An exploratory experiment on Multi-Nucleon Transfer (MNT) reactions was successfully conducted at the FRS Ion Catcher setup at GSI. The experiment demonstrated the production of MNT-driven radioactive ion beams (RIBs) produced by decelerated relativistic beams. A beam of 238U ions was reacted with a 209Bi target at near-Coulomb barrier energies inside the specially modified Cryogenic Stopping Cell (CSC) for the production and thermalization of MNT products. These products were then identified using a Multiple-Reflection Time-Of-Flight Mass Spectrometer (MRTOF-MS). The observation of target-like MNT fragments along the A = 211 isobaric chain provided a proof-of-principle for future MNT studies with the FRS Ion Catcher setup.

The masses of the ground and isomeric states in 124,125Ag have been measured using the phase-imaging ioncyclotron-resonance technique at the JYFLTRAP double Penning trap mass spectrometer. The ground states of 124Ag and 125Ag were found to be 30(250) keV and 250(430) keV less bound but 36 and 110 times more precise than in the Atomic Mass Evaluation 2020, respectively. The excitation energy of 124Agm, Ex = 188.2(25) keV, was determined for the first time. The new precise mass values have been utilized to study the evolution of nuclear structure via two-neutron separation energies. The impact on the astrophysical rapid neutron capture process has been investigated via neutron-capture reaction rate calculations. The precision measurements indicate a more linear trend in two-neutron separation energies and reduce the mass-related uncertainties for the neutron-capture rate of 124Ag(n, gamma ) 125Ag by a factor of around 100. The new mass values also improve the mass of 123Pd, previously measured using 124Ag as a reference.

Many observations strongly support the hypothesis that nuclei may fission through several independent fission modes (multimodal fission) interpreted as different prescission shapes and fission paths in a multidimensional potential energy landscape where shell effects are dominant. Mass distributions of the fission fragments are sensitive to the potential energy landscape and appear to be single humped (symmetric) or double humped (asymmetric). In many cases a mixture of both modes is observed. We propose here our study on 180Hg. Binary fission fragments formed in the reaction 68Zn + 112Sn → 180Hg at different excitation energies around the Coulomb barrier were detected using the double-arm time-of-flight technique with the spectrometers CORSET. The experiment was performed at JYFL (Jyvaskyla, Finland). We will discuss an analysis of the mass distributions in terms of fission modes predicted by a five-dimensional fission model. We have found out that the mass distributions can be well reproduced by considering a symmetric fission mode and two asymmetric modes at (AL ≈ 80, AH ≈ 100) and (AL ≈ 70 and AH ≈ 110).

Multinucleon transfer (MNT) reactions have been demonstrated as a promising pathway to produce and study very neutron-rich heavy nuclei, which can enhance our understanding of the nuclear structural features relevant to the r-process. Translead fragments were produced from the MNT reaction approach using Xe-136+Bi-209 at IGISOL utilizing an MNT gas cell. The Bi-211, (211)mPo, Po-211, and (212)mPo nuclei have been observed prominently in the a-decay spectrum. The GEANT4 simulation, which played a crucial role in optimizing the experimental parameters, reveals broader angular-energy distributions of MNT fragments released from a thick target compared to those observed from the GRAZING and Langevin models for a mono-energetic beam. Comparative yield analyses of MNT fragments for Xe-136+Bi-209 and Xe-136+Yb-176 reactions estimated using GEANT4 Simulation as well as analytical formula support the production of many neutron-rich unknown mass nuclei in the rare-earth region.

The multinucleon transfer (MNT) reaction approach was successfully employed for the first time to measure the isomeric ratios (IRs) of 211Po isomer (25/2+) and its ground state (9/2+) at the IGISOL facility using a 945 MeV 136Xe beam impinged on 209Bi and natPb targets. The dominant production of isomers compared to the corresponding ground states was consistently revealed in the α-decay spectra. Deduced IR of 211Po populated through the 136Xe+natPb reaction was found to have an enhancement of ≈1.8-times than that observed for the 136Xe+209Bi. State-of-the-art Langevin-type model calculations have been utilized to estimate the spin distribution of an MNT residue. The computations qualitatively corroborate with the considerable increase in the IRs of 211Po produced from 136Xe+natPb compared to 136Xe+209Bi. Theoretical investigations indicate a weak dependence of target spin on the IRs. The enhancement of the 211Po isomer in the 136Xe+natPb over 136Xe+209Bi can be attributed to the different proton (p)-transfer production routes. Estimations demonstrate an increment in the angular momentum transfer, favorable for isomer production, with increasing projectile energy. Comparative analysis reveals the two entrance channel parameters, projectile mass and p-transfer channels, strongly influencing the population of the high-spin isomer of 211Po (25/2+). This letter reports the first experimental and theoretical study on the IRs of nuclei formed via two different channels of MNT reactions.

The masses of Br-84, Mo-105, Pd-115,Pd-119,Pd-121, Ag-122, In-127,In-129, Sb-132, and their respective isomeric states have been measured with the JYFLTRAP Penning trap mass spectrometer using the phase-imaging ion-cyclotron-resonance technique. The excitation energies of the isomeric states in Sb-132 and Pd-119 were experimentally determined for the first time, while for Br-84, Pd-115, and In-127,In-129, the precision of the mass values was substantially improved. In Mo-105 and Pd-121 there were no signs of a long-lived isomeric state. The ground-state measurements of Pd-119 and Ag-122 indicated that both are significantly more bound than the literature values. For Ag-122, there was no indication of a proposed third long-lived state. The results for the N=49 nucleus Br-84 and isomers close to doubly magic Sn-132 have been compared to the shell-model and the microscopic quasiparticle-phonon model calculations.

Neutron-rich 120-124 In isotopes have been studied utilizing the double Penning trap mass spectrometer JYFLTRAP at the IGISOL facility.Using the phase-imaging ion-cyclotron-resonance technique, the isomeric states were resolved from ground states and their excitation energies measured with high precision in 121,123,124 In.In 120,122 In, the 1 + states were separated and their masses were measured while the energy difference between the unresolved 5 + and 8 -states, whose presence was confirmed by post-trap decay spectroscopy was determined to be ≤ 15 keV.In addition, the half-life of 122 Cd, T 1/2 = 5.98(10) s, was extracted.Experimental results were compared with energy density functionals, density functional theory and shell-model calculations.

The dependence of the properties of the fission fragments formed both in the fusion-fission and fast fission processes on the angular momentum still remains very unclear from an experimental as well as theoretical point of view. To study the properties of fast fission fragments of preactinide nuclei as function of the interaction energy and introduced angular momentum, the mass-energy distributions of ^184 Pb fission fragments formed in the ^40Ca+^144 Sm reaction at energies above the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET at the ^40 Ca ions’ energies of 212, 231, 244, and 277 MeV. The mass-energy distributions of the fast fission fragments have been extracted by subtracting the mass-energy matrices corresponding to the compound nucleus fission from those of all measured fissionlike events. The asymmetric fragments with masses 76 and 108 u were found to be the most probable in the fast fission of ^184 Pb. With increasing ^40 Ca energy from 231 to 277 MeV the mass distributions of fast fission fragments change weakly, whereas an increase in the TKE is about 20 MeV. The properties found for the fast fission fragments indicate the incomplete mass relaxation and not full energy dissipation.

We report on the first direct mass measurements of the 118,119Cd and 117-119In isotopes performed at the Ion Guide Isotope Separator On -Line facility using the JYFLTRAP double Penning trap mass spectrometer. The masses of 117In and 118Cd isotopes are in agreement with the literature, while 118,119In and 119Cd differ from literature by 49, 13, and 85 keV (6.1, 1.9, and 2.1 standard deviations), respectively. The excitation energy of the 118In first isomeric state, Ex = 40.3(25) keV, was determined for the first time. The updated mass values removed the fluctuations observed in the two -neutron separation energies and led to a smoother linear decrease of both isotopic chains. The log(ft) value for the 118Cd decay was also found to increase from 3.93(6) to 4.089(8). The reported results indicate an absence of significant structural changes around N = 70.

A research programme focused on the study of the nuclear structure of actinide isotopes has recently been implemented at the IGISOL facility, University of Jyväskylä. Within this scope, a new decay station named VADER (Versatile Actinides DEcay spectRoscopy setup) has been developed and commissioned. The system consists of a compact array of silicon detectors, a liquid-nitrogen-cooled silicon lithium (Si(Li)) detector and three broad energy germanium detectors (BEGe), placed around a thin implantation carbon foil. The combined use of different detectors allows the measurement of α particles, conversion electrons and de-excitation γ rays in coincidence, enabling a full reconstruction of nuclear decay schemes. The measurement of basic nuclear decay observables provides a picture of the nuclear shell evolution in neutron-deficient actinides, and highlights the possible emergence of reflection-asymmetric shapes in the region.

Background: The nature of asymmetric fission of preactinides is not yet understood in detail, despite intense experimental and theoretical studies carried out at present.Purpose: The study of asymmetric and symmetric fission of $^{180,182,183}\mathrm{Hg}$ and $^{178}\mathrm{Pt}$ nuclei as a function of their excitation energy and isospin.Methods: Mass-energy distributions of fission fragments of $^{180}\mathrm{Hg}, ^{178}\mathrm{Pt}$ (two protons less than $^{180}\mathrm{Hg}$), and $^{182}\mathrm{Hg}$ (two neutrons more than $^{180}\mathrm{Hg}$) formed in the $^{36}\mathrm{Ar}+^{144}\mathrm{Sm}, ^{142}\mathrm{Nd}$, and $^{40}\mathrm{Ca}+^{142}\mathrm{Nd}$ reactions were measured at energies near and above the Coulomb barrier. Fission of $^{183}\mathrm{Hg}$ obtained in the reaction of $^{40}\mathrm{Ca}$ with $^{143}\mathrm{Nd}$ was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in $^{183}\mathrm{Hg}$.The measurements were performed with the double-arm time-of-flight spectrometer CORSET.Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus.Conclusions: The investigated properties of asymmetric fission of $^{180,182,183}\mathrm{Hg}$ and $^{178}\mathrm{Pt}$ nuclei point out the existence of well-deformed proton shell at $Z\ensuremath{\approx}36$ and a less deformed proton shell at $Z$ \ensuremath{\approx} 46.

n Erratum to this paper has been published: https://doi.org/10.3103/S1062873822340019

An Erratum to this paper has been published: https://doi.org/10.3103/S1062873822340019

Background: The nature of asymmetric fission of preactinides is not yet understood in detail, despite intense experimental and theoretical studies carried out at present. Purpose: The study of asymmetric and symmetric fission of Hg-180,Hg-182,Hg-183 and Pt-178 nuclei as a function of their excitation energy and isospin. Methods: Mass-energy distributions of fission fragments of Hg-180, Pt-178 (two protons less than Hg-180), and Hg-182 (two neutrons more than Hg-180) formed in the( 36)Ar+Sm-144, Nd-142, and Ca-40+Nd-142 reactions were measured at energies near and above the Coulomb barrier. Fission of Hg-183 obtained in the reaction of Ca-40 with Nd-143 was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in Hg-183. The measurements were performed with the double-arm time-of-flight spectrometer CORSET. Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus. Conclusions: The investigated properties of asymmetric fission of Hg-180,Hg-182,Hg-183 and Pt-178 nuclei point out the existence of well-deformed proton shell at Z approximate to 36 and a less deformed proton shell at Z approximate to 46.

Asymmetric fission of mercury nuclei was initially observed in the low-energy region. In recent years, several experiments have been performed in this direction to investigate the asymmetric behaviour of Hg nuclei which supported the influence of shell effects on the asymmetric fission process. An experiment was performed using the CORSET setup. We investigated mass and energy distributions of fragments and fission characteristics of prolately-deformed Hg-182 and oblately-deformed Hg-183 nuclei formed in the Ca-40+Nd-142,Nd-143 reactions at three different beam energies - E-lab = 172, 192, and 212 MeV. We found no huge variation in mass-energy distributions of Hg-182 and Hg-183 at any of the measured energies. This gives us an outlook regarding the influence of shell structure, charge radii deformation, and factors associated with the potential energy surface that is responsible for fission in the Hg region.

A study is performed of the asymmetric fission of neutron-deficient mercury 180, 190 Hg isotopes obtained in the reactions of 36 Ar + 144, 154 Sm and 68 Zn + 112 Sn at incident energies near and above the Coulomb barrier. The relative contributions from asymmetric and symmetric fission change along with the excitation energy of the fissile compound nucleus. The effect the characteristics of the entrance channel have on the dynamics of the reaction is studied.

Background: The experimental knowledge of nuclear reaction data and decay properties plays a vital role in searching for novel and exotic radioisotopes, prompting us to widen the experimental study of heavy-ion induced reactions.Purpose: The aim is to study the production of mass separated (i.e., separation of different masses of residues, where each mass group consists of isobaric nuclei) evaporation residues (ERs) populated in $^{32}\mathrm{S}+^{70}\mathrm{Zn}$ and $^{32}\mathrm{S}+^{68}\mathrm{Zn}$ reactions within 115--135 and 130--150 MeV incident energy ranges, respectively, and optimization of masses 97 and 95 u that consist of $^{97}\mathrm{Pd}$, $^{97}\mathrm{Rh}$, $^{97}\mathrm{Ru}$, and $^{95}\mathrm{Pd}$, $^{95}\mathrm{Rh}$, $^{95}\mathrm{Ru}$, $^{95}\mathrm{Tc}$ isobaric residues, respectively.Method: Mass separation of ERs has been achieved at the focal plane of the Heavy Ion Reaction Analyser (HIRA) at the 15 UD Pelletron facility, IUAC, India. The residues were detected at the focal plane of HIRA using a multiwire proportional counter (MWPC).Results: Competing production of masses 97 and 95 u through the fusion of $^{32}\mathrm{S}$ ions with $^{70}\mathrm{Zn}$ and $^{68}\mathrm{Zn}$, respectively, have been observed in comparison to their neighboring masses within the measured energy range. The maximum cumulative production of $^{97}\mathrm{Ru}$ has been found to be $\ensuremath{\approx}99\ifmmode\pm\else\textpm\fi{}9.9$ $\mathrm{Bq}/\mathrm{h}\phantom{\rule{0.16em}{0ex}}\mathrm{pnA}(\mathrm{mg}/{\mathrm{cm}}^{2}$) at 125 MeV, while for $^{95}\mathrm{Ru}$ it is $\ensuremath{\approx}69\ifmmode\pm\else\textpm\fi{}6.9$ $\mathrm{Bq}/\mathrm{h}\phantom{\rule{0.16em}{0ex}}\mathrm{pnA}(\mathrm{mg}/{\mathrm{cm}}^{2}$) at 135 MeV. Comparisons of experimental results with the theoretical calculations indicate that the residues are mainly populated through the compound reaction mechanism.Conclusions: As anticipated from theory, significant yields of $^{97}\mathrm{Ru}$ and $^{95}\mathrm{Ru}$ in reactions $^{32}\mathrm{S}+^{70}\mathrm{Zn}$ and $^{32}\mathrm{S}+^{68}\mathrm{Zn}$ have been achieved via cumulative production of different isobars of mass 97 and 95 u, respectively. Cumulative yield of $^{97}\mathrm{Ru}$ has been found to be equivalent, i.e., the same order of magnitude [viz., $\ensuremath{\approx}{10}^{7}$ nuclei/h pnA(mg/${\mathrm{cm}}^{2}$)], compared to its independent production through $^{11}\mathrm{B}$ and $^{7}\mathrm{Li}$ projectile induced reactions.