The physics of antimatter induced fusion and thermonuclear explosions
The possibility of using antihydrogen for igniting inertia l confinement fusion pellets or triggering large-scale thermonuclear ex plosions is investigated. The number of antiproton annihilations required to start a thermonuclear burn wave in either DT or Li2DT is found to be about 10 21 /� 2 , where � is the compression factor of the fuel to be ignited. We conclude that the financial and energy investments needed to produce such amou nts of antiprotons would confine applications of antimatter trigger ed thermonuclear devices to the military domain.
Discontinuous Buckling of Wide Beams and Metabeams.
We uncover how nonlinearities dramatically alter the buckling of elastic beams. First, we show experimentally that sufficiently wide ordinary elastic beams and specifically designed metabeams-beams made from a mechanical metamaterial-exhibit discontinuous buckling, an unstable form of buckling where the postbuckling stiffness is negative. Then we use simulations to uncover the crucial role of nonlinearities, and show that beams made from increasingly nonlinear materials exhibit an increasingly negative postbuckling slope. Finally, we demonstrate that for sufficiently strong nonlinearity, we can observe discontinuous buckling for metabeams as slender as 1% numerically and 5% experimentally.
Fission of heavy hypernuclei formed in antiproton annihilation.
Heavy hypernuclei are produced in the annihilation of antiprotons in [sup 238]U. The delayed fission of heavy hypernuclei and hypernuclei of fission fragments are observed by using the recoil-distance method in combination with measurement of secondary electron multiplicity. The lifetime of hypernuclei in the region of uranium is found to be (1.25[plus minus]0.15)[times]10[sup [minus]10] sec. It is observed that [Lambda] hyperons predominantly stick to the heavier fission fragments. The yield of hypernuclei is found to be (7.4[plus minus]1.7)[times]10[sup [minus]3] per stopped antiproton. No coincidences with [ital K][sup +] were found. Statistical and systematic errors on the number of events expected do not rule out this possibility.