Some features of the ionization of nuclear reaction products

Abstract

The recoil-atom ionization of some isotopes from Sc to Po produced by heavy ioninduced nuclear reactions has been investigated. An analysis of the available data on the ionic charge distributions of nuclear reaction products has shown that atomic ionization in the mass range of A ~40-70 corresponds to the calculated values. It has been found that the contribution from additional ionization due to the formation of innershell vacancies as a result of the internal conversion of nuclear transitions grows as the atomic number and excitation energy of nuclei increase and reaches 90 % for Po recoil atoms from fusion reactions.

Charge distributions of Ra recoil ions produced in C12+Pb fusion-evaporation reactions

“…Thus in the study of the 16 O + 197 Au, 208 Pb fusion-evaporation reactions two components of the charge state distributions of ERs were clearly observed with an electrostatic deflector, measuring the yield of ERs as a function of the applied voltage [18]. In fact, the curves presented in [18] allow one to extract three charge components (two of them correspond to the nonequilibrated charges and the rest to the equilibrated one).…”

“…At the same time, for relatively light and fast reaction products with masses A ∼ 60 only the equilibrated component is clearly observed [10,16]. For heavy ERs the equilibrated component becomes clearly observable again, after passing a thin carbon foil of a sufficient thickness, installed at some distance from a 16 O + 197 Au reaction as a function of a high voltage applied to the deflector [18] (full circles). Our fits to the data with the two-and three-component log-normal function, corresponding to the two-and three-component charge distributions are shown by dotted line and solid line, respectively.…”

“…Very broad charge state distributions were also observed for the recoils of transuranium nuclei produced in the (α,xn) reactions [14], and later for Dy, Pb, and Po ERs produced in (HI,xn) reactions [10,15,16]. Note that the earlier data [11], as well as the later ones [10,15,16] obtained with magnetic spectrographs, do not reveal any division between the equilibrated and nonequilibrated components for Tb-Ho, Pb, and Po ERs similarly to those shown in Fig. 1 for Dy ERs.…”

“…1(a). In [16] some systematics of the mean charges of reaction products was proposed. It demonstrates a fast growth of the mean charge value with the velocity of ERs.…”

“…This foil (a plunger) resets the charge state distribution to the equilibrated (normal) one [10,16], as shown in Fig. 1(a).…”