Accuracy in the detemination of fusion barriers
N. Alamanos - A. Lumbroso
DAPNIA/SPhN, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
Received: 6 January 1999 / Revised version: 30 March 1999 Communicated by D. Guerreau
Abstract
Although there is no proof of the validity of the method, in a lot of papers, one computes
the Second derivative of the the experimental fusion cross section multiplied by the energy to extract
the fusion barriers directly from the experiment. The purpose of this paper is to check the
consistency of the method, as experimental points are sandwiched inside their error bars. We therefore
analysed the validity, by giving ourselves a cross section 
,
resulting from the coupled
channel calculation code ECIS, upon which, in spite of the complexity of the calculations, we have
full control. We took these calculated points as the "experimental" ones and we altered them by
multiplication by small random numbers. This is intended to simulate the error bars, of which we want
to examine the influence on the fusion barriers. We find that in spite of the rough predictions
yielded by the second derivative method, this task requires data with a precision difficult to
reach. Furthermore, a careful check of the predictions of this method for coupled channels
calculations shows that, due to the errors bars, this approach adds spurious results.
Copyright Società Italiana di Fisica, Springer-Verlag 2000
