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This work was supported by the Austrian Science Fund FWF (J3503), the Adolf Messer Foundation (Germany), the UK Science and Facilities Council (ST/M006085/1), and the European Research Council ERC-2015-StG No. 677497. We also acknowledge the support of the National Science Centre, Poland, under the grant UMO-2016/22/M/ST2/00183, the MSMT of the Czech Republic and the Croatian Science Foundation under the project IP-2018-01-8570., This manuscript summarizes the results of radiative neutron capture cross-section measurements on two stable germanium isotopes, Ge-70 and Ge-73. Experiments were performed at the n_TOF facility at CERN via the time-of-flight technique, over a wide neutron energy range, for all stable germanium isotopes (70,72,73,74, and 76). Results for Ge-70 [Phys. Rev. C 100, 045804 (2019)] and Ge-73 [Phys. Lett. B 790, 458 (2019)] are already published. In the field of nuclear structure, such measurements allow to study excited levels close to the neutron binding energy and to obtain information on nuclear properties. In stellar nucleosynthesis research, neutron induced reactions on germanium are of importance for nucleosynthesis in the weak component of the slow neutron capture processes., Austrian Science Fund (FWF) J3503, Adolf Messer Foundation (Germany), UK Science and Facilities Council ST/M006085/1, European Research Council (ERC), European Commission 677497, National Science Centre, Poland UMO-2016/22/M/ST2/00183, Ministry of Education, Youth & Sports - Czech Republic, Croatian Science Foundation IP-2018-01-8570

New measurements of the7Be(n,α)4He and7Be(n,p)7Li reaction cross sections from thermal to keV neutron energies have been recently performed at CERN/n_TOF. Based on the new experimental results, astrophysical reaction rates have been derived for both reactions, including a proper evaluation of their uncertainties in the thermal energy range of interest for big bang nucleosynthesis studies. The new estimate of the7Be destruction rate, based on these new results, yields a decrease of the predicted cosmological7Li abundance insufficient to provide a viable solution to the cosmological lithium problem.

An accurate measurement of the 235U(n,f) cross section from thermal to 170 keV of neutron energy has recently been performed at n_TOF facility at CERN using 6Li(n,t)4He and 10B(n,α)7Li as references. This measurement has been carried out in order to investigate a possible overestimation of the 235U fission cross section evaluation provided by most recent libraries between 10 and 30 keV. A custom experimental apparatus based on in-beam silicon detectors has been used, and a Monte Carlo simulation in GEANT4 has been employed to characterize the setup and calculate detectors efficiency. The results evidenced the presence of an overestimation in the interval between 9 and 18 keV and the new data may be used to decrease the uncertainty of 235U(n,f) cross section in the keV region.

We present calculations and simulations on the role of the $ {\rm p}+{}^{11}{\rm B}\rightarrow 3\alpha$ reaction in proton therapy. This reaction has been recently suggested to be responsible for a decrease in the survival probability of tumor cells previously treated with a boron compound, when they are irradiated with low-energy protons. However, at the concentration levels typical of the proposed boron carrier (sodium borocaptate, Na2B12H11SH, in short BSH), i.e. less than 100 parts per million (ppm), both calculations and Monte Carlo simulations suggest that the dose related to this reaction is orders of magnitude lower than the dose delivered by the primary proton beam inside the tissues. These calculations cast some doubts on the claim of an important role played by Proton Boron Capture in enhancing the therapeutic effectiveness of proton therapy, and suggest that other mechanisms should be investigated in order to explain the observed decrease in the survival probability.

The (n, γ) cross sections of the gadolinium isotopes play an important role in the study of the stellar nucleosynthesis. In particular, among the isotopes heavier than Fe, 154Gd together with 152Gd have the peculiarity to be mainly produced by the slow capture process, the so-called s-process, since they are shielded against the β-decay chains from the r-process region by their stable samarium isobars. Such a quasi pure s-process origin makes them crucial for testing the robustness of stellar models in galactic chemical evolution (GCE). According to recent models, the 154Gd and 152Gd abundances are expected to be 15-20% lower than the reference un-branched s-process 150Sm isotope. The close correlation between stellar abundances and neutron capture cross sections prompted for an accurate measurement of 154Gd cross section in order to reduce the uncertainty attributable to nuclear physics input and eventually rule out one of the possible causes of present discrepancies between observation and model predictions. To this end, the neutron capture cross section of 154Gd was measured in a wide neutron energy range (from thermal up to some keV) with high resolution in the first experimental area of the neutron time-of-flight facility n_TOF (EAR1) at CERN. In this contribution, after a brief description of the motivation and of the experimental setup used in the measurement, the preliminary results of the 154Gd neutron capture reaction as well as their astrophysical implications are presented.

Although the 12C(n,p)12B and 12C(n,d)11B reactions are of interest in several fields of basic and applied Nuclear Physics the present knowledge of these two cross-sections is far from being accurate and reliable, with both evaluations and data showing sizable discrepancies. As part of the challenging n_TOF program on (n,cp) nuclear reactions study, the energy differential cross-sections of the 12C(n,p)12B and 12C(n,d)11 B reactions have been measured at CERN from the reaction thresholds up to 30 MeV neutron energy. Both measurements have been recently performed at the long flight-path (185 m) experimental area of the n_TOF facility at CERN using a pure (99.95%) rigid graphite target and two silicon telescopes. In this paper an overview of the experiment is presented together with a few preliminary results.

The worldwide need to replace 3He for the neutron detection has triggered R&D on new technologies and methods. A promising one is based on commercial solid state silicon detectors coupled with thin neutron converter layers containing 6Li. After proving the feasibility of this technique, we characterized the behavior of such a detector with different converter layer thicknesses. In this paper we also disentangle other contributions to the overall spectrum shape observed with this kind of detector, proving that its detection efficiency can be made reasonably high and that the gamma/neutron discrimination capability is comparable to the one of 3He tubes., Submitted to Nuclear Instruments and Methods in Physics Research, section A

We report on the measurement of the $^{7}$Be($n, p$)$^{7}$Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n\_TOF facility at CERN. This reaction plays a key role in the lithium yield of the Big Bang Nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and showed a large discrepancy between each other. The measurement was performed with a Si-telescope, and a high-purity sample produced by implantation of a $^{7}$Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low-energy, relative to current evaluations, in the region of BBN interest the present results are consistent with the values inferred from the time-reversal $^{7}$Li($p, n$)$^{7}$Be reaction, thus yielding only a relatively minor improvement on the so-called Cosmological Lithium Problem (CLiP). The relevance of these results on the near-threshold neutron production in the p+$^{7}$Li reaction is also discussed.

International audience; One of the most puzzling problems in Nuclear Astrophysics is the “Cosmological Lithium Problem”, i.e the discrepancy between the primordial abundance of$^{7}$ Li observed in metal poor halo stars (Asplund et al. in Astrophys J 644:229–259, 2006, [1]), and the one predicted by Big Bang Nucleosynthesis (BBN). One of the reactions that could have an impact on the problem is$^{7}$ Be(n,p)$^{7}$ Li. Despite of the importance of this reaction in BBN, the cross-section has never been directly measured at the energies of interest for BBN. Taking advantage of the innovative features of the second experimental area at the n $\_$ TOF facility at CERN (Sabate-Gilarte et al. in Eur Phys J A 53:210, 2017, [2], Weiss et al. in NIMA 799:90, 2015, [3]), an accurate measurement of$^{7}$ Be(n,p) cross section has been recently performed at n $\_$ TOF, with a pure$^{7}$ Be target produced by implantation of a$^{7}$ Be beam at ISOLDE. The mesurement started in April 2016 and lasted for two months. The experimental procedure, the setup used in the measurement and the results obtained so far will be here presented.

The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with uranium to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. However, an extensive use of MOX fuels, in particular in fast reactors, requires more accurate capture and fission cross sections for some Pu isotopes. In the case of Pu242 there are sizable discrepancies among the existing capture cross-section measurements included in the evaluations (all from the 1970s) resulting in an uncertainty as high as 35% in the fast energy region. Moreover, postirradiation experiments evaluated with JEFF-3.1 indicate an overestimation of 14% in the capture cross section in the fast neutron energy region. In this context, the Nuclear Energy Agency (NEA) requested an accuracy of 8% in this cross section in the energy region between 500 meV and 500 keV. This paper presents a new time-of-flight capture measurement on Pu242 carried out at n-TOF-EAR1 (CERN), focusing on the analysis and statistical properties of the resonance region, below 4 keV. The Pu242(n,γ) reaction on a sample containing 95(4) mg enriched to 99.959% was measured with an array of four C6D6 detectors and applying the total energy detection technique. The high neutron energy resolution of n-TOF-EAR1 and the good statistics accumulated have allowed us to extend the resonance analysis up to 4 keV, obtaining new individual and average resonance parameters from a capture cross section featuring a systematic uncertainty of 5%, fulfilling the request of the NEA.

In the framework of the NUMEN project, aimed at the investigation of the nuclear matrix elements connected to the neutrinoless double beta decay by means of the Double Charge Exchange nuclear reactions (Cappuzzello et al., 2015), a high granularity stop detector for heavy ions is needed. It has to allow the identification of ions up to Z ≈ 10 while maintaining a total energy resolution around 2%. As the use of silicon detectors is not possible, due to their poor radiation hardness, scintillators are being investigated as possible candidates. In this paper we show a promising result obtained using a plastic + inorganic phoswich scintillator readout by means of a Silicon Photo Multiplier.

The 33S(n,α)30Si cross section measurement, using 10B(n,α) as reference, at the n TOF Experimental Area 2 (EAR2) facility at CERN is presented. Data from 0.01 eV to 100 keV are provided and, for the first time, the cross section is measured in the range from 0.01 eV to 10 keV. These data may be used for a future evaluation of the cross section because present evaluations exhibit large discrepancies. The 33S(n,α)30Si reaction is of interest in medical physics because of its possible use as a cooperative target to boron in Neutron Capture Therapy (NCT)., This work has been partially supported by the projects of Junta de Andalucía (P07-FQM-02894, FQM-220, P11-FQM-8229), Ministerio de Ciencia y Tecnología (FPA2011-28770-C03-02), CEI-Biotic Granada (P-BS-64), Mineco (FPA2013-47327-C2- 1-R, FPA2014-53290-C2-2-P, FIS2015-69941-C2-1-P) and the funding agencies of the participating institutes.

Research and development on alternative thermal neutron detection technologies and methods are nowadays needed as a possible replacement of 3He-based ones. Commercial solid state silicon detectors, coupled with neutron converter layers containing 6Li, have been proved to represent a viable solution for several applications as present in the literature. In order to better understand the detailed operation and the response and efficiency of such detectors, a series of dedicated GEANT4 simulations were performed and compared with real data collected in a few different configurations. The results show an excellent agreement between data and simulations, indicating that the behavior of the detector is fully understood. © 2017 Elsevier B.V.

One of the most puzzling problems in Nuclear Astrophysics is the “Cosmological Lithium Problem”, i.e the discrepancy between the primordial abundance of \(^{7}\)Li observed in metal poor halo stars (Asplund et al. in Astrophys J 644:229–259, 2006, [1]), and the one predicted by Big Bang Nucleosynthesis (BBN). One of the reactions that could have an impact on the problem is \(^{7}\)Be(n,p)\(^{7}\)Li. Despite of the importance of this reaction in BBN, the cross-section has never been directly measured at the energies of interest for BBN. Taking advantage of the innovative features of the second experimental area at the n\(\_\)TOF facility at CERN (Sabate-Gilarte et al. in Eur Phys J A 53:210, 2017, [2]; Weiss et al. in NIMA 799:90, 2015, [3]), an accurate measurement of \(^{7}\)Be(n,p) cross section has been recently performed at n\(\_\)TOF, with a pure \(^{7}\)Be target produced by implantation of a \(^{7}\)Be beam at ISOLDE. The mesurement started in April 2016 and lasted for two months. The experimental procedure, the setup used in the measurement and the results obtained so far will be here presented.

Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of funda- mental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the conceptual design of an ADS with high safety standards, but ample flexibility for measurements. The design assumes as base option the 70 MeV, 0.75 mA proton cyclotron facility planned to be constructed at the INFN National Laboratory in Legnaro, Italy and a Beryllium target, with Helium gas as core coolant. Safety is guaranteed by limiting the thermal power to 200 kW, with a neutron multiplication coefficient around 0.94, loading the core with fuel containing Uranium enriched at 20% and a solid-lead diffuser. The small decay heat can be passively removed by thermal radiation from the vessel. Such a system could be used to study, among others, some specific aspects of neutron diffusion in lead, beam-core coupling, target cooling and could serve as a training facility.

The design of a low-power prototype of neutron amplifier recently proposed within the INFN-E project indicated the need for more accurate called for detailed data on the neutron yield produced by a proton beam with energy of about 70 MeV impinging on a thick Beryllium target. Such measurement was performed at the LNS superconducting cyclotron, covering a wide angular range from 0 to 150 degrees and a complete neutron energy interval from thermal to beam energy. Neutrons with energy above 0.5 MeV were measured by liquid scintillators exploiting their Time of Flight to determine the kinetic energy. For lower energy neutrons, down to thermal energy, a $^3$He detector was used. The obtained data are in good agreement with previous measurements at 0 degree with 66 MeV proton beam, covering neutron energies >10 MeV, as well as with measurements at few selected angles with protons of 46, 55 and 113 MeV energy. The present results extend the neutron yield data in the 60-70 MeV beam energy range. A comparison of measured yields to MCNP and Geant4 Monte Carlo simulations was performed., 12 pages, 20 figures, sources include tables of all measured data

The energy-dependent cross section of the (7)Bed(n,alpha)He-4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be-7 and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure Be-7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be-7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

During the last decade the worldwide lack of He-3 for neutron detection has triggered research and development on alternative technologies and methods. One of the promising techniques consists of assembling sandwiches of fully depleted double sided Silicon detectors between thin layers of (LiF)-Li-6 neutron converter material. In this paper we show the very promising result of a comparative test of such a detector with respect to an elliptical section He-3 filled proportional counter for application at spallation neutron source facilities. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

This contribution explores the aggregation properties in solution of noncoordinating solvents of a series of amphiphilic Zn(salen) derivatives, through detailed (1)H NMR, DOSY NMR, and optical absorption spectroscopic studies. It is found that these aggregate species are involved in a unique structural interconversion between two defined dimers, A and B, driven by the concentration of water dissolved in chloroform. Dilute CHCl(3) solutions are characterized by the presence of dimeric species, A, in which both Zn(II) atoms of the Zn(salen) units mutually interact through a Zn···O axial coordination, likely adopting a square-base pyramidal structure. Investigations to higher concentrations indicate the existence of a new dimeric species, B, in equilibrium to that observed at lower concentrations, involving a coordination mode interconversion of an intermediate monomer presumably from a square-pyramidal to a trigonal bipyramidal structure. This behavior may be related to the nonconjugated, conformational flexible nature of the bridging diamine of the Schiff base, and is influenced by the solvent polarity. Variable-temperature (1)H NMR studies indicate the existence of a nonequivalent species B' in a fluxional equilibrium with species B.

Three new phosphonate-amine monomers were synthesized in high yields starting from commercially available aldehydes. Complete NMR and FAB-MS mass spectrometry characterization is reported for all compounds, which are useful monomers for the synthesis of phosphorus-containing flame-retardant polymers.

The synthesis, characterization, optical, and fluorescent properties of an amphiphilic Schiff-base bis(salicylaldiminato)zinc(II) complex are reported. Detailed (1)H nuclear magnetic resonance (NMR), diffusion-ordered spectroscopy (DOSY) NMR, optical absorption, and fluorescence spectroscopy studies indicate the existence of aggregate species in noncoordinating solvents. The degree and type of aggregation are related to the concentration and the polarity of the noncoordinating solvent. Dilute solutions are likely characterized by the presence of defined dimers, whereas larger oligomeric aggregates are conceivably formed at higher concentrations. The concentration needed to observe the formation of larger species depends upon solvent polarity. In coordinating solvents or in the presence of coordinating species, a complete deaggregation of the system occurs, because of the axial coordination to the Zn(II) ion, accompanied by considerable changes of (1)H NMR and optical absorption spectra. A dramatic enhancement of fluorescence emission is observed in dichloromethane solutions upon deaggregation with a coordinating agent. The formation of a defined 2:1 supramolecular structure is demonstrated in the case of a ditopic ligand as coordinating species. Overall, these complexes are promising systems for the development of new supramolecular architectures and supramolecular fluorescent probes.

In this paper we present the results of the first electrical and optical characterization performed on 1 mm2 total area Silicon Photomultipliers (SiPM) fabricated in standard silicon planar technology at the STMicroelectronics Catania R&D clean room facility. The device consists of 289 microcells and has a geometrical fill factor of 48%. Breakdown voltage, gain, dark noise rate, crosstalk, photon detection efficiency and linearity have been measured in our laboratories. The optical characterization has been performed by varying the temperature applied to the device. The results shown in the manuscript demonstrate that the device already exhibits relevant features in terms of low dark noise rate and inter-pixel crosstalk probability, high photon detection efficiency, good linearity and single photoelectron resolution. These characteristics can be considered really promising in view of the final application of the photodetector in the Positron Emission Tomography (PET).

The aim of the EXCYT (EXotics with CYclotron and Tandem) facility is the production and acceleration of radioactive ion beams (RIBs). A primary beam provided by the K-800 superconducting cyclotron will produce, in a target-ion source complex (TIS), the required nuclear species which can be used for low energy experiments (up to 300 keV) or at higher energy by post-accelerating them with the 15 MV tandem. The nuclear experiments programme started in July 2006 with the experiments BIGBANG and RCS using the post-accelerated 8Li ions. Since then 8Li, 9Li and 21Na beams have been already produced and in the near future production of oxygen, fluorine and chlorine beams have been planned, according to the experimental proposals, with beam intensities ranging between 104 to 106 pps and at the typical energies of our tandem.

We have synthetized medium-sized cyclophanes and macrocycles containing phosphonic groups, directly linked to the aromatic rings of the phanes or as pendant arms, for use as specific receptors for the selective complexation of neutral guests or for complexing lanthanides, as luminescent sensors and for diagnostic bioassays in medicine. Furthermore, because it would be of great interest for biochemistry as well as for pharmacological studies to dispose of preorganized rigid chiral hosts for biorelevant molecules we designed inter alia , some new chiral macrocycles capable of a triple binding mode and we used them for constructing macrocycles that could also be of interest for chiral recognition and chiral separations. Thus, in this paper we shall review the salient aspects of some macrocycles synthetized in our laboratory, all possessing the phosphonate moiety and a spirobisindanol scaffold and able to act as complexing agents for cations and organic substrates. In particular, we shall describe their NMR characterization, their stereochemistry in solution and in the solid state, and their use as chiral receptors for biorelevant molecules. Chiral HPLC resolution of some of them is also reported.

In this paper, we present the results regarding the electrical and optical characterization of bidimensional arrays of silicon single photon avalanche photodiodes (SPAD). Low average dark count rates and crosstalk probability, good timing jitter and high quantum detection efficiency in the visible range have been measured over 5 × 5 SPAD arrays with 40 μm single pixel active area diameter. Moreover, a very good uniformity of these parameters has been found over the single pixels. These good electro-optical performances make our photodiodes attractive for the fabrication of arrays with a larger number of SPAD. In view of the design of a dense array to be used as a silicon photomultiplier (SiPM) for medical diagnostic tools, 5 × 5 SPAD arrays have been also tested in the photon-resolving mode. Charge spectra show that the arrays, in this configuration, allow to resolve several photoelectron peaks with a good single photoelectron resolution.

In this letter we present the results regarding the electrical and optical characterization of Geiger mode silicon avalanche photodiodes (GMAP) fabricated by silicon standard planar technology. Low dark count rates, negligible afterpulsing effects, good timing resolution and high quantum detection efficiency in all the visible range have been measured. The very good electro-optical performances of our photodiodes make them attractive for the fabrication of arrays with a large number of GMAP to be used both in the commercial and the scientific fields, as telecommunications and nuclear medical imaging.

The synthesis of two novel furyl-containing bis(aminophosphonates) 1,5-bis[N-methyl(dimethoxyphosphonyl)-1-(2-furyl)]diaminonaphthalene (1) and 1,5-bis[N-methyl(diethoxyphosphonyl)-1-(2-furyl)]diaminonaphthalene (2) through an addition of dialkyl phosphites to N,N′-difurfurylidene-1,5-naphthalenediamine is reported. The compounds have been characterized by elemental analysis, TLC, IR and NMR (1H, 1C and 31P) spectra. Some new 31P NMR data of three previously described analogues (3–5) of the above bis(aminophosphonates) is also presented. The 31P NMR study reveals that in most of the cases (1, 3–5), the addition reaction is completely stereoselective, and only one diastereomer is formed. By the preparation of compound 2, this reaction proceeds not completely stereoselectively with the predominant formation (in 90%) of one of the two possible diastereomers.

We report on quite promising results obtained with a low-energy, low-intensity ion beam imaging system, using a CsI(Tl) scintillator plate. Surprising sensitivity, both in terms of beam energy and intensity, has been achieved as a prelude to additional more quantitative measurements, in view of novel applications to ion-source and ion-implanter precision diagnostics.

1,3-Bis[ N -methyl(diethoxyphosphonyl)-1-(2-furyl)]diaminobenzene has been synthesized through the addition of diethyl phosphite to the Schiff base N , N '-difurfurylidene- m -phenylenediamine. The compound has been characterized by elemental analysis, TLC, IR, and 1 H, 13 C, and 31 P NMR spectra. The NMR studies show that the reaction product is a mixture of two diastereomers ( meso and racemic forms). The 31 P NMR data revealed 61% content for the predominant and 39% for the minor form.

Some new aryl phosphonic acid ethyl ester analogs of acetyl salicylic acids, and bis- p -aminophenoxy-benzo-phosphonic acid ethyl esters have been prepared in good yield. Characterization by spectroscopic techniques indicates that in the phosphorus NMR spectra a significant change in chemical shift values between the starting phenolic phosphonate and both the corresponding derivative is observed; thus this up-field shift is very diagnostic for this type of compounds.

Acid-base properties and reactivity of series of alpha-aminophosphonates has been investigated. The reaction of addition of the aminophosphonates to phenylisocyanate was used as a model reaction. The influence of steric and electronic effects of substituents at alpha-carbon or nitrogen in amino group on the mechanism inversion from AdN to AdE is discussed.

The synthesis as well as the clathration properties of cyclophanes containing the chiral spirobiindanol phosphonate moiety is reported. Macrocycles have been synthesized in satisfactory yields by a two steps procedure. NMR spectroscopy reveals that in solution these compounds are arranged in a dissymetric structure (point group symmetry C2) with a great conformational mobility. By recrystallization of macrocycles from a mixture of cyclohexane and other organic solvents was found that all of them are able to form inclusion complexes only with cyclohexane. The crystal and molecular structure of one of them has benn determined by single crystal X-ray analyses.

We describe a dedicated experiment to measure the neutron yield produced by a 62MeV proton beam impinging on a beryllium thick target. The energy was chosen as close as possible to the 70MeV considered for the ADS layout described in this Focus Point. The neutron yield and energy spectra were measured at several angles with respect to the beam direction. The experiment was performed at the INFN Laboratori Nazionali del Sud in Catania, Italy, using the proton beam delivered by the Superconducting Cyclotron (CS).

A new detector technology was developed, particularly suitable for low-cost radioactivity monitoring in radwaste storage sites. It consists of a scintillating optical fiber coupled at each end to a silicon photomultiplier (SiPM). The single-photon sensitivity of the SiPM, along with the left-right coincidence constraint, allows the achievement of a reasonable sensitivity to gamma radiation even though a thin 1-mm-diameter plastic scintillating fiber is used. Simulation results are in perfect agreement with the measured behavior, and several implementations are under way. The possibility of choosing the fiber length and shape makes them very flexible both conceptually and mechanically. Any improvement in the SiPM development technology reflects immediately into an improvement in the detector performance.

By the reaction of para-formylcalix[4]arenes 1–6 with trialkyl phosphites in the presence of dry hydrogen chloride, calix[4]arenes 7–13 possessing dialkylphosphoryl-hydroxymethyl groupings at the upper rim were synthesized. Calix[4]arenes 18–23 functionalized with dialkylphosphoryl-alkyl(aryl)aminomethyl groups were obtained by sodium-promoted addition of dialkyl phosphites to C=N bonds of para-iminocalix[4]arenes 14–17. The consecutive treatment of α-hydroxy- or α-aminophosphonic acid dialkyl esters of calix[4]arenes 7, 10, 18, and 21 with bromotrimethylsilane and methanol gave dihydroxyphosphoryl derivatives of calix[4]arenes 24–27. It was shown that calix[4]arenes bearing at the macrocyclic upper rim hydroxymethylphosphonic fragments, as well as bis-hydroxymethyl(aminomethyl)phosphonic fragments, are able to undergo self-assembly with formation of dimeric OH···O=P hydrogen bonded associates. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:58–67, 2001

Arylidene bis-(N-diethylphosphonoacetamides) have been prepered in good yield. All compounds are white crystalline powders soluble in low boiling point organic solvents. Characterization by 1H-NMR technique indicates that the methyne proton appears in the aromatic region of the spectrum and the two methylene diastereotopic protons (CH2P) give rise to complex ABX system due to the coupling with the phosphorus atom, thus this pattern is very diagnostic for this tipe of compounds. The heteronuclear coupling was also investigated by 1H31P-NMR spectroscopy.

Condensation of the ethyl esters of phenyl carboxylic acids or phenyl-phosphonic acids with halonitrobenzenes in anhydrous acetonitrile in presence of potassium carbonate produces 4′-nitrophenoxy-benzoic or benzo-phosphonic acid ethyl esters in good yields. This procedure, which represents a new approach for the nucleophilic condensation, is particularly useful for substrates bearing ancillary reactive groups for which the usual procedure described in literature leads to decomposition products. Reduction of the parent nitro derivatives by hydrazine in the presence of palladium catalyst yields the corresponding amines in very high yield.

In this article we shall review the salient aspects concerning the syntheses, characterization, and complexing properties of variously substituted mono- and bis-(α-amino)- and (α-hydroxy)-phosphonates. Characterization of these compounds was mainly achieved by 1H, 13C, and 31P NMR spectroscopy, by FABMS techniques, and by X-ray diffraction analyses. Hydrolytic cleavage in alkaline solutions of the dialkyl esters gave the corresponding monoesters, which also show good complexing properties toward standard metals and lanthanides. The last section of this article is dedicated to a review of the synthesis, characterization and stereochemistry of cyclophanes, and macrocyclic compounds possessing phosphonate units. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:493–504, 2000

Two aminophosphonic acid dimethylesters 1 and 3 bearing COOH functions attached to UV-VIS absorbing groups were hydrolysed by aqueous NaOH to yield the corresponding monomethylesters 2 and 4. The rates of hydrolysis were monitored by UV-VIS methods. The type of reaction observed is of pseudo first order with rate constants k1[1 mol−1 s−1] of 1.92.10−6 (1, 25°C). 4.96.10−5(1, 50°C) and 4.63.10−5 (3, 50°C). Hydrolysis is sufficiently slow to enable the practically undisturbed determination of dissociation constants for 1-(4-carbxyphenyl)−1-(N-t. butyl)-aminomethylphosphonic acid dimethylester (1) and 1-(4-benzoic-acid)−1-(N-4-phenyl-azo-phenylene)-aminomethylphosphonic acid dimethyl ester (3).

A new ortho-hydroxy-aryl-phosphonate additive was used to improve the flame resistance of an epoxy/anhydride system. Thermal, rheological, L.O.l. and SEM experiments were carried out to show that the P-additive acts not only as a flame retardant but also as a curing agent.

Williamson condensation of bis-o-hydroxy aryl phosphonates with dihaloalkylaryl derivatives yields the title compounds. They show interesting stereochemical aspects and some of them can be used in chiral recognitions and separations.

Commercially available bridged bis-phenols react with diethylphosphite to give bis-phosphates, which are easily transformed by LDA, in good yields, to bis-ortho hydroxy aryl phosphonates. These new monomers are of great relevance for the synthesis of novel macrocycles and for thermal resistant polycondensates containing phosphonate moieties.

The enantiomers of 17 α-hydroxybenzylphosphonate diethylesters containing para, or ortho substituents or other aromatic rings (1-naphthyl, 2-naphthyl, and 2-thienyl) have been successfully separated by HPLC on a Whelk-O 1 chiral stationary phase which is superior to other CSPs. The effect of the substituents, particularly halogens, on the enantioselectivity was investigated and related to a chiral recognition model. The absolute configurations of 4-methyl and 2-methyl substituted α-hydroxybenzylphosphonates were obtained by measurement of the circular dichroism spectra of the isolated enantiomers. Chirality 10:100–105, 1998. © 1998 Wiley-Liss,Inc.

N-Substituted α-amino-arylmethyl-phosphonate monoesters have been prepared in moderate to good yields and in a high state of purity by a convenient one-step synthesis. New compounds incorporating the pyridin-2-yl group are prepared and fully characterised. The method described here has also been employed to synthesize two known compounds for comparison.

A general synthetic way for the preparation of a large variety of α-hydroxy phosphoryl compounds is here reported. In our approach, trialkyl phosphite is added in equimolar amount, at room temperature and under strong acidic conditions (HCI gas), to the corresponding carbonyl compound dissolved in anhydrous dioxane. The reaction is quite exothermic and cooling is often needed; 10–15 min reaction time is sufficient in order to assure almost quantitative yields in the desired product, which can be easily isolated as a white pure solid by concentration of the reaction mixture. The reaction works in an excellent way with all kind of aliphatic, aromatic and heteroaromatic aldehydes. The α-hydroxy phosphonates obtained were fully characterized by 1H- and 31P-NMR, by FAB-MS and IR spectroscopy. When o-carboxybenzaldehyde was used as a reagent, cyclic dialkyl phthalide-3-phosphonates were obtained in very good yields (≥90%).

New phosphonate mono-methyl esters which are designed to have properties intermediate between the acid and the diesters and thus able to form discrete metal complexes with enhanced solubility in water, were synthesized using 2-(2-aminoethyl) pyridine as starting reagent, considering that the presence of the pyridyl moiety in such aminophosphonates could be of great relevance for preparation of discrete metal complexes. The procedure used allowed to obtain in rather good yields the phosphonic acid mono-methyl esters directly in a one-pot synthesis starting from the corresponding Schiff bases (not isolated) and dimethyl phosphite.

Functionalization at the NH group (s) of 1-amino-1-arylmethyl phosphonic acid diethyl esters with monoisocyanates was performed in order to produce alkyl ureas bearing the phosphonate group. The condensation reaction is easily performed in dry toluene at 80°C using a catalytic amount of Et3N, and the white crystalline products are obtained in satisfactory yields. Characterizations of these new compounds, of potential applications in agrochemistry, were performed by 1H-NMR spectroscopy and by MS-FAB spectrometry, which reveals the presence of very diagnostic signals or peaks for structural assignments.

The synthesis and NMR characterization of some poly(ether ketone)/poly(ether sulfone) (PEK/PES) alternating copolymers together with a series of sequential homopolymers containing CO, O, S and SO 2 bridging groups, all obtained by electrophilic condensation reactions using phosphorus pentoxide/methanesulfonic acid as dehydrating agent, is here reported. Properties of such polymers are compared with those of their model compounds from which it can be inferred that both proton and carbon chemical shifts are very sensitive to the electronic environment generated by the O, S, CO and SO 2 bridges. Differential scanning calorimetry indicates that our polymers are essentially amorphous irrespective of the bridging sequence. From viscosity measurements the molecular weights of these copolymers are judged to be very low.

The crystal and molecular structure of the title compound has been determined by single crystal X-ray analysis. The complex is polymeric, the ligand coordinating in a bridging mode via two phosphoryl groups. The coordination environment at tin is octahedral with two methyl groups, two chlorine and two oxygen atoms occupying trans positions.

In this paper we shall review the salient aspects concerning the syntheses, characterization and complexing properties of variously substituted mono- and bis-amino-phosphonates.