ISSN:
1434-601X
Keywords:
14.60.Cd
;
25.70.Cd
;
25.70.Ef
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Positron lines were observed in heavy ion-atom collisions at bombarding energies close to the Coulomb barrier in subcritical systems with the sum of the atomic numbers of the colliding nucleiZ u =Z 1+Z 2 being smaller thanZ u =172. Each collision system, studied,208Pb +208Pb(Zu=164),238U+181Ta(Zu=165), and238Au(Zu=171), exhibits the emission of two positron lines withZ u -independent c.m. energies of ∼ 258 keV and ∼ 340 keV, and with widths of about 30 keV, superimposed on continuous positron spectra from nuclear pair decay and pair emission induced by the time changing Coulomb field of the collision. The production cross section of thee +-lines rises with a high power ofZ u (ocZ u 22), which is comparable to theZ u 20-dependence for the collision induced positrons.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01290655
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