Proton resonance elastic scattering in inverse kinematics on the medium heavy nucleus 68Zn

Abstract

Abstract. An isobaric analog resonance of 69 Zn was studied by the resonance elastic scattering of p( 68 Zn, p) with a 5.5 MeV/nucleon 68 Zn beam and a thick polyethylene target. The excitation function of the differential cross-section of proton elastic scattering was measured around 0 degrees in the laboratory frame by the thick target inverse kinematics method. The angular momentum, and proton and total widths of the resonance assigned using an R-matrix calculation are in good agreement with earlier measurements performed using normal kinematics, demonstrating that the thick target inverse kinematics method is a useful tool for studying the single-particle structures of neutron-rich nuclei.Systematic studies of the neutron single-particle states in neutron-rich nuclei give direct evidence of shell evolution with increasing neutron richness, thereby providing a test of current nuclear-structure models. These states are also important for determining the cross-sections of neutron radiative capture reactions in r-process nucleosynthesis. The recent advent of radioactive ion beam (RIB) facilities provides opportunities for investigating the states of neutron-rich nuclei located far from the stability line by direct reactions.A straightforward way to study neutron single-particle states in neutron-rich nuclei is the one-nucleon transfer reaction, e.g., (d, p) reaction, in inverse kinematics [1][2][3]. The final states in these reactions are identified by measuring the proton energy. The spin-parities (J π ) and spectroscopic factors are extracted from the angular distributions of differential cross-sections around 0 degrees in the center-of-mass (c.m.) frame. 0 degrees in the c.m. frame corresponds to 180 degrees in the laboratory (lab.) frame, where the energies of protons are often too low to separate the neighboring states, particularly for heavy nuclei which have highly crowded level densities [3]. In order to measure the low-energy protons in wide angular range and to improve the reconstructed energy resolution in the c.m. frame, a large solid-angle silicon semiconductor detectors a e-mail: nobuaki.imai@kek.jp (SSDs) array with a high segmentation [4][5][6][7] is often employed.The same spectroscopic information can be obtained by investigating the isobaric analog resonances of the final states through measuring proton resonance elastic scattering at a few points of scattering angles. Under the assumption of isospin symmetry, the neutron single-particle configuration of states in a nucleus A+1 Z would be the same as the proton single-particle configuration of states at the high excitation energies in the neighboring nucleus A+1 (Z + 1), called isobaric analog states. When the analog state is above the proton separation energy, the state will be observed in the proton elastic scattering excitation function of a target nucleus A Z as a resonance, called the isobaric analog resonance (IAR). The resonance energy, width, and J π can be obtained from the excitation function by R-matrix analysis [8,9].For unstable n...

Isobaric analog resonances of theN=21nucleus35Si

“…energy is also projected to a laboratory-energy interval that is wider, and largest at 0 • where it is four times wider. In addition, since the stopping power of protons is much smaller than that of the heavy incident ions, the elastic scattering excitation function may be measured over a wide range of energies with the use of a single fixed incident beam energy [20][21][22][23][24][25][26][27].…”

Observation of T=3/2 Isobaric Analog States in 9Be using p+8Li resonance scattering

“…to the already mentioned experiments, there were two more applications of this approach to study the structure of light, neutron rich nuclei, 9 He [11] and 13 B [12] and several recent studies in medium mass region [13][14][15][16] that applied the TTIK technique with rare isotope beams to study 47 Ar, 68 Zn, 35 Si, and 31 Mg.…”