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We analyzed the $^{93}Nb$ on $^{nat}Mg$ reaction at 30 MeV/nucleon in the aim of disentangling binary sequential decay and multifragmentation decay close to the energy threshold, i.e. $\simeq 3$ MeV/nucleon. Using the backtracing technique applied to the statistical models GEMINI and SMM we reconstruct simulated charge, mass and excitation energy distributions and compare them to the experimental ones. We show that data are better described by SMM than by GEMINI in agreement with the fact that multifragmentation is responsible for fragment production at excitation energies around 3 MeV/nucleon., 16 pages, 12 figures, 5 tables Soumis \`a Nuclear Physics A

The 121 Sb(p,t) 119 Sb reaction has been measured in a high-resolution experiment at an incident energy of 21 MeV. Accurate measurement of the (p,t) reaction angular distributions for the transitions to the levels of 119 Sb allows us to determine energies of 59 levels, 23 of which have been identified for the first time, and to assign the angular momentum transfer values and a welldefined range for the J values. DWBA analysis has been performed in a finite-range approximation, assuming a dineutron cluster pickup mechanism, by using conventional Woods–Saxon potentials for the entrance proton and exit triton channel. The present (p,t) data have been supplemented by microscopic calculations in the framework of the quasiparticle–phonon model, giving a reasonably good description of the experimental fragmentation of the integrated cross sections and the absence of (p,t) strength above 2.9 MeV.

The 91 Zr(p, t) 89 Zr reaction has been studied in a high-resolution experiment at an incident proton energy of 25 MeV. Angular distributions for transitions to 44 levels of 89 Zr up to an excitation energy of ∼ 3.650 MeV have been measured. DWBA analysis, with conventional Woods–Saxon potentials, allowed the assignment of the transferred angular momenta L . The energy spectrum of 89 Zr has been studied in the framework of the shell model, using the large-basis shell-model code OXBASH. The structure of both positive- and negative-parity states of 89 Zr has been investigated using the PMM90pn residual interaction, and discussed in comparison with the experimental findings from the 91 Zr(p, t) 89 Zr reaction.

Biological vision processes are at the basis of many studies in the image-processing field. In this context, neural networks developed by S. Grossberg constitute an interesting approach. The paper presents a novel method for the automatic analysis of scatter plots from CHIMERA experimental data based on Grossberg's pre-attentive neural systems. The design and implementation of a system developed for this purpose are illustrated. The proposed method yields satisfactory results also in very noisy cases.

The on-line computation of special algorithms, such as those required for controlling multidetectors in heavy-ion nuclear physics experiments, is a fundamental problem. It requires real-time computational resources capable of satisfying the associated time constraints. The work presented describes general considerations on real-time architectures, and tests performed employing, as a benchmark, the computation of a power law, used for particle identification in nuclear physics experiments.

The (p,α) reaction on 90Zr has been studied in a high resolution experiment at an incident proton energy of 22 MeV. The cross section and asymmetry angular distributions for transitions to 36 levels of 87Y with an excitation energy up to 3 MeV have been measured. DWBA analyses of experimental angular distributions, using either Woods-Saxon or Double Folded potentials for the exit channel, have been done, allowing either the confirmation of previous spin and parity values or the assignment of new spin and parity to a large number of states. The structure of low lying states of 87Y has been studied in the framework of the shell model, using the OXBASH code. With the interaction PMM90 reasonable agreement is obtained for part of the negative parity spectrum.

The computation complexity of a large number of applications, makes useful the development of new design strategies both in the direction of correctness and reduction of computational time and size of the used devices. Since a large part of numerical algorithms involves the computation of polynomial expansions in terms of sum and products of floating point numbers, a way for reducing both dimension and execution time of the devices, is to adapt the elementary operators and the number of terms of the polynomial expansion to the very computational needs. In this work a design method consisting in using an ad hoc designed set of Elementary Floating Point Operators parametrically defined is presented. Moreover, we discuss the mantissa size influence on real-time computation of numerical algorithms, in order to state the truncation limit for which the correctness constraints are anyhow saved for different applications in order to allow a more reliable choice of the hardware, and to limit also the general costs.

The structure of both low-lying and highly excited states and electromagnetic transitions in ${}^{206}\mathrm{Pb}$ and ${}^{205}\mathrm{Tl}$ has been studied within the framework of the shell model. The calculation predicts the occurrence of states in ${}^{206}\mathrm{Pb}$ with a structure homologous to parent states in ${}^{205}\mathrm{Tl},$ a phenomenon experimentally reported in these systems via $(p\ensuremath{\rightarrow},\ensuremath{\alpha})$ reactions, in analogy with other regions of the mass table. This feature is not restricted to configurations where the two neutron holes are coupled to angular momentum zero, but also applies to higher configurations corresponding to angular momentum recoupling of the two neutron holes. The calculated results, obtained with both a modified surface delta interaction and Kuo-Herling interaction, are in good agreement with the experimental data, further supporting the ability of these interactions to describe nuclear properties in the lead region.

The91Zr(\(z\bar p\),α)88Y reaction has been studied at incident energy of 22 MeV using a polarized proton source and a Q3D spectrometer. The differential cross sections and asymmetries for transitions to levels of88Y homologous to the lowest excitation energy states of87Y have been measured and interpreted both in terms of the experimental differential cross sections and asymmetries of the parent87Y states and by means of the finite-range distorted wave Born approximation theory using conventional Woods-Saxonα-particle potential. The advantage of the concept of homology consists in having to deal with a uniquel-transfer, that given by the transition to the corresponding parent state. In order to validate the concept of homology as a spectroscopic tool to identify spin, parity and dominant configuration of highly excited states in (\(z\bar p\),α) reaction on odd mass target nuclei, shell model calculations have been performed. Several new attributions of spin and parity for88Y residual nucleus are proposed.

The ${}^{114}$Sn($p$,$t$)${}^{112}$Sn reaction has been investigated in a high resolution experiment at incident proton energy of 22 MeV. Angular distributions for 28 transitions to levels of ${}^{112}$Sn up to the excitation energy of 3.624 MeV have been measured. The spin and parity identification has been carried out by means of a distorted-wave Born approximation (DWBA) analysis, performed by using conventional Woods-Saxon potentials. A shell-model study of ${}^{112}$Sn nucleus has been performed using a realistic two-body effective interaction derived from the CD-Bonn nucleon-nucleon potential. The energy spectra have been calculated and compared with the experimental ones, while the theoretical two-nucleon spectroscopic amplitudes, evaluated in a truncated seniority space, have been used in the microscopic DWBA calculation of the cross-section angular distributions.

We show new data from the $^{64}$Ni+$^{124}$Sn and $^{58}$Ni+$^{112}$Sn reactions studied in direct kinematics with the CHIMERA detector at INFN-LNS and compared with the reverse kinematics reactions at the same incident beam energy (35 A MeV). Analyzing the data with the method of relative velocity correlations, fragments coming from statistical decay of an excited projectile-like (PLF) or target-like (TLF) fragments are discriminated from the ones coming from dynamical emission in the early stages of the reaction. By comparing data of the reverse kinematics experiment with a stochastic mean field (SMF) + GEMINI calculations our results show that observables from neck fragmentation mechanism add valuable constraints on the density dependence of symmetry energy. An indication is found for a moderately stiff symmetry energy potential term of EOS., Comment: Talk given by E. De Filippo at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS)

This paper is an extension of a previous study of the [sup 206]Pb nucleus in the framework of the homology concept. It is concerned with the multiplet of states homologous to the 1.484 MeV, 11/2[sup [minus]] level of [sup 205]Tl, due to [vert bar]9/2[sup [minus]][direct product] 11 / 2 [sup [minus]][r angle] coupling. The results obtained and the new assignments attributed to [sup 206]Pb confirm the importance of the homology concept in the spectroscopy of high excitation energy levels.

A facility of the Italian Laboratorio Nazionale del Sud , used for systematic investigation of heavy ion reactions with activation techniques since October 1991, is described.

The 40Ca(6Li, d)44Ti reaction at the 60.1 MeV incident energy is measured using the Q3D spectrometer. The angular distributions of 30 levels from 4° to 42° and in the excitation energy range up to 9.5 MeV are obtained. The angular distributions are analyzed using the breakup-fusion model.

A computer aided vacuum chamber for the automatic determination of thickness and uniformity of up to 44 thin films (on a frame of 50 × 50 mm 2 ) using the energy loss method is described.

The [sup 209]Bi([ital [rvec p]],[alpha])[sup 206]Pb reaction has been studied at an incident proton energy of 22 MeV using a polarized proton source and a quadrupole-dipole-dipole-dipole spectrometer. The differential cross sections and asymmetries for transitions to levels of [sup 206]Pb up to an excitation energy of 5.333 MeV have been measured. Evidence for the presence of multiplets of [sup 206]Pb states homologous to the parent [sup 205]Tl states is discussed. The differential cross sections and asymmetries for the transitions to these homologous states are interpreted in terms of the experimental differential cross sections and asymmetries of the parent states as well as by theoretical calculations using both conventional Woods-Saxon and double-folded [alpha]-particle potentials. The differential cross sections and asymmetries for the low-energy states of [sup 206]Pb which involve the pickup of the [ital h][sub 9/2] proton outside the closed shell are analyzed.

An analog-to-digital fast readout, using a 8-bit flash ADC, for dc-coupled microstrip detectors, has been developed with automatic pedestal and offset subtraction. The system (readout+detector) was preliminary tested with special pulsers, beta-sources and, at the end, in a minimum ionizing particle beam. The performance and the experimental results obtained are similar to conventional systems employing larger dynamic ADCs.

This analog unit is designed to be used with multiparametric data acquisition systems, and in general with usual MCAs, to reduce the number of ADCs needed and to compact electronic chains. Its main characteristic consists of the capability to accept coincident events.

The (p\ensuremath{\rightarrow},\ensuremath{\alpha}) reaction on $^{208}\mathrm{Pb}$ has been studied at an incident proton energy of 22 MeV using a polarized proton source and a spectrometer. The angular distributions and the asymmetries for transitions to levels of $^{205}\mathrm{Tl}$ up to an excitation energy of 3 MeV have been measured. The analysis of these data by means of the finite-range distorted-wave Born approximation theory using either conventional Woods-Saxon and double-folded \ensuremath{\alpha}-particle potentials has allowed us to make several new attributions of spin and parity.

Cross-section angular distributions of 38 ($p$, $t$) transitions to final states of $^{118}\mathrm{Sn}$ up to an excitation energy of 3.597 MeV have been measured in a high-resolution experiment at an incident proton energy of 21 MeV. A distorted-wave Born approximation (DWBA) analysis of the 38 experimental differential cross sections, carried out by using conventional Woods-Saxon potentials, allowed us either 18 confirmations of previous spin and parity values or new assignments of spin and parity to 14 states of $^{118}\mathrm{Sn}$. A shell-model calculation has been performed by using a realistic two-body effective interaction derived from the CD-Bonn nucleon-nucleon potential. The doubly-magic nucleus $^{132}\mathrm{Sn}$ is assumed as a closed core, with 14 valence neutron holes occupying the five levels of the 50--82 shell. Within this model space the calculations are performed by employing the seniority scheme including states with seniority up to 4. The energy spectrum of $^{118}\mathrm{Sn}$ has been calculated and compared with the experimental one. The theoretical two-neutron spectroscopic amplitudes are used in the microscopic DWBA calculations of some cross-section angular distributions.

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.

The capability of digital pulse shape technique to acquire data from CHIMERA detection cells (Si-CsI(Tl) telescopes) has been evidenced in our previous works. We have now applied this technique to the charge discrimination of the products stopped in the silicon detectors. Large area totally depleted CHIMERA planar silicon detectors (5 cmtimes5 cm area, 300 mum thick) in both rear and front side injection have been used. In preliminary tests full charge identification for the reaction products up to Z=11 have been obtained for products both crossing (DeltaE-E technique) and stopping in the silicon detector, using a 21 MeV/u 20Ne beam at the LNS Superconducting Cyclotron in Catania. The quality of the obtained results clearly indicates that the digital signal processing approach is able to give excellent results in this application, too

Isotopic identification of nuclear products in heavy-ion physics with stable and exotic beams (RIB) is of crucial importance for understanding the behaviour of nuclear matter far away from normal density. This is true for both nuclear structure and nuclear reaction studies. The recent upgrading of the 4pi CHIMERA detector by pulse shape methods in silicon detectors in connection with the time of flight (TOF) and the energy loss (DE-E) methods allows for light charged particles and light fragments (Z < 10) identification in a broad kinetic energy range from the Coulomb barrier up to tens of MeV/nucleons. After a brief discussion of the experimental methodology used in the detector to identify the particles some relevant applications in the field of nuclear reaction studies with stable and exotic beams.

(p,α) reactions on near magic nuclei was used to assign unambiguously spin and parity to higher excited states using the homology concept, in the regions A∼208 and A∼90. Here some preliminary results, both experimental and theoretical for the 122Sn(p,α)119In reaction are presented.

Angular distributions of tritons from the ${}^{123}\mathrm{Sb}{(p,t)}^{121}\mathrm{Sb}$ reaction induced by 26 MeV protons have been measured up to an excitation energy of about 3 MeV using a Q3D spectrometer. Many previously unknown levels of ${}^{121}\mathrm{Sb}$ have been observed. Microscopic calculations of the ${}^{123}\mathrm{Sb}{(p,t)}^{121}\mathrm{Sb}$ reaction cross sections, using the quasiparticle-phonon model, give a reasonably good description of the fragmentation of the (p,t) cross sections and the lack of (p,t) strength above 2.7 MeV of excitation energy. The experimental results from the ${}^{122}\mathrm{Sn}{(p,t)}^{120}\mathrm{Sn}$ reaction have been used to discuss the role of the unpaired quasiparticle in ${}^{121}\mathrm{Sb}$ in determining the properties of its levels.

Plasma effects for heavy ions in implanted silicon detectors have been investigated for different detector characteristics as a function of type and energy of the detected particles. A new approach is presented and used to reproduce the effect of the plasma delay in the timing performances. The results are in good agreement with the present data and with previous measurements found in the literature.

Prototypes of new passivated implanted planar silicon detectors, obtained for the first time from 6 in. silicon slices, have been tested. The time and energy resolutions have been studied as a function of the type and energy of the detected particles, in order to test the performances of these detectors for time of flight measurements in the Chimera project. Some problems arising from edge effects observed in double-pad detectors have been solved by using a guard ring.

The light response of large CsI(TI) crystals supplied by various companies and coupled to photodiodes has been investigated. Energy resolution measurements and Z = 1 isotopic identification using the two gates method have been performed with in-beam experiments.

This paper presents the first evaluation prototype of an advanced application of microprogrammed hierarchical architecture to solve a typical problem arising in nuclear electronics: the on line processing of data acquired in digital form by an electronic chain of detectors used in nuclear experiments.

The present paper describes a two-module analog device for particle identification and spectra acquisition, using the power law technique with a counter telescope.

This paper describes a new kind of pulse generator, able to provide not only two pairs of coincident pulses, with continuously variable amplitude (0–5 V) for each pulse and delay (40–150 μs) between the two pairs — energy simulation — but also the corresponding timing signals — time of flight simulation — with different intrinsic variable delays ranging from 50 ps up to 128 ns, in steps of 50 ps, with a proper time resolution better than 15 ps. Some experimental results, obtained using the present device, are also reported.

This paper presents an unusual approach to the testing of digital devices. In order to test real time systems, we have designed, built, and used a digital generator able to send 2047 quadruples of 12-bit words, with a frequency range of up to 0.7 MHz.

This paper discusses the simulation of analog signals from a nuclear radiation detector telescope. This goal is reached by means of a generator that reads 39 pairs of digital data punched on a paper tape and presents, as output, the corresponding analog pulses at a frequency variable up to 60 kHz.

Calculations, in the framework of the exciton model, of angle-integrated energy distributions and angular distributions of alpha particles emitted in (nucleon, α) reactions are presented. The reaction mechanism is assumed to be a knock-on process involving α particles pre-formed in the target nucleus. The results obtained indicate that a satisfactory reproduction of the (nucleon, α) process is achieved. The main contribution to the process derives from interactions involving pre-formed α particles of energy comparable with the Fermi one.

The excitation functions of the reactions 169 Tm, 181 Ta and 209 Bi (p, x n) for x = 3, 4 have been measured at proton energies from 20 to 45 MeV. The experimental curves are analysed in terms of a sum of statistical and pre-compound contributions, the last one evaluated according to the model proposed by Griffin and Blann. The cross section for pre-compound neutron and proton emission appears to constitute a relevant portion of the total reaction cross section σ R in all the energy interval examined. Correspondingly, the fraction of σ R accounted for by the compound nucleus formation cross section is found to be as low as some 30 % for 30 ⪅ E p ⪅ 40 MeV.