@article{29f0966ad3c742b2932de7f743afed46,

title = "The critical distance in collisions of heavy ions",

abstract = "There is a large discrepancy in published values of the critical distance in heavy-ion collisions. We have recalculated the critical distance by a more accurate method for symmetric collisions of point nuclei as a function of Z. The reasons for the discrepancy are discussed.",

author = "Johann Rafelski and Berndt M{\"u}ller",

note = "Funding Information: The spontaneous positron production in supercritical potentials has been a matter of recent interest \[1, 2\] ; it has been shown that in sub-Coulomb heavy-ion collisions sufficiently strong electrostatic potentials will be created to test the theoretical predictions concerning the spontaneous decay of the neutral vacuum \[2\]. The essential parameter in all calculations is the distance between the heavy ions at which the binding energy of the quasi molecular 1 so electron equals twice its rest mass. This critical distance, R c, is the maximal separation between the heavy ions at which spontaneous positron production in the decay of the neutral vacuum may occur. If the combined charge of projectile and target nuclei, Z 1 +Z 2 is less than a -1 = 137, no spontaneous positron production can occur. Other significant effects like the finite size of the nuclear charge distribution, electron screening, shift this point nucleus limit to Z 1 +Z 2 ~ 173 \[2\]. In this note we report the results of our new calculations of the critical distance, which are of great importance in the forthcoming experiments. It is the resolution of the present discrepancy (~ 20 fm) in the published \[3-10\] numerical values of R c for point nuclei potentials which is more important than the inclusion of the combined effect of the finite nuclear Work performed under the auspices of the U.S. Energy Research and Development Administration. t Supported by Bundesministerium ffir Forschung und Tech-nologie, by the Deutsche Forschungsgemeinschaft and by the Gesellschaft fiir Schwerionen (GSI).",

year = "1976",

month = nov,

day = "22",

doi = "10.1016/0370-2693(76)90163-5",

language = "English (US)",

volume = "65",

pages = "205--208",

journal = "Physics Letters B",

issn = "0370-2693",

publisher = "Elsevier",

number = "3",

}