Nuclear fusion: Hit and mix

The fusion of atomic nuclei has been the subject of considerable research, and despite numerous studies over the past 30 years, the process is still far from being understood. Unstable heavy atomic nuclei can be created by fusing two highly charged stable nuclei in a process analogous to colliding droplets of liquid. But instead of undergoing fusion to form a single heavy nucleus, the system almost always separates in a process known as quasi-fission, involving transfer of mass from the heavier of the two nuclei to the lighter one. Theory predicts that this fusion-inhibiting process should occur when the product of the two nuclear charges exceeds a threshold value. However, new measurements show that formation of superheavy nuclei is inhibited at about half of this theoretical value, suggesting that a rethink of the standard model of nuclear fission and fusion is needed.

Unexpected inhibition of fusion in nucleus-nucleus collisions
A. C. BERRIMAN, D. J. HINDE, M. DASGUPTA, C. R. MORTON, R. D. BUTT & J. O. NEWTON
Nature 413, 144–147 (13 September 2001)
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Nuclear physics: Sizing up the heavyweights
YURI OGANESSIAN
Colliding a heavy projectile with an even heavier target nucleus only occasionally produces superheavy elements. Analyses of the processes that prevent fusion suggest that projectile size is one of the problems.
Nature 413, 122–125 (13 September 2001)
| Full Text | PDF (169 K) |

13 September 2001 table of contents