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Nuclear Physics
Most commonly known for its applications in nuclear energy and nuclear weapons, Nuclear Physics also has applications in medicine and archaeology. This category is for questions about the branch of physics that deals with the study of the forces, reactions, and internal structures of atomic nuclei, Nuclear Physics.
3,164 Questions
What is meant by half life in radiocarbon dating?
Half-life in radiological terms is the length of time for one half of an isotope to undergo decay to something else. It is an inverse exponential function, in that after successive half-lives there will be 1/2, 1/4, 1/8, 1/16, etc. of the original isotope remaining. The equation for half-life is ...
AT = A0 2(-T/H)
... where A0 is the starting activity or mass, AT is the activity or mass at time T, and H is the half-live in units of T.
The half-life of 6C14 is 5730 years. By measuring its ratio to 6C12 and 6C13 in a carbonaceous sample, such as plant life remains, scientists can estimate the age of the sample. It is a relatively straightforward process, except that the ratio changes over time due to variations in cosmic ray levels from the Sun as well as due to climate changes that disturb deep reservoirs of carbon, so scientists calibrate by comparing samples using other dating techniques to cross-check.
Some of the elements in your body are naturally radioactive. e.g. potassium, some carbon, etc.
You get a larger exposure to radiation from the decay of potassium in your body, than you will from a smoke detector based upon radioactive americium.
How do the waste products of nuclear fusion differ from nuclear fission?
Yes, they are quite different. The deuterium-tritium reaction produces a helium nucleus, which is harmless. There will be an intense neutron bombardment of the enclosure holding the fusion plasma, and this will result in the structure becoming radioactive, but that will be a problem for decommissioning rather than operation.
Scientists originally promised fusion as a clean source of energy, and whilst it is not entirely so, it is far cleaner than fission. The only problem is finding how to make it work in a practical power producing plant.
When an oxygen19 nucleus undergoes beta decay the nucleus formed is that of?
When an oxygen-19 nucleus undergoes beta decay, a nitrogen-19 nucleus is formed. In beta decay, a neutron is converted into a proton, causing the atomic number to increase by one while keeping the mass number the same.
What is 3 advantages of nuclear fission?
it can produce electricity
poopoopop
It is a clean and green source of electricity. Unfortunately, as with many things, the US is far behind the rest of the world in utilizing this form of energy.
A lamp or an X-ray tube cannot be used to "add neutrons" to other nuclei because lamps and X-ray tubes are not neutron sources.
Neutron activation is generally something we do in an operating nuclear reactor. In the core of the reactor, there is a high neutron flux. Many, many neutrons are being released in the fissions that are going on in the nuclear core. Materials that are to be activated are lowered through ports and brought down into the neutron flux. Activation occurs. Lamps or X-rays do not produce neutrons, and cannot be used in neutron activation activities. No neutrons means no neutron activation.
Is radon-222 a product of organic decay?
Yes, radon-222 is produced through the decay of radium-226, which is a product of uranium decay. While radon is not directly produced from organic decay, radon can be found in soil and rocks where decay of radioactive elements occurs.
Do radiotracers generally have long or short half-lives?
Radiotracers generally have short half lives. Detection requires a number of decay events. Using material with a short half life means a smaller amount is required and that after the detection the amount of residual radiation is reduced.
Can the chain reaction of nuclear fission be stopped or controlled?
Yes, the chain reaction of nuclear fission can be controlled by using control rods made of materials like boron or cadmium that absorb neutrons, thus regulating the rate of fission. Additionally, cooling systems can also be used to control the temperature and prevent the reactor from overheating.
What is size of beta particles?
Alpha radiation is essentially a Helium nucleus without any electrons- thus an alpha particle is as large as the four constituent nucleons.
Gamma radiation is made up of photons- thus gamma radiation is much like light in that it is energy traveling in a wave with particle properties.
The nuclide Sn is unstable what decay types would Sn be expected to undergo?
The nuclide Sn can undergo beta-minus decay, beta-plus decay, electron capture, or alpha decay, depending on its specific isotope. Each decay type involves the transformation of the nucleus to a more stable state by emitting different particles or radiation.
What After the nucleus of a radioactive element undergoes the element can transform into?
There are many radio active elements which decay into lighter elements and give off charged particles in the process.
The best place to find this voluminous information is in a 'Table of the Nuclides'.
What are the three main types of nuclear radiation and how are they different from each other?
Alpha particles are identical to the helium-4 atom nucleus, i.e., 2 protons and 2 neutrons. They carry a charge of +2. Because of their mass, they can barely get thru a sheet of paper or human skin. They don't go far, but they are the most destructive.
Beta particles are essentially 'free range' electrons that have escaped from the nucleus of their parents. This type of decay occurs when a neutron in the parent becomes unstable and decays. Example: H-3 (at no 1 at wt 3) decays to He-3 (at no 2, at wt 3) The energy loss in the nucleus is transferred to an electron (aka, beta particle) and an antineutrino. The amount of energy transferred is a characteristic of the parent, unstable isotope. Betas can have sufficient energy to travel several feet in air. Because of their lack of mass and and smaller charge, they are not as destructive at close range as Alphas.
Gamma rays are extremely high energy electromagnetic rays.
Their parent nuclei are the products of other types of radioactivity (alpha and beta decay) or of some other nuclear process. They end up with more than their normal energy, which they dump by emitting gamma ray photons. Gamma rays are by far the most penetrating of the three major types of radiation and require the most shielding ... tons of Lead, feet of concrete, etc.
What are the benefits of nuclear testing?
Over the past 40 years, a disease known as rinderpest, or "cattle plague", has been devastating for farmers in Africa, claiming the lives of millions of cattle and severely hurting farm production and income. Especially in the 1980s, serious outbreaks of rinderpest in livestock were reported throughout Africa.
Today, that picture has changed. Out of 18 African countries where cattle once were infested with rinderpest, only two show signs of the disease today. Instrumental to this remarkable turnabout has been a Pan-African campaign that incorporated the application of a new nuclear-based testing technique developed jointly by the IAEA, Food and Agriculture Organization (FAO) of the United Nations, and a laboratory in the United Kingdom in 1987. The application has radically increased the effectiveness of vaccination campaigns against cattle plague, enabling African countries to declare themselves free of the disease. Veterinarians in these countries received support from the IAEA's technical co-operation programme and an FAO/IAEA coordinated research programme. They were supplied with necessary testing kits, equipment, training, and technical support to ensure the correct use of the technique in national veterinary laboratories. Participating laboratories throughout Africa now have acquired the expertise and skills they need to carry out effective testing.
The project's success is leading to similar work in other regions of the world. A global rinderpest campaign has been launched with the aim of eradicating the disease over the next 20 years. Under a 4-year IAEA technical co-operation project, the techniques developed through the FAO/IAEA's work in Africa will be part of efforts for rinderpest surveillance and control in West Asia. Countries there currently are suffering millions of dollars in losses from animal deaths. The IAEA regional project aims to help these countries eradicate rinderpest by the turn of the century.
The case of rinderpest is just one example of how international and national scientists are working together to bring practical benefits to people through technology-transfer projects supported by the IAEA. In other fields as well including medicine, environmental protection, and food preservation, for example - nearly, 1300 IAEA-supported projects are making key contributions around the world. This article looks at the kinds of projects cooperatively undertaken through IAEA mechanisms to extend the reach of beneficial nuclear technologies in response in increasing demands for technical support and assistance from its Member States.
Evolution of international nuclear co-operationIn the early 1950s, the international community was first becoming aware of the great opportunities that peaceful applications of atomic energy could offer for economic and social development. It was also becoming apparent that, for most countries, these opportunities could be materialized in a most effective manner through extensive and concerted international efforts.In this environment, on 4 December 1954, the United Nations General Assembly unanimously passed an "Atoms for Peace" resolution expressing the hope that an international atomic energy agency would be established without delay to facilitate the use by the entire world of atomic energy for peaceful purposes, and to encourage international co-operation in the further development and practical use of atomic energy for the benefit of humanity.
At the time when the IAEA was established in 1957, only a limited number of countries had knowledge and experience in nuclear research, and especially its practical application. At the first International Conference on the Peaceful Uses of Atomic Energy, held in Geneva in August 1955 and attended by scientists and engineers from 73 countries, less than half of participating States were able to present reports on nuclear science or technology and only 12 of these States were from developing areas of the world.
In framing the IAEA's Statute, governments sought to create an international institution through which countries could receive multilateral technical assistance on peaceful nuclear research and applications. The Statute stipulates a range of conditions for countries to receive such assistance. These include, inter alia, the usefulness of the project, including its scientific and technical feasibility; the adequacy of plans, funds, and technical personnel to assure the effective execution of the project; and the adequacy of proposed health and safety standards for handling and storing materials and for operating facilities.
Back in 1957, however, the basis for technical assistance activities was fairly weak. The sphere of co-operation was relatively limited covering mainly nuclear power and aspects of its fuel cycle, and to a certain extent some aspects of radiation applications. Very few peaceful nuclear technologies had reached the level of maturity which enabled them to be effectively used for practical applications. At that time as well, most developing countries were not yet at the stage where they could effectively apply nuclear science and technology. It should also be noted that, in the early years, none of the three partners involved in the technical assistance process i.e. donor countries, recipient countries, and the IAEA - had neither the required experience nor administrative arrangements for multilateral intergovernmental co-operation.
Today, the situation is different. Most IAEA Member States from the developing world have gained knowledge and experience in many fields of nuclear research and applications, mainly those related to basic human needs. Mechanisms for technology transfer have been put into place, and their effectiveness is continually reviewed. IAEA activities cover practically all areas of peaceful applications of nuclear energy, and interest in receiving technical assistance is growing.
People in many countries around the world are seeing benefits of nuclear technologies in their lives, through IAEA-supported projects in fields of health care, water management, agriculture, and industry, for example. (Credits: J: Aranyossy and V. Mouchkin, IAEA)
Priorities and needsWhat kinds of technical assistance are countries receiving? In terms of total annual disbursements through the IAEA's technical co-operation programme, the largest share is for projects related to nuclear applications in food and agriculture, which accounted for about 22% of disbursements in 1994. Nuclear-related methods are widely used in developing countries in such areas as plant breeding, soil fertility studies, insect and pest control, animal production and health, and studies of the fertilizer efficiency and the fate of agrochemicals and residues. The technology of food irradiation additionally is finding increasing acceptance as an effective means of protecting agriculture products from spoilage, and as a method for controlling pathogens associated with serious food-borne diseases and for meeting the strict quarantine requirements of international food trade.Another major area of interest is the use of nuclear technologies in physical and chemical sciences, and in fields of industry and earth science. This includes the utilization of research reactors and particle accelerators for scientific studies, production of isotopes; the application, maintenance and repair of nuclear instrumentation; and the preparation and utilization of radiopharmaceuticals. Over the 1990-94 period, the share of total disbursements in this area have ranged between 18% and 25%. Other areas showing high levels of interest are nuclear applications in industry and earth sciences - including non-destructive testing of materials and products, radiation processing, and development of water resources, for example and nuclear-related health care and treatment. Greater support, for instance, is being requested in the use of nuclear techniques for the diagnosis of many diseases, such as leishmaniasis, Chagas disease, iodine deficiencies, and sickle cell diseases. At the same time, the use of ionizing radiation to treat cancer is drawing more and more interest. Currently the IAEA has 40 technical co-operation projects associated with radiotherapy in 29 countries. Additionally, nuclear methods and technologies are used for sterilization of biological tissues and medical supplies, and for nutritional and health-related environmental studies.
An area of shifting demand is nuclear power and safety. While nuclear power programmes in many countries have been cut back or halted, there is increasing awareness of the needs for nuclear safety and radiation protection. The share of disbursements on nuclear power has dropped from about 12% in the late 1980s to 6% in the 1990s, whereas the share for safety and radiation protection has grown. Projects being supported include those related to strengthening national infrastructures for radiation protection; occupational safety of radiation workers; safety of nuclear installations; the safe management, storage, and disposal of radioactive wastes; and nuclear emergency planning and preparedness.
On average over the past 5 years, countries have received technical assistance from the IAEA valued at about US $40 million per year through expert services, provision of equipment, and training activities. All told over the past 25 years, the cumulative resources available to the IAEA's technical co-operation programme amount to nearly US $690 million.
Realizing the benefitsAs the rinderpest example illustrates, a number of techniques developed and applied with the IAEA's assistance are significantly contributing to the solution of serious problems hampering social and economic development. Some selected other cases may help to indicate the number of different ways in which the IAEA's assistance can be applied.Water resources. The assessment and development of water resources has been a major area of IAEA activity for more than 30 years. Nuclear and isotope techniques play a valuable role in hydrological investigations. Under one current project, in Venezuela, IAEA scientists are helping local water authorities in Caracas study the potential of an aquifer to provide additional water for residential, agricultural, and industrial needs. A rapid increase in the population of Caracas has led to a deficit of nearly 20% in the water supply, and more water resources must be found. Studies will help Venezuelan authorities make decisions concerning the best use of the aquifer, and how to protect its water from pollution.
Animal health and productivity. Buffaloes and cattle in Asia are fed mainly with rice straw and native grasses. However, these materials are very indigestible and have only limited amounts of the protein, energy, and minerals needed to provide a balanced diet. Poor nutrition seriously compromises the ability of the animals to produce meat and milk and to provide draught power. Through projects jointly supported by the IAEA and United Nations Development Programme (UNDP), assistance was provided to India and Indonesia in using isotopes for investigating the efficiency of the processes involved in feed digestion. As a result, the best combination of local materials for supplementing grass or straw was determined.
In both countries the effect of the introduction of this feed supplementation method has been very high. For example, in India the amount of milk collected by the largest milk co-operative in 1989 increased by 30%, and the price was 25% less than the price of producing milk by the other methods of feed supplementation.
Quality control in industry. Non-destructive testing (NDT) techniques are widely applied in industry and manufacturing for quality control purposes. In Latin America and the Caribbean, an IAEA-supported NDT regional project involving 18 countries was conducted from 1983-94. The overall objective was to assist them in developing an autonomous capability for applying NDT, largely by providing support in areas of training.
The evaluation review carried out by independent experts in 1994 showed that the project had been instrumental in providing the region with a significant technological tool for the advancement of the region's industrialization. This enabled the development of local industries and the displacement of NDT services previously provided from outside the region. The project marked a significant change for the region's own technological development. In previous years, the input from experts from outside of the region was the dominant mode of dissemination of NDT technology. This was often in the context of regional courses, with typically one participant from each project country. Gradually, the dominant mode changed from using external experts to using regional experts and further evolved to the use of national experts teaching courses solely in their respective countries.
Health care. Nuclear and related techniques play an especially vital role in health care and treatment. Among important diagnostic tools is a technique known as radioimmunoassay. With the IAEA's support, more than 250 radioinimunoassay laboratories have been established or upgraded in Africa, Asia, and Latin America, and supplied with reagents in bulk form. has allowed recipient countries to provide reasonable clinical diagnostic services covering important substances such as hormones, vitamins, enzymes and even some tumor markers. The cost of each test is less than US 50 cents per patient sample, which on average is ten times less than the application of complete commercial kits. In some countries, where some of the primary reagents needed are being produced locally, the cost per test is significantly lower. More important than the lower cost is the fact that many people now have access to reliable diagnostic tests that play a key role in the improvement of their health care and treatment.
Future directionsIn its current and planned programmes, the IAEA is placing increasingly more emphasis on cost-effective projects that promise significant social and economic benefits, that have a lasting and environmentally sound impact on a country's development, and that clearly demonstrate the value of nuclear applications for end users. The IAEA's Member States have strongly supported this move towards impact-oriented technical co-operation. At an IAEA Technical Cooperation Policy Review Seminar in September 1994, for example, governmental representatives provided the Agency with valuable recommendations regarding the practical implementation of projects important to them.Undoubtedly the major challenge facing the IAEA's technical co-operation programme in years ahead is the availability of sufficient financial resources to effectively carry out approved projects. In terms of its funding base, the IAEA occupies a place far behind large bilateral and multilateral agencies. Even so, the trend in contributions to the IAEA's technical co-operation programme over the past 5 years has been negative, and many sound projects have had to go unfunded. In response to the situation, the IAEA has taken a number of administrative and programmatic measures intended to stretch its limited resources so as to obtain the best possible results.
These efforts are part of steps to improve programme efficiency, and to attract greater resources enabling the IAEA to enhance its support for technology-transfer activities that are not only operationally sound but visibly effective. As the main channel for global nuclear co-operation, the IAEA possesses an exceptionally high level of technical expertise and experience to identify and carry out a multitude of projects that can make a lasting difference to a country's sustainable development.
Mr. Qian was Deputy Director General of the IAEA Department of Technical Co-operation and Mr. Rogov was a staff member in the department.
aquired from
http://www-tc.iaea.org/tcweb/archives/articles/atomsforpeace.asp
How are thermal neutrons detected?
Neutrons from fission have a natural energy of about 2 Mev. In a thermal reactor these are slowed to thermal equilibrium by a moderator, at about 0.025 ev.
At these lower energies (= slower speeds) we have more time to have them react with a measuring device, commonly a particle detector. Or a scintillation detector with associated light detector..
Is a geiger counter better than a bubble chamber?
Neither is better. They are used for different purposes.
Geiger counters detect rates of beta and gamma radiation, emitting clicks as they are detected. Some types can detect alpha particles also. They are used as devices in the field, to determine such things as safety of an object or place.
Bubble chambers also detect ionizing radiation, but they do so by recording, rather than rates of emission. They have historically been used for research, though they are used less now than they have been in the past.
The generalized exponential half-life equation is ...
AT = A0 2(-T/H)
... where A0 is the initial activity, AT is the final activity at time T, and H is the half-life in units of time T.
Example using the specific question, for an elapsed time of 50 days, is ...
A50 = (381) 2(-50/75) = 240
Why does alpha radiation produce the greatest change in mass number?
Alpha radiation involves the ejection of a helium nucleus, which has a mass number of 4. This results in the largest change in mass number compared to beta and gamma radiation, which involve the emission of electrons or photons with much smaller masses.
Is it true or false that a gamma ray is a very high-speed particle with no charge?
True. A gamma ray is a high-energy photon, and thus moves at the speed of light. And, like all photons, it has no charge.
How can you obtain Al-k alpha radiation?
K alpha and L alpha are secondary radiation lines that are peculiar to a given element bombarded with radiation (Xray tube).
When you radiate an element, it gives off secondary radiation measured as K alpha and L alpha lines. This secondary radiation is given off at an angle peculiar to the element being radiated. Hence one is able to analyse a mineral ore sample for wanted elements by setting up radiation detectors at the various angles peculiar to the elements being sort.
This process is used in auto-assay equipment used by mining companies wanting to reduce the time it takes to analyse samples chemically.
What are the requirements for nuclear fission to take place?
To initiate nuclear fission, a nucleus must absorb a neutron, leading to its instability and subsequent splitting into two or more lighter nuclei, along with the release of additional neutrons and a large amount of energy. Additionally, a critical mass of fissile material, such as uranium-235 or plutonium-239, must be present for a sustained chain reaction to occur. The process is typically moderated by materials like water or graphite to control the rate of fission.
Which stars produce most of their energy by the CNO cycle?
Stars that produce most of their energy by the CNO cycle are predominantly those with a mass about 1.3 times the mass of our Sun or greater.
Our Sun, and stars comparable in mass or less, predominantly use the proton-proton cycle.
Is it difficult to start nuclear fission or nuclear fusion?
Both nuclear fission and nuclear fusion require extreme conditions to start the reactions, such as high temperatures and pressures. Nuclear fission involves splitting heavy atomic nuclei, while nuclear fusion involves combining light atomic nuclei. The technical challenges differ for each process, but both are complex and require precise control to sustain the reactions.
What is the place where controlled nuclear fission reactions take place?
The place where controlled nuclear fission reactions take place is called a nuclear reactor. In a nuclear reactor, uranium atoms are split in a controlled manner to produce heat energy, which is used to generate electricity.
