A new possibility of identifying high-spin-states at high excitation energies

Abstract

The great amount of theoretical predictions [1 4] on the structure of high lying high-spin states and yrast lines in light nuclei (A 1 0 brought a new impetus to the experimental investigations. However the actual confinement of the experimental knowledge to the region E 10MeV in light nuclei is the use of high-spin selective compound reactions [5, 6]. Together with statistical model calculations the "relative" cross sections yield directly the spins of the high-spin states and the critical angular momentum J~it limiting the formation of the compound nucleus. This method is limited, however, for high spins by the loss of selectivity for spins near J~it [7] and is limited further for high excitation energies (E > 20 MeV) by the high level density of low-spin states [7]. The high level density also affects double and triple angular correlation methods which have a further even lower limitation in excitation energy due to the fact that the sequential decay of these highly excited states cannot be in general expected to proceed via a spin-zero state in the final nucleus. The high level density limits also the accuracy of spin measurements by selective direct transfer reactions [-8, 9]. In the present work a new procedure for identifying highly excited high-spin states will be presented which