A measurement of the Li(n,α) cross-section

The relative shape of the ⁶Li(n,α)/²³⁵U(n,f) cross-section ratio has been determined in the range of incident neutron energy from 2 to 800 keV. The measurements were made by the time-of-flight method using the Harwell 45 MeV linac to provide the pulsed source of neutrons. A thin ⁶Li-glass scintillator was used to register the (n,α) events, and the (n,f) events (in a metallic sample of ²³⁵U) were registered with fission neutron detectors. The shape of the ⁶Li(n,α) cross-section was obtained by combining the measured ⁶Li(n,α)/²³⁵U(tn,f) cross-section ratio with an evaluation of the ²³⁵U(n,f) cross-section. The cross-section so derived was placed on an absolute scale by normalization in the neutron energy interval 2–10 keV, where the ⁶Li(n,α) cross-section is accurately known. The cross-section at the peak of the prominent p-wave resonance near 240 keV is found to be 3.29 ± 0.12 b. The results are compared with other measurements and also with a recent theoretical calculation of the cross-section.     

Primary study on holdup measurement of ^235U in pipe using γ-ray spectrometry and Monte Carlo simulation

The pipe holdup measurement is very important for decommissioning nuclear facilities and nuclear-material control and accounting. The absolute detection efficiencies （εsp） of full-energy γ rays peak under different source density distribution function have been simulated using the Monte Carlo （MC） software, and the counting rates （no） of the characteristic γ rays have been measured using the γ spectrometer followed by the calculation of the holdup. The holdup is affected by the energy of γ rays, distance at which they are detected, pipe material, thickness, and source distribution of pipe, especially source distribution at a short distance. The comparative test of ^235U reference materials on the inner wall of Fe and A1 pipes （the total mass of ^235U is 44.6 mg and 222.8 mg, respectively） have been accomplished using this method. The determined result of ^235U is 43.2mg （U0.95rel=5.4%） and 216.2mg （U0.95rel= 3.2%）, respectively, which are in accordance with the reference values.     

Cross-sections of B(p,α)Be reaction for boron analysis

Nuclear reaction, ¹¹B(p,α)⁸Be, shows great potentials in boron characterization of materials due to its large cross-section at the broad resonance at 660 keV. Unfortunately, the existing cross-section data on this reaction show errors of up to 30% and inconsistency as high as 50%. All previously published cross-sections of this reaction were based on assumptions or on more or less arbitrary convention. We present an accurate measurement of the cross-sections of nuclear reaction ¹¹B(p,α₁)⁸Be^* using self-supported ¹¹B foil target, high resolution detection and careful analysis of the α-spectra. An accurate cross-section with α₁ was obtained with careful spectrum stripping of α₁ from the α₁₂ continuum. Cross-section with α₁+α₁₂ under more definite and realistic convention is also given for practical applications. Cross-sections are given in graphical form for θ_lab=150°.     

Excitation functions of alpha-particle induced nuclear reactions on natural ytterbium

Excitation functions of the reactions ^natYb(α,xn)^{170,171,173,175,177m2}Hf, ^natYb(α,x)^{171g,172g,177g,178m}Lu and ^natYb(α,x)^169g,177gYb have been measured up to 39 MeV, among them seven (^{170,171,173,177m2}Hf, ^177g,178mLu, ^177gYb) are reported for the first time. The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE and to the only data-set found in the literature. Yields of different production routes of the therapeutically relevant ¹⁷⁷Lu are compared.     

Measurement of (n,α) cross-sections for short-lived products by 13.4–14.9 MEV neutrons

Twelve (n,α) activation cross-sections leading to short-lived nuclei with half-lives between 37s and 15 min were measured in the energy range between 13.4 and 14.9 MeV by the activation method. The measured reactions involved the isotopes of ²⁶Mg, ³⁰Si, ³¹P, ⁵⁴Cr, ⁶³Cu, ⁶⁴Ni, ⁶⁹Ga, ⁷¹Ga, ⁸⁷Rb, ⁸⁹Y, ¹⁰⁴Ru and ¹¹²Cd as the target. The intense 14 MeV neutron source facility (OKTAVIAN) at Osaka University was used for irradiation. The γ-rays emitted from the irradiated samples were measured with high-purity germanium detectors. All cross-section values were obtained relative to the standard cross-section of the ²⁷Al(n,α)²⁴Na reaction. The cross-sections of three reactions were measured for the first time. The present experimental data were discussed by comparing them with previously reported experimental data and the evaluated data of JENDL-3 and ENDF/B-VI. Six evaluated items of data in JENDL-3 show reasonable agreement (within 7%), but the evaluation of the ²⁶Mg(n,α) reaction is 25% higher than our data. Two items of evaluation data of ENDF/B-VI agree well, and one agrees within 25%.     

Investigation of activation cross-sections of deuteron induced reactions on vanadium up to 40 MeV

Experimental excitation functions for deuteron induced reactions up to 40 MeV on natural vanadium were measured with the activation method using a stacked foil irradiation technique. From high resolution gamma spectrometry cross-section data for the production of ⁵¹Cr, ⁴⁸V, ^48,47,46Sc and ⁴⁷Ca were determined. Comparisons with the earlier published data are presented and results for values predicted by different theoretical codes are included. Thick target yields were calculated from a fit to our experimental excitation curves and compared with the earlier experimental data. Depth distribution curves used for thin layer activation (TLA) are also presented.     

Activation cross sections of the Yb(p,xn)Lu reaction for indirect production of the therapeutic radionuclide Yb

Activation cross sections of the ^natYb(p,xn)¹⁶⁹Lu reaction have been measured for the first time up to 70 MeV to investigate the production possibility of the radionuclide ¹⁶⁹Yb through decay of its parent ¹⁶⁹Lu. The cross sections were measured using the stacked foil irradiation technique and gamma spectrometry. The experimental data were compared with the results of the ALICE-IPPE theoretical model code. Different production routes were compared for the internal radiotherapy related radioisotope ¹⁶⁹Yb. Above 30 MeV proton energy the integral yield of the ^natYb(p,xn)¹⁶⁹Lu reaction is higher than that of the earlier investigated ¹⁶⁹Tm(p,n)¹⁶⁹Yb, ¹⁶⁹Tm(d,2n)¹⁶⁹Yb, ^natEr(α,xn)¹⁶⁹Yb, ^natYb(α,x)¹⁶⁹Lu and ^natHf(p,x)¹⁶⁹Lu reactions at the equivalent particle energies.     

Evaluation of neutron nuclear data for Technetium-99

Neutron nuclear data of ⁹⁹Tc was evaluated, considering cross-sections and spectra provided from recent experiments. The evaluation was made in the incident neutron energy range from 1 keV to 20 MeV, using the optical model and nuclear reaction models. The optical model calculation based on the coupled-channels method was performed for the interaction of neutrons with ⁹⁹Tc, and potential parameters appropriately chosen reasonably explain the measured data of total cross-section. The cross-section of inelastic scattering, capture, (n, 2n), (n, p), (n, α) and (n, n′α) reactions, and γ-ray emission spectra were calculated on the basis of statistical model with preequilibrium and direct components, and they were compared with available experimental data. It is found that the presently evaluated cross-sections and γ-ray emission spectra well reproduce those experimental values and that there is a large discrepancy among the present result and evaluated data for neutron emission spectra. The obtained capture cross-section increases at the energies below 1 MeV, relative to that in JENDL-4.0. This makes the transmutation efficiency of ⁹⁹Tc into stable ¹⁰⁰Ru by accelerator driven system enhanced. The production cross-section of ⁹⁹Mo important for the medical use of nuclear diagnostics reduces by 5–30% at the energies above 12 MeV, compared with JENDL-4.0.     

Excitation functions of Ir formed in proton-induced reactions on highly enriched Os up to 66 MeV

Cross sections of proton-induced nuclear reactions on highly enriched ¹⁹²Os were measured up to 66 MeV by using the stacked-foil irradiation technique. Excitation functions are presented for the reactions ¹⁹²Os(p,n)¹⁹²Ir, ¹⁹²Os(p,3n)¹⁹⁰Ir, ¹⁹²Os(p,4n)¹⁸⁹Ir, ¹⁹²Os(p,5n)¹⁸⁸Ir, ¹⁹²Os(p,6n)¹⁸⁷Ir and ¹⁹²Os(p,7n)¹⁸⁶Ir. No earlier experimental cross-section data could be found in the literature except for the ¹⁹²Os(p,n)¹⁹²Ir process. Our new experimental results are compared with theoretical predictions by means of the theoretical model code ALICE/ASH. Integral thick-target yield calculations were also performed for the ¹⁹²Os(p,n)¹⁹²Ir and ¹⁹²Os(p,3n)¹⁹⁰Ir reactions to evaluate the ¹⁹⁰Ir contamination level, as a function of energy, in the case of ¹⁹²Ir productions.     

Measurement of thermal neutron cross-section and resonance integral for the Ho(n,γ)Ho reaction using electron linac-based neutron source

The thermal neutron cross-section and the resonance integral of the ¹⁶⁵Ho(n,γ)^166gHo reaction have been measured by the activation method using a ¹⁹⁷Au(n,γ)¹⁹⁸Au monitor reaction as a single comparator. The high-purity natural Ho and Au foils with and without a cadmium shield case of 0.5 mm thickness were irradiated in a neutron field of the Pohang neutron facility. The induced activities in the activated foils were measured with a calibrated p-type high-purity Ge detector. The correction factors for the γ-ray attenuation (F_g), the thermal neutron self-shielding (G_th), the resonance neutron self-shielding (G_epi) effects, and the epithermal neutron spectrum shape factor (α) were taken into account. The thermal neutron cross-section for the ¹⁶⁵Ho(n,γ)^166gHo reaction has been determined to be 59.7 ± 2.5 barn, relative to the reference value of 98.65 ± 0.09 barn for the ¹⁹⁷Au(n,γ)¹⁹⁸Au reaction. By assuming the cadmium cut-off energy of 0.55 eV, the resonance integral for the ¹⁶⁵Ho(n,γ)^166gHo reaction is 671 ± 47 barn, which is determined relative to the reference value of 1550 ± 28 barn for the ¹⁹⁷Au(n,γ)¹⁹⁸Au reaction. The present results are, in general, good agreement with most of the previously reported data within uncertainty limits.     

On the Lambropoulos-Luco's δ-“no go” conjecture in variational flux synthesis

The Lambropoulos-Luco's δ-“no go” conjecture and related controversies in the domain of the variational flux synthesis with discontinuous trial functions are completely resolved in terms of the functionals, ^(±)δ⁽ⁿ⁾(x − x_o), in the frame of the new spaces of functionals, which are topological dual spaces of discontinuous complex valued functions spaces occurring with left and right continuities.     

Study of activation cross-sections of deuteron induced reactions on rhodium up to 40 MeV

In the frame of a systematic study of the activation cross-sections of deuteron induced nuclear reactions, excitation functions of the ¹⁰³Rh(d,x) ^100,101,103Pd, ^{100g,101m,101g,102m,102g}Rh and ^103gRu reactions were determined up to 40 MeV. Cross-sections were measured with the activation method using a stacked foil irradiation technique. Excitation functions of the contributing reactions were calculated using the ALICE-IPPE, EMPIRE-II and TALYS codes. From the measured cross-section data integral production yields were calculated and compared with experimental integral yield data reported in the literature. From the measured cross-sections and previous data, activation curves were deduced to support thin layer activation (TLA) on rhodium and Rh containing alloys.     

Nuclear Data Sheets for A=75

The experimental nuclear data for mass=75 have been reviewed, superceding 1981 evaluation by Ekstrom (81Ek02). Detailed level and decay schemes together with summary (adopted), arguments for Jπ assignments and experimental data of the known nuclei (Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb) are presented. ⁷⁵Cu has been identified as a β⁻ delayed neutron emission precursor while ⁷⁵Ga has been studied in detail in ⁷⁵Zn β⁻ decay recently. In ⁷⁵Ge, there are quite a few new data available, specially on particle-transfer reactions. Not much new information is known for ⁷⁵As except for a particle transfer reaction and ⁷⁵Se ε decay. The same is true for ⁷⁵Se except for a neutron capture study. New data have been reported for ⁷⁵Kr and ⁷⁵Br.     

The solid solubility of Fe in α-Zr: A secondary ion mass spectrometry study

Secondary ion mass spectrometry techniques have been used to determine the terminal solid solubility (TSS) of Fe in α-Zr. Single crystals of nominally pure and Fe-doped α-Zr were annealed in the temperature range 770–1100 K to promote equilibration of Fe between surface Zr₃Fe precipitates, or β-Zr(Fe), and α-Zr. The results are fair in overall agreement with a recent investigation, based on thermoelectric power measurements, but they differ in detail. In particular this work indicates two regions of temperature dependence: above 930 K the TSS (ppma) is given by C_Fe = 1.56 × 10¹⁰exp(−1.70 ± 0.05 eV/kT), at lower temperatures a weaker temperature dependence is associated with extrinsic effects. In addition, the eutectoid temperature is shown to lie between 1063 and 1068 K.     

A New Comparison of Empirical and Semi-empirical Formulae for the (n, 3He) Reaction Cross-sections at 14–15 MeV

New empirical and semi-empirical formulae have been suggested for the (n, ³He) reaction cross-sections with dependent on asymmetry parameter, S = (N − Z)/A. The (n, ³He) reaction cross-sections at the energy of 14–15 MeV have been investigated for two different parameters groups by the classification of nuclei into 31 ≤ A ≤ 103 and 133 ≤ A ≤ 181. The obtained results have been compared with the other systematics and experimental data for the (n, ³He) reaction cross-sections. Some improvement has been got in describing the (n, ³He) reaction cross-sections compared with the existing relations.     

Activity level of gross α and gross β in airborne aerosol samples around the Qinshan NPP

The monitoring results of gross α and gross β activity from 2001 to 2005 for environmental airborne aerosol samples around the Qinshan NPP base are presented in this paper. A total of 170 aerosol samples were collected from monitoring sites of Caichenmen village, Qinlian village, Xiajiawan village and Yangliucun village around the Qinshan NPP base. The measured specific activity of gross α and gross β are in the range of 0.02 - 0.38 mBq/m^3 and 0.10 - 1.81 mBq/m^3, respectively, with an average of 0.11 mBq/m^3 and 0.45mBq/m^3, respectively. They are lower than the average of 0.15 mBq/m^3 and 0.52mBq/m^3, of reference site at Hangzhou City. It is indicated that the specific activity of gross α and gross β for environmental aerosol samples around the Qinshan NPP base had not been increased in normal operating conditions of the NPP.     

Neutron excitation functions for Sc, Nb, and Ni in the energy range 13–19 MeV

Activation techniques have been used to measure the excitation functions for ⁴⁵Sc(n, 2n)^{44m + g}Sc and Nb(n,2n)^92mNb in the energy range 13–19 MeV and ⁵⁸Ni(n,p)^{58m + g}Co and ⁵⁸Ni(n,2n)⁵⁷Ni in the energy range 13–17 MeV. The neutrons were produced by the ³H(d,n)⁴He reaction with the Auburn University 3 MV Dynamitron accelerator. Absolute cross-sections were measured using the mixed powder method with ²⁷Al(n,α)²⁴Na as the monitor reaction. The experimental isomeric-yield ratios were determined by measuring the ground state gamma activity resulting from the reaction and making a least squares fit to the time behavior of the activity in which the cross-section ratio was treated as a variable parameter. Cross-sections calculated from the semi-empirical relation due to Pearlstein are given for qualitative comparisons with the present results.     

Measurement of α particle energy loss in biological tissue below 2 MeV

The energy loss of α particles crossing biological tissue at energies between 0.8 and 2.2 MeV has been measured. This energy range is very important for boron neutron capture therapy, based on the ¹⁰B(n,α)⁷Li reaction, which emits α particles with energies of 1.78 and 1.47 MeV. One of the methods used for the measurement of the boron concentration in tissue is based on the deconvolution of the α spectra obtained from neutron irradiation of thin (70 μm) tissue samples. For this technique, a knowledge of the behaviour of the energy loss of the particles in the irradiated tissue is of critical importance. In particular, the curve of the residual energy as a function of the distance travelled in the tissue must be known. In this paper, the results of an experiment carried out with an ²⁴¹Am source and a series of cryostatic sections of rat-lung tissue are presented. The experimental measurements are compared with the results of Monte Carlo calculations performed with the MCNPX code.     

Effect of irradiation by 140 Mev Ag ions on the optical and electrical properties of polypropylene/TiO2 composite

Changes in the optical, structural, dielectric properties and surface morphology of a polypropylene/TiO₂ composite due to swift heavy ion irradiation were studied by means of UV–visible spectroscopy, X-ray diffraction, impedance gain phase analyzer and atomic force microscopy. Samples were irradiated with 140 MeV Ag¹¹⁺ ions at fluences of 1 × 10¹¹ and 5 × 10¹² ions/cm². UV–visible absorption analysis reveals a decrease in optical direct band gap from 2.62 to 2.42 eV after a fluence of 5 × 10¹² ions/cm². X-ray diffractograms show an increase in crystallinity of the composite due to irradiation. The dielectric constants obey the Universal law given by ε α f ⁿ⁻¹, where n varies from 0.38 to 0.91. The dielectric constant and loss are observed to change significantly due to irradiation. Cole–cole diagrams have shown the frequency dependence of the complex impedance at different fluences. The average surface roughness of the composite decreases upon irradiation.