FORMULA FOR THE RADIUS OF THE SUPPORT OF THE POTENTIAL IN TERMS OF SCATTERING DATA

Let q(r), r = \x\, x is an element of R-3 be a real-valued square inte grable compactly supported function, and [0,a] be the smallest interva l containing the support of q(r). Let A(alpha', alpha) = A(alpha'- alp ha) be the corresponding scattering amplitude at a fixed positive ener gy, k(2) = 1. Let delta(l) be the phase shifts at k = 1. It is proved that lim(l)->x)(2e+1/e /delta e\(1/2e)) = a, provided that q(r) does n ot change sign in some, arbitrary small, neighbourhood of a.