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A castable polyurethane (PUR) with soft segment made by polytetrahydrofuran polyol (or polytretramethylene ether glycol = PTMEG) derived from renewable sources was used as polymer matrix to prepare neutron shields. The PUR polymer matrix was filled with 20.4% of amorphous boron or with 20.9% by weight of hexagonal boron nitride (h-BN). The PUR composites were cast in foils 2 mm thick and tested as thermal neutron shields against reference unfilled PUR foils. The method of sandwitched copper wire activation till saturation was used for the determination of the neutron shielding effectiveness. Both the linear and massic attenuation coefficient of the two PUR composites were determined. Making 100 the linear attenuation coefficient μ of unfilled PUR, the μ value of 20.4% amorphous boron filled composite was found at 224 while that of 20.9% filled BN was found at 182. Making 100 the mass attenuation coefficient μ/ρ of the unfilled PUR the amorphous boron PUR filled composite was found at 311 while the BN filled PUR composite stopped at 178. Unfilled PUR and PUR composites were studied with FT-IR spectroscopy and DSC before and after neutron processing with a total dose of 1.5 × 1013 cm−2. No significant changes were detected neither in the FT-IR spectra nor in the DSC thermal behaviour confirming the excellent radiation resistance of PUR and its suitability as polymer matrix for neutrons and more in general radiation shielding. [ABSTRACT FROM AUTHOR]

Lithium bis(oxalato) borate (LiBOB) was neutron bombarded with a flux of 2.40 × 10 n cm s for 1, 2, 3 and 4 h. The neutron damaged LiBOB was studied by FT-IR and Raman spectroscopy as well as by DSC (Differential Scanning Calorimetry). It is shown that the neutron bombardment causes the radiolysis of the oxalate ligand of LiBOB producing boric acid. The kinetics of LiBOB radiolysis under neutron bombardment was fitted according to the pseudofirst order kinetics law using either the FT-IR data or the decomposition enthalpy data leading in both cases to a rate constant of 9.2 × 10 s. Pristine LiBOB is not a paramagnetic solid but after neutron bombardement it gives a very clear and stable ESR signal attributed to trapped spins in the radiolysis products. [ABSTRACT FROM AUTHOR]

In this paper, evaluation of neutron flux parameters of TRIGA Mark II reactor in Pavia was carried out. For any of the three irradiation positions investigated, this work represented the first experimental evaluation of α. Moreover, in addition to α, values of other parameters such as f, Φ and Φ were also calculated and compared with the existent literature data from other TRIGA Mark II reactors and the Pavia's facility. Results obtained in the present study represent a mandatory step ahead for future application of k -Neutron Activation Analysis method ( k -NAA) at Pavia's facility. [ABSTRACT FROM AUTHOR]

In the present work the characterization of six ingots of ancient Roman Lead, found on the seabed near Mal Di Ventre Isle (Sardinia-Italy), is presented. The ingots come from three different foundries, defined by following codes found on the particular ingots selves: SOCPONTILIENORUMMF, QAPPCF and MCPONTILIENORUMMF. The foundries were active about 2000 years ago in Sierra de Cartagena (Spain) where some of the most important lead mines of the Roman Empire were located. In order to identify the provenance of the ingots and to shed some lights on their manufacturing we applied a multi-analytical method, based on instrumental neutron activation analysis and thermal ionization mass spectrometry. Coupling the two techniques it was possible to obtain an accurate multi-elemental and isotopical fingerprint of the different ingots, giving some important results in the field of archeo-metallurgy. The possibility to perform such measurements with a non-destructive approach satisfies a very important request of the cultural heritage authorities involved in the protection and conservation of similar goods. [ABSTRACT FROM AUTHOR]

The application of instrumental neutron activation analysis (INAA) for multi-elemental analysis of samples of extremely reduced mass such as dust samples extracted from ice cores requires specific efforts towards the development of a 'low level counting' analytical technique. An analytical protocol specifically designed for this kind of samples, based on low-background INAA (LBNAA) is here presented. A first application of the method was successfully performed on samples from the new alpine firn core NextData-LYS12. Sub-ng detection limits were reached for many elements. According to this point the technique is also potentially suitable to be applied to polar ice core samples. [ABSTRACT FROM AUTHOR]