Nonstatistical fluctuations for deep inelastic processes inAl27+Al27

Abstract

The excitation functions (EFs) for different fragments produced in the 27 Al+ 27 Al dissipative collisions have been measured in steps of 250 keV in the incident energy range 122-132 MeV. Deep inelastic processes have been selected by integrating events on a total kinetic energy loss window of 12 MeV between 20 and 32 MeV. Large fluctuations are observed in all the studied EFs. Large-channel cross-correlation coefficients confirm the nonstatistical origin of these fluctuations. The energy autocorrelation function (EAF) shows damped oscillation structure as expected when a dinuclear system with a lifetime [τ = (5.1 ± 2.1) · 10 −21 s], similar with its revolution period (T = 4.9 · 10 −21 sec), is formed. From the periodicity of the EAF oscillations, information on the deformation of the 27 Al+ 27 Al dinucleus is inferred.

Cross-Correlation of Excitation Functions for Different Fragments and Different Scattering Angles in 27 Al( 19 F,x)y Reactions

“…In Refs. [5][6][7][8][9][10][11] we can see that both the Z cross-correlation and θ cross-correlation coefficients are much larger than the ones predicted by statistical theory. Several models [11−15] have been developed to describe these phenomena.…”

“…The Z cross-correlation coefficients in Table 2 are much larger compared to those corresponding to a pure statistical de-excitation, since in the latter case C(Z 1 , Z 2 ) should be theoretically equal to zero when Z 1 is different from Z 2 . [3] The averaged 5,6,7,8,9,10) are presented in Table 4. For the projectile-like fragments with Z smaller than the projectile Z = 9, the more the nucleons transferred from the projectile, the longer the lifetime τ for the corresponding IDS.…”