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1.
Four basic schemes for a nuclear gamma-ray laser (NGL) are analyzed using the “NGL-hyper-bola” as a generalized comparative criterion: solid state Mössbauer scheme; stimulated gamma-emission in cooled ensembles of free nuclei with hidden population inversion of nuclear states; nuclear gamma-ray lasing without inversion; and Bose-Einstein condensate as a hypothetical active medium for NGL. 相似文献
2.
This paper studies nuclear excitation by electron transition (NEET) and is potential application in developing gamma-ray laser.A quantum mechanics formula to calculate NEET probabilities was presented with emphasis on the calculations of the transition matrix elements and discussions of the transition selection rules.The NEET probabilities for a number of nuclides were calculated.The upper limit of NEET probability is evaluated to be about 10-5.The possibility for applying the technique of NEET in the development of gamma laser was investigated. 相似文献
3.
E. D. Arthur D. C. George 《Journal of Quantitative Spectroscopy & Radiative Transfer》1988,40(6):651-662
A search of two nuclear structure data bases, CDRL82 and ENSDF, was undertaken in order to identify nuclei attractive for gamma-ray laser applications. Level pairs for 32 such candidate nuclei were determined that had properties (spacings, half-lives) attractive for possible gamma-ray laser use. However, many of these pairs suffer from details (for example, required spin transfers) that may take their use difficult in actual laser concepts. To complicate the problem, present data bases are deficient in the formation needed to identify additional, more promising candidates. Nuclear model calculations are suggested as a way to remedy such deficiencies in the near term. Examples from nuclear structure analyses are provided that impact consideration of current nuclear candidates or that may help identify new ones. 相似文献
4.
F.J. Agee 《Hyperfine Interactions》1997,107(1-4):69-79
In the basic research efforts to define the optimum isomers for making a gamma-ray laser, a variety of radiation sources have
been used to find the nuclear gateways that make the idea possible. The radiation sources have several roles to play in the
gamma-ray laser process, including pumping isomers to excited states with long lifetimes and in subsequently pumping these
to short-lived states that quickly decay. This paper reviews the technology of the radiation sources and the desirable characteristics
relative to pumping and triggering in gamma-ray laser research.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Various effects leading to modifications of Mössbauer spectra as a result of interaction of nuclei with external electromagnetic fields of different frequency ranges (dc, radio-frequency, microwave and optical) are reviewed. Special attention is paid to the coherent effects, where interference of nuclear transitions plays a decisive role. Possible applications of these effects in gamma-ray spectroscopy, quantum computations, and resolution of the gamma-ray laser problem are discussed. 相似文献
6.
A gamma-ray laser would stimulate coherent emission of radiation at wavelengths below 1 Å from excited states of nuclei. However, the difficulties in realizing such a device were considered insurmountable when the first cycle of study ended in1981. Since then, research on the feasibility of a gamma-ray laser has taken on a completely new character. A nuclear analog of the ruby laser has been proposed and many of the component steps for pumping the nuclei have been demonstrated experimentally. A quantitative model based upon the new data and the concepts of this decade shows the gamma-ray laser to be feasible if some real isotope has its properties sufficiently close to the ideals. The greatest positive impact has come from the discovery of giant resonances for pumping nuclei with photons that greatly reduce the levels of input power needed. Most recently, attention has been focused upon efforts to demonstrate prelasing levels of fluorescence from simulation nuclides and actual gamma-ray laser candidates. Problems being addressed are the acquisition of macroscopic samples of the best nuclei for testing and the demonstration of appropriate instrumentation. 相似文献
7.
G.R. Hoy 《Hyperfine Interactions》1997,107(1-4):381-399
This paper deals with the interaction of electromagnetic radiation with matter assuming the matter to have nuclear transitions
in resonance with incident electromagnetic radiation. The source of the radiation is taken to be of two types; natural radioactive
gamma decay and synchrotron radiation. Numerical examples using 57Fe are given for the two types of source radiation. Calculated results are contrasted for the two cases. Electromagnetic radiation
produced by recoil-free gamma-ray emission has essentially the natural linewidth. Electromagnetic radiation from a synchrotron,
even with the best monochromators available, has a relatively broad-band spectrum, essentially constant for these considerations.
Polarization effects are considered. In general, the nuclear-resonant medium changes the polarization of the input radiation
on traversing the medium. Calculations are presented to illustrate that synchrotron radiation studies using nuclear-resonant
forward scattering have the potential for making high-precision measurements of hyperfine fields and recoilless fractions.
An interesting aspect of nuclear-resonant forward scattering, relative to possible gamma-ray laser development, is the so-called
“speed-up” effect.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
Johndale C. Solem 《Journal of Quantitative Spectroscopy & Radiative Transfer》1988,40(6):713-715
A crucial step in the development of gamma-ray lasers will be the discovery of an efficient mechanism for nuclear interlevel transfer. One promising mechanism uses the near-field interaction between the nucleus and laser-driven collective electronic oscillations. I prove an important theorem relating spatial and temporal harmonics: 22n-poles are driven only at even multiples of the laser frequency, while 22n+1-poles are driven only at odd multiples of the laser frequency. I comment on the theorem's relevance to a proposed interlevel-transfer experiment. 相似文献
9.
Frank Stedile 《Hyperfine Interactions》2002,143(1-4):133-142
Quite a number of proposals for a gamma-ray laser have been made over the years. One first step on the way to a gamma-ray
laser is an inversion between nuclear states. For the natural isotope 103Rh we have the favorable condition that there are two low-lying nuclear levels at energies of 357 keV and 295 keV with lifetimes
of 107 ps and 9.7 ps, respectively. With two Nuclear Resonance Fluorescence (NRF) measurements the population of these low-lying
levels via feeding from higher-lying levels was investigated. Altogether 26 higher-lying nuclear levels that show a branching
to one or even both interesting low-lying levels have been found. Summing over all contributions from these feeding levels
this results in a population inversion between the levels at 357 keV and 295 keV of 103Rh.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
High-order harmonic generation from muonic atoms exposed to intense laser fields is considered. Our particular interest lies in effects arising from the finite nuclear mass and size. We numerically perform a fully quantum mechanical treatment of the muon-nucleus dynamics by employing modified soft-core and hard-core potentials. It is shown that the position of the high-energy cutoff of the harmonic spectrum depends on the nuclear mass, while the height of the spectral plateau is sensitive to the nuclear radius. We also demonstrate that gamma-ray harmonics can be generated from muonic atoms in ultrastrong VUV fields, which have potential to induce photonuclear reactions. 相似文献
11.
A. A. Zadernovsky 《Laser Physics》2007,17(4):316-323
A comparative analysis of various schemes of a gamma-ray laser is presented. All of the schemes employ a hidden inversion of nuclear states, which appears in cooled nuclear ensembles due to nuclear recoil in the emission and absorption of gamma photons. 相似文献
12.
《Nuclear Physics A》1988,486(2):271-277
Laser-induced nuclear transitions between isomeric states were calculated by means of a parametrization approach, taking laser linewidths into account. With the calculated transition probabilities, the optical laser-stimulated conversion from long to shorter lifetime isomers were studied to explore possibilities for changing the lifetime of the long-lived isomer in terms of the induced two-step cascade and for developing a gamma-ray laser. Numerical estimates show that the laser intensity needed to generate coherent gamma radiation is higher than that available with current technology. 相似文献
13.
Spectroscopic and radiation-resistant properties of Er,Pr:GYSGG laser crystal operated at 2.79 μm
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We demonstrate the spectroscopic and laser performance before and after 100 Mrad gamma-ray irradiation on an Er,Pr:GYSGG crystal grown by the Czochralski method. The additional absorption of Er,Pr:GYSGG crystal is close to zero in the 968 nm pumping and 2.7-3 μm laser wavelength regions. The lifetimes of the upper and lower levels show faint decreases after gamma-ray irradiation. The maximum output powers of 542 and 526 mW with the slope efficiencies of 17.7% and 17.0% are obtained, respectively, on the GYSGG/Er,Pr:GYSGG composite crystal before and after the gammaray irradiation. These results suggest that Er,Pr:GYSGG crystal as a laser gain medium possesses a distinguished antiradiation ability for application in space and radiant environments. 相似文献
14.
随着激光技术的不断发展,激光功率突破10 PW量级,激光与物质相互作用进入近量子电动力学(QED)范畴。从弱相对论激光到相对论激光再到强相对论激光,激光场与物质的耦合可以产生能量从keV到MeV甚至GeV的X/γ射线。这些辐射具有通量大、亮度高、能量高和脉宽短等特点,在核物理、高能量密度物理、天体物理等基础研究以及材料科学、成像、医学等领域具有广泛应用前景。系统梳理了近年来相对论强激光与气体、近临界密度等离子体及固体靶相互作用,通过诸如同步辐射、betatron和类betatron辐射、Thomson散射和非线性Compton散射过程等产生高能X/γ射线的最新研究进展,总结了各种方案产生的X/γ射线的品质因子和潜在应用,并为下一步基于强激光大科学装置的实验研究提供理论参考。 相似文献
15.
J. J. Carroll S. A. Karamian L. A. Rivlin A. A. Zadernovsky 《Hyperfine Interactions》2001,135(1-4):3-50
X-ray-driven gamma emission describes processes that may release nuclear energy in a ‘clean’ way, as bursts of incoherent
or coherent gamma rays without the production of radioactive by-products. Over the past decade, studies in this area, as a
part of the larger field of quantum nucleonics, have gained tremendous momentum. Since 1987 it has been established that photons
could trigger gamma emission from a long-lived metastable nuclear excited state of one nuclide and it appears likely that
triggering in other isotopes will be demonstrated conclusively in the near future. With these experimental results have come
new proposals for the creation of collective and avalanche-like incoherent gamma-ray bursts and even for the ultimate light
source, a gamma-ray laser. Obviously, many applications would benefit from controlled bursts of gamma radiation, whether coherent
or not. This paper reviews the experimental results and concepts for the production of gamma rays, driven by externally produced
X-rays.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Forrest J. Agee 《Hyperfine Interactions》2002,143(1-4):1-6
Induced gamma emission with the potential for substantial energy gain is an exciting area of research. This paper reviews
related work done internationally, including some that has potential for a gamma-ray laser.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
Ledingham KW Spencer I McCanny T Singhal RP Santala MI Clark E Watts I Beg FN Zepf M Krushelnick K Tatarakis M Dangor AE Norreys PA Allott R Neely D Clark RJ Machacek AC Wark JS Cresswell AJ Sanderson DC Magill J 《Physical review letters》2000,84(5):899-902
When a laser pulse of intensity 10(19) W cm(-2) interacts with solid targets, electrons of energies of some tens of MeV are produced. In a tantalum target, the electrons generate an intense highly directional gamma-ray beam that can be used to carry out photonuclear reactions. The isotopes 11C, 38K, (62,64)Cu, 63Zn, 106Ag, 140Pr, and 180Ta have been produced by (gamma,n) reactions using the VULCAN laser beam. In addition, laser-induced nuclear fission in 238U has been demonstrated, a process which was theoretically predicted at such laser intensities more than ten years ago. The ratio of the 11C and the 62Cu beta(+) activities yields shot-by-shot temperatures of the suprathermal electrons at laser intensities of approximately 10(19) W cm(-2). 相似文献
18.
Summary We reveal the fallacies in recent gamma-ray laser schemes that propose to obtain gain by stimulating transitions from a long-lived
upper to a short-lived lower nuclear state. We point out the errors in recent derivations of the stimulated-emission coefficients,
derive the correct formulae, and submit an alternative explanation for an experiment purported to observe stimulated emission
from a long-lived isomer. 相似文献
19.