239:
performed by former collaborators (Carroll). " In addition, the report summary states, page 65: "Our conclusion is that the utilization of nuclear isomers for energy storage is impractical from the points of view of nuclear structure, nuclear reactions, and of prospects for controlled energy release. We note that the cost of producing the nuclear isomer is likely to be extraordinarily high, and that the technologies that would be required to perform the task are beyond anything done before and are difficult to cost at this time."
180:
138:. The half-life of Hf is 31 years or 1 Gs (gigasecond, 1,000,000,000 seconds), so that a gram's natural radioactivity is 2.40 TBq (65 Ci). The activity is in a cascade of penetrating gamma rays, the most energetic of which is 0.574 MeV. Substantial shielding would be needed for human safety if the sample were to be one gram of the pure isomer. However, so far the nuclear isomer exists only at low concentrations (<0.1%), within multi-isotopic hafnium.
227:
g of TNT, corresponding to 40 to 400 kJ, at a cost of tens of dollars or at least 10,000 times less than this estimate for isomeric energy content in the nucleus. Such an excessive cost makes any device based on nuclear isomers much too expensive to be practical, and research motivated by potential applications thereof a waste of money (in contrast to research on nuclear isomers purely for scientific purposes that do not claim any practicality).
35:. Per event the energy release is 5 orders of magnitude (100,000 times) more energetic than in a typical chemical reaction, but 2 orders of magnitude less than a nuclear fission reaction. In 1998, a group led by Carl Collins of the University of Texas at Dallas reported having successfully initiated such a trigger. Signal-to-noise ratios were small in those first experiments, and to date no other group has been able to duplicate these results.
76:. If much lower-energy radiation from some agent could "trigger" a release of that stored energy before most of this triggering radiation would be dissipated in competing processes, and if the triggering radiation could be regenerated efficiently by the 2.5 MeV gamma, it might be possible start a cascade of gamma photons. The long half life of
242:
In 2009, S.A. Karamian et al. published the results of a four-nation team's experimental measurements at Dubna for the production of quantities of Hf by spallation at energies as low as 80 MeV. In addition to significantly lowering the projected cost of production, this experimental result proved the
226:
In 2007, Pereira et al. estimated that the cost of the electrical energy to store energy in the nuclear isomer is on the order of $ 1/J; building and maintaining the particle accelerator needed for the purpose is extra. Any reasonable explosive device, e.g., a hand grenade, may contain from 10 to 100
222:
By 2006, there were 2 articles that claimed to disprove possibilities for IGE from Hf and three theoretical articles written by the same individual saying why it should not be possible to occur by the particular steps the author envisioned. The first two described synchrotron experiments in which the
148:
with extremely high power on the order of 1 GJ/ns or 1 exawatt (1 x 10 W). However, quantitative estimates indicate that the energy released by the nuclear isomer is much less than the energy needed to initiate the process; the power needed to initiate IGE would have to occur over a shorter time
99:
in 1995. Although the proposal was to use incident protons to bombard the target, α-particles were available when the first experiment was scheduled. It was done by a French, Russian, Romanian and
American team. Results were said to be extraordinary, but the results were not published. Nevertheless,
230:
On
February 29, 2008, DARPA distributed some of the 150 copies of the final report of the TRIP experiment that had independently confirmed the "gold standard" of hafnium-isomer triggering. Sustained by peer review, the 94-page report is distributed for official use only (FOUO) by the DARPA Technical
198:
The first focus of SIER was whether significant amounts of Hf could be produced at acceptable costs for possible applications. A closed panel called HIPP was charged with the task and concluded that it could. However, a scientist on that confidential DARPA HIPP review panel "leaked" prejudicial but
174:
published a relevant public report saying that they concluded that such a thing would be impossible and should not be attempted. Despite intervening publications in peer-reviewed journals of articles written by an international team reporting IGE from Hf, around 2003 IDA took testimony, again from
156:
Both the proposal to the NATO-ARW and the fragmentary results from the subsequent experiment indicated that the energy of the photon needed to initiate IGE from Hf would be less than 300 keV. Many economical sources of such low energy X-rays were available for delivering quite large fluxes to
238:
released the 110-page evaluation of the DARPA TRIP experiment. Quoting from page 33, "Overall, the X-ray Hf experiments by
Collins et al. are statistically marginal and inconsistent. None of the reported positive triggering results were confirmed by independent groups, including those experiments
152:
The characteristic scales of times for processes involved in applications would be favorable for consuming all of the initial radioactivity. The process for triggering a sample by IGE would use photons to trigger and produce photons as a product. The propagation of photons occurs at the speed of
112:
is difficult to make and virtually impossible to separate from the Hf ground state, the absorption of lower-energy triggering x-rays by the bound electrons around the Hf nucleus, and the minute probability to recreate the trigger-capable x-ray starting with the triggered x-ray itself by multiple
202:
Having satisfied the charge to the HIPP panel to explore the problem of production at acceptable cost, the SIER program turned to the matter of definitive confirmation of the reports of IGE from Hf. A task of TRiggering Isomer Proof (TRIP) was mandated by DARPA and assigned to a completely
203:
independent team from those reporting success previously. The "gold standard" of hafnium-isomer triggering was set as the Rusu dissertation. The TRIP experiment required independent confirmation of the Rusu dissertation. It was successful, but could not be published.
206:
By 2006, the
Collins team had published multiple papers supporting their initial observations of IGE from Hf. Reprints (available at the link) of articles that were published after 2001 describe work conducted with tunable monochromatic X-ray beams from the
153:
light while mechanical disassembly of the target would proceed with a velocity comparable to that of sound. Untriggered Hf material might not be able to get away from a triggered event if the photons did not interact first with the electrons.
183:
Experiment producing IGE from a sample of the nuclear isomer Hf. (left to right) Students on duty; (w/ladder) the world's most stable beamline for monochromatic X-rays, BL01B1; (rt.) main ring of the SPring-8 synchrotron at
199:
preliminary concerns to the press. This unsubstantiated assertion set into motion the subsequent cascade of inaccurate reports about the so-called "outrageous costs" of isomer triggering.
500:
91:
With all the caveats about dissipation of the triggering photon, and its efficient recreation by the energetic photon that is being triggered, the process could, in principle, lead to
95:
engines, along with more precise radiometric devices. A proposal to show the efficacy for "triggering" Hf was approved by a NATO-Advanced
Research Workshop (NATO-ARW) held in
175:
relevant scientists on matters of the credibility of reported results. Professor Carl
Collins, the lead U.S. member of the team publishing the successes, did not testify.
621:
C.B. Collins, N.C. Zoita, F. Davanloo, Y. Yoda, T. Uruga, J.M.Pouvesle, and I.I. Popescu (2005). "Nuclear resonance spectroscopy of the 31-yr isomer of Hf-178".
193:
initiated exploratory research termed stimulated isomer energy release (SIER) and public interest was aroused, at both popular levels and at professional levels.
84:, i.e. a gamma-ray laser. While induced emission of a high-energy photon by a lower-energy photon adds power to a radiation field, stimulated emission adds
264:
Collins, C.B., Davanloo, F., Iosif, M.; et al. (1999). "Accelerated
Emission of Gamma Rays from the 31-yr Isomer of Hf Induced by X-Ray Irradiation".
100:
Hf was implied to be of special importance to potential applications of IGE. A controversy quickly erupted, mostly between the original proponents of
108:
weapon or a non-neutronic but still nuclear-like explosive, and critics who discounted such possibilities due to practical obstacles along the way:
664:
348:
299:
449:
508:
582:
313:
Collins, C.B., Davanloo, F., Rusu, A.C.; et al. (2000). "Gamma emission from the 31-yr isomer of Hf induced by x-ray irradiation".
1025:
160:
Samples of Hf were and remain available only at low concentrations (<0.1%), without any clear way to increase this concentration.
144:
If all the energy in the nucleus could be released within a short time (e.g., one nanosecond), one gram of pure Hf would produce an
604:
39:(an American nuclear physicist and arms control expert) described claims of weaponization potential as having been based on "
402:
620:
928:
Hartouni, E.P, et al., "Theoretical
Assessment of Hf De-excitation, LLNL Report TR-407631, October 9, 2008, p.33.
52:
1006:
942:
171:
680:"Search for X-Ray Induced Acceleration of the Decay of the 31-Yr Isomer of Hf Using Synchrotron Radiation"
530:
149:
scale than the release of the nuclear energy, and would therefore be even more extremely disproportionate.
23:
was a debate over the possibility of 'triggering' rapid energy releases, via gamma ray emission, from a
772:
Tkalya, Eugene V. (2003). "Probability of L-shell nuclear excitation by electronic transitions in Hf".
453:
1040:
563:
371:
170:
Around 1997, the JASONS advisory group took testimony about the triggering of nuclear isomers. The
1035:
576:
80:
might make it possible to engineer a substance with enough of these energetic nuclei needed for
807:
Tkalya, Eugene V. (2005). "Induced decay of Hf: Theoretical analysis of experimental results".
366:
61:
658:
342:
293:
842:
Tkalya, Evgenii V (2005). "Induced decay of the nuclear isomer Hf and the 'isomeric bomb'".
117:
into something useful (rather than an intriguing nucleus suitable for academic study only).
957:
895:
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691:
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273:
8:
85:
81:
961:
899:
855:
820:
785:
742:
695:
634:
542:
326:
277:
911:
867:
754:
646:
531:"Conflicting Results on a Long-Lived Nuclear Isomer of Hafnium Have Wider Implications"
414:
113:
random scattering. Still, the military application was enticing enough to try to make
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accessibility to sources of Hf to be within the capabilities of the several idle
135:
105:
36:
929:
727:"Search for x-ray induced decay of the 31-yr isomer of Hf at low x-ray energies"
969:
828:
793:
750:
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134:
of energy, the equivalent in about 300 kilograms (660 pounds) of the explosive
24:
907:
126:
Hf has the highest excitation energy of any comparably long-lived isomer. One
1019:
998:
711:
642:
141:
All energy released would be in the form of photons; X-rays and gamma rays.
72:
per nucleus higher than that of ground-state Hf, and it has a long 31-year
69:
40:
993:
Imaginary
Weapons: A Journey Through the Pentagon's Scientific Underworld
145:
418:
312:
575:
C. Rusu (PhD Dissertation, U of Texas at Dallas, 2002)Available from:
550:
263:
244:
131:
73:
943:"Spallation and fission products in the (p+Hf) and (p+Hf) reactions"
726:
679:
410:
473:
450:"Link to review of "Isomer Triggering history from one participant"
394:
478:; J. Katz; S. Koonin; P. Weinberger; E. Williams (October 1997).
231:
Information Office, 3701 N. Fairfax Dr., Arlington, VA 22203 USA.
96:
28:
212:
886:
Pereira; et al. (2007). "Economics of isomeric energy".
190:
367:"The Strange Tale of the Hafnium Bomb: A Personal Narrative"
235:
127:
611:, University of Texas at Dallas Retrieved on 2010-12-12.
950:
528:
990:
841:
806:
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940:
361:
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104:as having potential military applications as a
602:Publications by Center for Quantum Electronics
930:https://e-reports-ext.llnl.gov/pdf/366265.pdf
498:
431:Proceedings of the NATO-ARW are collected in
663:: CS1 maint: multiple names: authors list (
537:. Vol. 57, no. 5. pp. 21–24.
347:: CS1 maint: multiple names: authors list (
298:: CS1 maint: multiple names: authors list (
60:is a particularly interesting candidate for
474:N. Lewis; R. Garwin; D. Hammer; W. Happer;
985:
386:
724:
677:
178:
885:
395:"Pumping Up Hope for a Gamma Ray Laser"
392:
130:of pure Hf contains approximately 1330
1018:
941:Karamian, S. E.; et al. (2009).
501:"Scary things come in small packages"
597:
595:
403:Society for Science & the Public
157:target samples of modest dimensions.
247:devices scattered around the world.
16:Gamma emission debate, 1997 to 2009
13:
529:Bertram Schwarzschild (May 2004).
393:Thomsen, D. E. (1 November 1986).
14:
1052:
592:
507:. Washington Post. Archived from
1026:Nuclear interdisciplinary topics
934:
922:
879:
864:10.1070/PU2005v048n05ABEH002190
835:
800:
765:
725:Ahmad, I.; et al. (2003).
718:
678:Ahmad, I.; et al. (2001).
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614:
569:
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499:S. Weinberger (28 March 2004).
53:Particle-induced gamma emission
522:
492:
481:High Energy Density Explosives
467:
442:
425:
355:
306:
257:
223:X-rays were not monochromatic.
1:
704:10.1103/PhysRevLett.87.072503
251:
120:
46:
172:JASON Defense Advisory Group
165:Chronology of notable events
7:
564:San Jose newspaper article.
64:(IGE) experiments, because
10:
1057:
970:10.1016/j.nima.2008.12.001
829:10.1103/PhysRevC.71.024606
794:10.1103/PhysRevC.68.064611
751:10.1103/PhysRevC.67.041305
505:Sunday Supplement Magazine
335:10.1103/PhysRevC.61.054305
286:10.1103/PhysRevLett.82.695
50:
908:10.1134/S1054660X0706014X
372:American Physical Society
684:Physical Review Letters
580:(Order Number: 3087127)
266:Physical Review Letters
643:10.1002/lapl.200410154
433:Hyperfine Interactions
321:(5): 054305–054305–7.
185:
62:induced gamma emission
623:Laser Physics Letters
182:
234:On October 9, 2008,
962:2009NIMPA.600..488K
900:2007LaPhy..17..874P
856:2005PhyU...48..525T
821:2005PhRvC..71b4606T
786:2003PhRvC..68f4611T
743:2003PhRvC..67d1305A
696:2001PhRvL..87g2503A
635:2005LaPhL...2..162C
543:2004PhT....57e..21S
327:2000PhRvC..61e4305C
278:1999PhRvL..82..695C
82:stimulated emission
21:hafnium controversy
987:Weinberger, Sharon
607:2007-09-28 at the
585:2005-10-15 at the
439:, pp 3–492 (1997).
186:
809:Physical Review C
774:Physical Review C
731:Physical Review C
551:10.1063/1.1768663
315:Physical Review C
209:synchrotron light
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1041:Proposed weapons
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566:, October, 2003.
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452:. Archived from
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93:nuclear reaction
68:s energy is 2.5
41:very bad science
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1016:
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844:Physics-Uspekhi
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609:Wayback Machine
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489:Sect. 4, p. 13.
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106:gamma-ray laser
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37:Peter Zimmerman
17:
12:
11:
5:
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1038:
1036:Fringe physics
1033:
1028:
1014:
1013:
1007:
976:
975:
956:(2): 488–497.
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921:
894:(6): 874–879.
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850:(5): 525–531.
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629:(3): 162–167.
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51:Main article:
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25:nuclear isomer
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888:Laser Physics
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815:(2): 024606.
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535:Physics Today
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511:on 2011-08-23
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487:. JSR-97-110.
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456:on 2011-07-26
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365:(June 2007).
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659:cite journal
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513:. Retrieved
509:the original
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458:. Retrieved
454:the original
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399:Science News
398:
388:
376:. Retrieved
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343:cite journal
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294:cite journal
269:
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219:in Villigen.
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57:
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32:
20:
18:
146:x-ray burst
1020:Categories
1008:1560258497
980:Also note:
515:2009-05-03
476:R. Jeanloz
460:2010-03-31
252:References
132:megajoules
121:Importance
47:Background
916:122665613
872:250864125
759:209833094
651:121707178
245:cyclotron
86:coherence
74:half life
989:(2006).
712:11497887
605:Archived
583:Archived
578:Proquest
213:SPring-8
211:sources
1031:Hafnium
958:Bibcode
896:Bibcode
852:Bibcode
817:Bibcode
782:Bibcode
739:Bibcode
692:Bibcode
631:Bibcode
539:Bibcode
419:3970900
378:5 March
323:Bibcode
274:Bibcode
97:Predeal
29:hafnium
1005:
914:
870:
757:
710:
649:
417:
184:Hyogo.
946:(PDF)
912:S2CID
868:S2CID
755:S2CID
647:S2CID
485:(PDF)
415:JSTOR
191:DARPA
1003:ISBN
708:PMID
665:link
380:2016
349:link
300:link
236:LLNL
128:gram
19:The
966:doi
954:600
904:doi
860:doi
825:doi
790:doi
747:doi
700:doi
639:doi
547:doi
437:107
407:doi
331:doi
282:doi
217:SLS
136:TNT
70:MeV
66:Hf'
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