Inelastic p9Be scattering and halo-structure of excited states of 9Be

Abstract

The calculation of differential cross section of inelastic p 9 Be scattering (to the levels J π = 1/2 + + , 3/2 ) was made in the framework of the Glauber diffraction theory. We have used the wave function of 9 Be in the ground and excited states in the threebody 2αn model. Expansion in series by gaussoids of the wave function of 9 Be and presentation of the Glauber's operator Ω in the form, conjugated with three-body wave function. It allows us to analytically calculate the matrix elements of inelastic scattering, taking into account all of the multiplicities of scattering and rescattering on clusters and nucleon, that are the components of 9 Be. The drawn up profiles of excited state functions allow us to make conclusion on their extended neutron distribution. The differential cross section with the wave function in model 1 (with the αα-Ali-Bodmer potential) is in a good agreement with available experimental data at E = 180 MeV.Keywords: Glauber diffraction theory; three-body cluster model; differential cross section, multiple scattering. PACS Number(s): 21.45.+v, 21.60.Gx, 24.10.Ht, 25.40.Cm. IntroductionNew stimulus for the research on weakly bound nuclei was the discovery of the exotic structure (halo and skin) of the series of unstable neutron-and proton-rich isotopes. The measurement of elastic scattering and reactions (breakup of light nucleus in the field of heavy one, stripping/transfer of weakly bound nucleon or cluster) in experiments involving such nuclei, indicate that these processes offer broad opportunities to understand the underlying cluster structure effects.9 Ве is a stable nucleus, strongly deformed (quadrupole moment Q = 52.88(38) mb) [1] and the weakly bound in 9 8 9Ве → Ве + n (ε = 1.67 MeV) [1] and Ве → α + α + n (ε = 1.57 MeV) [1] channels, which is a direct indication of its three-body α+α+n structure. The wave functions (WFs) taking into account this fact, calculated in 2αn model [2−5], provide a good description of its static observables (〈r 2 1/2 〉 , Q, μ), electromagnetic form factors and characteristics of the elastic π-, K-and p-9 Ве scattering [5−8].This nucleus − is a Borromian nucleus, because within the three-body 2αn picture of 9 Be there are no two components that could form a bound system, as in the case of 6 11 He and Li. Although, the value of the root mean square (rms) radius (〈r 2 1/2 〉 = 2.45(1) fm) [1] does not indicate the halo structure in this nucleus in its ground state, but in excited states J π = 1/2 + , 3/2 + the rms radii are greater: 2.83 fm and 2.98 fm, respectively. It seems that being excited, the nucleus increases in size and changes his structure to halo. As it is shown below (under review of

Static Properties of Neutron-Rich and Proton-Rich Isotopes

“…Many nucleon-nucleon potentials such as Woods-Saxon potential [5,6], Frost-Musulin potential [7], Pöschl-Teller potential [8] and Eckart potential [1,9] are being used by different researchers. 9 Be is only stable isotopes of beryllium and strongly deformed [10]. The cluster structure of 9 Be is interesting for studying the dynamics of reactions with weakly bound nuclei and also nuclear astrophysics [10].…”

“…9 Be is only stable isotopes of beryllium and strongly deformed [10]. The cluster structure of 9 Be is interesting for studying the dynamics of reactions with weakly bound nuclei and also nuclear astrophysics [10]. 9 B has a structure similar to 9 Be, with the odd-neutron replaced by the odd-proton [11].…”