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In the framework of multi-fragmentation experiments the evolution towards two- (or more) particle correlations with stable and radioactive beams calls for the development of a novel detection system featuring high angular and energy resolution and able to reconstruct the particles momentum at high precision. The proposed detection system, named FARCOS (Femtoscopy ARray for COrrelations and Spectroscopy) will be beneficial for different physical cases. To this aim we are building a prototype detection system featuring four telescopes. Each telescope features an active area of 6.4 cm × 6.4 cm and is composed of three detection stages. The first ΔE stage is a Double Sided Silicon Strip Detector (DSSSD), 300 μm thick, featuring 32 × 32 strips. The second ΔE stage is again a DSSSD, 1500 μm thick, featuring 32 × 32 strips. The third stage, acting as calorimeter, is composed by four CsI(Tl) crystals with an active area of 3.2 cm × 3.2 cm and an absorption length of 6 cm forming a 2 × 2 matrix. The scintillators are readout by a Silicon photodiode 300 μm thick. The paper presents the relevant features of FARCOS and the expected performance of the silicon detection layers, with a special focus on the requirements of the frontend electronics for the DSSSD and the qualification of the DSSSD. In addition we report the first results of the preliminary on-beam tests. © 2012 IEEE.

We present the current status of nuclear dynamics studies performed by the BREAKUP group with the 4π CHIMERA array, for the system 197 Au + 197 Au at 23 AMeV.

Heavy ion reactions induced by few tens MeV/nucleon beams constitute an ideal framework for producing and studying nuclear excited states close to the decay threshold. The fragmentation of quasi-projectiles from the nuclear reaction 40Ca+12C at 25 MeV/nucleon performed at LNS-Catania was employed in order to populate the Hoyle state of 12C and investigate the theoretically predicted molecular structures. Complete kinematic characterization of individual decay events, made possible by the CHIMERA high-granularity 4π charged particle multi-detector, reveals that 7.5±4.0% of the particle decays of the Hoyle state correspond to direct decays in three equal-energy α-particles and thus fulfill the decay criteria of an α-particle condensate. Moreover, events with increased kinetic energy dispersion in the 12C center of mass, which amount to 9.5±4.0%, point toward the occurrence of a second competing molecular configuration, a linear α-chain type. Both α-particle condensate and linear chain structures have been theoretically predicted but, to our knowledge, not experimentally confirmed so far.

Gli Schwannomi costituiscono il 6,8% dei tumori intracranici ed originano solitamente dai nervi sensitivi, con particolare predilezione per il V e VIII nervo cranico. Uno schwannoma a partenza da un nervo oculomotore costituisce invece una evenienza piuttosto rara, e solo 17 casi di s. del III n.c. sono stati documentati in letteratura. Sono da considerare ancora più rari gli schwannomi ad esclusiva localizzazione intraorbitaria (1–5, 7% dei tumori orbitari). Solitamente tipico dell'uomo adulto, con l'eccezione dei soggetti affetti da Neurofibromatosi di tipo 2, lo schwannoma orbitario esordisce solitamente come un processo espansivo a lento accrescimento, determinante diplopia, esoftalmo ed una tumefazione palpabile ma comprimibile, affiorante a volte al di sotto del velo palpebrale. Gli autori descrivono un caso di schwannoma intraorbitario studiato mediante unità RM operante a medio campo ed analizzano retrospettivamente la letteratura esistente sull'argomento.

Fusion and transfer $+$ breakup channels have been studied in the collision induced by the two-neutron-halo ${}^{6}$He on a ${}^{64}$Zn target at energies from below to above the Coulomb barrier. For comparison, the reaction induced by the stable isotope ${}^{4}$He on the same target has been studied. The fusion cross section has been measured by using an activation technique, detecting off-line the delayed x-ray activity following the electron capture decay of the evaporation residues. New measurements of the ${}^{4}$He $+$ ${}^{64}$Zn fusion cross section at sub-barrier energies have been performed in order to cover the same energy range of the ${}^{6}$He $+$ ${}^{64}$Zn fusion cross section and to compare the excitation functions for the two systems down to the lowest energy data point measured for ${}^{6}$He. From the new comparison a sub-barrier fusion enhancement has been observed in the ${}^{6}$He case with respect to the ${}^{4}$He one whereas no effect on the ${}^{6}$He fusion cross section has been seen at energies above the barrier. It has been concluded that such enhancement seems to be due to the diffuse halo structure properties of the ${}^{6}$He nucleus. Moreover, the reactions induced by ${}^{6}$He have shown a strong yield of $\ensuremath{\alpha}$ particles coming from direct processes.

The design of modern multi-detector arrays for Intermediate Energy Nuclear Physics experiments has to face the problem of the improvement of the Charge and Mass Identification of Heavy and Light Charged Products. Most of the detector arrays developed for the identification of mass and atomic number of the emitted fragments, use detection units composed by thin silicon detectors and by thick scintillator crystals read-out by photodiodes. The light output of the CsI(TI) crystal can be modeled - at least in a given energy range - with a combination of two exponential functions with different time constants. The possibility of storing the digitized waveforms allows performing further off-line analyses. In the present work we determine - by direct least-square fitting of the base-line subtracted output waveforms - the four-vector defining the light output ( τ ƒ , τ s , h ƒ , h s ). In this way it is possible to provide an experimental determination of the scintillator parameters for a wide energy range and for different particle types. The proposed method has been applied to the waveforms acquired with the CHIMERA 4π detector array during runs at the INFN Laboratori Nazionali del Sud Superconducting Cyclotron in Catania, Italy with different beam/target pairs. In this paper we present the results obtained with a 21.5 MeV/u 20Ne beam bombarding a 12C target.

Even-odd effects in $Z$ and $N$ distributions of light fragments emitted at forward angles in nuclear collisions ${}^{40}$Ca $+$ ${}^{40}$Ca, ${}^{40}$Ca $+$ ${}^{48}$Ca, and ${}^{48}$Ca $+$ ${}^{48}$Ca at 25 MeV/nucleon and identified in charge and mass with the Chimera multidetector have been analyzed. The amplitude of even-odd staggering effects seems to be related to the neutron to proton ratio $N/Z$ of the entrance channels. A qualitative explanation of this effect, taking into account the deexcitation phase of primary excited fragments, is discussed.

Isospin dependence of dynamical and thermodynamical properties observed in reactions 40Ca+ 40,48Ca and 40Ca + 46Ti at 25 MeV/nucleon has been studied. We used the CHIMERA multi-detector array. Strong isospin effects are seen in the isotopic distributions of light nuclei and in the competition between different reaction mechanisms in semi-central collisions. We will show also preliminary results obtained in nuclear collision 48Ca + 48Ca at 25MeV/nucleon, having very high N/Z value in the entrance channel (N/Z = 1. 4). The enhancement of evaporation residue production confirms the strong role played by the N/Z degree of freedom in nuclear dynamics.

An exclusive study of 17F breakup reactions has been performed at the FRIBs facility of the Laboratori Nazionali del Sud in Catania (Italy). The experiment has been performed with the aim of testing the accuracy of the Coulomb‐breakup indirect technique used to infer radiative‐capture cross sections at low energies. This technique has been used in the 7Be(p,γ)8B case, but has never been tested. By measuring the breakup of 17F into 16O+p, and comparing the inferred cross section for 16O(p,γ)17F to direct precise measurements, the influence of E2 transitions and higher‐order effects, that are predicted to be significant in Coulomb‐breakup reactions, can be evaluated. The first results and preliminary model comparison are reported.

We report the results obtained by applying digital pulse shape acquisition and digital signal processing to the signals from CsI(Tl) scintillators read out by photodiodes at high incident energy (400 MeV/u). The digitized signals allows the discrimination of light charged particles by computing the Fast and Slow components and the Rise Time of the output pulses of the CsI(Tl). When the energies of the light charged particles exceed those corresponding to their ranges in CsI(Tl), the points related to the punching-through particles gather in the corresponding scatter plots giving rise to a cusp. The punching-through points are used as energy calibration points for the reaction products stopped in the CsI(Tl). The obtained results suggest that at relativistic beam energies it is possible to perform efficient discrimination in charge and mass of light charged particles by using the energy vs. rise time computation. © 2011 IEEE.

The fragmentation of quasi-projectiles from the nuclear reaction $^{40}$Ca+$^{12}$C at 25 MeV/nucleon was used to produce excited states candidates to $\alpha$-particle condensation. Complete kinematic characterization of individual decay events, made possible by a high-granularity 4$\pi$ charged particle multi-detector, reveals that 7.5$\pm$4.0% of the particle decays of the Hoyle state correspond to direct decays in three equal-energy $\alpha$-particles., Comment: Phys. Lett. B, in press

Non-statistical gamma rays of energy ranging in the interval from 5 MeV to 12 MeV are found to be emitted in coincidence with projectile-like fragments from the quasi-elastic 28 Si + 64 Ni reaction measured at E lab = 143 MeV. Boltzmann-Nordheim- Vlasov calculations are consistent with the hypothesis that they are originated from surface oscillations, of quadrupole or higher multipolarity, of the two colliding nuclei.

Equilibration and equilibration rates have been measured by colliding Sn nuclei with different isospin asymmetries at beam energies of E/A=35 MeV. Using the yields of mirror nuclei of {sup 7}Li and {sup 7}Be, we have studied the diffusion of isospin asymmetry by combining data from asymmetric {sup 112}Sn+{sup 124}Sn and {sup 124}Sn+{sup 112}Sn collisions with those from symmetric {sup 112}Sn+{sup 112}Sn and {sup 124}Sn+{sup 124}Sn collisions. We use these measurements to probe isospin equilibration in central collisions where nucleon-nucleon collisions are strongly blocked by the Pauli exclusion principle. The results are consistent with transport theoretical calculations that predict a degree of transparency in these collisions, but inconsistent with the emission of intermediate mass fragments by a single chemically equilibrated source. Comparisons with quantum molecular dynamics calculations are consistent with results obtained at higher incident energies that provide constraints on the density dependence of the symmetry energy.

An interesting process of violent reseparation of a heavy nuclear system into three or four fragments of comparable size was recently observed in {sup 197}Au+{sup 197}Au collisions at 15 MeV/nucleon. Combined analysis of the binary deep inelastic events and the ternary and quaternary breakup events demonstrates that the newly observed ternary and quaternary reactions belong to the same wide class of deep inelastic collisions as the conventional (binary) damped reactions. It is shown that the ternary and quaternary breakup reactions occur at extremely inelastic collisions corresponding to small impact parameters, while more peripheral collisions lead to well-known binary deep inelastic reactions.

A quantitative comparison is made between the absolute cross sections associated with statistical and dynamical emission of heavy fragments in the {sup 124}Sn+{sup 64}Ni and {sup 112}Sn+{sup 58}Ni collisions experimentally investigated at 35A MeV beam energy using the multidetector CHIMERA. The result shows that the dynamical process is about twice as probable in the neutron-rich {sup 124}Sn+{sup 64}Ni system as in the {sup 112}Sn+{sup 58}Ni neutron-poor one. This unexpected and significant difference indicates that the reaction mechanism is strongly dependent on the entrance-channel isospin (N/Z) content.

We discuss results on the emission of light clusters in nuclear reactions 40 Ca + 40,48 Ca ,46 Ti at 25 MeV/nucleon. They were detected and identified in mass and charge by means of the CHIMERA 4π array. Inclusive emission at forward angles shows that isotopic yields of Li and Be nuclei are related to the N/Z values of entrance channels. Moreover, structure effects and even-odd staggering in charge distributions of intermediate mass fragments emitted at forward angles will be shown. In agreement with previous experimental findings, odd-even effects are clearly visible in N ≈ Z systems, while are less pronounced in the neutron rich collision 40 Ca +48 Ca . These experimental findings are compared to preliminary data obtained in 40 Ca +48 Ca . collision at 25 MeV/nucleon.

Collisions of a very heavy nonfusing nuclear system $^{197}\mathrm{Au}$$+$$^{197}\mathrm{Au}$ were studied at an energy of $15$ MeV/nucleon. An interesting process of violent reseparation of this heavy system into three or four fragments of comparable size was observed. In the case of ternary partitioning, either the projectile-like fragment (PLF) or target-like fragment (TLF) breaks up almost collinearly with the PLF-TLF separation axis. In the case of quaternary reactions, both PLF and TLF were observed breaking up along this direction. By comparison with a dynamical model of deep inelastic collisions it was concluded that the ternary and quaternary reactions occur in semiperipheral collisions, in a range of angular momenta corresponding to about $0.5--0.7$ of the maximum $L$ value for grazing collisions. The time elapsing from the scission of the binary PLF $+$ TLF system to the secondary scission of PLF or TLF was estimated to be of about $70--80$ fm/$c$ for the ternary reactions and $80--100$ fm/$c$ for the quaternary reactions.

New monolithic silicon telescopes act as high performance and versatile devices to detect and identify charged particles. Their features allow their use also as position sensitive detectors.

International audience; The interaction of ion beams with insulators leads to charging-up phenomena, which at present are under investigation in connection with guiding phenomena in nanocapillaries with possible application in nanofocused beams. We studied the charging dynamics of insulating foil targets [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Ag, and Xe at 40, 23, 40, and 30 MeV/u, respectively) via the measurement of the slowing down of fast binary-encounter electrons. Also, sandwich targets (Mylar covered with a thin Au layer on both surfaces) and Mylar with Au on only one surface were used. Fast-electron spectra were measured by the time-of-flight method at the superconducting cyclotron of Laboratori Nazionali del Sud (LNS) Catania. The charge buildup leads to target-material-dependent potentials of the order of 6.0 kV for Mylar and 2.8 kV for PP. The sandwich targets, surprisingly, show the same behavior as the insulating targets, whereas a single Au layer on the electron and ion exit side strongly suppresses the charging phenomenon. The accumulated number of projectiles needed for charging up is inversely proportional to electronic energy loss. Thus, the charging up is directly related to emission of secondary electrons.

Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Results from present work are compared to constraints put forward in other recent analysis., Comment: 8 pages, 4 figures,accepted for publication in Phy. Rev. Lett

Various aspects observed in the reactions 40Ca+40,48 Ca,46Ti at E =25 MeV / nucleon , studied by means of the CHIMERA detector, will be discussed. An isospin effect on the competition between heavy residue production and binary-like channels has been observed in incomplete fusion events. From the thermodynamical point of view, kinetic energy spectra of protons emitted in fusion-evaporation events were fitted with two maxwellian functions. Despite of the different neutron richness of the populated sources, the average temperatures obtained for the quasi-fused systems are similar ( T ≃5.2 MeV ). We also performed a preliminary reconstruction of the excitation energy reached by quasi-fusion sources populated in the studied reactions.

International audience; A quantitative comparison regarding absolute cross sections associated to Statistical and Dynamical Fission processes in the 124Sn+64Ni and 112Sn+58Ni collisions experimentally investigated at 35 AMeV beam energy using multi-detector CHIMERA is presented. It results that Dynamical Fission process is about two times more probable in the neutron rich 124Sn+64Ni system than in the 112Sn+58Ni neutron poor one. The observed difference could indicate an influence of the entrance channel Isospin (N/Z) content on the reaction mechanisms.

40Ca+;{40,48}Ca,46Ti reactions at 25 MeV/nucleon have been studied using the 4pi CHIMERA detector. An isospin effect on the competition between fusionlike and binarylike reaction mechanisms has been observed. The probability of producing a heavy residue is lower in the case of N approximately Z colliding systems as compared to the case of reactions induced on the neutron rich 48Ca target. Predictions based on constrained molecular dynamics II calculations show that the competition between fusionlike and binary reactions in the selected centrality bins can constrain the parametrization of the symmetry energy and its density dependence in the nuclear equation of state.

We show the possibility to use a new kind of monolithic silicon telescope as position sensitive detector.

We investigated the dynamical dipole mode, related with entrance channel charge asymmetry effects, in the 40Ar+92Zr and 36Ar+96Zr fusion reactions at Elab = 15.1 A and 16 A MeV, respectively. These reactions populate, through entrance channels having different charge asymmetries, a compound nucleus in the A = 126 mass energy region, identical spin distribution at an average excitation energy of about 280 MeV. The compound nucleus average excitation energy and average mass were deduced by the analysis of the light charged particle energy spectra. By studying the γ‐ray energy spectra and the γ‐ray angular distributions of the considered reactions, the dynamical nature of the prompt radiation related to the dynamical dipole mode was evidenced. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics.

At LNS are available radioactive beams at tandem and intermediate energies provided respectively by the EXCYT and by the fragmentation FRIBS facilities. Using these beams, and the 4π detector CHIMERA, we want to study excitation and decay of resonances in light exotic nuclei populated with pick‐up stripping and other reaction mechanisms. Some preliminary results obtained with stable and unstable beams are reported.

The excitation functions of dissipative products have been measured in the reaction 27Al+27Al at incident energies from 114 to 127 MeV in steps of 200 keV. Detection angles vary continuously from 10.4° to 57.4° in laboratory system. An angular coherent width more than 40° in center of mass is obtained. The results from the analysis of excitation functions with nonself-averaging are characterized by a quasi-periodic long-range energy structure embedded in the disorder Ericson fluctuation.

A new reaction mechanism of violent reseparation of a heavy nucleus-nucleus system, {sup 197}Au+{sup 197}Au, into three or four massive fragments in collisions at 15 MeV/nucleon has been observed. After reseparation, the fragments are almost exactly aligned, thus showing a very short time scale of the reseparation process, of about 70-80 fm/c.

Two-proton decay from (18)Ne excited states has been studied by complete kinematical reconstruction of the decay products. The (18)Ne nucleus has been produced as a radioactive beam by (20)Ne primary projectile fragmentation at 45 AMeV incident energy on a Be target. The (18)Ne at 33 AMeV incident energy has been excited via Coulomb excitation on a (nat)Pb target. The obtained results unambiguously show that the 6.15 MeV (18)Ne state two-proton decay proceeds through a (2)He diproton resonance (31%) and democratic or virtual sequential decay (69%). The quoted branching ratio has been deduced from relative angle and momentum correlations of the emitted proton pairs.

Signatures of isospin effects were investigated for neutron-rich ({sup 124}Sn+{sup 64}Ni) and neutron-poor ({sup 112}Sn+{sup 58}Ni) systems at 35 MeV/nucleon for noncentral collisions. The centrality dependence of these signatures was tested for several impact parameter estimators. Our main observations are (i) the yields of {sup 1}H and {sup 3}He particles in the neutron-poor system are strongly enhanced with respect to the neutron-rich system, and the yields of {sup 3}H, {sup 6}He, and {sup 7,8}Li are suppressed at all impact parameters, (ii) the yields of {sup 2}H, {sup 4}He, and {sup 6}Li particles are almost the same for both systems, (iii) the N/Z ratio of intermediate mass fragments is correlated with the neutron richness of the system and is weakly dependent on the centrality of the collision, and (iv) the neutron richness of the detected fragments increases strongly with decreasing rapidity in the range from that of the projectile-like fragment to the c.m. region. The gross features of experimental data are reproduced by quantum molecular dynamics model calculations. A comparison between model calculations and the data indicates that the fragments produced in the c.m. regions are weakly excited.

CHIMERA is the only 4 pi-multidetector, used in intermediate nuclear physics experiments, able to perform mass identification of the reaction products. To this purpose, it employs time of flight measurements done with traditional time to digital converters. In order to improve the resolution in mass identification, we have applied digital signal processing to time of flight measurements. This paper presents the methodology for data analysis, the adopted algorithms and the results obtained at different sampling frequencies (mass identification up to A = 33 for the reaction products produced by a 20.5 MeV/u 20Ne beam on 27Al target).

In order to simplify the electronic chain with respect to the traditional one, we decided to apply Digital Pulse Shape Acquisition (DPSA) to collect signals from the ΔE and E stages of a monolithic silicon detector telescope, directly from the preamplifier. The collected pulse shapes are digitally processed in order to obtain the physical observables. To verify the device capability of position measurement we have bombarded the 16 strips in different points along the vertical position as well as in some points from the centre of the strip. The position information has been deduced from the signal induced on different strips by the charge collected in the E stage of the telescope. In order to explain the behavior of the induction signals, a basic model of charge generation in the monolithic telescope and of the induction for different irradiation is presented.

Two‐proton radioactivity studies have been performed on excited states of 18Ne produced by 20Ne fragmentation at the FRIBS facility of the Laboratori Nazionali del Sud and excited via Coulomb excitation on a 209Pb target. Decay of 18Ne levels has been studied by complete kinematical reconstruction. Present results shows unambiguously that the 6.15 MeV 18Ne state two‐proton decay proceeds through a true 2He resonance (diproton).

The prompt γ-ray emission is investigated in the 16 A MeV energy region by means of the 36,40Ar + 96,92Zr fusion reactions leading to a compound nucleus in the vicinity of 132Ce. The dynamical nature of this radiation is confirmed. We show that the prompt γ radiation has an angular distribution pattern consistent with a dipole oscillation along the symmetry axis of the dinuclear system. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics.

Coherence energies extracted from excitation functions and angular distributions for the fragments emitted in the19F+63Cu reaction, measured in the range θlab=10° to 120° at incident energies between 100 to 108 MeV (lab.), were compared to the Kun model of dissipative collisions. An overall agreement was found for the angular distributions at forward angles. The general behavior of coherence energies was also properly described and interaction times were deduced.

Elastic scattering angular distributions of $^{32,36}\mathrm{S}$ (beams)${+}^{58.64}$Ni have been measured at several energies around the Coulomb barrier. An optical-model analysis of the data reveals remarkable energy dependences of the potentials at the strong absorption radii, in all cases. The largest effects are observed for $^{32}\mathrm{r}$/rS${+}^{64}$Ni. This is due to the coupled reaction channels which also strongly influence the sub-barrier fusion cross sections. Coupled-channels calculations of elastic scattering and fusion have been performed, including the inelastic excitations of projectile and target; the need for considering additional (transfer) channels is made evident. We also have indications that sub-barrier fusion is not merely tunneling through a potential barrier, although energy dependent, as absorption into fusion takes place at larger internuclear distances. Older fusion and quasielastic transfer data are overviewed and compared with the reaction cross sections extracted from elastic scattering. Open questions still remain about the role of specific channels in determining the observed isotopic differences.

Two-proton decay from (18)Ne excited states has been studied by complete kinematical reconstruction of the decay products. The (18)Ne nucleus has been produced as a radioactive beam by (20)Ne primary projectile fragmentation at 45 AMeV incident energy on a Be target. The (18)Ne at 33 AMeV incident energy has been excited via Coulomb excitation on a (nat)Pb target. The obtained results unambiguously show that the 6.15 MeV (18)Ne state two-proton decay proceeds through a (2)He diproton resonance (31%) and democratic or virtual sequential decay (69%). The quoted branching ratio has been deduced from relative angle and momentum correlations of the emitted proton pairs.

Collisions of a very heavy nuclear system, 197 Au + 197 Au , were studied at the energy of 15 MeV/nucleon with the aim to identify and investigate main macroscopic modes of re-separation of such a heavy nuclear system. The experiment was performed at the INFN LNS laboratory in Catania by using the multidetector array CHIMERA. Along with binary strongly damped collisions, a strong component of a new re-separation mode: the "fast ternary fission" in characteristic nearly co-linear configuration was observed and the time scale of this process was determined.

Multi-breakup processes for the {sup 124}Sn+{sup 64}Ni system at 35 MeV/nucleon have been studied with the forward part of the CHIMERA detector. An extensive comparison between experimental data corresponding to almost complete ternary events and constrained molecular dynamics (CoMD-II) calculations suggests different characteristic times in the selected processes. This is in agreement with previous studies of the same reaction already published concerning the prompt intermediate-mass-fragment emission. Stimulated by CoMD-II calculations, we investigate the existence of more complex dynamical multi-breakup processes occurring on the same time scale. A detailed study of the rotational dynamics leading to slower dynamical fission processes is also presented.

Radioactive Ion Beams (RIBs) are produced In‐Flight at the Laboratori Nazionali del Sud (LNS) by projectile fragmentation on light targets at intermediate energies. RIBs rates up to 105 ions/sec have been measured and about 95% of secondary beam has been transported up to one of the experimental caves. The ΔE‐ToF identification method was successfully applied to tag, event‐by‐event, the RIBs before the interaction with a secondary reaction target.

The digital pulse shape data acquisition (DAQ) system used by the large area telescopes of the 4pi-multidetector CHIMERA requires transferring large amount of data to the computer. This is necessary so that the same information can be extracted from the detector pulses as in previous analog based systems. To overcome this problem, we have used a sampling ADC-board equipped with two TigerSHARC digital signal processors. The board receives the data and reconstructs the event parameters online. The data volume is significantly reduced by transmitting to the DAQ only the reconstructed event parameters

We present some preliminary results of the two proton decay of 18Ne excited levels. The cross section for Coulomb excitation and the yield ratio of the 1p and 2p decay channels are reported. The CM proton spectra of the 2p decay channel are also shown.

Ternary events originating from the 197 Au + 197 Au reaction at 15 MeV/nucleon, studied by using the multidetector array CHIMERA at LNS Catania, have been collected in almost complete 2π range of the forward hemisphere of CHIMERA thus extending the angular range of our previously reported preliminary data. Energy- and time calibrations for heavy fragments at large angles were supplemented with an analysis of coincidence events of binary strongly damped reactions. Contrary to the previous preliminary results, the new complete data clearly show presence of sequential fission processes in which one of Au -like nuclei undergoes fission after re-separation of the primary binary system. Mechanism of these two types of reactions observed in our data, sequential fission reactions and prompt ternary processes, are presently studied using comparisons with predictions of the stochastic BNV model of Baran, Colonna and Di Toro and the QMD model of Łukasik.

T. Cap1∗, K. Siwek-Wilczynska1, I. Skwira-Chalot1, J. Wilczynski2, F. Amorini3,4, L. Auditore5, G. Cardella6, E. De Filippo6, E. Geraci4,6, L. Grassi4,6, A. Grzeszczuk7, E. La Guidara8, J. Han3, T. Kozik9, G. Lanzalone3,10, I. Lombardo11, R. Najman9, N. G. Nicolis12, A. Pagano6, M. Papa6, E. Piasecki2,13, S. Pirrone6, R. P laneta9, G. Politi4,6, F. Rizzo3,4, P. Russotto3,4, A. Trifiro5, M. Trimarchi5, G. Verde6 and W. Zipper7

The systems 124 Sn+64 Ni and 112 Sn+58 Ni at 35 AMeV were analyzed in previous experiments, by using the 4π multi-detector CHIMERA in order to investigate the time-scale and mechanisms of fragments formation. By comparing the two systems, effects that have been correlated to Isospin transport in reaction dynamics and symmetry energy term of nuclear equation of state at sub-saturation density were found. Recently, in order to disentangle the Isospin effects from size effects the 124 Xe+64 Ni reaction was investigated at the same beam energy of 35 AMeV.

As a result of a collaboration between SGS-Thomson and INFN, a Monolithic Silicon Detector Telescope with *E/E of 4] 4m m 2with an ultra-thin *E stage (1 lm) has been recently presented as a tool to identify low-energy heavy ions. The good performances obtained in the charge identification are anyway limited by the relatively small active area. We report on two new larger area *E/E telescopes. The first one, a five strip detector with each *E strip 3] 4m m 2and a common E stage, has given on-beam good results. The second one, a 20]20 mm2 active area, is under test and is limited by the high capacitance of the *E stage (40 nF) requiring a suitable front-end electronics, presented in a di⁄erent communication. ( 1998 Elsevier Science B.V. All rights reserved.