Investigation ofHe6cluster structures

Abstract

The α+2n and t+t clustering of the 6 He ground state were investigated by means of the transfer reaction 6 He(p,t) 4 He at 25 MeV/nucleon. The experiment was performed in inverse kinematics at GANIL with the SPEG spectrometer coupled to the MUST array. Experimental data for the transfer reaction were analyzed by a DWBA calculation including the two neutrons and the triton transfer. The couplings to the 6 He → 4 He + 2n breakup channels were taken into account with a polarization potential deduced from a coupled-discretized-continuum channels analysis of the 6 He+ 1 H elastic scattering measured at the same time. The influence on the calculations of the α+t exit potential and of the triton sequential transfer is discussed. The final calculation gives a spectroscopic factor close to one for the α+2n configuration as expected. The spectroscopic factor obtained for the t+t configuration is much smaller than the theoretical predictions.

Improved di-neutron cluster model forHe6scattering

“…In the applications of the di-neutron model done so far to 6 He [17][18][19][20][21][22], the binding energy of the di-neutron has been taken as the two-neutron separation energy of 6 He, i.e., | b | = S 2n = 0.975 MeV. It should be noticed that, with this choice, one is assuming implicitly that the relative wave function of two neutrons within 6 He would be in a state similar to that of two neutrons with zero relative energy.…”

Fractal geometrical properties of nuclei

“…For example, the fractal dimensions of the isobars with twobody structure type, ( 5 Li, 5 He), ( 8 Li, 8 Be, 8 B), ( 10 Be, 10 B), ( 11 C, 11 B), ( 13 N , 13 C) and ( 16 C, 16 N ), are almost same respectively. For nuclei with same A, the fractal dimensions of the nuclei with three-body structure, such as, 6 He, 8 He, 10 C, 11 Li and 14 Be, are distinctly lower than the nuclei with two body structure type. The values of fractal dimension decrease due to the increase of nuclear mass number, which may be associated with the scale r s .…”

“…In the present work, we have done some calculations and obtained some results for light nuclei in ground states. Combining the analyses given in [1][2][3][4][5][6][7][8][9][10][11][12] and [24][25][26] and the consideration that the rational fractal structure of one nucleus is determined by making the seperated energy of NFCs be minimum possibly, the possible NFC structures for these nuclei are shown in TABLE I. We consider that the scale r s is about 1.25 fm, which is the half of the maximum size of one nucleon.…”

“…The nuclear distribution is non-uniform especially for halo nuclei. For instance, 11 Li has a core and valence nucleons ( 9 Li + n + n) halo structure and the matter distribution is much non-uniform [10,13]. Its radius is much larger than given by the usual expression (r 0 A 1 3 ), which depends on the uniform-density liquid drop model.…”

“…Both in theory [1][2][3][4][5] and experiment [6][7][8][9][10][11][12], the concept of the cluster structure plays an important role in nuclear reaction, nuclear structure and the nuclear excitation. The nuclear distribution is non-uniform especially for halo nuclei.…”