Research in reactor physics spans a broad set of specialties including fuel damage, fuel recycling, safeguards, and waste management. Nuclear physics plays a direct role in addressing each of these. For nuclear fusion, the plasma physics community is exploring a number of methods to achieve the necessary conditions for controlled energy release. In nuclear fusion, plasma conditions approaching those in burning stars are required, and nuclear physics plays a significant role in diagnosing the conditions achieved in the plasma.
Nuclear Fission Reactors. These and other so-called second-generation nuclear reactors are safe and reliable, but they are being superseded by improved designs. Over the past decade, nuclear engineers have been researching advanced reactor designs, and there is a worldwide movement toward to a new generation of reactors. Some of the advanced designs include fast reactors, high-temperature graphite-moderated reactors, thorium-uranium-fueled reactors, pebble bed designs, and mixed oxide fuel MOX plutonium reactors.
Such measurements are quite challenging. The fact that many of them are also important to stockpile stewardship and nuclear forensics greatly enhances our ability to bring together the teams of scientists needed for these experiments. The accurate characterization of decay heat is crucial for the reactor shutdown process, since it is the main source of heating after neutron-induced fission is terminated.
The decay heat, and in particular the high-energy part of the radiation, is a key aspect in the proper design of shielding and storage casks for transporting and storing spent nuclear fuel. MTAS complements other instruments designed to directly measure neutron emissions following beta decay of fission fragments, neutrons that contribute to the neutron budget in a reactor and help to ensure stable reactor operation. The decay heat and beta-delayed neutron measurements are also important for understanding r-process nucleosynthesis.
Irradiation of both nuclear fuel and structural materials in reactors produces material defects that limit the safe lifetime of these materials. Numerous irradiation effects can cause material damage, and a number of ongoing collaborations between nuclear physicists, material scientists, and reactor engineers are examining and characterizing these effects in detail. One example is the buildup of helium at grain boundaries and its effect on the embrittlement of reactor structural materials.
The embrittlement of metals such as nickel, iron, and copper has been demonstrated to be a function of both temperature and helium concentration. New cross section measurements have resulted in significant changes in estimates of the probable safe lifetime of structural reactor materials. Rykaczewski, , Viewpoint: Conquering nuclear pandomenium, Physics 3: A state-of-the-art device is being commissioned at ORNL to measure the decay heat of fission fragments with high accuracy.
Its total volume will be about seven times that of the largest existing total absorption spectrometer. In the coming decade, FRIB will produce a greatly expanded set of fission fragments and enable precision measurements of their detailed decay modes. Courtesy of K. Rykaczewski and M. Gas bubbles can cause changes in internal gas pressure, thermal conductivity, temperature gradients, and material stress and strain, thus inducing damage or even failure in fuel and cladding materials over time.
Understanding the formation and properties of these bubbles and how to detect the gases if released is the focus of a joint collaboration between materials and nuclear scientists. One advanced concept is the fast reactor, wherein the neutron flux is considerably higher in energy than in standard thermal reactors. The dominant neutron energies for a fast reactor are 0. Fission cross sections are considerably less well known at fast reactor energies than at thermal energies. And the situation is most serious for the transuranic fuels. New programs are under way to measure. In addition to the fission cross sections, accurate knowledge of the neutron capture cross sections on the minor actinides is important.
Many of these actinides are radioactive, restricting measurements to small targets. International collaborations are addressing these problems using the DANCE detector at LANSCE, which is designed to study neutron capture reactions on small quantities, about 1 mg, of radioactive and rare stable nuclei.
Others are using the TPC displayed in Figure 3. One major attractive characteristic of fast reactors is their enhanced ability to burn up highly toxic transuranic fuel produced as waste from light water reactors. At these higher neutron energies, there are a number of nuclear properties of reactor fuels that need to be determined to considerably higher accuracy than is presently possible, including reactions of neutrons with unstable fission products.
In the future, FRIB will extend capabilities by allowing studies of a considerably larger class of unstable isotopes. For several key nuclides that have longer half-lives, FRIB will provide separated samples that can be used to measure neutron capture probabilities at neutron beam facilities. For isotopes with shorter lifetimes, indirect reaction measurements at FRIB will provide information to help constrain theoretical models for neutron-capture probabilities, using techniques that will also advance basic nuclear science and nuclear astrophysics.
When two light nuclei interact, they can fuse to form a heavier nucleus, accompanied by the release of a large amount of energy. The conditions found in stellar environments are ideal for sustained fusion chains, and our sun is a natural fusion reactor. However, achieving these hot, dense conditions in the laboratory is very challenging, and to date the only successful terrestrial events have been thermonuclear explosions.
Currently there are two main research approaches to fusion: Probing physics at high energy densities is central to several subfields of nuclear physics, including the study of nucleosynthesis, the quark-gluon plasma, and neutron stars. NIF is designed to compress capsules containing a mixture of deuterium d and tritium t to temperatures and.
The temperature in kelvins as a function of the number of charged particles per cubic meter for a wide range of physical systems is displayed. The National Ignition Facility produces plasmas via inertial confinement fusion that are comparable to the interior of the sun. Courtesy of the Contemporary Physics Education Project. Laser pulses, directed into a hohlraum cylinder containing the target capsule, create an X-ray bath sufficient to compress the capsule through ablation of an outer layer of material. Achieving the conditions needed for ignition is challenging but made more tractable with the use of advanced diagnostics, many of which are based on nuclear physics.
Neutrons are one of the main products of the fusion reactions. Nuclear physicists are developing tools to diagnose the conditions in the NIF d-t capsules. On the left is a simulation of an expected neutron image; on the right is a reconstruction of an actual neutron image of a capsule taken at NIF. The image determines the size of the hotspot and the asymmetry of the implosion. One of the important diagnostics for understanding capsule behavior is neutron imaging.
The image of the primary MeV neutrons determines the size of the burning fuel region the hotspot. The lower-energy, downscattered neutrons provide information on the average density as a function of radial distance from the center of the fuel and on how symmetric or asymmetric an implosion was achieved. Nuclear physics is fundamentally cross-disciplinary in nature, providing experimental and theoretical tools and concepts for countless other sciences and.
The applications and manifestations are so entrenched in our daily lives as to be ubiquitous, from simple everyday household items to technologies that provide significant portions of the foundation of medical procedures. Nuclear science has and will continue to play a substantial role in developing solutions for energy, climate, and environmental challenges. Further, the primary tools of modern nuclear science—accelerators and computers—have spawned many applications and economic benefits, some of which are discussed here.
Beams of high-energy particles, produced by accelerators, are essential for both fundamental and applied research and for technical and industrial fields. Accelerators have become prevalent in our lives, and there are now over 30, accelerators worldwide. Of these, the largest number about 44 percent are used for radiotherapy, while 41 perecnt are used for ion implantation, 9 percent for industrial research, and about 4 percent for biomedical research.
The remaining 1 to 2 percent of accelerators are very high-energy accelerators used in nuclear and particle physics to probe the fundamental nature of the matter making up our universe. All accelerators can be described as devices that use electric fields to accelerate charged particles such as electrons or ions to high energies, in well-defined beams. Since the discovery of the X-ray in by Roentgen, many famous nuclear physicists have made seminal contributions to new accelerator technologies, including John D.
Cockcroft, Ernest Walton, Earnest O.
Applications of Nuclear Physics
Lawrence, and Robert Van de Graaff. Today accelerator technologies range from the Large Hadron Collider LHC capable of producing TeV particles to the lowest energy accelerators used by industry. Accelerators form the basis for many diagnostic systems, from chest X-ray machines to whole-body X-ray scanners capable of creating a three-dimensional image of the living body. Accelerators such as cyclotrons enable protons and other light nuclei to be used to produce radioactive nuclei that are used in diagnostic medicine.
Radioisotopes such as thallium are used to diagnose heart disease. The production of the unstable isotopes of the elements of life, such as oxygen, carbon, nitrogen, and the pseudo-hydrogen fluorine, has led to the field of PET. These positron-emitting radionuclides are attached to biologically active molecules.
When the tagged molecules are injected, the annihilation radiation can be imaged and the functional capacity of the patient can be determined, as discussed in the PET highlight, located between Chapters 2 and 3. Today PET scanners. CT and PET scanners have revolutionized nuclear medicine. Intense X-rays are now one of the primary modes of treating cancer. Accelerators throughout the world generate beams of electrons that are directed to targets that create X-rays, which are then directed at the tumors to destroy them.
The modern therapy machine has become extremely sophisticated in that the electron beam can be modulated to increase and decrease the flux to alter the dose of X-rays and thereby spare healthy tissue while maximizing the dose to the tumor. While the standard of care for cancer treatment includes X-ray therapy, there is a growing use of high-energy protons to ablate the tumors. The idea is to deposit as much energy as possible in the tumor cells while sparing the surrounding tissues.
In the United States, partnerships between industry and nuclear science laboratories have led to new accelerator developments for medical applications. This work has resulted in the miniaturization of the cyclotron so that it will fit on a gantry and rotate around the subject, simplifying beam delivery and allowing for tighter control of radiation dose delivery. NSCL has also designed and constructed a gantry-mounted, superconducting K medical cyclotron, funded by Harper Hospital in Detroit, for neutron therapy.
The success of proton therapy has stimulated interest in using heavier hadrons, such as carbon ions, with the potential of depositing more energy to a small area. Several synchrotrons delivering carbon for therapy have been installed in Europe and Japan. There is a vast enterprise of techniques that use accelerators in a wide range of industries to polymerize plastics, to sterilize food and medical equipment, to weld materials using an electron beam, to implant ions into materials, to etch circuits on electronic devices, to examine the boreholes of oil wells, and to search for dangerous goods.
There are approximately 8, such devices worldwide. Electron beams dominate the industrial uses, with the curing of wire-cable tubing and of ink accounting for more than 60 percent of the market. Other electron beam uses include shrinking films, cross bonding of fibers in tires, and irradiation. Here, electron beams replace traditional thermal heating approaches because of the gain in efficiency that comes from the more uniform distribution of energy. A number of major accelerator developments related to nuclear energy are being pursued, including plasma heating for fusion reactors, inertial fusion reactors, nuclear waste transmutation, electronuclear breeding, and accelerator-driven subcritical reactors.
The breadth of scientific disciplines that make use of accelerators to perform their studies is considerable. Cutting-edge materials research makes use of synchrotron radiation having a wide range of wavelengths. Muon beams and neutrons produced from spallation sources probe the properties of materials such as the high-temperature superconductors. Mass spectroscopy is a standard analytical technique for chemists. As discussed at the end of this chapter, high-resolution mass spectrometry is used in archaeology and geology for dating artifacts by determining the ratio of stable to long-lived isotopes.
A free-electron laser FEL is a powerful source of coherent electromagnetic radiation that is produced by a relativistic electron beam propagating through a periodic magnetic field see Figure 3. FELs are capable of producing intense radiation over a wide range of the electromagnetic wave spectrum, from microwave to hard X-ray, with average beam powers up to tens of kilowatts and peak powers up to tens of gigawatts.
FELs are used for research in many fields, including materials science, surface and solid-state physics, chemical, biological and medical sciences, and nuclear physics.
While the principle of operation of all FELs is the same, each device is optimized for its main application. FELs that are used in applications that require high average power are typically operated in the infrared IR region and are driven by a high-repetition-rate linear accelerator with an optical resonator.
Nuclear physics accelerator facilities are leading new developments in FEL technologies. New investigations in condensed matter studies at accelerator labs in the United States and Germany have already identified previously unknown interstellar molecular emission lines, developed new processes for production of boron nitride nanotubes, and produced nonthermal pulsed laser deposition of complex organics on arbitrary substrates.
Superconducting radiofrequency technology developed at the Continuous Electron Beam Accelerator Facility CEBAF nuclear physics accelerator is now being commercialized for future implementation in weapons. They are used in numerous basic and applied science applications, including probing materials, biological systems, and nuclei. Shown is a schematic diagram of the basic layout of an FEL. The electron beam is transported through the periodically varying magnet field of an undulator magnet.
An FEL can be operated with either an optical resonator or in a single-pass configuration with a long undulator section. DESY And FEL technologies and applications are strongly coupled to nuclear physics research, including the technologies needed for a future electron-ion collider. Information and Computer Technologies. Both nuclear physics experiments and theory have been enabled by and, in turn, have spawned, advances in computer science and technology.
For experimentalists, the enormous quantity of data that characterize modern nuclear physics experiments has required that systems be devised to handle and make such data meaningful. RHIC experiments now routinely collect petabyte scale data sets each year, at rates of 1 GB per second. Analysis of such data sets drives technology development for the sustained use of data grids.
For example, the computing groups. This allows next-day access to fresh data from the experiments for analysis. Analogous progress has come out of the need for massive and reliable computational approaches to address some of the fundamental problems in nuclear theory. Lattice quantum chromodynamics QCD calculations of the structure and properties of protons and hot quark-gluon plasmas that begin with fundamental quark and gluon building blocks are among the most demanding numerical computations in nuclear physics.
Advancing this basic science drives innovation in computer architectures. In a lattice QCD calculation, space and time are rendered as a grid of points, and the quarks and gluons at one point interact only directly with those at other nearby points. This localization of the particles and their interactions makes these numerical computations particularly well suited for massively parallel supercomputers, with communications between processors having a simple pattern that enables the efficient use of a very large number of processors.
This characteristic of lattice QCD calculations drove some physicists to design special-purpose supercomputers that attracted attention in the broader computer hardware arena by achieving lower price-to-performance ratios than contemporary commercial supercomputers. A particularly successful group designing special-purpose lattice QCD supercomputers was based at Columbia University, working in partnership with IBM, which manufactured the computer chips.
Originally, the group built a machine based on a low-power, simple, digital signal-processing chip similar to those in cell phones and a special-purpose serial communication network. Recently, the LHC, which enables particle and heavy-ion nuclear physics research at the energy frontier, has reached unprecedented volumes of data and requirements for data transfer rates and data processing power. This has led to the development of technology that allows extraordinary data transfer rates at large distances. At Super Computing , the International Conference for High Performance Computing, Networking, Storage and Analysis, held in Seattle, Washington, in November , a new world record of bidirectional data transfer rate was achieved: Such technology eventually will influence the Internet infrastructure used in our everyday life.
Lattice QCD machines, QCDOC in particular, became the paradigm for a new generation of world-leading massively parallel supercomputers that are currently. Department of Energy, in partnership with IBM. Examples of calculations now possible with the most powerful computers are given in the lower figures.
Displayed are lattice QCD calculations of the transverse charge distributions of a proton lower left and a neutron lower right , polarized in the x-direction, as a function of the radial distance from the center of the nucleon computed. These transverse charge densities are shown in a reference frame in which the observer is riding along with the photon the Breit frame.
In both cases, the charge distribution has an electric dipole component in the y-direction. This effect is entirely due to the interplay of special relativity and the internal structure of the nucleon. Cohen, University of Washington. In particular, IBM built the successful commercial Blue Gene line of computers, which engaged several former Columbia students and postdoctoral scholars. In addition to lattice QCD calculations, these supercomputers have been just as successful in simulating exploding stars or nuclear reactors, both of which require enormous computing power.
Genomic sequencing, protein folding, materials science, and brain simulations are also prominent on the list of successful Blue Gene applications. Cosmic rays are continuously bombarding Earth: When cosmic rays, or radiation from their secondary products, interact with an electronic device, the function of that device can be compromised.
The resulting errors in the functionality of an electronic device, such as the one displayed in Figure 3. A single event upset SEU refers to a change in the state of the logic or support circuitry of an electronic device caused by radiation striking a sensitive location or node in the device. SEUs can range from temporary nondestructive soft errors to hard error damage in devices.
The detailed physics determining the rate at which SEUs occur is both complicated and device dependent. Circuit manufacturers try to design around the risks posed by cosmic ray interactions by introducing redundancy or other protective measures to compensate for the radiation-induced errors. To do so requires detailed knowledge of the expected rates and types of SEUs that can occur. Thus, experimental testing of semiconductor device response to radiation requires beams of particles that provide realistic analogs of cosmic rays and their secondary products.
The main particles responsible for SEUs are neutrons, protons, and alpha particles, as well as heavy ions. Thus, the beams needed for this large experimental program require a range of nuclear accelerator facilities to test for device vulnerabilities and to characterize the radiation-induced failure modes of the electronic chips. For this, nuclear physics accelerator facilities are a unique resource, and agencies and companies from all over the world purchase beam time at accelerator facilities to test for device vulnerabilities and to characterize the radiation-induced failure modes of the electronic chips.
In the United States. Applications of nuclear techniques are used to advance other scientific disciplines, including climate science, cosmochemistry, geochronology, paleoclimate, paleo-oceanography, and geomorphology. Since , when Willard Libby first demonstrated carbon dating, the field of trace analyses of long-lived cosmogenic isotopes has steadily grown. Because they are chemically inert, noble gases play a particularly important role as tracers in environmental studies. Owing to their inertness, the geochemical and geophysical behavior of these gases and their distribution on Earth is simpler to understand than that of reactive elements.
In addition,. Precision tools and techniques developed for basic nuclear physics continue to be applied to answer open questions in climatology, geology, and oceanography. Krypton, which is produced by cosmic-ray-induced spallation in the atmosphere, has been identified as an ideal chronometer for determining fluid residence times on the 10 5 6 year timescale.
However, since krypton is such a rare isotope it has been extremely difficult to measure its abundance. A new method, atom trap trace analysis ATTA , was developed at Argonne National Laboratory to analyze krypton in environmental samples. With a half-life of , years and an atmospheric isotopic abundance of one part per trillion, krypton can provide unique information on terrestrial issues involving million-year timescales. Individual krypton atoms can be selectively captured and detected with a laser-based atom trap.
Joining low-level counting and accelerator mass spectrometry AMS , two methods previously developed by nuclear physicists, ATTA is the newest method to detect tracers with an isotopic abundance at parts per trillion. Using ATTA, krypton atoms in environmental samples can now be counted and the isotopic abundance of krypton measured. In the first application of ATTA to a groundwater study, a team of geologists and physicists from the United States, Switzerland, and Egypt sampled krypton from the Nubian Aquifer ground-water displayed in Figure 3.
These results characterized the age and hydrologic behavior of this huge aquifer, with important implications for climate history and water resource management in the region. The success of this project suggests that widespread application of krypton in earth sciences is now feasible. In a collaboration of nuclear scientists and geoscientists, the precision technique of atom-trap analysis was used to measure the radioactive isotope krypton in deep wells of the Nubian Aquifer in Egypt.
Applications of Nuclear Physics - ppt download
The map shows sample locations and their krypton ages in , years in relation to oasis areas shaded green. Groundwater flow in the Nubian Aquifer is toward the northeast. Adapted from N. Sturchio et al. Copyright American Geophysical Union. The whole cycle takes about 1, years. It is becoming increasingly clear that the amount of heat transported from the tropics to the polar regions by the oceans. AMS of the radioactive isotope argon will be used to explore this conveyor belt and its impact on climate. National Oceanic and Atmospheric Administration. Therefore, it is very important to understand this system.
With a half-life of years, argon is particularly well suited to study questions related to ocean circulation. AMS using the ATLAS heavy ion accelerator at Argonne National Laboratory has been successful in separating argon from its ubiquitous potassium iso-baric background, the latter being orders of magnitude more intense. Breed Tritium in Lithium blanket. Toroidal field: Poloidal fields: RF power accelerates electrons Current pulse causes further heating. Ratio decreases when plant dies.
Presentation on theme: "Applications of Nuclear Physics"— Presentation transcript:
Which is better? Needed for practical calculations. Can also define differential cross sections, as a function of reaction product, energy, transverse momentum, angle etc.
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Uncertainty relationship Determine lifetimes of states from width. Density of states ni E. Definition of s and flux F: Form factors is F. Wednesday December 17, Lecture 27 Nuclear Reactions Chapter Neutral Particles.
Applications of Nuclear Physics - PowerPoint PPT Presentation
Neutrons Neutrons are like neutral protons. Reminder n Please return Assignment 1 to the School Office by Power of the Sun. Similar presentations. Upload Log in. My presentations Profile Feedback Log out.
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