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With the use of the results from the previous paper1 and from the papers of the other authors it has been ascertained that in some solid solutions with fcc lattice the self-diffusion frequency factorD oAB A and activation enthalpy ΔH AB A of the element A in the alloy A-B are given by the equations , whereK 0,K 1 are constants,T m andT m A are melting points of the alloy or of element A respectively,X B is the atomic percent of element B,D o A A and ΔH A A are diffusion characteristics of the pure element A. For the frequency factor of regular or nearly regular solid solutions with fcc lattice that present a mutual solubility and for which the diffusion data for the whole concentration interval are available, the following relation has been found For the activation enthalpy of these solutions the equation $$\Delta H_{AB}^A = {{T_m } \over {100}}\left[ {{{\Delta H_A^A } \over {T_{mA} }}X_A + {{\Delta H_B^A } \over {T_{mB} }}X_B } \right]$$ is satisfied, whereD oB A and ΔH B A are the characteristics of heterodiffusion of element A in element B andT m B is the melting point of element B.

In the present paper the results of measuring the self-diffusion coefficients for Co in Ni-Co alloy in the composition interval 20–100 at. % Co, and in the temperature range 1057–1306°C are given. The measurements were carried out by the Gruzin method using the radioisotope Co-60. On the curves indicating the concentration dependence of the diffusion coefficient arid of the diffusion characteristics log D0 and ΔAH, extrema appear in the neighbourhood of the compositions 70at.% Co and 25at.% Co. The existence of these extrema is discussed from the point of view of the equilibrium diagram Ni-Co, the extremum near 25at.% Co is explained by means of the Cohen-Fine model for short range order.

Self-diffusion coefficients of copper in Cu−Al solid solutions in the concentration interval 0 to 19 at. pct Al and in the temperature range 800° to 1040°C have been determined by the residual activity method using the isotope Cu64. The values of the self-diffusion coefficients in the concentration interval 0 to 14.5 at. pct Al satisfy the Arrhenius relation and their temperature dependence can be expressed by the following equations $$\eqalign{ & D_{Cu}^{Cu} = \left( {0.43_{ - 0.11}^{ + 0.15} } \right) exp \left( { - {{48,500 \pm 700} \over {RT}}} \right) cm^2 /\sec \cr & D_{Cu - 2.80 at. pct Al}^{Cu} = \left( {0.46_{ - 0.16}^{ + 0.23} } \right) exp \left( { - {{48,000 \pm 900} \over {RT}}} \right) cm^2 /\sec \cr & D_{Cu - 5.50 at. pct Al}^{Cu} = \left( {0.30_{ - 0.07}^{ + 0.09} } \right) exp \left( { - {{47,000 \pm 600} \over {RT}}} \right) cm^2 /\sec \cr & D_{Cu - 8.83 at. pct Al}^{Cu} = \left( {0.46_{ - 0.09}^{ + 0.11} } \right) exp \left( { - {{47,100 \pm 500} \over {RT}}} \right) cm^2 /\sec \cr & D_{Cu - 11.7 at. pct Al}^{Cu} = \left( {0.61_{ - 0.13}^{ + 0.17} } \right) exp \left( { - {{47,200 \pm 600} \over {RT}}} \right) cm^2 /\sec \cr & D_{Cu - 14.5 at. pct Al}^{Cu} = \left( {4.2_{ - 1.5}^{ + 2.2} } \right) exp \left( { - {{51,110 \pm 1000} \over {RT}}} \right) cm^2 /\sec \cr} $$ An analysis of the results leads to the conclusion that, in the concentration interval 0 to 11.7 at. pct Al, the frequency factor and activation enthalpy concentration dependences can be described by the following equations whereD 0Cu Cu and ΔH Cu Cu are diffusion characteristics for self-diffusion in pure copper,X Al is the atomic percent of aluminum, andK andB are experimental constants.

This paper describes the properties of some heavy metal ferrocyanides from the standpoint of their use as ion exchangers for caesium. Among the ferrocyanides studied, the zinc and copper compounds were found to be the most promising materials for column operation.

In the present paper the self-diffusion coefficients of iron in α-iron and in Fe-Cr alloys in the temperature range 660–890°C and in the concentration interval 0–11.8 wt.% Cr were determined. The residual activity method has been applied using the isotope 59Fe. Special attention was payed to the close neighbourhood of the Curie temperature. The obtained data confirmed the effect of ferromagnetic ordering on the iron self-diffus ion in pure Fe and in all the investigated Fe-Cr alloys. An empiric relation was found between the excess free activation enthalpy of diffusion and the spontaneous magnetization that yields a picture about the magnetic ordering of the used materials.

Neutron rich nuclei around 48Ca have been measured with the CLARA–PRISMA setup, making use of 48Ca on 64Ni binary reactions, at 5.9 MeV/A. Angular distributions of γ rays give evidence, in several transfer channels, for a large spin alignment (≈70%) perpendicular to the reaction plane, making it possible to firmly establish spin and parities of the excited states. In the case of 49Ca, states arising from different types of particle–core couplings are, for the first time, unambiguously identified on basis of angular distribution, polarization and lifetime measurements. Shell model and particle–vibration coupling calculations are used to pin down the nature of the states. Evidence is found for the presence, in the same excitation energy region, of two types of coupled states, i.e. single particle coupled to either 48Ca or 50Ca simple configurations, and particle–vibration coupled states based on the 3− phonon of 48Ca., This work was supported by the Italian Istituto Nazionale di Fisica Nucleare and partially by the Spanish MICINN (ACI2009-1070 bilateral action) and Generalitat Valenciana (Grant Nos. BEST/2009/073 and PROMETEO/2010/101). The work has also been partially supported by the Polish Ministry of Science and Higher Education (Grant No. N N202 309135).

The high‐energy and discrete γ‐ray spectra, as well as the charged particle angular distribution have been measured in the reaction 105 MeV 18O+28Si using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition in light nuclei. A comparison of the GDR line shape data with the predictions of the thermal shape fluctuation model, based on the most recent rotating liquid drop LSD calculations, shows evidence for such Jacobi shape transition in hot, rapidly rotating 46Ti. The found narrow low‐energy component in the GDR line shape is interpreted as the consequence both of the elongated shape and of the Coriolis effect.

The feasibility of the entire process of $\gamma$ -ray tracking is demonstrated experimentally for the first time. The accuracy of the results is tested by the capability for Doppler correction of $\gamma$ -rays emitted in flight. The resolution of the 847.8 keV ( $2^ + \to 0^ + $ ) transition detected with the MARS detector after Coulomb excitation of a 56Fe beam could be improved from 15 keV to below 5 keV (FWHM).

Deep-inelastic and multi-nucleon transfer reactions can be used to populate nuclei with relatively large neutron excess. Recently, at the Laboratori Nazionali di Legnaro, a setup consisting on an efficient $\gamma$-ray detection system CLARA coupled to the large acceptance magnetic spectrometer PRISMA, capable of tracking the trajectories of the reaction products, has been assembled. During the first year of activity, the experiments performed with the CLARA-PRISMA setup, have been focused mainly on the nuclear structure of neutron-rich nuclei. In particular, nuclei around N=20, N=50 and lying in the A~60 transitional region with N

This paper gives a brief overview of the technical progress that can be achieved with the newly available segmented HPGe detectors. Gamma-ray tracking detectors are a new generation of HPGe detectors which are currently being developed to improve significantly the efficiency and resolving power of the 4 … germanium detectors arrays for high-precision ∞-ray spectroscopy. They consist of highly segmented HPGe detectors associated with fast digital front-end electronics. Through the pulse-shape analysis of the signals it is possible to extract the energy, timing and spatial information on the few interactions a ∞-ray undergoes in the HPGe detector. The tracks of the ∞-rays in the HPGe detector can then be reconstructed in three dimensions based on the Compton scattering formula. Such a detector has been used for the first time during an in-beam experiment. The ∞-decay of the Coulomb excitation of a 56 Fe nucleus was measured with the highly segmented MARS prototype positioned at 135 degree. The energy resolution has been improved by a factor of 3 as compared to standard HPGe detectors due to very precise Doppler correction based on knowledge of the ∞-ray track. I Introduction The future facilities for radioactive beams will allow, for the first time, the exploration of a new large area of the nuclear landscape. In connection with the study of the ∞-radiation, it is important to point out that the intensity of such radioactive beams is expected to be much smaller than that of stable beams, Doppler Effects in many experiments are expected to be much stronger and an intense background of X-rays could be present. Consequently, a new generation of powerful HPGe arrays with segmented detectors is being designed. Both in USA and in Europe several projects, based on segmented HPGe detectors, have already started and are in an advanced status of realization. The objective of the more recent R&D efforts is to improve the total efficiency by removing the BGO shields without affecting the P/T ratio with the use of the tracking technique, namely the reconstruction of the ∞-ray path to identify the ∞-incident direction (for the Doppler correction), the removal of the background and to check whether or not the ∞ was fully absorbed in the array. Such development implies unprecedented R&D efforts where completely new technology has to be applied, tested or developed in all the constituents of an HPGe array, from the detector to the front-end electronics. The typical feature of the energy deposition of a ∞-ray is that of interacting in a limited number of positions. ∞-tracking of this hits is a very challenging and ambitious task. First, one has to identify, isolate and localize each hit inside a segmented detector with pulse shape analysis based on the study of the physical mechanism of the pulse generation or with Artificial Intelligence techniques (like Neural Networks or Genetic Algorithm [1]) of the direct and induced electrical pulses produced by every interacting ∞-rays. Second, a tracking algorithm has to reconstruct the real trajectory from the list of interaction points through statistical techniques. The result is expected to be the complete reconstruction of the track of the incident ∞, namely the complete description of the interacting ∞-ray. Worldwide efforts have been done using simulations and proof-of-principle measurements and turned out to be successful. The feasibility of the entire process of ∞ray tracking is demonstrated in this paper based on an experiment, done at the LNL in Italy, using the MARS prototype detector.

In this paper, the results of measurements of chemical diffusion of C in weldments of Fe- C-Mn alloys with content of 0-15 % Mn, are reported. Alloys were cast in induction furnace under protective Ar atmosphere. They were hot-forged to rods of diameter 15 mm, machined down to diameter 12 mm, and cut into pieces of 4 mm thickness. These cylindrical samples were metallographically polished. Diffusion couples, welded by electrical impulse, were sealed together with Ti-chips, into evacuated silica ampoules. After that, they were annealed at 1073-1373 K for 96-1.5 hours, respectively. Measurement of C redistribution was done in a normal direction to welding interface using electron-scanning microscope Philips SEM-505WDS equipped with Microspec WDX-2A. Diffusion coefficients of C were obtained and the relations between manganese and carbon were found.

The study of the collective properties of a nuclear system is a powerful tool to understand the structure which lies inside the nucleus. A successful technique which has been used in this field is the measurement of the gamma-decay of the highly collective Giant Dipole Resonance (GDR). In fact, GDR can be used as a probe for the internal structure of hot nuclei and, in addition, constitutes a clock for the thermalization process. Using the fusion evaporation reaction, it has been recently possible to study (i) the yield of the high-energy gamma-ray emission of the Dynamical Dipole which takes place during the fusion process and (ii) the degree of isospin mixing at high temperature in the decay of (80)Zr. In the first case it is important to stress the fact that the predictions of the theoretical models might differ depending on the type of nuclear equation of state (EOS) and on the N-N in-medium cross-section used in the calculations while, in the second physics case, the data are relative to the heaviest N = Z nucleus which has been possible to populate in the I = 0 channel using fusion evaporation reaction. Both experiments were performed at the Laboratori Nazionali di Legnaro using the HECTOR-GARFIELD array. The high-energy gamma-rays were measured in coincidence with light charged particles and fusion evaporation residues.

Matière Nucléaire

The measured properties of the Giant Dipole Resonance in hot rotating nuclei are successfully described with the model of thermal fluctuations, even though there are still some open problems especially at very low (T < 1.2MeV), very high (T > 2.5MeV) temperatures and missing data in some mass regions. Recent experimental works have addressed more specific problems regarding the nuclear shape and its behaviour in very particular and delimited phase space regions. In this paper will be discussed new exclusive measurements of the GDR decay in heavy 216Rn nuclei (where the shape of nuclei surviving fission have been probed) and some preliminary data on the 132Ce nuclei at very high excitation energy.

The \gamma -ray emission due to dynamical dipole oscillations during fusion process was measured for the N/Z asymmetric reaction 16O + 116Sn at 8.1 and 15.6 MeV/u. High-energy \gamma -rays and light charged particles were measured in coincidence with the recoiling residual nuclei. The measured yield of the high-energy \gamma -rays exceeds that of the thermalized compound nucleus and this extra-yield increases with beam energy. Data are compared with theoretical predictions of a dynamical calculation based on Boltzmann–Nordheim–Vlasov (BNV) model.

The 132Ce compound nucleus was formed in fusion reactions 64Ni + 68Zn and 16O + 116Sn at different excitation energies. High energy gamma-rays have been measured in coincidence with Evaporation Residues (ER) in these reactions. At the same time Light Charged Particles (LCP) were measured with the same gate on ER for all the reactions in order to verify and compare the amount of pre-equilibrium emission using mass-symmetric and mass-asymmetric entrance channels. Results on alpha-particle spectra will be presented together with a moving source fit analysis.