Conceptual Design Report for the Scientific Program of the Super-FRS Experiment Collaboration

This Conceptual Design Report (CDR) presents the plans of the Super-FRS Experiment Collaboration for a variety of experiments, which build on the versatile high-resolution separator and spectrometer performance of the Super-FRS. The characteristic feature of these experiments is the fact that they use the separator as an integral part of the measurement. These experiments build on the experience of the collaboration and their scientific program pursued at the FRS in the last 25 years, but also includes recently developed novel topics.Under these premises, the Super-FRS Experiment Collaboration has identified ten major topics of current interest and with far-reaching scientific potential. In this CDR, the scientific case is briefly recapitulated and the conceptual design of the experiments, the setups and their implementation are described. Much of the needed equipment is already available or, if not, will be realized with new, additional resources and efforts outside the FAIR Cost Books. The related R&D works and some pilot experiments can be carried out at the existing FRS of GSI in FAIR Phase-0. On the midterm, the science program of this collaboration can start at the commissioning phase of the Super-FRS and will continue on the long term with the established full performance. Accordingly, the prototype equipment and other already existing devices can be tested and used at the FRS and can later, when completed or upgraded, be moved to the Super-FRS, see Appendix I. The related developments and organization of the Super-FRS Experiment Collaboration are described in Appendices II and III, respectively; the collaboration partners and institutes are listed in Appendix IV. The Super-FRS Experiment Collaboration is formally and firmly established and is a comprising part of the NUSTAR Collaboration. A large variety of modern nuclear physics experiments with new scientific possibilities and outstanding scientific potential were presented in the scientific program (GSI-Report 2014-4), which was very positively evaluated and approved by the FAIR-ECE in its 4th meeting in June 2014. In its report, the ECE encouraged the collaboration to develop TDRs. The present CDR is the next step on the way to TDRs for the ancillary equipment, that shall be integrated in the Super-FRS

IKEDA, the partner for exploring the nuclear highland far from the valley of stability

I have been collaborating with Ikeda since 1980’s when I started the experiment with radioactive nuclear beams. He has been interested in explaining the halo structure and binding energy of 11Li from the very beginning. From these studies, new basic concepts have been introduced, one of such important ideas is the soft resonance and cluster structure of halo nuclei. He also introduced the importance of the tensor forces on the halo formation, in particular for the correlation of two halo neutrons though s- and p- wave mixing. As an experimentalist, I have been trying to provide data to help him to develop these ideas. Here, I present the recent progresses in experimental studies. One is the first measurement of the two-neutron transfer reaction of 11Li to study the correlation between two halo neutrons. The other is a new on going experiment to obtain the direct evidence of the tensor forces in nuclei

Macroscopic nucleon-nucleon correlations caused by the bounce-off process in energetic collisions of heavy nuclei

Two-particle correlation data are presented for the reaction Ar (800 MeV/ nucleon) + Pb. The experimental results are analyzed in the nuclear fluid dynamical and in a linear cascade model. We demonstrate that the collective hydrodynamical correlations dominate the measured two-particle correlation function for the heavy system studied. We discuss the transition from the early stages of the reaction which are governed by few nucleon correlations, to the later stages with their macroscopic flow which can only be reached using heavy colliding systems. The sensitivity of the correlation data on the underlying compressional dissipative processes is analyzed

Constraining equation of state of nuclear matter by charge-changing cross section measurements of mirror nuclei

The nuclear symmetry energy plays a key role in determining the equation of state (EoS) of dense, neutron-rich matter, which connects the atomic nuclei with the hot and dense matter in universe, thus has been the subject of intense investigations in laboratory experiments, astronomy observations and theories. Various probes have been proposed to constrain the symmetry energy and its density dependence. Currently, the extensive data yield already a good and consistent constraint to the symmetry energy ( ) at saturation density, but do not yet give a consistent result of one critical EoS parameter, L, the density dependence of the symmetry energy. In this work, we report a new probe of L at saturation density. A good linear correlation is found between L and the charge changing cross section difference ( ) of mirror nuclei 30Si-30S for both the Skyrme-Hartree-Fock theory (SHF) and covariant (relativistic) density functionals (CDF). We found that the pairing effect for this mirror pair is essential to get a consistent correlation between L and in both the SHF and CDF. Here, the cross sections are calculated on the same target and at the same energy using the zero-range optical-limit Glauber model. The linearity is found to be in the same precision as those found between L and neutron skin thickness or proton radius difference

Charge-changing cross section measurements of 300 MeV/nucleon 28^{28}Si on carbon and data analysis

Charge-changing cross section ($\sigma_{\text{cc}}$) measurements via the transmission method have made important progress recently aiming to determine the charge radii of exotic nuclei. In this work, we report a new $\sigma_{\text{cc}}$ measurement of 304(9) MeV/nucleon $^{28}$Si on carbon at the second Radioactive Ion Beam Line in Lanzhou (RIBLL2) and describe the data analysis procedure in detail. This procedure is essential to evaluate the systematic uncertainty in the transmission method. The determined $\sigma_{\mathrm{cc}}$ of 1125(11) mb is found to be consistent with the existing data at similar energies. The present work will serve as a reference in the $\sigma_{\text{cc}}$ determinations at RIBLL2.Comment: 9 pages, 13 figures, to be published in Chinese Physics

Active target MAIKo to investigate cluster structures in unstable nuclei

Study on clustering of nucleons in nuclei is recently focusing on unstable nuclei where new kinds of structures, namely molecular structures with excess nucleons, are predicted. The Coulomb shift of energy in the mirror system is suggested to reflect the size of these structures. Although the missing mass spectroscopy is expected to give access to these structures even beyond particle decay thresholds without any biases in excitation energy spectra but the detection of very low energy particles is challenging. To satisfy the requirement, a new active target system MAIKo has been developed at RCNP. The detector was commissioned using a 13C beam under the same kinematical condition as that of RI beam experiments