Types of radiation

The nature of the radioactive decay is characteristic of the element and can be used to fingerprint the substance. Decay continues until both the original element and its daughter isotopes are non-radioactive. The half-life, i.e. the time taken for half of an element s atoms to become non-radioactive, varies from millions of years for some elements to fractions of a second for others. 

y-Radiation is similar to, but shorter in wavelength than, X-rays and is associated with many a- or P-radiations. y-Radiation does not transform isotopes/elements. Like X-rays, y-rays are very penetrating they are capable of penetrating the whole body and require heavy shielding, e.g. y-rays from 60 Co penetrate 15 cm steel. 

X-Radiation like y-radiation is electromagnetic in nature. It can be emitted when P-particles react with atoms, but is more often electrically generated by accelerating electrons in a vacuum tube. Obviously, the latter source can be switched off. X-rays are extremely penetrating and are merely attenuated by distance and shielding. 

Neutron radiation is emitted in fission and generally not spontaneously, although a few heavy radionucleides, e.g. plutonium, undergo spontaneous fission. More often it results from bombarding beryllium atoms with an a-emitter. Neutron radiation decays into protons and electrons with a half-life of about 12 min and is extremely penetrating. 

The same type of radiation emitted by different isotopes may differ significantly in energy, e.g. y-radiation from potassium-42 has about four times the energy of y-radiation from gold-198. 

In the case of a-decay, dipositively charged particles (helium nuclei) of 

206) with the emission of OL -radiation but also B -and y -rays. Similar 

The second type of corpuscular radiation in radioactive decay is B -radiation. In this case, negatively charged electrons are ejected from the radionuclide. The atomic mass number of the radionuclide does not change. 

The emission of B -radiation creates a daughter nuclide of the same mass as the parent isotope and located immediately to the right of it in the periodic system of elements, owing to the loss of a negative charge. 

A B -radiating nuclide existing naturally in water is potassium 0. Potassium, which exists dissolved in small quantities in practically every kind of natural water, is a mixture of isotopes with a proportion of approximately 0.012 % of the B -radiating radionuclide potassium 40. 

The isotopes in each class are listed in order of increasing atomic number 

Very high toxicity High toxicity Moderate toxicity 

a-Particles (helium nuclei, i.e. 2 neutrons plus 2 protons) on emission die original isotope degrades into an element of two atomic numbers or less, e.g. uranium 238 produces diorium 234. Such transformations are usually accompanied by Y-radiation or X-radiation. a-Particles have a velocity about one-tendi dial of light with a range in air of 3-9 cm. Because of dieir relatively 

1 About 1 5% of those exposed show symptoms of loss of appetite, nausea, vomiting, fatigue etc. 1 Gy delivered 

There are two types of radiation ionizing and nonionizing. Ionizing radiation involves particles and waves of energy traveling in a wave-like motion. Examples 

There is a third type of radioactive particle, but it does not occur naturally. The neutron particle is the result of splitting an atom in a nuclear reactor or accelerator, or it may occur in a thermonuclear reaction. When an atom is split, neutron particles are thrown out. You would have to be inside a nuclear reactor or experience a thermonuclear explosion to be exposed to neutron particles. 

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The importance of these tlnee phenomena varies from one image to an other according to the nature of the metal, the thickness of the piece and the type of radiation employed. 

The paper presents the results from systematic comparisons of contrast and resolution obtained with different types of radiation sources on steel thicknesses from 5 to 40 mm. These results have been taken into account with the definitions of the European standard for radiographic inspection of weldments (EN 1435) that is approved since 1997. Conclusions from practical investigations on pipe line sites, in petrochcemical plants and in nuclear power stations will be discussed as well. Furthermore, the presentation will stipulate a variety of advantages obtained from the new source in terras of coUimation and radiation protection. 

The degree to which radiation exposure affects FEP resins is determined by the energy absorbed, regardless of the type of radiation. Changes in mechanical properties depend on total dosage, but ate independent of dose rate. The radiation tolerance of FEP in the presence or absence of oxygen is higher than that of PTFE by a factor of 10 1. 

Zinc compounds are generally colorless unless the other component, eg, chromate, is colored. The lack of color of most zinc compounds in visible light is a great advantage in that they do not color paint films, plastics, mbber, cosmetics, etc. However, when excited by various types of radiation and at various temperatures, zinc oxide, sulfide, selenide [1315-09-9], and related compounds exhibit luminescence, ie, they emit colored light (see Luminescent materials). Zinc-based phosphors can be produced in many colors, depending upon the added dopants. They are used in television tubes, luminescent glasses, and various specialty products. 

Activation Process of inducing radioactivity in a material by bombardment with other types of radiation, such as neutrons. 

Combining Tr + Tr for a point source gives equation 8.3-10. Radiation is attenuated by the distance from the source, the shielding material for the type of radiation and the thickness of shield that it must penetrate. 

Everyone receives small radiation doses every day Figure 8.3-5 illustrates some of the doses received from background and other types of radiation. Note that the scale is logarithmic , and that background and cosmic-ray doses vary over an order of magnitude just with location and elevation. In addition to these natural sources, most people receive some medical and dental doses each year. 

The extent of damage from radiation depends mainly on two factors. These are the amount of radiation absorbed and the type of radiation. The former is commonly expressed in rads (radiation absorbed dose). A rad corresponds to the absorption of 10 z J of energy per kilogram of tissue ... 

Wave-height-concentration plot 604 Wave height measurement of, 605 Wavelengths approximate of colours, 646 limits of various types of radiation, 647 units for, 647 Wave numbers 646... 

We have limited our investigations to the action of gamma-rays and fast neutrons on aromatic, alicyclic, aliphatic, and ionic compounds. The absorption coefficients for these types of radiation have an order of magnitude of lO /cm which is particularly adequate. Shallow penetrating radiations would only alter the superficial layers and would obviously not be able to affect the intensity of the quadrupole line substantially. This is for instance the case for ultraviolet light which has been shown to be unable to produce any effect on the resonance line of iodoform (CHI3 3Sg)... 

The three types of radiation commonly resulting from the decay of specific nuclides are ... 

Other techniques utilize various types of radiation for the investigation of polymer surfaces (Fig. 2). X-ray photoelectron spectroscopy (XPS) has been known in surface analysis for approximately 23 years and is widely applied for the analysis of the chemical composition of polymer surfaces. It is more commonly referred to as electron spectroscopy for chemical analysis (ESCA) [22]. It is a very widespread technique for surface analysis since a wide range of information can be obtained. The surface is exposed to monochromatic X-rays from e.g. a rotating anode generator or a synchrotron source and the energy spectrum of electrons emitted... 

A university student recently had a busy day. Each of the student s activities on that day (reading, having a dental x-ray, making popcorn in a microwave oven, and getting a suntan) involved radiation from a different part of the electromagnetic spectrum. Complete the following table and match each type of radiation to the appropriate event ... 

Complete the following table and match each type of radiation to the appropriate event ... 

Rutherford found that a second type of radiation was attracted to the positively charged electrode. He proposed that this type of radiation consists of a stream of negatively charged particles. By measuring the charge and mass of these particles, he showed that they are electrons. The rapidly moving electrons emitted by nuclei are called (3 particles and denoted (3". Because a (3 particle has no protons or neutrons, its mass number is 0 and it can be written Je. 

The third common type of radiation that Rutherford identified, y radiation, is not affected by an electrical field. Like light, y radiation is electromagnetic radiation but of much higher frequency—greater than about 1020 Hz and corresponding to... 

The most common types of radiation emitted by radioactive nuclei are a particles (the nuclei of helium atoms), /3 particles (fast electrons ejected from the nucleus), and 7 rays (high-frequency electromagnetic radiation). 

The dose equivalent is the actual dose modified to take into account the different destructive powers of the various types of radiation in combination with various types of tissue. It is obtained by multiplying the actual dose (in gray) by the value of Q for the radiation type. The result is expressed in the SI unit called a sievert (Sv) ... 

State whether the following statements are true or false. If false, explain why. (a) The dose equivalent is lower than the actual dose of radiation because it takes into account the differential effects of different types of radiation, (b) Exposure to 1 X 1 ()x Bq of radiation would be much more hazardous than exposure to 10 Ci of radiation, (c) Spontaneous radioactive decay follows first-order kinetics, (d) Fissile nuclei can undergo fission when struck with slow neutrons, whereas fast neutrons are required to split fissionable nuclei. 

Radiopharmaceuticals have one of two general functions (1) they may be used to detect or image biological problems such as tumors and (2) they may be used to treat an illness. Which type of radiation (a, p, or y) would be the most suitable for (a) detection and (b) therapy Justify your selections, (c) From standard literature sources, find at least two radionuclides that have been used for imaging body tissues, (d) What are the half-lives of these radionuclides ... 

Figure 12. A one hour dark image from LBNL p-channel CCD with several types of radiation events. Figure provided by D, Groom (LBNL),...

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