. -M.: Bustard, Additional: Fedorova V.N. A short course in medical and biological physics with elements of rehabilitation science: a textbook. -M.: Fizmatlit, Antonov V.F. Physics and biophysics. Course of lectures: textbook.-M.: GEOTAR-Media, Bogomolov V.M. General physiotherapy: textbook. -M.: Medicine, Samoilov V.O. Medical biophysics: textbook. -SPb.: Spetslit, Guide to laboratory work in medical and biological physics for self. student work / comp. O.D. Bartseva and others. Krasnoyarsk: Litera-print, Collection of problems in medical and biological physics: a textbook for self-study. student work / comp. O.P. Kvashnina and others - Krasnoyarsk: type. KrasGMA, Physics. Physical research methods in biology and medicine: method. instructions for extra-audit. work of students in special – pediatrics / comp. O.P. Kvashnina and others - Krasnoyarsk: type. KrasSMU, Electronic resources: EBS KrasSMU Internet resources Electronic medical library. T.4. Physics and biophysics. - M.: Russian doctor, 2004.

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Types of radiation: infrared, ultraviolet, x-ray

Physics lesson in 11th grade

Teacher: Vlasova O.V.

NOU Secondary School No. 47 JSC Russian Railways

Ingol village, Krasnoyarsk Territory

Visible spectrum

400THz 800THz

760nm 380nm

History of the discovery of infrared radiation

English astronomer and physicist

William Herschel.

History of discovery

Beyond the visible red stripe, the temperature of the thermometer rises.

Atoms and molecules of matter.
All bodies at any temperature.

Infrared radiation sources

Sun.

Incandescent lamps.

Wave and frequency range of infrared radiation

Wavelength

λ = 8*10 -7 – 2*10 -3 m.

Frequency

υ= 3*10 11 – 4*10 14 Hz

Properties of infrared radiation

Invisible.
Produces a chemical effect on photographic plates.
Water and water vapor are not transparent.
When absorbed by a substance, it heats it up.

Biological effect

At high temperatures it is dangerous for the eyes and can cause vision damage or blindness.

Means of protection:

special infrared glasses.

Infrared heater

Thermal imager

Thermogram

Applications of infrared radiation

In night vision devices:

binoculars;
glasses;
sights for small arms;
night photos and video cameras.

Thermal imager is a device for monitoring the temperature distribution of the surface under study.

Application of IR radiation

Thermogram - image in infrared rays showing the distribution pattern of temperature fields .

Infrared radiation in medicine

Thermograms are used in medicine to diagnose diseases.

Application of infrared radiation in thermal imagers

Monitoring the thermal state of objects.

Infrared radiation in construction

Checking the quality of building materials and insulation .

Applications of infrared radiation

Remote control.

The total length of fiber-optic communication lines is more than 52 thousand kilometers.

Application of infrared radiation on railways

Providing light to fiber optic communication systems using infrared lasers.

Used in railway transport

one-, two- and three-cable methods of organizing communication lines. Optical cables contain

4, 8 and 16 fibers.

Fiber – optical communication system

Simultaneous transmission

10 million telephone conversations and

1 million video signals.

Fiber – optical communication system

The fiber lifetime exceeds 25 years.

Application of infrared radiation on railways

Control of rolling stock from the transportation dispatch control center.

History of discovery

German physicist Johann Wilhelm Ritter.

English scientist

W. Wollaston.

UV sources

Sun, stars.
High temperature plasma.
Solids with

temperature

above 1000 0 WITH.

All bodies are heated

over 3000 0 WITH.

Quartz lamps.
Electric arc.

Wave and frequency range of ultraviolet radiation

Wavelength

λ = 10 -8 – 4*10 -7 m.

Frequency

υ= 8*10 14 – 3*10 15 Hz

Properties of ultraviolet radiation

Invisible.
All properties of electromagnetic waves (reflection, interference, diffraction and others).
Ionizes the air.
Quartz is transparent, glass is not.

Biological effect

Kills microorganisms.
In small doses, it promotes the formation of vitamins D, growth and strengthening of the body.
A tan.
In large doses, it causes changes in cell development and metabolism, skin burns, and eye damage.

Methods of protection:

glass glasses and sunscreen.

Features of ultraviolet radiation

With an increase in altitude for every 1000 m

UV level

increases by 12%.

Application of Ultraviolet Radiation

Creation of luminous colors.

Currency detector.

A tan.

Making stamps.

in medicine

Germicidal lamps and irradiators.

Laser biomedicine.

Disinfection.

In cosmetology – solarium lamps.

in the food industry

Sterilization (disinfection) of water, air and various surfaces.

Application of Ultraviolet Radiation in Forensic Science

In devices for detecting traces of explosives.

in Printing

Production of seals and stamps.

To protect banknotes

Protection of bank cards and banknotes from counterfeiting.
Currency detector.

The service life of an incandescent lamp is no more than 1000 hours.

Luminous efficacy 10-100 lm/W.

Application ultraviolet radiation on the railway

LED Lifespan

50000 hours

and more.

Luminous output exceeds

120 lm/W and constantly growing.

Application of ultraviolet radiation on railways

Emitter

with a small temperature shift along the wavelength and a long lifetime.

History of discovery

German physicist Wilhelm Roentgen.

Honored

Nobel Prize.

X-ray sources

Free electrons moving with high acceleration.
Electrons of the inner shells of atoms changing their states.
Stars and galaxies.
Radioactive decay of nuclei.

Laser .

X-ray tube.

Wave and frequency range of X-ray radiation

Wavelength

λ = 10 -8 – 10 -12 m.

Frequency

υ= 3 . 10 16 – 3 . 10 20 Hz

Properties of X-rays

Invisible.
All properties of electromagnetic waves (reflection, interference, diffraction and others).
Great penetrating power.
Strong biological effect.
High chemical activity.
Causes some substances to glow - fluorescence.