Narrow Results

Comparative studies of hadron-induced interactions and heavy ion collisions have been performed at beam energies of 158 GeV/nucleon, corresponding to . They indicate that the heavy ion reaction is a mixture of various processes, including multiple nucleon collisions, isospin effects, and final state Coulomb interactions. The latter interactions result in surprising phenomena, like the presence of large and strongly varying structures in the shape of double-differential particle spectra. These phenomena depend on the initial conditions of the reaction and therefore can provide new information on the space and time evolution of the non-perturbative meson production process.

We measured the excitation functions for nine evaporation residues for the ¹²C + ¹¹⁵In system in the energy range well beyond the Coulomb barrier. The experimental results are compared with the theoretical values calculated using the Monte Carlo simulation code PACE2. Several complete and incomplete fusion products are observed in the present study. It is observed that a definite amount of incomplete fusion contribution is present, even at the lowest energy. The results clearly show the incomplete fusion contributions in the iodine and antimony products.

With the motivation of studying complete and incomplete fusion reactions in a ¹²C+⁵⁹Co projectile target system, the excitation functions for (C, p3n), (C, 2p2n), (C, αn), (C, α2n), (C, αp3n) and (C, 2α2n) reactions have been measured up to 80 MeV. The well-known activation technique followed by offline high purity Ge γ-ray spectroscopy was used. The measured experimental values were compared with the statistical model calculations by using the ALICE-91 and CASCADE codes. For the calculations obtained by CASCADE, the variation of parameter F_θ, which is the ratio of actual moment of inertia to the rigid body value have also been studied. Considerable enhancement of the measured excitation functions compared to theoretical predictions for some channels clearly indicates the presence of incomplete fusion with complete fusion in the present projectile energy range. The measurements of forward recoil range distribution of evaporation residues at 80 MeV projectile energy confirm these observations.

The experiments were performed to study excitation functions (EFs) of evaporation residues (ERs), i.e. ^103,102,101Ag, ^101,100,99Pd, ^101,100Rh, ⁹⁷Ru, ⁹⁶Tc, ⁹⁵Tc, ⁹⁴Tc, ⁹³Mo^m, ⁹²Nb^m populated in the reactions induced by ¹²C on ⁹³Nb for exploring the reaction dynamics involved at energies ≈ 47–75 MeV. The activation technique followed by offline γ-ray spectrometry has been employed to measure EFs. These measurements were simulated with other reported values available in literature as well as with theoretical predictions based on computer code PACE-2. The effect of variation of level density parameter involved in this code has also been studied. An excellent agreement was found between theoretical and experimental values in some of the fusion evaporation channels. However, significant enhancement of cross-section as observed in α-emission channels may be due to incomplete fusion (ICF) process and/or direct reaction process. To confirm the aforesaid reaction mechanism, Recoil Range Distributions (RRDs) of various ERs have been measured at ≈ 80 MeV. Moreover, an attempt is made to separate the percentage relative contributions of complete and incomplete fusion components from the analysis of the measured RRDs data. Further, the relative percentage ICF fraction, also estimated from EFs data, was found to be sensitive with the projectile energy.

The quest for the nuclear equation of state (EoS) at high densities and/or extreme isospin is one of the longstanding problems of nuclear physics. In the last years substantial progress has been made to constrain the EoS both, from the astrophysical side and from accelerator based experiments. Heavy ion experiments support a soft EoS at moderate densities while recent neutron star observations require a "stiff" high density behavior. Ab initio calculations for the nuclear many-body problem make predictions for the density and isospin dependence of the EoS far away from the saturation point. Both, the constraints from astrophysics and accelerator based experiments are shown to be in agreement with the predictions from many-body theory.

An extensive program on synthesis of superheavy elements (SHE) and investigating their nuclear structure as well as their chemical properties has been performed at the UNILAC accelerator at GSI during the past three decades. Highlights of this research program were the identification of the new elements with atomic numbers Z = 107-112, detailed nuclear structure investigations and discovery of new K isomers in the transfermium region, first chemical characterization of element 108 (hassium) and identification of the deformed doubly magic nucleus ²⁷⁰Hs. Part of the latest results are presented and discussed. Current and prospected upgrades of the facility and the experimental set-ups are presented.