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We summarize some initial results in our investigation of the nuclear physics issues of gamma-ray lasers. We describe what is known thus far from existing experimental data and illustrate how theoretical models may be employed for systematic searches of candidate nuclei.
Presented are initial results in our investigation of the nuclear physics issues of gamma-ray lasers. These include the questions of what is known from existing experimental data, where does one optimally search for nuclei displaying simultaneously both closely lying levels and nuclear isomerism, and which theoretical models does one employ for systematic searches for candidate nuclei and for calculation of detailed candidate level properties.
We present results of theoretical nuclear structure model calculations for the gamma-ray laser candidate nucleus 186Re proposed by Collins. Our calculations of this odd-odd transitional nucleus are based on an axially-asymmetric (particle plus triaxial rotor) model for constructing the orbitals of the odd nucleons that couple under the influence of the residual neutron-proton interaction. We include pairing correlations in the determination of these orbitals by using the BCS approximation with newly determined pairing strengths. The matrix elements of the residual neutron-proton interaction are obtained using phenomenological spin-dependent delta function potentials of both surface and volume forms. We examine the sensitivity of the calculated low-excitation level structure of 186Re to the strength of these potentials. Calculated energy levels of 186Re will be presented and compared with experiment. The impact of our results on the proposed use of 186Re as a gamma-ray laser will be discussed. In addition, based upon these and other model calculations to be described, we assess the level of effort necessary in a full-scale theoretical search for a viable candidate nucleus for a gamma-ray laser. 17 refs., 1 fig., 3 tabs.
Provides a definitive overview of the current status of gamma-ray lasers including contributions from scientists pursuing active research in areas relevant to the graser problem. Describes a range of programmes which deal with selecting candidate nuclei, procuring the right lasing medium and forming it into an acicular geometry, working in an energy regime that enables utilizing the Mossbauer Effect, using the Campbell-Borrmann Effect to decrease electronic absorption, designing basic experiments that demonstrate critical steps necessary to produce a graser, and clarifying a number of theoretical problems specific to the nuclear laser.
Recent approaches to the problem of the gamma-ray laser have focused upon upconversion techniques in which metastable nuclei are pumped with long wavelength radiation. At the nuclear level the storage of energy can approach tera-Joules per liter for thousands of years. However, any plan to use such a resource for a gamma-ray laser poses problems of a broad interdisciplinary nature requiring the fusion of concepts taken from relatively unrelated field of physics. Our research group has described several means through which this energy might be coupled to the radiation fields with cross sections for stimulated emission that could reach 10 to the minus 17th power sq. cm. Such a stimulated release could lead to output powers as great as 3 X 10 to the 21st power Watts/liter. Since 1978 we have pursued an approach for the upconversion of longer wavelength radiation incident upon isomeric nuclear populations that can avoid many of the difficulties encountered with traditional concepts of single photon pumping. Recent experiments have confirmed the general theory and have indicated that a gamma-ray laser is feasible if the right combination of energy levels and branching ratios exists in some real material. Of the 1,886 distinguishable nuclear materials, the present state-of-the-art has been adequate to identify 29 first-class candidates, but further evaluation cannot proceed without remeasurements of nuclear properties with higher precision.
Results from a data base search of computerized nuclear structure libraries have been extended and augmented so as to expand the information available for nuclei suitable as gamma-ray laser candidates. The spectrum of nuclear levels occurring in deformed rotational nuclei have been calculated and have been used in conjunction with isomeric state data for odd-A systems. The results of this augmentation effort are presented with particular emphasis on results obtained for 177Lu, 177Hf, and 179Hf. For these cases some possibly interesting cases were identified that met energy spacing criteria. However, significant hindrance factors exist for them which negate their interest for gamma-ray laser applications. 9 refs., 1 fig., 1 tab.
The most productive approaches to the problem of the gamma ray laser have focused upon upconversion techniques in which metastable nuclei are pumped with long wavelength radiation. At the nuclear level the storage of energy can approach tera-Joules (10(exp 12)J) per liter for thousands of years. However, any plan to use such a resource for a gamma ray laser poses problems of a broad interdisciplinary nature requiring the fusion of concepts taken from relatively unrelated fields of physics. Our research group has described several means through which this energy might be coupled to radiation field with cross sections for stimulated emission that could reach 10(exp -17) sq cm. Such a stimulated release could lead to output powers as great as 3 x 102 Watts/liter. Since 1978 we have pursued an approach for the upconversion of longer wavelength radiation incident upon isomeric nuclear populations that can avoid many of the difficulties encountered with traditional concepts 0 single-photon pumping. Experiments have confirmed the general theory and have indicated that a gamma-ray laser is feasible if the right combination of energy levels and branching ratios exists in some real material. Of the 1,886 distinguishable nuclear materials, the present state-of-the-art has been adequate to identify 29 first-class candidates, but further evaluation cannot proceed without remeasurements of nuclear. A laser-grade database of nuclear properties does not yet exist but the techniques for constructing one have been developed and utilize under this contract.
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Nuclear nonproliferation is a critical global issue. A key technological challenge to ensuring nuclear nonproliferation and security is the detection of long-lived radioisotopes and fissionable nuclides in a non-destructive manner. This technological challenge requires new methods for detecting relevant nuclides and the development of new quantum-beam sources. For example, one new method that has been proposed and studied is nuclear resonance fluorescence with energy-tunable, monochromatic gamma-rays generated by Compton scattering of laser photons with electrons.The development of new methods requires the help of researchers from a wide range of fields, such as nuclear physics, accelerator physics, laser physics, etc. Furthermore, any new method must be compatible with the requirements of administrators and nuclear-material inspectors.
The most productive approaches to the problem of the gamma-ray laser have focused upon upconversion techniques in which metastable nuclei are pumped with long wavelength radiation. At the nuclear level the storage of energy can approach tera-Joules (10(exp 12)J) per liter for thousands of years. However, any plan to use such a resource for a gamma-ray laser poses problems of a broad interdisciplinary nature requiring the fusion of concepts taken from relatively unrelated fields of physics. Our research group has described several means through which this energy might be coupled to radiation fields with cross sections for stimulated emission that could reach 10(exp -17)sq cm. Such a stimulated release could lead to output powers as great as 3 x 1021 Watts/liter. Since 1978 we have pursued an approach for the upconversion of longer wavelength radiation incident upon isomeric nuclear populations that can avoid many of the difficulties encountered with traditional concepts of single photon pumping. Experiments have confirmed the general theory and have indicated that a gamma- ray laser is feasible if the right combination of energy levels and branching ratios exists in some real material. Of the 1,886 distinguishable nuclear materials, the present state-of-the-art has been adequate to identify 29 first- class candidates, but further evaluation cannot proceed without remeasurements of nuclear properties with higher precision. Gamma-ray laser, Ultrashort wavelength laser.