N and Z odd-even staggering in Kr + Sn collisions at Fermi energies

The odd-even staggering of the yield of final reaction products has been studied as a function of proton (Z) and neutron (N) numbers for the collisions 84 Kr+112 Sn and 84 Kr+124 Sn at 35 MeV/nucleon, in a wide range of elements (up to Z ~ 20). The experimental data show that staggering effects rapidly decrease with increasing size of the fragments. Moreover the staggering in N is definitely larger than the one in Z. Similar general features are qualitatively reproduced by the GEMINI code. Concerning the comparison of the two systems, the staggering in N is in general rather similar, being slightly larger only for the lightest fragments produced in the n-rich system. In contrast the staggering in Z, although smaller than that in N, is sizably larger for the n-poor system with respect to the n-rich one.Comment: 6 pages, 5 figures, Revtex forma

Isospin transport in ^{84}Kr + ^{112,124}Sn reactions at Fermi energies : first physics results from FAZIA

The FAZIA Collaboration studied collisions of a ^{84}Kr beam at 35 AMeV with ^{112}Sn and ^{124}Sn targets by means of a three-layer telescope. A good isotopic resolution up to Z = 20 was reached. The isotopic content of the products was found to depend on the neutron richness of the target, which is an evidence of isospin diffusion. Neutron-rich light fragments emitted from the phase space close to the centre-of-mass were observed, which can be interpreted as an effect of isospin drift in the neck region of low density

From light to heavy nuclear systems, production and decay of fragments studied with powerful arrays

Reactions between heavy-ions at various energy regimes produce many nuclear fragments which can be populated in highly excited states. The study of these fragments, detected at the end of their particle decay, is important to investigate nuclear forces and structure effects. In recent years there have been many efforts to extend these studies towards the drip-lines, i.e. to systems far from the β-stability valley, by using accelerated radioactive beams. The development of such infrastructures is accompanied by the development of more powerful detectors and associated electronics, capable to identify ions with very different sizes and kinetic energies. Here we give two examples which show how advanced arrays can contribute to the studies on nuclear phenomena. The examples come from the European FAZIA collaboration and from recent campaigns with the GARFIELD apparatus, the latter in operation at the INFN Legnaro Laboratory (Italy) where the SPES RIB facility is under construction

Synthesis of estimators for objects with a serial structure

Artykuł dotyczy zdecentralizowanego podejścia do syntezy estymacji stanu obiektu złożonego poprzez rozdzielenie problemu optymalizacyjnego na podproblemy o mniejszej wymiarowości. Główna idea metody polega na przyporządkowaniu podobiektom indywidualnych wskaźników jakości i prowadzeniu syntezy estymatorów w sposób sekwencyjny. Wzmocnienia filtru złożonego wyznacza się rozwiązując problemy małej wymiarowości (wymiarowość podobiektów). Uzyskuje się strukturę odpowiadającą lokalnemu, klasycznemu filtrowi Kalmana oraz sprzężeń skrośnych.The paper concerns the presentation of a certain approach, in which decentralization of calculations associated with the synthesis of object state estimation is presented. It is realized by dividing the optimization problem into sub-problems of smaller dimensionality. For this purpose, a differential Nash game for objects with a serial structure was utilized. The main idea of the method is to assign individual quality indicators to each sub-object and to carry out the synthesis of estimators in a sequential manner, starting with the last sub-object. Implementation of the estimation process requires knowledge about the measurements of the individual sub-objects. Parameters of local controllers are calculated based on the individual Riccati equations for sub-objects. Strengthening cross-linkage connections was established based on the solutions of certain bilinear equations. The presented method leads to a structure that fits the local classical Kalman filter and cross-coupling

The european FAZIA initiative: a high-performance digital telescope array for heavy-ion studies

The european Fazia collaboration aims at building a new modular array for charged product identification to be employed for heavy-ion studies. The elementary module of the array is a Silicon-Silicon-CsI telescope, optimized for ion identification including pulse shape analysis, too. The achievement of top performances imposes specific electronics which has been developed by the FAZIA collaboration and includes high quality charge and current preamplifiers, coupled to fully digital front-end. During the initial R&D phase, original and novel solutions have been tested in prototypes, obtaining unprecedented ion identification capabilities. FAZIA is now constructing a demonstrator array consisting of about two hundreds telescopes arranged in a compact and transportable configuration. In this contribution, we mainly summarize some aspects studied by FAZIA to improve the ion identification. Then we will briefly discuss the FAZIA program focused on experiments to be done with the demonstrator. First results on the isospin dynamics obtained with a reduced set-up demonstrate well the performance of the telescope and represent a good starting point towards future investigations with both stable and exotic beams

Extracting information from partially depleted Si detectors with digital sampling electronics

A study of the identification properties and of the energy response of a Si-Si-CsI(Tl) ΔE-E telescope exploiting a partially depleted second Si stage has been performed. Five different bias voltages have been applied to the second stage of the telescope, one corresponding to full depletion, the others associated with a depleted layer ranging from 60% to 90% of the detector thickness. Fragment identification has been obtained using either the ΔE-E technique or the Pulse Shape Analysis (PSA). Charge collection efficiency has been evaluated. The ΔE-E performance is not affected by incomplete depletion. Isotopic separation capability improves at lower bias voltages with respect to full depletion, though charge identification thresholds increase