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ITO International Research Center, on the campus of the University of Tokyo, June 1 to 6, 2014; http://ribf.riken.jp/ARIS2014/index.html

The age of a recent, i.e., fresh, nuclear event can be determined by measuring the activity of short-lived parent and daughter fission products. The event studied was a short irradiation, of a small sample of uranium, in a nuclear reactor. Two clocks were investigated, 92Sr-92Y and 135I-135Xe. Measurements of the source by gamma-spectrometry yielded very good agreement between true and measured ages. The upper and lower age limits of applicability for the clocks in question were defined. The half-life of 92Sr was found 2.635±0.008 hours and of 135I 6.65±0.04 hours.

The present paper reports a new precision measurement of the cross sections of the direct capture reaction 3He(4He,γ)7Be in the region of E c.m. = 400 keV to 950 keV by measuring the ensuing 7Be activity. This reaction plays an important role in determining the high energy solar neutrino flux and in understanding the abundances of primordial 7Li. Various recent theoretical models are fitted to obtain a consistent extrapolated value of S34(0) = 0.53(2)(1) keV-b.

Production of the radiopharmaceutical nuclide 177Lu, by direct thermal neutron activation of 176Lu, poses a discrepancy between experimentally measured and theoretically predicted activities. It was found that in the irradiation at the pneumatic transfer tube ('Rabbit') of the IRR-1 reactor, the exper./theor. ratio was 1.858±0.051. This ratio was determined also by comparing the activities of 177Lu and 176mLu. The significant deviation of 176Lu from the 1/v behavior explained this disagreement. The ratio exper./theor. is the Westcott g(T n )-factor and was used to yield the neutron temperature T n = 311±8 K.

The age of a nuclear event can be determined by measuring the activity of two fission products. The event studied was a short irradiation, of a small sample of uranium, in a nuclear reactor. Two types of a clock were investigated: non-isobaric and isobaric parent–daughter fission products. Measurements of the source by gamma spectrometry yielded very good agreement between true and measured ages. The accuracy of each clock and the upper and lower age limits of applicability were studied.

Among the many production and destruction nuclear reactions that bear on the net 44 Ti yield in the supernova environment, recently highlighted by γ-ray astronomy observations, the α capture on 40 Ca stands out in the α-rich freezeout phase conjectured by astrophysical models. We activate a He-gas target with a 40 Ca beam and implant recoiling 44 Ti nuclei (∼10 6 ) in a Cu catcher. The 44 Ti atoms chemicallyextracted with a nat Ti carrier are counted by accelerator mass spectrometry (AMS). The measurement of the 44 Ti/Ti ratio, together with the amount of Ti carrier added, determine the number of 44 Ti nuclei produced in the activation, independent of chemical yield or transmission efficiency. The resonance strength (7.4±2.5 eV) at E cm ∼1.1 MeV/n determined for two close-by levels of 44 Ti is in excellent agreement with previous prompt-γ measurements. We plan to extend our experiments to the lower energy range.

An important characteristic of a high-purity germanium detector for gamma spectrometry is the volume of the crystal, which relates to the detection efficiency and to the measured background level. The crystal dimensions provided by the detector manufacturer were used to calculate the crystal volume. The calculation method accounts for the various sub-volumes of the crystal, in particular the contact hole in the back face and the rounding of the 90° right edge in the front face. The calculation was corroborated using the INVENTOR(®) 3D software. The crystal volume was calculated to be 419.7 cm(3) compared with the 413 cm(3) stated by the manufacturer.

The algorithm used to calculate a minimum detectable activity (A(D)) of an environmental volume sample measured by gamma-ray spectrometry was modified and adapted for in situ measurements performed at the standard 1 m height above ground. AD values of target radionuclides were determined from the in situ spectra collected at two disparate sites. A linear relationship between the two sets of A(D)s was found and the ratio between these two sets is equal to the square root of the ratio of the two respective absorbed dose rates measured at the sites at 1 m height. Absorbed dose rates were calculated using the concentration of potassium, thorium and uranium in the soils at the sites and found to agree well with the measured values. A(D) values can be predicted easily in in situ gamma spectrometry applying a simple experimental procedure that is based on the linear relationship.

Passive gamma-ray spectrometry was applied to analyze the isotopic composition of uranium in U3O8. Depleted and enriched U3O8 standard reference materials were used to calibrate the system. An independent calibration was performed by standard gamma-ray point sources. U3O8 SRM samples of the 950 series were analyzed. The present results show that the isotopic abundances of 235U in SRMs 950, 950a and 950b are higher by +3.6, +0.9 and +0.9% (relative deviation) than the natural value 0.7200%, while relative precisions were ±0.4, ±0.7 and ±0.3%, respectively.

An analytical method for the determination of uranium enrichment in uranium oxide without using any calibration standards is described. Very good agreement between the measured and certified values was obtained in the analysis of a Standard Reference Material. Precise energies and emission probabilities were derived for two weak gamma-rays of234mPa: at 258.227±0.003 keV, (0.076±0.002)% and 742.813±0.005 keV, (0.106±0.002)%.

The concentration of 238U in a phosphate ore quarry was measured in situ. Independently, soil samples collected from the site were measured in the laboratory. It was found that radon emanation from the soil lowers in situ results that are derived from radon daughters. The uranium concentration was found to be 121.6±1.9 mg kg-1.

A new assembly dedicated for the low-level ψ-ray spectrometric measurements of environmental samples have been installed recently at the International Atomic Energy Agency's Laboratories, Seibersdorf. Calibration of the detection efficiency was performed by a set of 14 IAEA Certified Reference Materials, a standardized solution of134Cs, solutions of 2 pure potassium salts, and 2 mixed radionuclide gamma reference standard solutions. These materials, in 1.3 liter Marinelli beakers, were measured by a large HPGe detector. The high precision and accuracy of the calibration procedure is shown by the high significance achieved in the linear fits of the efficiency results, which are traceable to certified and standard reference materials. Small biases between some calibrands were detected. A new corrected result is the 1.37±0.05 Bq/kg activity concentration of137Cs in IAEA-A-14 Milk Powder.

This paper describes the amount-of-substance analysis of the long-lived naturally occurring radionuclides 40K, 232Th, 235U and 238U by the method of non-destructive passive gamma-ray spectrometry. Calibrands used were standard reference materials and high-purity analytical grade chemicals. Traceability of the measured results to reference materials was established. The emission probabilities of several high-energy gamma-rays were determined. High-energy gammas were measured to decrease the effect of gamma self-attenuation.

L'encre rouge de quatre fragments des Manuscrits de la Mer Morte a ete analysee par fluorescence X et diffraction X. Le pigment rouge a ete identifie comme un sulfure de mercure (HgS), le cinabre. La portee archeologique et historique de cette decouverte est commentee

We report on a new measurement of the cross section of this reaction, following our previous experiment with an implanted 7 Be target, a raster scanned beam and the elimination of the backscattering loss. Measurements were done at energies above and below the resonance as well as a detailed measurement of the resonance. We obtain an extrapolated value of S 17 (0) = 21.2 ± 0.7 from the entire set of measurements.

We report on a new cross-section measurement for the ${}^{3}$He($\ensuremath{\alpha}$, $\ensuremath{\gamma}$)${}^{7}$Be reaction at three medium energies of ${E}_{\mathrm{c}.\mathrm{m}.}$ between 1 and 3 MeV. The interest stems from the significant role played by the reaction in calculating an accurate solar neutrino flux and the primordial ${}^{7}$Li abundance. The energy dependence of the astrophysical ${S}_{34}$ factor observed in the present work, especially above 1 MeV, highlights the need to constrain theories in order to obtain a precise extrapolated value for ${S}_{34}(0)$. In this context, a comparison with the recent theoretical work in a fully microscopic fermionic molecular dynamics approach and a few other representative calculations emphasize the need for further experimental as well as theoretical work to resolve the existing conflicts.

A basic result in gamma spectrometry is the count rate of a relevant peak. Correction for decay during counting and expressing the count rate at the beginning of the measurement can be done by a multiplicative factor that is derived from integrating the count rate over time. The counting time substituted in this factor must be the live time, whereas the use of the real-time is an error that underestimates the count rate by about the dead-time (DT) (in percentage). This error of underestimation of the count rate is corroborated in the measurement of a nuclide with a high DT. The present methodology is not applicable in systems that include a zero DT correction function.

Two new species of materials were studied by neutron radiography: lithium-bearing ceramics and glasses, and titanium aluminide alloys. Various types of discontinuities, including voids and bulk density reduction, were detected. Hydrogen absorption by a titanium aluminide alloy was measured as a function of exposure lime, with ‘as received’ and polished samples. The interaction of hydrogen with the metal lattice is likely to cause embrittlement, leading to material failure by the loss of tensile ductility. The effects of a rough surface and an oxide layer on the rate of hydrogen absorption were observed

Instrumental neutron activation analysis (INAA) was applied to the rapid determination of aluminium in drinking water. Aluminium content was quantitatively determined by measuring the γ-ray photopeak at 1778 keV of the short-lived radionuclide28Al (half-life 2.25 min). The experimental procedure was aimed at reducing significantly all contributions to the background. The aluminium concentration in various sources of drinking water was found to range from 80 to 170 μg·1−1, well within the recommended European Standard of 200 μg·1−1. The limit of detection (LOD), when assaying a sample of 10 ml under the specified experimental conditions, is 100 ng of Al.

The concentration of cobalt in 2 solid matrices was determined by neutron activation analysis (NAA) using standard solutions which were prepared by dissolving pure cobalt in nitric acid. The matrices assayed were a cobalt-aluminium wire and an iron foil and the respective Co concentrations found were 0.488% and 0.138%. Both solid materials can equally be used as standard references of cobalt in NAA. Subcadmium and epicadmium neutron fluxes in the reactor core were determined using Co−Al and Au−Al alloy wires. Very good agreement was obtained for all irradiation configurations of the target monitors cobalt and gold.

The electron-capture (EC) decay rate of $^{7}\mathrm{Be}$ in metallic Cu host and the ${\ensuremath{\beta}}^{\ensuremath{-}}$-decay rate of $^{198}\mathrm{Au}$ in the host alloy Al-Au have been measured simultaneously at several temperatures, ranging from 0.350 K to 293 K. No difference of the half-life of $^{198}\mathrm{Au}$ between 12.5 K and 293 K is observed to a precision of 0.1%. By utilizing the special characteristics of our double-source assembly, possible geometrical effects that influence the individual rates could be eliminated. The ratio of $^{7}\mathrm{Be}$ to $^{198}\mathrm{Au}$ activity thus obtained also remains constant for this temperatures range to the experimental precision of $0.15\ifmmode\pm\else\textpm\fi{}0.16%$. The resulting null temperature dependence is discussed in terms of the inadequacy of the often-used Debye-H\"uckel model for such measurements.

The half-life of 176 Lu was determined by measuring the disintegration rate of a solution of lutetium oxide, using a calibrated HPGe detector, and found to be (3.69±0.02)×10 10 y. It is recommended that the current adopted value be calculated from the grouping of three published values since 1983, including our value, the weighted mean of which is (3.73±0.01)×10 10 y.

A controlled and precise determination of the cross sections of the fusion reactions {sup 7}Be(p,{gamma}){sup 8}B and {sup 3}He({sup 4}He,{gamma}){sup 7}Be, which play an important role in determining the solar neutrino flux, necessitates the knowledge of a precise value of the electron-capture half-life of {sup 7}Be. This half-life may depend on the material hosting the {sup 7}Be atoms via small modifications of the electron density around the {sup 7}Be nucleus. In this brief communication we report on the measurement of {sup 7}Be implanted in four materials: copper, aluminum, sapphire, and PVC. The four results are consistent with a null host dependence within two standard deviations and their weighted average of 53.236(39) d agrees very well with the adopted value in the literature, 53.22(6) d. The present results may exhibit a slight (0.22%) increase of the half-life at room temperature for metals compared to insulators that requires further studies.

Energy-dispersive X-ray fluorescence (XRF) was employed for the determination of chemical element abundances in silver and copper coins and associated casting items of a hoard discovered in an antique minting facility. The precise and accurate results obtained lead to conclusions about material batches used in the casting, and about concentration variation phenomena occurring at the coin surfaces. The validity of the present method was checked by participating in an intercomparison.

The 3He(4He,gamma) 7Be reaction plays an important role in determining the high energy solar neutrino flux and in understanding the abundances of primordial 7Li. This Letter reports a new precision measurement of the cross sections of this direct capture reaction, determined by measuring the ensuing 7Be activity in the region of Ec.m.=420 to 950 keV. Various recent theoretical fits to our data result in a consistent extrapolated value of S34(0)=0.53(2)(1) keV b.

The 3He(4He,gamma) 7Be reaction plays an important role in determining the high energy solar neutrino flux and in understanding the abundances of primordial 7Li. This Letter reports a new precision measurement of the cross sections of this direct capture reaction, determined by measuring the ensuing 7Be activity in the region of Ec.m.=420 to 950 keV. Various recent theoretical fits to our data result in a consistent extrapolated value of S34(0)=0.53(2)(1) keV b.

The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted target, a raster scanned beam and the elimination of backscattering losses. The new measurement incorporates a higher activity 7Be target and a number of improvements in design and procedure. The cross section at Ec.m. = 850 keV was measured several times under varying expermental conditions, yielding a value of S17(Ec.m.=850 keV) = 24.0 +/- 0.5 eV b. Measurements were carried out at lower energies as well. We obtain from the entire set of measurements an extrapolated value of S17(0) = 21.2 +/- 0.7 eV b.

The $^{7}\mathrm{B}\mathrm{e}(p,\ensuremath{\gamma})^{8}\mathrm{B}$ reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted $^{7}\mathrm{B}\mathrm{e}$ target, a raster-scanned beam, and the elimination of the backscattering loss. The new measurement incorporates a more abundant $^{7}\mathrm{B}\mathrm{e}$ target and a number of improvements in design and procedure. The point at ${E}_{\mathrm{l}\mathrm{a}\mathrm{b}}=991\text{ }\text{ }\mathrm{k}\mathrm{e}\mathrm{V}$ was measured several times under varying experimental conditions, yielding a value of ${S}_{17}({E}_{\mathrm{c}\mathrm{.}\mathrm{m}\mathrm{.}}=850\text{ }\text{ }\mathrm{k}\mathrm{e}\mathrm{V})=24.0\ifmmode\pm\else\textpm\fi{}0.5\text{ }\text{ }\mathrm{e}\mathrm{V}\text{ }\mathrm{b}$. Measurements were carried out at lower energies as well. Because of the precise knowledge of the implanted $^{7}\mathrm{B}\mathrm{e}$ density profile, it was possible to reconstitute both the off- and on-resonance parts of the cross section and to obtain from the entire set of measurements an extrapolated value of ${S}_{17}(0)=21.2\ifmmode\pm\else\textpm\fi{}0.7\text{ }\text{ }\mathrm{e}\mathrm{V}\text{ }\mathrm{b}$.

The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted 7Be target, a raster-scanned beam, and the elimination of the backscattering loss. The new measurement incorporates a more abundant 7Be target and a number of improvements in design and procedure. The point at E(lab)=991 keV was measured several times under varying experimental conditions, yielding a value of S17(E(c.m.)=850 keV)=24.0+/-0.5 eV b. Measurements were carried out at lower energies as well. Because of the precise knowledge of the implanted 7Be density profile, it was possible to reconstitute both the off- and on-resonance parts of the cross section and to obtain from the entire set of measurements an extrapolated value of S17(0)=21.2+/-0.7 eV b.

The angular response of a HPGe detector used in in situ measurements was determined empirically as a function of gamma-ray energy at two source–detector geometries — the standard 1 m and the non-standard 0.1 m heights above ground. Values calculated by a Monte Carlo code were found to agree well with the experimental values. The code is thus labor-saving, because it can spare many measurements required for the empirical determination of the angular response in an unknown experimental configuration.

Some statistical properties of the essential physical quantity "Minimum Detectable Activity" were analyzed, as well as the limits of its applicability in gamma-ray spectrometry. It was shown that the Minimum Detectable Activity is not linear with respect to the quantity of the measured sample and it is advisable not to calculate the Minimum Detectable Activity per unit mass or volume (in Bq kg-1 or Bq cm-3). The MDA has a clear decisive relevance to samples that have an identical geometry and chemical composition with that of the sample that was used to derive the MDA. The relative uncertainty of the Minimum Detectable Activity is approximately +/- 32%. It is recommended not to exclude from evaluations those results that are below minimum detectable activities.

The astrophysical S factor for the 4He(3He,γ)7Be direct capture reaction plays a major role in the context of solar neutrino flux and primordial 7Li abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of ECM = 900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor.

A procedure has been developed for the determination by thermal neutron activation analysis of trace amounts of total chlorine in the Electro-Hydraulic-Control /EHC/ fluid used by the Hadera Power Station in various hydraulic systems. Irradiation for 1 min near the core of a nuclear reactor is followed by high resolution gamma-ray spectrometry using a Ge/Li/ detector. Chlorine amount is quantitatively determined by measuring the gamma-ray photopeaks of the radioactive nuclide38Cl. The system response is linear in the concentration ranges investigated. Chlorine concentration in a fresh hydraulic fluid sample was found to be 17.6±0.5 ppm. The limit of detection, when assaying a 1 cm3 sample of fluid under the present experimental conditions, is 1 μg of chlorine and the corresponding concentration is 1 ppm.

Delayed neutron counting for uranium assay was coupled with γ-ray spectrometry in order to measure radionuclides of F, Al, Ca and V produced by neutron activation. For this measurement, the delay time required for U determination was exploited. Calibration of the method was provided by standards based on a CaCO3 matrix and validity of results was verified against other analytical methods. A single sample can be analyzed for the five elements in 3 min with a precision of ∼±10%. The method developed was applied in the exploration of phosphate ores. The measured total concentrations permitted the disclosure of correlations between various elements and constituents in the samples. Chemical and mineralogical properties were obtained as well.

A preliminary study was carried out in order to compare the selenium concentration in breast cancer patients and healthy subjects (controls) in Israel. Blood serum samples were obtained from 32 breast cancer patients and 36 controls and were analyzed for selenium by the XRF method. A weighted mean of 0.076 +/- 0.014 ppm Se in the blood serum of breast cancer patients, as compared to 0.119 +/- 0.023 ppm Se for controls, was obtained. These results indicate that the concentration of selenium in breast cancer patients is significantly lower than in controls. The relationship between selenium concentration and malignancy stage shows an inverse dependence, i.e., the concentration decreases with stage number.

An integrated target-ion source for surface ionization was developed for routine operation at temperatures as high as 1900°C. The release of fission products from the source was found to be well represented by a single exponent function of time. Delay half-times were determined as a function of temperature for Rb and Cs isotopes. Values observed at 1850°C were 0.5 s for Rb and Cs and greater than 200 and 300 s for Sr and Ba isotopes, respectively. The high temperatures attained facilitated the measurements of short-lived activities of 94–98Rb, 94–98Sr, 96Y, 143–146Cs, 143–148Ba and 146–148La with half-lives extending from 80 to 0.1 s. The main characteristics of the source, such as delay times, efficiency and selectivity of separation of alkalis and alkaline earths are discussed.

Independent fission yields of 92–99Rb, 94–100Sr, 142–148Cs and 143–149Ba in the thermal neutron fission of 235U were determined at the SOLIS on-line mass separator. The independent fission yields of 99Rb, 147, 148Cs and 145–149Ba were measured for the first time. For all the elements a “wing effect” is apparent, i.e. the experimental independent fission yields in the wings of the isotopic (isobaric) yield distributions are considerably higher and their decline with mass (charge) less steep than predicted by fission yield systematics. To account for this effect a corrected semi-empirical distribution function for fission yields is proposed. Comparison of the experimental fission yields with the predictions of theoretical fission models also shows the existence of the “wing effect”. Since the theory predicts primary fission yields a correction due to prompt neutron emission was calculated. It is shown that the effect of prompt neutron emission is to broaden the isotopic distributions in the wing of heavy isotopes only slightly, and in the wing of light isotopes more significantly, but it does not explain the “wing effect” which seems to originate in the fission process.

An efficient surface ionization target-ion source for Sr and Ba isotopes for use with an on-line isotope separator was developed. Delay half-times of (1.4±0.3) s and (1.0±0.4) s for Sr and Ba isotopes, respectively, were achieved at target temperatures of about 2100°C.

Using the on-line mass spectrometer technique we have investigated neutron-deficient Rb and Cs nuclides produced by the bombardment of heavy elements with 24 GeV protons.

The applicability of the Prompt Neutron Activation Analysis (PNAA) method to large (100kg) coal samples has been demonstrated in a laboratory system developed by SAI, Sunnyvale(1–3). The PNAA technique is based on irradiating the coal with neutrons and simultaneously detecting the characteristic prompt gamma radiation resulting from thermal neutron absorption in various elements in the sample. Detailed elemental analysis of the sample is obtained through careful analysis of the emitted gamma-ray spectrum. The accuracy of this method depends on the availability of a reliable set of coal standards. The elemental composition of this set should be well known and uncertainties of the order of ± 1% are desirable. The present available standards of coal are very small (1 g) and therefore not suitable for PNAA work. The aim of the present study was to develop and calibrate a new set of large coal standards which would be used in future PNAA field systems. This set has to cover a broad range of different types of coals, taking into account physical characteristics and elemental compositions. The present set of standards was calibrated against the sampling and analytical ASTM methods which were found to give reliable values.

Neutron radiography was utilized to develop a nondestructive testing technique for the determination of compressed nitrogen gas pressure in sealed stainless-steel containers. This technique provides a means for measuring pressures of small volumes of gas, where weighing or using a gauge is unfeasible. Containers were radiographed for 22 min in the neutron radiography facility of the Soreq Nuclear Research Center reactor. A gadolinium metal converter was used to image the containers on Kodak SR film. Optical densities were measured and gas pressures were evaluated by a calibration curve. A precision of ± 5% was obtained for a single measurement in the region of 3000 psi.

A new procedure for the relative calibration of neutron sources having different energy spectra, based on equating the effective centers for each neutron source is presented. An example of the procedure is given.

The feasibility of using tungsten as a thermal neutron flux monitor at very high temperatures was studied experimentally. The flux was calculated from the absolute activity of 187 W measured with a calibrated Ge(Li) detector. Good results were obtained at temperatures in the vicinity of 2000°C.