Comment on “Accelerated Emission of Gamma Rays from the 31-yr Isomer of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>178</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi>Hf</mml:mi></mml:math>Induced by X-Ray Irradiation”

Olariu, Silviu; Olariu, Agata

doi:10.1103/physrevlett.84.2541

Cited by 27 publications

(13 citation statements)

References 5 publications

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“…Two notable examples on triggered γ-emission from nuclear isomers by x-ray absorption are 180m Ta [19][20][21] and 178m2 Hf [22], though the results reported in Ref. [22] remain under debate [21,[23][24][25][26][27]. As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Three-beam setup for coherently controlling nuclear-state population

2013

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The controlled transfer of nuclear state population using two x-ray laser pulses is investigated theoretically. The laser pulses drive two nuclear transitions in a nuclear three-level system facilitating coherent population transfer via the quantum optics technique of stimulated Raman adiabatic passage. To overcome present limitations of the x-ray laser frequency, we envisage accelerated nuclei interacting with two copropagating or crossed x-ray laser pulses in a three-beam setup. We present a systematic study of this setup providing both pulse temporal sequence and laser pulse intensity for optimized control of the nuclear state population. The tolerance for geometrical parameters such as laser beam divergence of the three-beam setup as well as for the velocity spread of the nuclear beam are studied and a two-photon resonance condition to account for experimental uncertainties is deduced. This additional condition gives a less strict requirement for the experimental implementation of the three-beam setup. Present experimental state of the art and future prospects are discussed.

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Section: Introductionmentioning

confidence: 99%

Three-beam setup for coherently controlling nuclear-state population

2013

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“…Such a state could then decay promptly to a lower-lying level in the K = 8 band and thence rapidly to the J π = 8 -bandhead, which in turn decays in a well understood cascade to the nuclear ground state. A drawback with this explanation is that the measurement implies that the initial resonant absorption has an integrated cross section (1 x 10 -21 cm 2 keV), which exceeds the values normally found for nuclear photoabsorption in this mass region by about 7 orders of magnitude [5].…”

Section: "Triggering" In 178 M2 Hfmentioning

confidence: 84%

“…Here we discuss two processes, which occur with low probability, but which nevertheless are of interest from a fundamental point of view and may have significant potential for various applications. These are 1) NEET (Nuclear Excitation by Electronic Transition), which has only recently, after many erroneous claims by several groups over a period of almost thirty years, been definitively observed in the nucleus 197 Au [1], and 2) the acceleration of the decay of long-lived nuclear isomers by "triggering" with x-ray irradiation, a process that has been claimed [2 -4] to have been observed in the second isomeric state (16 + ) of the nucleus 178 Hf, but that is disputed by other authors [5,6].…”

Section: Introductionmentioning

confidence: 99%

Nuclear Transitions Induced by Synchrotron X-rays

Gemmell¹

2003

AIP Conference Proceedings

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Abstract. We discuss two rare but interesting processes by which synchrotron x-rays with energies up to about 100 keV may be used to induce nuclear transitions.In the NEET (Nuclear Excitation by Electronic Transition) process, an intense x-ray beam is employed to make vacancies, e.g. K-holes, in the atoms of a specific nuclear isotope. When a vacancy is filled by an electronic transition from a higher atomic level, there is some probability that instead of the usual x-ray or Auger emission, the nucleus of the atom itself will be excited. This is then followed by a nuclear decay exhibiting characteristic gamma-rays or other types of radiation, with time delays typical of the nuclear states involved. The probability for NEET increases when the energies of the atomic and the nuclear transitions become close. We address some theoretical aspects of the process and describe experimental efforts to observe it in 189 Os and 197 Au.The second process to be discussed is the possibility of "triggering" the decay of a nuclear isomer by irradiation with an x-ray beam. We focus on the case of the 31-year, 2.4-MeV, 16+ isomer of 178 Hf. There has been speculation that if one could isolate gram quantities, say, of this isomer and then have the capability to accelerate its decay in a controlled way, one would have a powerful triggerable source of enormous energy. This could be used to generate explosions, for rapid irradiations, or for more general energy-storage applications, depending on the rate of energy release. We describe attempts to observe this process.

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“…The low energy of the accelerating potential, 90 kV, implied that triggering required x rays of less energy and that the process was quite efficient due to the ability to observe even a small enhancement of the gamma-ray lines with such a weak x-ray source. The large magnitude of the effect was a cause for concern in comparison with estabUshed nuclear systematics [21][22][23][24]. Unfortunately, relatively few experiments have been performed at such low energies -in general, the extensive literature of photonuclear reaction studies is confined to higher energies, greater than about 1 MeV and to excitation rather than triggering of isomers.…”

Section: Triggeringmentioning

confidence: 99%

Study of Triggering of Electromagnetic Pulses From Isomeric Materials

Carroll¹

2006

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Comment on “Accelerated Emission of Gamma Rays from the 31-yr Isomer of178HfInduced by X-Ray Irradiation”

Cited by 27 publications

References 5 publications

Three-beam setup for coherently controlling nuclear-state population

Three-beam setup for coherently controlling nuclear-state population

Nuclear Transitions Induced by Synchrotron X-rays

Study of Triggering of Electromagnetic Pulses From Isomeric Materials

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