Accelerated γ-emission from isomeric nuclei

Collins, C. B.; Zoita, C.N.; Davanloo, F.; Emura, S.; Yoda, Yoshitaka; Uruga, Tomoya; Pàtterson, B. D.; Schmitt, B.; Pouvesle, Jean-Michel; Popescu, Iovitzu; Kirischuk, V. I.; Strilchuk, N. V.

doi:10.1016/j.radphyschem.2004.04.033

Cited by 20 publications

(32 citation statements)

References 12 publications

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“…In our work the process has been confirmed as a significant effect, being characterized by a cross section approximately equal to 0.16% of the total for the photoionization of the L-shell electrons in Hf. The triggered decay of the 1 78 Hf, 2 isomer is immediate [8,9]. It bypasses the statistical time lag of the 4 second level that affects all spontaneous decay.…”

Section: Technical Backgroundmentioning

confidence: 98%

Use of L and M Shell Electrons to Trigger Nuclear Spin Isomers

Collins¹

2007

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The public reporting burden for this collection of information i2 estinated to averege 1 hour per response includOing the time for reviewinlg ontructognz. newctmng **isting data sources gothermlg and meainta"'kng thne dole needed. end completing and reviewing the collection Of information. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORIMONITOR'S ACRONYM(S)USAF, AFRL AF Office of Scientific Research 875 N. Randolph St. Roomn 3112 SPONSORIMONITOR'S REPORT NUMBERIS)Arlingtoll. VA '))')3& Jl__ -^__1_.Iq 8 DISTRIBUTION/AVAILABILITY STATEMENT j AFRL-SR-AR-TR-07-0442Approved for public release; distribution unlimited. SUPPLEMENTARY NOTES ABSTRACTPopulations of nuclear spin isomiers of 1781 Ifm2 can be triggered to release their stored energies by the absorption of x-rays having energies in the range 9-13 keV. We have found the basic absorption spectrum for triggrering to be approximately 0.16d/ of the cross section for photoionization of the L-shell electrons surrounding the isomneric nuclei. The maximum effect is induced by X-rays with energies exceeding the threshold for the pholoionization of L3 electrons by amounts less than 10 eV. Absorption of a photon of that energy. around 9567 eV triggers the release of 2.446 MeV, thus producing a gain of radiative energy of'256 times for each event. Confidence ill the observations of such triggering is better than 10 followed by 1823 zeros to I. SUBJECT TERMSNuclear spin isomers. FHigh energy density materials.

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Section: Technical Backgroundmentioning

confidence: 98%

Use of L and M Shell Electrons to Trigger Nuclear Spin Isomers

Collins¹

2007

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“…The physical cross-sections for high-spin isomer production via spallation of different targets by 600 MeV proton beam have been systematically measured at Dubna, Refs. [21,22], Definitely, the high yield characterizing spallation reactions was confirmed and quantitatively specified. The l76 Yb( 4 He, 2/?)…”

Section: Discussionmentioning

confidence: 90%

“…The latter aspect is similar in concept to that described in Ref. [21]. The present system was designated as the YSU miniball, stressing its similarities with much larger arrays, although its design is predicated on a very specific type of experiment.…”

Section: Design Requirements and Configurationmentioning

confidence: 86%

“…Development of a general expression applicable to any regular peak for arbitrary detected fold and arbitrary summed energy is a complex problem that can be satisfactorily solved by Monte Carlo methods or the advanced approach of Ref. [21]. However, for the specific case of i78m2 Hf decay all the relevant cascade data are available.…”

Section: P Ugorowski El At / Nuclear Instruments and Methods In Phymentioning

confidence: 99%

“…This has a unique combination of high energy and long half-life, arising from a K= 16, 4-quasiparticle configuration. Targets with more than 10 14 atoms of l78m2 Hf have been used for several nuclear physics experiments, such as deuteron scattering [21], but target impurities have limited the quality of the data obtained. Attempts at photo-destruction of the isomer have been controversial [22], but so far only upper limits have been reliably determined [23] in the photon energy range 5-IOOkeV.…”

Section: Isomer Targetsmentioning

confidence: 99%

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Foundations of Isomer Physics for Energy Applications

Carroll¹

2008

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Nuclear resonance spectroscopy of the 31-yr isomer of Hf-178

et al. 2004

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Induced release of the high energy densities stored in isomeric nuclear states may be important in the development of ultrashort wavelength lasers. Such a release could compensate the spontaneous power density radiated from the laser medium at threshold. The most promising candidate for such a role seems to be the 31-yr isomeric nucleus of Hf-178 that stores 1.3 GJ/g in the electromagnetic excitation of its constituent protons and neutrons. Successful studies of the induced release of energies from such isomeric states have required an extension of techniques for nuclear resonance spectroscopy using synchrotron radiation (SR) that had previously been applied only to ground state materials. In 2004, monochromatic X-rays from the SPring-8 SR source were used to identify one of the excited nuclear states that mediates the induced decay of the 31-yr isomer of Hf-178. That trigger level was found to lie at 2457.20(22) keV. It was excited when an isomeric nucleus absorbed an incident X-ray photon. We found that one branch of its subsequent decay consisted of a strong electromagnetic transition to the ground state of the nucleus. The energy of the γ-photon emitted was equal to the energy of the trigger level. Proximity in energy of that level to the energy of 2446.06 keV stored by the isomer makes it easy to induce a release of the stored energy and encourages prospects for the development of a gamma ray laser. Spectrum of γ-photons emitted from a sample of the 31-yr isomeric (16+) state of Hf-178 being irradiated with monochromatic X-rays from the SPring-8 synchrotron source.

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Accelerated γ-emission from isomeric nuclei

Cited by 20 publications

References 12 publications

Use of L and M Shell Electrons to Trigger Nuclear Spin Isomers

Use of L and M Shell Electrons to Trigger Nuclear Spin Isomers

Foundations of Isomer Physics for Energy Applications

Nuclear resonance spectroscopy of the 31-yr isomer of Hf-178

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