| Vol.
53, No. 3 September 1999 pp. 395-404 Experimental investigations of the nuclear level density by using heavy ion reactions G VIESTI, M LUNARDON, D FABRIS, G NEBBIA, M CINAUSERO* , E FIORETTO* ,G PRETE* , J B NATOWITZ§ , K HAGEL§ and R WADA§ *
Dipartimento di Fisica dell' Universit´ a di Padova and
I.N.F.N., I-35131 Padova, Italy § Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA Abstract. The transition of the level density parameter aeff from the low excitation energy value aeff = A/ 8 MeV _ 1 to the Fermi gas value a FG ~ A/ 15 MeV_ 1 was discovered a few years ago studying particle spectra evaporated from hot compound systems of A~ 160. A number of experiments have been recently performed to confirm the earlier findings and extend the investigation to other mass regions and to higher excitation energies. Furthermore, precision coincidence experiments have been done in the lead region in which evaporation residues are tagged by low energy gamma rays. Those experiments open the possibility of a detailed study of the level densities in nuclei where the shell effects are important. Keywords. Heavy-ion reactions; measured light-charged-particle multiplicity and energy spectra; deduced level density parameter mass dependence features. PACS Nos 21.10.Ma; 25.70.Gh; 25.70.Jj; 27.80.+w |