Abstract A two-step resonance photo-ionization scheme has been used to ionize samarium atoms in the SPES tantalum hot-cavity ion source. The effect of the ion load on the ion beam time structure and ...the laser enhancement of the ion yield has been studied at different ion source temperatures. Generally, the introduction of more positive ions (ion load) affects negatively the overall confinement of the laser ions inside the volume of the ion source. Possible enhancement of the laser ion confinement through the introduction of neutrals is observed as well. The ion load is also observed to affect the confinement in the transfer line much more than in the hot cavity. Measurement of the time structure with inverted polarity of the cavity DC heating supply confirmed the significance of the longitudinal potential for ion extraction. The laser enhancements of the ion yield are found to be sensitive to the ion load at low operating temperature of the ion source i.e. 1800°C, whereas at 2050°C and 2200°C, they are relatively stable till an ion load value of 1.2 µA.
The SPES project (Selective Production of Exotic Species) is currently under advanced construction phase at the INFN-LNL (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro) for ...the production of Radioactive Ion Beams. Several typologies of target systems will be used in different SPES production phases. The irradiated target system has a limited lifetime and has to be regularly replaced. As a consequence, the handling and the temporary storage of exhausted radioactive targets are a major concern for the management of the entire facility. Monte Carlo simulation codes as FLUKA and MCNPX are used for shielding design. Results of shielding simulations are here presented, realized using a complete FLUKA model of the system and multi-step simulations. In particular, two case studies are discussed, referring to the management of different phases of the SPES project which require human intervention. The results allow some conclusions about the safe design of shieldings to be drawn.
Scaling analysis of trends using DFA Vjushin, Dmitry; Govindan, R.B.; Monetti, Roberto A. ...
Physica A,
12/2001, Letnik:
302, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
We study two aspects of the detrended fluctuation analysis (DFA) method, namely the scaling behavior of the leading terms of the best-fit polynomials and the detection of trends. We show analytically ...and numerically that the standard deviation of the leading terms of the best-fit polynomials used in DFA displays scaling behavior. Furthermore, we demonstrate that the distribution of these terms can be used to reveal the presence of trends in the data. We also argue that this distribution can be used as a sensitive tool for identifying weak trends.
Worldwide efforts to tackle the nature of exotic nuclei comprise the construction of new-generation Radioactive Ion Beam facilities. The Italian community is deeply involved in the process and the ...construction of SPES at Legnaro National Laboratories (INFN) is progressing. This contribution describes the layout of SPES in all its flavours, from Nuclear Physics to Applications in Nuclear Medicine and Neutron Physics. In particular, the status of the SPES-β ISOL facility, together with some of the relevant physics cases and the associated equipment are described.
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In a collaboration between the INFN-SPES project and iThemba LABS, an on-line test of the power dissipation of a multi-slice target concept for radioactive-ion beam production has been performed. ...Using the 66MeV proton beam from the iThemba LABS Separated Sector Cyclotron, a total power of 4kW was deposited in the target complex, consisting of 13 Silicon Carbide (SiC) discs of about 1 millimetre thickness housed in a graphite cylinder. The results of the measurements fully validate thermal FEM simulations and confirm that the multi-foil target system is a reliable and affordable device for second-generation ISOL-RIB facilities like SPES.
Adulterations detection in concentrated rectified musts (CRM) could be strengthened by either making acceptance criteria capable of better reflecting the features of genuine samples or employing ...additional tracers suitable to ascertain the addition of exogenous sugars. In fact, thanks to their purity, CRM are an ideal substrate for adulterations with sugars of plants other than grape, in particular beet sucrose, able to emulate genuine samples. The present work shows that, moving from well-established standard methods like isotopic analysis of D/H and 13C/12C ratios and presence determination of myo-inositol, a better definition of genuineness characteristics could be achieved through a multivariate approach integrated with the measurements of myo-inositol and its isomer scyllo-inositol. The separation between adulterated and genuine samples has been obtained by implementing a multivariate version of the expectation-maximization (EM) algorithm, and the estimates have been later used to derive a classification rule based on generalized Mahalanobis distances. In this way it has been possible to highlight the effects of adulterations, in particular the dilution of polyalcohols, and the shortcomings of the present regulations. As a consequence, especially to solve the intermediate cases where attribution is normally difficult, we suggest a narrowing of the acceptance region by a true multiparametric approach integrated with scyllo-inositol
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