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The mass-energy distributions of fragments of the reaction 32S + 232Th leading to the formation of 264Sg (Z = 106) at energies of incident ions 32S of 165, 181 and 200 MeV are measured. The contribution from the quasifission process is found at energies below and above the Coulomb barrier in the region of symmetric masses (АCN/2 ± 20). A high-energy symmetric fission mode is found at an energy of 165 MeV, which corresponds to the excitation energy of the compound 264Sg nucleus 45 MeV.

t—The mass–energy distributions of fission fragments of excited 180,190Hg nuclei formed in 36Ar + 144,154Sm reactions are measured at incident 36Ar energies of 158, 181, and 222 MeV using the double-arm time-of-flight spectrometer CORSET. The asymmetric fission of 180,190Hg with the most probable masses of light and heavy fragments of 79 and 101 amu, and 84 and 106 amu, respectively, is observed in mass distributions of 180,190Hg at energies of excitation of up to 75 MeV. Two components manifesting the symmetric and asymmetric fission modes are observed in the kinetic energy distributions.

The mass-energy distributions of fragments formed in reactions 16,18O + 232Th, 238U, and 22Ne + 232Th, 238U at energies near the Coulomb barrier are measured to study the role of multimodal fission in the reactions of light ions with strongly deformed actinide nuclei. It is found that at these energies, multimodal fission affects significantly the mass–energy and angular distributions of fragments that results in an increase of the width of mass distributions and large angular anisotropy as in the case of quasifission.

Background: Observation of asymmetric fission of $^{180}\mathrm{Hg}$ has led to intensive theoretical and experimental studies of fission of neutron-deficient nuclei in the lead region.Purpose: The study of asymmetric and symmetric fission modes of $^{180,190}\mathrm{Hg}$ and $^{184,192,202}\mathrm{Pb}$ nuclei.Methods: Mass-energy distributions of fission fragments of $^{180,190}\mathrm{Hg}$ and $^{184}\mathrm{Pb}$ formed in the $^{36}\mathrm{Ar}+^{144,154}\mathrm{Sm}$ and $^{40}\mathrm{Ca}+^{144}\mathrm{Sm}$ reactions, respectively, at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET and compared with previously measured $^{192,202}\mathrm{Pb}$ isotopes produced in the $^{48}\mathrm{Ca}+^{144,154}\mathrm{Sm}$ reactions. The mass distributions for $^{180,190}\mathrm{Hg}$ and $^{184,192,202}\mathrm{Pb}$ together with old data for $^{187}\mathrm{Ir}, ^{195}\mathrm{Au}, ^{198}\mathrm{Hg}, ^{201}\mathrm{Tl}, ^{205,207}\mathrm{Bi}, ^{210}\mathrm{Po}$, and $^{213}\mathrm{At}$ [J. Nucl. Phys. 53, 1225 (1991)] have been decomposed into symmetric and asymmetric fission modes. The total kinetic-energy distributions for different fission fragment mass regions have been analyzed for $^{180,190}\mathrm{Hg}$ and $^{184}\mathrm{Pb}$.Results: The stabilization role of proton numbers at $Z\ensuremath{\approx}36$, 38, $Z\ensuremath{\approx}45$, 46, and $Z=28/50$ in asymmetric fission of excited preactinide nuclei has been observed. The high ($\ensuremath{\approx}145\text{\ensuremath{-}}\mathrm{MeV}$) and the low ($\ensuremath{\approx}128\text{\ensuremath{-}}\mathrm{MeV}$) energy components have been found in the total kinetic-energy distributions of $^{180,190}\mathrm{Hg}$ fission fragments corresponding to the fragments with proton numbers near $Z\ensuremath{\approx}46$ and $Z\ensuremath{\approx}36$, respectively. In the case of fission of $^{184}\mathrm{Pb}$ only the low-energy component ($\ensuremath{\approx}135\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$) for the fragments with masses corresponding to the proton numbers $Z\ensuremath{\approx}36$ and 46 has been found.Conclusions: The studied properties of asymmetric fission of $^{180,190}\mathrm{Hg}$ and $^{184,192,202}\mathrm{Pb}$ nuclei point out the existence of well deformed proton shell at $Z\ensuremath{\approx}36$ and less deformed proton shell at $Z\ensuremath{\approx}46$.

A study is performed of the asymmetric fission of neutron-deficient mercury 180, 190Hg isotopes obtained in the reactions of 36Ar + 144, 154Sm and 68Zn + 112Sn 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.

International audience; The overlap in the mass symmetric region of the reaction products from fusion-fission and quasifission complicates the assignment of symmetric events to complete fusion on the basis of the mass distribution alone. Additional observables, besides mass distribution, should be used. The approach proposed here relies on the fact that fusion-fission and quasifission are characterized by different timescales. Within this framework, we performed a detailed study to find out how timescales can be probed via angular momentum transfer as measured via γ-ray multiplicities. The proof of principle was carried out by measuring the γ rays in coincidence with fusion-fission and quasielastic binary fragments in the reaction S32 + Au197 at beam energy near the Coulomb barrier. The experiment was performed at the Accélérateur Linéaire Tandem à Orsay (ALTO) facility at the Institut De Physique Nucléaire (IPN) in Orsay (France) using a detection setup consisting of ORGAM (ORsay GAMma) and PARIS (Photon Array Radioactive Ion Stable beams) γ-detectors arrays coupled with the CORSET (CORrelation SETup) time-of-flight spectrometer. Results of the sensitivity of this method to distinguish reaction channels with different dynamics are discussed.

Light charged particles emitted by the compound nucleus $^{158}\mathrm{Er}$ produced in the reaction $^{32}\mathrm{S}$ $(180 \mathrm{MeV})+^{126}\mathrm{Te}$, at the excitation energy ${E}_{x}=92$ MeV, have been measured at Laboratori Nazionali di Legnaro in coincidence with fission fragments and evaporation residues. The $4\ensuremath{\pi}$ detector array $8\ensuremath{\pi}\mathrm{LP}$ coupled to a system of parallel-plate avalanche counters to detect evaporation residues has been used. Data have been analyzed in the framework of the statistical model of evaporation with the code pace2_n11. This enlarged version of the code pace2 has been used to reproduce the large set of observables measured in the fusion-evaporation and fusion-fission channels along with experimental prescission neutron multiplicity and fission cross section taken from literature. It is found that the simultaneous reproduction of the prescission neutron, proton, and $\ensuremath{\alpha}$-particle multiplicities can be obtained with zero fission delay without dynamical effects. However, the same set of model input parameters does not allow us to reproduce proton and $\ensuremath{\alpha}$-particle multiplicities in the evaporation channel. Extensive calculations, with different sets of parameters, show the limits of the statistical model in reproducing the whole set of data. This work evidences the importance of measuring a large set of observables in order to obtain a reliable description of the decay of the compound nucleus, and in particular of the fission process.

International audience; The features of fission fragments formed in the near barrier reaction $^{32}\hbox {S}$ + $^{197}\hbox {Au}$ ($E^\mathrm{lab}_\mathrm{beam}=166\,\hbox {MeV}$) are investigated. The measurement was performed at the ALTO facility of IPN Orsay, France, with the aim of clarifying the quantitative contribution of the quasi-fission process to the total fission events. The mass and total kinetic energy of the fission fragments were compared to the expectations of the liquid drop model, revealing an asymmetric fission component which may be traced back to a quasi-fission process mixed with the fusion–fission events. The $\gamma $-rays and neutrons measured in coincidence with the fission fragments were used to yield additional information for the discrimination of the two aforementioned mechanisms. All observed trends are consistent and fairly well reproduced by the statistical model.

International audience; The mass, energy and angular distributions of binary fragments formed in the reactions $^{64}$Ni + $^{238}$U, $^{58}$Fe + $^{244}$Pu, $^{52}$Cr + $^{248}$Cm, $^{54}$Cr + $^{248}$Cm at energies near the Coulomb barrier have been measured. The analysis of energy distributions of the symmetric fragments with mass numbers ${{{{A}_{{{\text{CN}}}}}} \mathord{\left/ {\vphantom {{{{A}_{{{\text{CN}}}}}} 2}} \right. \kern-0em} 2} \pm 20$ formed in these reactions have been applied to separate compound nucleus fission and quasi-fission. The estimated fusion probability for the reactions Cr, Fe, and Ni ions with actinide targets shows an exponential dependence on the mean fissility parameter of the system and shows also that reaction with Cr ions is more favorable for production of the super heavy element with Z = 120.

Mass–energy distributions of fission fragments are measured in the proton energy region of 7 to 55 MeV in order to study shell effects in the fissioning of 232Th nuclei induced by protons at low and intermediate energies. Experiments at proton energies of 13 to 55 MeV are performed using proton beams from the K-130 cyclotron at the University of Jyvaskyla (Finland) using the CORSET two-armed time-of-flight spectrometer. Experiments at proton energies of 7, 10, and 13 MeV are performed using the beam from the U‒150M cyclotron at the Institute of Nuclear Physics in Almaty (Kazakhstan) using a 2Е spectrometer for detecting fission fragments. It is found that the yield of symmetric fragments falls along with the proton energy, while the yield of asymmetric fragments rises. Deep below the Coulomb barrier at the lowest proton energy of 7 MeV, an increased yield of fission fragments is observed in the region of 60−70 a.m.u., which corresponds to the superasymmetric mode of fission.

The mass and energy distributions of fission fragments in reactions 16O + 232Th, 16O + 238U, 22Ne + 232Th, and 22Ne + 238U are measured to investigate the role of closed proton and neutron shells in the fission of 248Cf, 254Fm, and 260No nuclei at excitation energies of 40–45 MeV. Experiments are performed on the U-400 cyclotron at the Flerov Laboratory of Nuclear Reactions (Dubna, Russia) using the CORSET double-arm time-of-flight spectrometer. For compound nucleus 260No* formed in the reaction 22Ne + 238U, an increase in the fragment yields is observed in the superasymmetric mass region 52/208 amu, which corresponds to the formation of fissioning pairs of two double-magic nuclei, 48Ca and 208Pb. Superasymmetric fission at a mass yield level of 10−5 was not observed for compound nuclei 248Cf and 254Fm* formed in reactions 16O + 232Th, 16O + 238U, and 22Ne + 232Th at an initial excitation energy of 40−45 MeV. Bimodal fission was observed for the 260No*compound nucleus at an initial excitation energy of 41 MeV. In the symmetric mass split, both fission fragments are in this case close to double-magic 132Sn.

To investigate the impact shell effects have in the formation of neutron-rich fragments in multinucleon transfer reactions, a series of experiments to explore the binary channel in 156,160Gd + 186W reactions at energies near and above the Coulomb barrier is performed at the Flerov Laboratory’s U-400 accelerator using the CORSET setup. These experiments are aimed mainly at obtaining the production cross sections of leadlike fragments in the process of inverse quasifission. The mass, energy, and angular distributions of the binary reaction products are measured at energies of 860 and 935 MeV of 160Gd ions and 878MeV in the case of 156Gd ions. The excitation energies of primary fragments are estimated using their measured mass–energy distributions. Enhanced yields of products with masses of 200–215 amu are observed for both reactions. At energies above the barrier for side-to-side collisions (935 MeV), the yield of lead-like fragments is an order of magnitude larger than at energies near the Coulomb barrier, due possibly to the influence of orientation effects. The enhancement observed in the yield of reaction products with masses heavier than the target mass confirms that multinucleon transfer reactions can be used to obtain new neutron-rich isotopes, and to synthesize new superheavy elements.

New experimental data on energy loss of 4 He, 16 O, 40 Ar, 48 Ca and 84 Kr ions in thin, self-supporting foils of C, Al, Ni, Ag, Lu, Au, Pb and Th are presented. The measurements, using the TOF-E method, were done in a very broad energy range around the stopping power maximum; typically from 0.1 to 11 MeV/u. When available, the extracted stopping power values are compared with the previously published data. The overall agreement is good although a fair comparison is difficult as the covered energy range is much larger than in previous measurements. The small error bars and a broad coverage allowed us to test the predictions of theoretical codes: PASS, CasP, and semi-empirical programs: SRIM, LET, MSTAR, and the Hubert table predictions. The deviations of PASS predictions from the experimental data do not exceed 20% for all the measured combinations. CasP predictions are within 15% from the data for heavier ions but diverge up to 40% for lighter ions. Semi-empirical approaches, including SRIM, deviate from the experimental data by less than 5% for the regions already covered by previous experiments but err by about 10–20% for the ion/target combinations that were not measured before: Ca in Lu as well as Kr in Lu, Pb, and Th.

For the 68Zn + 112Sn reaction the Coulomb parameter Z 1 Z 2 is equal to 1500 that is close to the threshold value for the appearance of quasifission process. It was found that mass-energy distributions of the reaction fragments differ significantly from those obtained in the 36Ar + 144Sm reaction leading to the formation of the same composite system of 180Hg at similar excitation energies of about 50 MeV. In the case of the reaction with 68Zn ions, the mass distribution of fissionlike fragments has a wide two-humped shape with maximum yields at 70 and 110 u for the light and heavy fragments, respectively, instead of 80 and 100 u observed in the fission of 180Hg formed in the 36Ar + 144Sm reaction. The difference is explained by an unexpectedly large contribution (more than 70%) of quasifission in the case of the 68Zn + 112Sn reaction.

Fusion excitation function of $^{35}$Cl + $^{130}$Te system is measured in the energy range around the Coulomb barrier and analyzed in the framework of the coupled-channels approach. The role of projectile deformation, nuclear structure, and the couplings of inelastic excitations and positive Q$-$value neutron transfer channels in sub-barrier fusion are investigated through the comparison of reduced fusion excitation functions of $^{35,37}$Cl +$^{130}$Te systems. The reduced fusion excitation function of $^{35}$Cl + $^{130}$Te system shows substantial enhancement over $^{37}$Cl + $^{130}$Te system in sub-barrier energy region which is attributed to the presence of positive Q-value neutron transfer channels in $^{35}$Cl + $^{130}$Te system. Findings of this work strongly suggest the importance of +2$n$ - transfer coupling in sub-barrier fusion apart from the simple inclusion of inelastic excitations of interacting partners, and are in stark contrast with the results presented by Kohley \textit{et al.}, [Phys. Rev. Lett. 107, 202701 (2011)]., 6 pages, 4 figures

International audience; The overlap in the mass symmetric region of the reaction products from fusion-fission and quasi-fission complicates the assignment of symmetric events to complete fusion on the basis of the mass distribution alone. Additional observables, besides mass distribution, should be used. The method proposed here relies on the fact that fusion-fission and quasifission are characterized by a different timescale. Within this framework we performed a detailed study to find out if timescales can be probed via angular momentum as measured via γ rays multiplicity. The proof of principle was carried out by measuring the γ rays in coincidence with two fragments in the reaction 32S + 197Au at beam energy near the Coulomb barrier. The experiment has been performed at the Tandem ALTO facility at IPN Orsay using a detection setup consisting of ORGAM and PARIS γ detector arrays coupled with the CORSET time-of-flight spectrometer. Preliminary results on the sensitivity of this method to distinguish reaction channels with different dynamics are discusses.

Nuclear viscosity is an irreplaceable ingredient of nuclear fission collective dynamical models. It drives the exchange of energy between the collective variables and the thermal bath of single particle degrees of freedom. Its dependence on the shape and temperature is a matter of controversy. By using systems of intermediate fissility we have demonstrated in a recent study that the viscosity parameters is larger for compact shapes, and decreases for larger deformations of the fissioning system, at variance with the conclusions of the statistical model modified to include empirically viscosity and time scales. In this contribution we propose an experimental scenario to highlight the possible dependence of the viscosity from the temperature.

International audience; Compound nucleus fission and quasi-fission are both binary decay channels whose common properties make the experimental separation between them difficult. A way to achieve this separation could be to probe the angular momentum of the binary fragments. This can be done detecting gamma rays in coincidence with the two fragments. As a case study, the reaction 32S + 197Au near the Coulomb barrier has been performed at the Tandem ALTO facility at IPN ORSAY. ORGAM and PARIS, two different gamma detectors arrays, are coupled with the CORSET detector, a two-arm time-of-flight spectrometer. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments coupled with gamma multiplicity and spectroscopic analysis. Preliminary results of will be shown.

Multi-nucleon transfer reactions are nowadays the only known mean to produce neutron-rich nuclei in the Terra Incognita. The closed-shell region N=126 is crucial for both studying shell-quenching in exotic nuclei and the r-process, being its last "waiting-point". The choice of suitable reactions is challenging and a favorable case is 136Xe+208Pb, near the Coulomb barrier, because their neutron shell-closures play a stabilizing role, favoring the proton-transfer from lead to xenon. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments. Preliminary results of an experiment held at Laboratori Nazionali di Legnaro with PRISMA, aimed at A and Z identification of the products, will be shown. peerReviewed

Background: Low-energy multinucleon transfer reactions may be used for production of new neutron-enriched heavy nuclei.Purpose: Our aim is to investigate the influence of proton ($Z=82$) and neutron ($N=82$, 126) shells as well as orientation effects on the formation of reaction products in the inverse quasifission process in the reactions $^{156,160}\mathrm{Gd}+^{186}\mathrm{W}$.Methods: Mass, energy, and angular distributions of primary binary fragments formed in the reactions $^{156}\mathrm{Gd}+^{186}\mathrm{W}$ at an energy of 878 MeV, and $^{160}\mathrm{Gd}+^{186}\mathrm{W}$ at 860 and 935 MeV, have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR), Dubna.Results: Enhancement in the yield of products with masses 200--215 u has been found for both reactions. The cross sections of the formation of trans-target fragments with masses around 208 u are found to be about 10 \ensuremath{\mu}b at the Coulomb barrier energy and reach the level of 0.5 mb at the energy above the barrier for side-to-side collision.Conclusions: The enhanced yield of products with masses heavier than the target mass confirms the important role of the closed shells at $Z=82$ and $N=82$, 126 in the inverse quasifission process in low-energy damped collisions. The orientation effect caused by the strong deformation of colliding nuclei can result in a gain in the yield of heavy target-like fragments.

The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion–fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of 136Xe with 208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N = 126.

Background: Suppression of compound nucleus formation in the reactions with heavy ions by a quasifission process in dependence on the reaction entrance channel.

The pathway toward the production of superheavy elements (SHE) crosses with the one of an in-depth study of the fission and quasifission processes. Quasifission affects the probability of forming a compound nucleus (CN) after capture and fission plays a decisive role during the cooling of the CN. To search for optimal reactions to produce SHE in fusion reactions and to provide an estimate of their production cross section measurements of the capture and fusion cross sections along with the survival probabilities are a mandatory task. Here an overview of the impact of fission and quasifission over the synthesis of SHE is discussed along with the need to perform measurements over a wide range of masses and energies.

A new setup is proposed to produce and investigate heavy neutron-rich nuclei located along the neutron closed shell N = 126. This "blank spot" of the nuclear map can be reached neither in fusion-fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be rather high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of 136Xe with 208Pb. This setup could definitely open a new opportunity in the studies at heavy-ion facilities and will have significant impact on future experiments. © 2013 Springer Science+Business Media Dordrecht. ispartof: pages:109-113 ispartof: Hyperfine Interactions vol:216 issue:1-3 pages:109-113 ispartof: 6th International Conference on Laser Probing (LAP) location:Paris, FRANCE date:4 Jun - 8 Jun 2012 status: published

International audience; The path to the synthesis of super heavy elements is strongly hindered by the competition between fusion and quasi-fission in heavy ions reactions at near barrier energies. We report on a recent experimental investigation performed at the ALTO facility of IPN Orsay, France on the heavy-ion collision around the Coulomb barrier of 32S+197Au. The fission-fragment mass and total kinetic energy were measured by the double arm mass spectrometer for binary fragments CORSET, using the double time of flight approach. The asymmetric structure on top of the predominant symmetric one may suggests the contribution from either quasi-fission or pre-equilibrium fission or might be driven by shell effects in the compound nucleus fission. To get further insight on such puzzling cases situated at the crossroads of the various opened channels, we extended the measurement to coincident prompt γ -rays, of low and high energy. For this purpose, the prompt γ-rays following fission were detected by the coupled high efficiency ORGAM array consisting of 10 Compton suppressed Germanium detectors (BGO shielded), located at backward angles and the first cluster of the future PARIS calorimeter consisting of 9 close packed phoswich detectors and another single phoswich, together covering a wide angular and energy range.

The current status of fission dynamics studies in heavy-ion collisions around the Coulomb barrier is illustrated with the 34S + 186W reaction. The fission-fragment mass and total kinetic energy were measured at the ALTO facility at IPN Orsay, France, with a dedicated set-up using the (v, E) approach. The measurement reveals the presence of an asymmetric fission component on top of a predominantly symmetric distribution. The asymmetric structure, pointed out for the first time, is discussed along with results of previous experiments studying the same reaction. While these analyses suggested the contribution from either quasi-fission or pre-equilibrium fission, we offer an alternative interpretation, in terms of shell-driven compound-nucleus fission. The present measurement demonstrates the critical influence of resolution when addressing puzzling cases, situated at the crossroads of the various channels opened in a heavy-ion collision. Current status in the field clearly calls for innovative measurements involving manifold correlations and new observables. The outcome of the attempt done in this work in this direction, based on the coincident measurement of prompt \( \gamma\)-rays is reported, and encouraging perspectives are discussed.

This work is a study of the influence of shell effects on the formation of binary fragments in damped collision. We have investigated binary reaction channels of the composite system with Z = 108 produced in the reaction 88Sr+176Yb at an energy slightly above the Bass barrier (Ec.m./EBass = 1.03). Reaction products were detected by using the two-arm time-of-flight spectrometer CORSET at the K130 cyclotron of the Department of Physics, University of Jyv¨askyl¨a. The mass-energy distribution of primary binary fragments has been measured. For targetlike fragments heavier than 190 u, which correspond to a mass transfer as large as twenty nucleons or more, an enhancement of the yields is observed. This striking result can be ascribed to the proton shells at Z = 28 and 82 and implies the persistence of the shell effects in the formation of reaction fragments even for large mass transfers.

Expérience LNL/PRISMA; International audience; The unexplored area of heavy neutron rich nuclei is extremely important for nuclearastrophysics investigations and, in particular, for the understanding of the r-process ofastrophysical nucleogenesis. For the production of heavy neutron rich nuclei located along theneutron closed shell N=126 (probably the last "waiting point" in the r-process of nucleosynthesis)the low-energy multi-nucleon transfer reaction 136Xe+208Pb at Elab=870MeV was explored.Due to the stabilizing eect of the closed neutron shells in both nuclei, N=82 and N=126, andthe rather favorable proton transfer from lead to xenon, the light fragments formed in this processare well bound and the Q-value of the reaction is nearly zero.Measurements were performed with the PRISMA spectrometer in coincidence with an additionaltime-of-flight (ToF) arm on the +20 beam line of the PIAVE-ALPI accelerator in Legnaro, Italy.The PRISMA spectrometer allows identication of the A, Z and velocity of the projectile-likefragments (PLF), while the second arm gives access to the target-like fragments (TLF).Details on the experimental setup and preliminary results are reported.

The mass-energy distributions and cross sections of proton-induced fission of Th-232 have been measured at the proton energies of 7, 10, 13, 20, 40, and 55 MeV. Experiments were carried out at the proton beam of the K-130 cyclotron of the JYFL Accelerator Laboratory of the University of Jyvakyla and U-150m cyclotron of the Institute of Nuclear Physics, Ministry of Energy of the Republic of Kazakhstan. The yields of fission fragments in the mass range A = 60- 170 a.m.u. have been measured up to the level of 10(-4)%. The three humped shape of the mass distribution up has been observed at higher proton energies. The contribution of the symmetric component grows up with increasing proton incident energy; although even at 55 MeV of proton energy the shoulders in the mass energy distribution clearly indicate the asymmetric fission peaks. Evolution of shell structure was observed in the fission fragment mass distributions even at high excitation energy.

We investigated the formation of nuclear molecules and the occurrence of time delays in reactions of the superheavy systems 64Ni + 207Pb ( $ Z_{1}+Z_{2}=110$ ), 132Xe + 208Pb ( $ Z_{1}+Z_{2}=136$ ) and 238U + 238U ( $ Z_{1}+Z_{2}=184$ . In deep inelastic binary reactions of Ni + Pb and Xe + Pb we observed clear signatures for the formation of long-living molecule-like nuclear systems which rotate by large angles of 180 degree. The evolution of the nuclear molecules was accompanied by large energy dissipation and a strong deformation of the nuclear system. The results from the giant system U + U revealed striking similarities to the ones from Ni + Pb and Xe + Pb , showing that significant time delays still occur in the heaviest accessible systems. The experiments were performed at the velocity filter SHIP at GSI and at the VAMOS spectrometer at GANIL.

Mass and energy distributions of fission-like fragments obtained in the reactions with 26Mg, 36S and 58Fe ions leading to the formation of the Z=108 composite nucleus are reported. From the analysis of TKE distributions for symmetric fragment it was found that at energies below the Coulomb barrier the bimodal fission of 274Hs, formed in the reaction 26Mg+248Cm, is observed, while in the reaction 36S+238U at these energies the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier the fusion-fission is a main process leading to the formation of symmetric fragment for the both reactions.

The energy loss of 132Xe-ions in C, Al, Ni, Ag, Lu, Au, Pb and Th foils was measured in the energy range from 0.1 to 5 MeV/u using the TOF-E method. The results are compared with previously published data and with the predictions of several computer codes. They include theoretical codes: PASS, CASP, semi-empirical programs: SRIM, LET and the Hubert table predictions.

Mass and energy distributions of binary fragments are discussed for a wide range of nuclei with Z = 82–122 produced in reactions induced by 12 C , 16 O , 26 Mg , 48 Ca , 50 Ti , 58 Fe , 64 Ni and 86 Kr ions at energies close and below the Coulomb barrier. It is found that clustering phenomena have a great influence on the formation of the reaction products for fusion-fission and quasifission processes.