A compilation of charged particle production cross sections by 14 MeV neutrons for Ti,V, Cr and Mn isotopes

A compilation of the cross sections (n, p), (n, n′ p), (n, α), (n, n′ α) and (n, He³) for Ti-46,-47,-48,-49,-50; V-51; Cr-50,-52,-53,-54 and Mn-55 by 14 MeV neutrons is presented in the form of a table containing the results of some 170 different measurements, mainly obtained by activation analysis. Brief assessments of the experimental methods and the data status are given.     

A compilation of cross-sections for charged particle production by 14 MeV neutrons for Fe,Co and Ni isotopes

A compilation of the (n, p), (n, n′p), (n, α, (n, n′α) and (n,³He) cross-sections for⁵⁴Fe,⁵⁶Fe,⁵⁷Fe−⁵⁸Fe,⁵⁹Co,⁵⁸Ni,⁶⁰Ni,⁶¹Ni,⁶²Ni and-⁶⁴Ni by 14 MeV neutrons is presented in the from of a table containing the results of some 180 different measurements, mainly obtained by activation analysis. Brief assessments of the experimental methods and the data status are given.     

Radiochemical methods in the determination of nuclear data for fusion reactor technology

Nuclear data needs for fusion reactor design are briefly outlined. A summary is given of the radiochemical methods like precipitation, co-precipitation, liquid-liquid extraction, ion-exchange and high-pressure liquid chromatography which have been applied in the determination of cross-section data for (n, p), (n, n' p), (n, α), (n, n′p), (n, α), (n, n′ α), (n, t) and (n³He) reactions at 14 MeV, especially on potential wall materials and transmuted species. The measured data are discussed briefly. A radiochemical method is described for the experimental determination of space dependent tritium production rate in a lithium model blanket. Tritium was separated from Li by vacuum extraction and was determined quantitatively by gas phase β⁻-counting. A comparison of the experimental and computational results is given.     

Measurement of neutron-induced activation cross sections of lanthanum at 14.8 MeV

Cross-sections for (n,p), (n,α), (n,n′α), (n,t) and (n,2p) reactions have been measured on ¹³⁹La isotope at the neutron energy 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Neutrons were produced via the ³H(d,n)⁴He reaction using a solid tritium–titanium target. The neutron fluences were determined using the monitor reaction ²⁷Al(n,α)²⁴Na. The neutron energy in this measurement was determined by cross section ratios for the ⁹⁰Zr(n,2n)^89m+gZr and ⁹³Nb(n,2n)^92mNb reactions. Data are reported for the following reactions: ¹³⁹La(n,p)¹³⁹Ba, ¹³⁹La(n,α)¹³⁶Cs, ¹³⁹La(n,n′α)^135mCs, ¹³⁹La (n,t)^137mBa, and ¹³⁹La(n,2p)¹³⁸Cs. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.0, JENDL-3.3, JEFF-3.1/A, and TENDL-2008 libraries.     

Observation of a Doppler broadening of the 4438 keV gamma-line of12C in processes12C(n,n′γ)12C and9Be(α, nγ)12C

A Doppler broadening is described of the 4438 keV spectral gamma-line observed by means of a Ge(Li) detector during the deexcitation of nuclei of¹²C in an inelastic scattering¹²C(n, n′γ)¹²C using an²⁴¹Am−Be source as well as during the reaction⁹Be(α, nγ)¹²C taking place in the Am−Be source. The FWHM of the spectral line is equal to (90±4) keV in the latter reaction and (64±8) keV in the former process. Experimental values agree well with theoretical ones. Presented at the Instrumental Activation Analysis Conference, IAA 79, June 4–8, 1979, Klučenice, Czechoslovakia.     

Determination of fluorine by the spectrometry of prompt gamma-rays

The use, for analysis, of prompt gamma-rays excited by 5 MeV alpha-particles from the reactions¹⁹F(α,α′γ)¹⁹F,¹⁹F(α, nγ)²²Na and¹⁹F(α, pγ)²²NE, was studied. The precision of the analyses depended on the gamma-ray energy used for the measurement. Relative standard deviations were ±1.8, ±0.9 and ±1.3% using the 110-, 197- or 1275 keV gamma-rays. The method was tested with N. I. M. standard materials of calcium fluoride and fluorspar, and was used as a rapid method for the determination of fluorine in cements.     

Determination of relative and absolute abundance of stable nitrogen isotopes by proton induced nuclear reactions

Thick-target yield of γ-rays emitted in the reactions¹⁴N(p,p′γ₁)¹⁴N and¹⁵N(p,αγ₁)¹²C were measured as a function of bombarding energy in order to select the conditions favoring the employment of these reactions in nitrogen isotopic analysis. The applicability of these reactions in the determination of relative as well as absolute nitrogen isotopic abundances was demonstrated at 4.3 MeV bombarding energy. Supported in part by the International Atomic Energy Agency, Vienna, Austria.     

Cross sections for fast-neutron interaction with erbium isotopes

Cross-sections for (n,2n), (n,p), (n,α), and (n,d*) (The expression (n,d*) cross section used in this work includes a sum of (n, d), (n, np) and (n, pn) cross sections) reactions have been measured on erbium isotopes at the neutron energies from 13.5 to 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Data are reported for the following reactions: ¹⁶²Er(n,2n)¹⁶¹Er, ¹⁶⁴Er(n,2n)¹⁶³Er, ¹⁶⁸Er(n,α)^165mDy, ¹⁶⁶Er(n,p)^166gHo, ¹⁷⁰Er(n,α)¹⁶⁷Dy, ¹⁶⁸Er(n,p)^168m+gHo, ¹⁷⁰Er(n,p)^170gHo, and ¹⁷⁰Er(n,d*)¹⁶⁹Ho. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.0 and l JEFF-3.1/A libraries.     

Neutron induced reactions at the Athens Tandem Accelerator NCSR “Demokritos”

The neutron facility at the 5.5 MV tandem T11/25 Accelerator of NCSR “Demokritos” can deliver monoenergetic neutron beams in the energy range from thermal to 450 keV, 4–11.5 MeV and 16–20.5 MeV via the ⁷Li(p,n), ²H(d,n) and ³H(d,n) reactions, respectively. The flux variation of the neutron beam is monitored by using a BF₃ counter and a liquid scintillator BC501A detector. The ²³²Th(n,2n)²³¹Th and ²⁴¹Am(n,2n)²⁴⁰Am as well as (n,2n), (n,p) and (n,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method. The cross section values have been determined relative to the ¹⁹⁷Au(n,2n)¹⁹⁶Au, ²⁷Al(n,α)²⁴Na and ⁹³Nb(n,2n) reference reaction cross sections.     

Titanium(<Emphasis Type="SmallCaps">IV</Emphasis>) chloride complexes with chiral tetraaryl-1,3-dioxolane-4,5-dimethanol ligands as a new type of catalysts of ethylene polymerization

Titanium complexes of chiral ligands, (4R,5R)-2,2-dimethyl-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4,5-dimethanol and its structural analogs, activated by polymethylalumoxane catalyze ethylene polymerization with an activity from 3 to 530 (kg polyethylene) (mol Ti h atm)⁻¹. An increase in the bulk of the aryl substituents results in a decrease in the catalytic activity of the complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2275–2280, October, 2005.     

Hydrothermal synthesis and structural characterization of novel α-Keggin unit-supported Cu(II)- and Mn(II)-bipyridine complexes from a <Emphasis Type="Italic">tri</Emphasis>-lacunary precursor

Blue [{Cu(2,2′-bipy)₂}₂{α-SiW₁₂O₄₀}] (bipy = bipyridyl) (1) and pale yellow [Mn(2,2′-bipy)₃]₂[α-SiW₁₂O₄₀] (2) have been synthesized hydrothermally and characterized by IR spectroscopy and single crystal X-ray structure analysis. In 1, the [α-SiW₁₂O₄₀]⁴⁻ ion acts as a bridge between the two [{Cu(2,2′-bipy)₂]²⁺ moieties via coordination through the terminal oxygen atoms, while in 2, the [Mn(2,2′-bipy)₃]²⁺ ion balances the charge on the polyoxo anion without forming any covalent bond. To the best of our knowledge, this is the first example of transition metal-mediated transformation of [α-SiW₉O₃₄]¹⁰⁻ to [α-SiW₁₂O₄₀]⁴⁻. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A Dehydrogenated Cycloadduct of N-Phenylmaleimide and the Azomethine Ylide Derived from Ninhydrine and Phenylalanine: Structure and Conformation

Summary.  The structure of the dehydrogenation product 1′,3a′-dihydro-3′-((1,3-dioxoindan-2-ylidene)-phenyl-methyl)-5′-phenyl-spiro-(indan-2,1′-pyrrolo[3,4-c]pyrrole)-1,3,4′,6′-(5′H, 6a′H)-tetrone derived from the cycloadducts (±)-(3a′S,6a′R)-1′,3a′-dihydro-3′-((R)-α-(1,3-dioxoindanyl)-benzyl)-5′-phenyl-spiro-(indan-2,1′-pyrrolo[3,4-c]pyrrole)-1,3,4′,6′(5H,6a′H)-tetrone and/or (±)-(3a′S,6a′R)-1′,3a′-dihydro-3′-((S)-α-(1,3-dioxoindanyl)-benzyl)-5′-phenyl-spiro-(indan-2,1′-pyrrolo[3,4-c]pyrrole)-1,3,4′,6′(5H,6a′H)-tetrone, which were synthesized by 1,3-dipolar cycloaddition of N-phenylmaleimide to 2-((2-(1,3-dioxoindan-2-yl)-2-phenyl-ethenyl)-imino)-indan-1,3-dione, was determined by X-ray analysis. Crystal data (CCD, 180 K): rhombohedral, R&3macr;;, a = 34.0871(7), c = 13.9358(5) ?, Z = 18; the structure was solved by direct methods and refined by full-matrix least-squares procedures to R(F, I ≥ 3σ(I)) = 0.053. The molecule contains a central folded ring system of two cis-fused 5-membered heterocyclic rings; each ring is nearly planar, and the angle between the rings amounts to 59.0°. Dynamic ¹H NMR spectroscopy of the product revealed an exchange process caused by restricted rotation of the double bonded 1,3-indandione moiety and the phenyl group about the C_sp2-C_sp2 single-bonds. Molecular modeling and complete lineshape analysis indicated a four site exchange process for which free energies of activation and free energies could be established. ΔG ^‡ values for the barriers of rotation are in the range of 57–59 kJ · mol^− 1 at 273 K, which is unusually high for an unsubstituted phenyl group. Received May 3, 2001. Accepted (revised) June 8, 2001     

Oxidation of secondary alkanols with the system cerium ammonium nitrate—lithium bromide into ketones, α-bromo ketones,and α,α′-dibromo ketones

Oxidation of secondary alkanols with the system Ce(NH₄)₂(NO₃)₆—LiBr in aqueous acetonitrile gave ketones, α-bromo ketones, or α,α′-dibromo ketones. The selectivity of the reaction under standard conditions depends only on the molar ratio of the reagents (alkanol: Ce^IV: LiBr).     

Etude de quelques reactions nucleaires induites par les neutrons rapides de pile

Conclusion Dans une première partie, l’étude des réactions engendrées par les neutrons rapides de pile sur douze éléments a montré que certaines de celles-ci pouvaient être utilisées pour un dosage quantitatif. Dans une seconde partie, nous proposons un dosage radiochimique du silicium par la réaction²⁸Si(n, p)²⁸Al qui a, dans nos conditions de travail, sa limite de détermination à 620 μg. A titre de comparaison, signalons que cette limite se situe par irradiation avec des neutrons de 14 MeV, produits au moyen d’un accélérateur (flux de 5·10⁸ n·cm⁻²·sec⁻¹), à environ 10 μg. Le dosage non destructif du silicium dans le diméthylpolysilane est décrit.

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In the first part, the fast-neutron flux available in reactor cores was utilized to define experimentally the sensitivity for the determination of 12 different elements, based on fast-neutron nuclear reactions. The fluxes available with our AGN-201 P reactor are in the range of 10⁹–10¹⁰ n·cm⁻²·sec⁻¹ in the 1–4 MeV region. A good sensitivity was obtained for²⁷Al,⁵²Cr,⁵⁶Fe,²⁸Si,²³Na [by (n, p) reaction],²⁷Al,³¹P,⁸⁹Y [by (n, α) reaction] and¹⁹⁷Au,¹⁸³W,⁸⁹Y [by (n, n′) reaction]; the elements Cl, Ca, Pb failed to give reactions. In the second part, a non-destructive method for the determination of silicium based on the reaction²⁸Si(n, p)²⁸Al is proposed. The limit of determination is about 0.6 mg for a neutron flux of 10⁹ n·cm⁻²·sec⁻¹. As an example, Si in dimethylpolysilane was determined.

     

Determination of the fission averaged cross sections of some threshold reactions induced on chlorine, potassium, and calcium, and their role in the development of self-validated methods of neutron activation analysis

The feasibility of validating data obtained in the determination of chlorine, potassium, and calcium by neutron capture activation analysis, through their determination using threshold reactions has been studied. To this purpose the authors experimentally determined the following fission neutron spectrum averaged cross sections (in mb):³⁷Cl(n,p)³⁷S, 0.234±0.015;⁴¹K(n,α)³⁸Cl, 0.740±0.044;⁴²Ca(n,p)⁴²K, 3.09±0.22;⁴³Ca(n,p)⁴³K, 2.27±0.12;⁴⁴Ca(n,p)⁴⁴K, 0.074±0.013. The application of these values to the analysis of some reference materials are presented. Also, the problem of mutual interferences has been addressed for the following pairs:³⁶S(n,Γ)³⁷S and³⁷Cl(n,p)³⁷S;³⁷Cl(n,Γ)³⁸Cl and⁴¹K(n,α)³⁸Cl;⁴¹K(n,ψ)⁴²K and⁴²Ca(n,p)⁴²K.     

Recent developments in the analytical application of prompt spectrometry

A survey of the possibilities of analysis by alpha-induced prompt gamma-ray spectrometry is reported for 57 elements at a bombarding energy of 5 MeV. Additional data obtained at 11 and 16 MeV are given. Interference-free sensitivities are presented. The use of the position sensitive detector is introduced to overcome problems such as occur in prompt alpha spectrometry from (p, α) reactions. The technique is illustrated by studies on the reaction¹⁹F(p, α)¹⁶O and severely tested for boron analysis using the reaction¹¹B(p, α)⁸Be and measuring the α₀ and α₁ groups.     

The Solvent-Like Nature of Silica Particles in Organic Solvents

 Kamlet-Taft’s α (hydrogen bond donor acidity) and π^* (dipolarity/polarizability) values of various silica batches measured in various solvents are presented. The α and π^* parameters for the various solid acids are analyzed by means of Fe(phen)₂(CN)₂ (cis-dicyano-bis-(1,10)-phenanthroline-iron(II), 1), Michler’s ketone (4,4′-bis-(dimethylamino)-benzophenone, 2), and two hydrophilic derivatives of 2, (4-(dimethylamino)-4′-(di-2-hydroxyethyl)-amino-benzophenone (3a) and 4,4′-bis-(di-(2-hydroxyethyl)-amino)-benzophenone (3b) as well as coumarin 153 (4) as solvatochromic surface polarity indicators. Apparent β (hydrogen bond acceptor basicity) parameters for bare silica have been evaluated by means of an aminobenzodifuranone dye (5) as solvatochromic probe. The chemical interpretation of the α and π^* parameters and the nature of the solvent/surface interaction which they reflect are discussed. It can be shown that an increase of the HBA (hydrogen bond accepting) capacity of the solvent significantly decreases the HBD (hydrogen bond donating) capacity of the surface environment, whereas the dipolarity/polarizability value of the silica/solvent interface is a composite of many effects. The classification of the polarity of silica particles in organic solvents compared to pure liquids is outlined.     

Pseudo[3]rotaxane Type Compelxation between α- and β-Cyc1odextrins and N,N′-Dsiheptyl-4,4′-bipyridinium

Pseudo[3]rotaxane type complexation of α- and β-cyclodextrins (α- and β-CDs, respectively) with N,N′-Diheptyl-4,4′-bipyridinium (diheptyl viologen; HV²⁺) was investigated. A spectral displacement method using p-nitrophenol as a dye revealed that α-CD and HV²⁺ formed a 2:1 host-guest complex with stability constants being 3280 and 976 M⁻¹ as the first and second steps of complexation, respectively. ¹H-NMR spectra strongly indicated that α-CD accommodated the heptyl groups of HV²⁺. Although previous studies based on circular dichroism spectroscopy suggested the primary hydroxy side of α-CD faced to the positively charged bipyridinium moiety od HV²⁺, 2D-NMR studies clearly demonstrated that the secondary hydroxy side of α-CD faced to the bipyridinium moiety. β-CD also formed a 2:1 complex with HV²⁺ with a similar fashion.     

The Solvent-Like Nature of Silica Particles in Organic Solvents

Summary.   Kamlet-Taft’s α (hydrogen bond donor acidity) and π^* (dipolarity/polarizability) values of various silica batches measured in various solvents are presented. The α and π^* parameters for the various solid acids are analyzed by means of Fe(phen)₂(CN)₂ (cis-dicyano-bis-(1,10)-phenanthroline-iron(II), 1), Michler’s ketone (4,4′-bis-(dimethylamino)-benzophenone, 2), and two hydrophilic derivatives of 2, (4-(dimethylamino)-4′-(di-2-hydroxyethyl)-amino-benzophenone (3a) and 4,4′-bis-(di-(2-hydroxyethyl)-amino)-benzophenone (3b) as well as coumarin 153 (4) as solvatochromic surface polarity indicators. Apparent β (hydrogen bond acceptor basicity) parameters for bare silica have been evaluated by means of an aminobenzodifuranone dye (5) as solvatochromic probe. The chemical interpretation of the α and π^* parameters and the nature of the solvent/surface interaction which they reflect are discussed. It can be shown that an increase of the HBA (hydrogen bond accepting) capacity of the solvent significantly decreases the HBD (hydrogen bond donating) capacity of the surface environment, whereas the dipolarity/polarizability value of the silica/solvent interface is a composite of many effects. The classification of the polarity of silica particles in organic solvents compared to pure liquids is outlined. Theoretical E _T(30) values of the solid/solvent interfaces are calculated by applying linear solvation energy (LSE) relationships using the independently measured α and π^* values of the solid acids according to Received February 2, 2001. Accepted (revised) March 3, 2001     

Charged particle activation analysis of phosphorus in biological materials

Charged particle activation analysis of phosphorus in biological materials using the³¹P (α,n)^34mCl reaction has been studied. Since^34mCl is also produced by the³²S (α,pn) and the³⁵Cl (α, α′ n) reactions, the thick-target yield curves on phosphorus, sulfur and chlorine were determined in order to choose the optimum irradiation conditions. As a result, it was found that the activation analysis for phosphorus without interferences from surfur and chlorine is possible by bombarding with less than 17 MeV alphas. The applicability of this method to biological samples was then examined by irradiating several standard reference materals. It was confirmed that phosphorus can readily be determined at the detection limit of 1 μg free from interferences due to the matrix elements.