80MeV/u 20Ne轰击9Be碎裂产物反应总截面的测量

介绍了用透射法测量中能区²⁰Ne打⁹Be靶碎裂产生的次级束与Si靶作用的核反应总截面的方法,以及实验的探测器布局、实验过程和实验结果.并对理论上预言有奇异结构的核¹²N,¹⁷Ne和¹⁷F的实验结果与其相邻核进行了比较.     

Radioactive beam facilities: European perspectives

During the last ten years, the cooperation in Nuclear Physics between the different European countries has significantly increased, in particular through extensive discussions initiated by NuPECC, the Nuclear Physics European Collaboration Committee. In this context, perspectives in physics with radioactive beams have been reviewed and a high priority has been given to the developments of performing facilities in Europe including both in-flight and ISOL facilities. In this presentation, the main challenges are recalled and the various existing national and transnational projects are reviewed as well as the accompanying research and development programs. A special attention is given to the EURISOL project, a European program aiming at a preliminary design study of a second-generation European ISOL radioactive beam facility. Received: 1 May 2001 / Accepted: 4 December 2001     

Yields of neutron-rich isotopes around Z = 28 produced in 30 MeV proton-induced fission of 238U

Heavy ^65-70Co, ^68-74Ni, ^70-76Cu and ^74-81Ga isotopes were produced at the LISOL facility by means of 30 MeV proton-induced fission of ²³⁸U. Production rates were deduced and compared to two types of cross-section calculations: the empirical model (V. Rubchenya, private communication) and the PROFI code. Comparison with experimental data favors the latter model. Yields using different beam-target combinations and different energies are calculated and discussed. Received: 11 February 2002 / Accepted: 26 April 2002     

Synthesis and Sorption Behaviour of Some Radioactive Nuclides on Sodium Titanate as Cation Exchanger

Crystalline (Na₄TiO₄·0.32H₂O) and amorphous (Na₂TiO₃·1.45H₂O) forms of sodium titanate were prepared by fusion reaction of TiO₂ and Na₂CO₃ at 1100°C in molar ratios of 2:1 and 1:2, respectively. The prepared products were characterized using IR, DTA-TG, X-ray and elemental analyses. Kinetic studies of the order of reaction (n) and activation energy (E _a) for crystallization transformation step (for crystalline sodium titanate only) have been determined from DTA thermogram and their values were found to be 0.87 (univalent order) and 3.97 kJ mol^–1, respectively. Ion exchange capacities and some distribution studies were carried out at different conditions in the presence of some complexing agents (EDTA, boric and citric acids) and the results showed that the capacities of the crystalline form are always less than the amorphous one.     

Magnetic resonance in systems with equivalent spin-1/2 nuclides. Part 1

Electron paramagnetic resonance (EPR) spectra of S=1/2 systems XL(n) with n equivalent nuclei having spin I=1/2 have been simulated for microwave frequencies in the L-, X-, and W-bands. It has been shown that for n>2 nuclei, the EPR spectra have a more complicated form than anticipated from the usual oversimplified analysis, which predicts n+1 lines with intensity ratios given by the coefficients of the binomial expansion. For the XL(n) system with n=3, the EPR spectra in fact consist of six lines. The exact solution of the spin-hamiltonian for this case has been obtained, which gives four levels in zero magnetic field. For n>2 systems, the degeneracy of the energy levels cannot be completely removed by the Zeeman electronic and nuclear interactions. For n>4, certain spin states cannot occur, consistent with the (generalized) Pauli exclusion principle. Discussion of the underlying theory, invoking exchange degeneracy and the appropriate permutation group theory, is included in some detail. Analogous considerations hold for NMR spectroscopy of non-radicals.     

Fission fragment production from uranium carbide disc targets

A possible solution for a target system aimed at the production of exotic nuclei as a result of high-energy fissions in ²³⁸U compounds has been analyzed. The configuration proposed is constituted by a primary proton beam (40 MeV, 0.4 mA) directly impinging on a UC₂ multiple-disc target inserted within a cylindrical tungsten box. In order to extract the fission fragments, the tungsten box has to be kept at 2000 ^°C. This system has been conceived to obtain both a high number of fission fragments (about 2 ^. 10¹³ atoms/s) and a quite low power deposition in the target. The power release and the fragment distribution have been calculated by means of the Monte Carlo code MCNPX. The thermal analysis of the proposed configuration shows the capability of the thermal radiation to cool the discs with a reasonable margin below the material melting point. Moreover, the possibility of increasing such margin with simple modifications of the target design is shown by means of parametric analyses. The thermal analysis of the tungsten box, also cooled by radiation, points out the necessity to heat it and/or shield it thermally, in order to take it at the requested temperature. Preliminary calculations of the target-induced activity have also been performed.     

Response of the REWARD detection system to the presence of a Radiological Dispersal Device

The objective of the REWARD project consisted in building a mobile system for real time, wide area radiation surveillance, using a CdZnTe detector for gamma radiation and a neutron detector based on novel silicon technologies. The sensing unit includes a GPS system and a wireless communication interface to send the data remotely to a monitoring base station, where it will be analyzed in real time and correlated with historical data from the tag location, in order to generate an alarm when an abnormal situation is detected. The main objective of this work consisted in making predictions regarding the behavior of the REWARD system in the presence of a Radiological Dispersion Device (RDD), one of the reference scenarios foreseen for REWARD, using experimental data and the Monte Carlo simulation program MCNP6. Experimental tests were performed at the Fire Brigades Facilities in Rome and at the Naples Fire Brigades. The response of the REWARD detection system to the presence of an RDD is predicted and discussed.     

Zur Einführung der neuen „Anordnung über den Transport radioaktiver Stoffe — ATRS”

Die im Juni 1967 erschienene und im Februar 1971 ergänzte ?Anordnung über den Transport radioaktiver Stoffe – ATRS” [1 –4] hat lange Zeit als gesetzliche Grundlagc für die Lösung der Verpackungs- und Transportprobleme der Kerntechnik in der DDR gedient. Gegenwärtig machte sich eine Überarbeitung und Neufassung notwendig, weil sowohl die internationalen Vorschriften, die von der Atomenergiebehörde (IAEA) in Wien herausgegeben werden [5], als auch weitere nationale und internationale Vorschriften der Verkehrsträger über den Transport gefährlicher Güter in veränderter Fassung vorliegen bzw. neu erschcinen warden.     

间接测量中重放射性核中子俘获截面——替代比率法

s过程中的放射性核素中子俘获截面对天体核合成和核素丰度有重大影响, 在直接测量异常困难的情况下, 替代比率法是获得放射性核素中子俘获截面数据的一种间接新方法。 简单介绍了替代比率法理论, 并简要论述了用替代比率法推导中重核区放射性核素中子俘获截面的可行性。 The radioactive nuclei neutron capture cross section is very important to nuclearsynthesis and nuclide abundance in s process, but it is difficult to be measured directly because of the target production. A new method, surrogate ratio method which is developed from surrogate method, could be used to determine the cross section of radioactive nuclei neutron capture. In this paper, the surrogate ratio method was introduced and the feasibility was discussed to deduce the desired neutron capture cross sections with surrogate ratio method.     

用198Au示踪法从氰化液中萃取微量金

198Au同位素示踪法;胺类萃取剂;溶剂萃取;用198Au示踪法从氰化液中萃取微量金