Beta-ray Spectra Research Articles

Detection of β-ray from 3H with back illuminated sCMOS imager

Tritium occurs in nuclear power plants. The energy of beta-rays from tritium is so low that detecting the beta-rays is challenging. Therefore, method of measuring tritium surface contamination is required. Liquid scintillators are generally used to measure the beta-rays. However, this method is complicated to use on-site. To measure tritium surface contamination on-site, we attempted to detect tritium using the GSENSE2020BSI back-illuminated sCMOS imager.We used a tritium areal radiation source to validate the detection of beta rays from tritium. The beta-rays cause bright spots in images and spread to multipixel. The average number of the pixels by the beta-rays was 4.6 and covered within a 3x3 pixel region. The energy spectrum from 10,000 images with 3x3 binning patterns showed a continuous shape spectrum. The spectra shape was characteristic of beta-ray spectra, demonstrating that the energy spectrum could be obtained with low-energy beta rays from tritium using the back-illuminated sCMOS image sensor. The spectral shape was produced from a radiation simulation using Geant4. From the simulation, the sCMOS sensor was able to measure tritium contamination of 10 becquerels (Bq)/cm2 within 100 s and 4 Bq/cm2 within 480 s.

Optimization and characterization of a coincidence beta-ray spectrometer

Aimed at beta spectrometry and dosimetry for mixed beta-gamma fields, a Si-plastic scintillator coincidence beta-ray spectrometer has been developed. The spectrometer collects pure beta-ray spectra by rejecting the gamma-ray detection events through coincidence. Both pulse height and arrival time of each detection event were recorded in list mode by a compact digital processing system. Spectral measurements were carried out using mixed beta-gamma fields from 90Sr/90Y and 137Cs sources for various beta and gamma count rates to evaluate the system performance. Coincidence beta spectra were collected for four fixed beta count rates (7.3–241 cps) from 90Sr/90Y while the gamma count rate from 137Cs was varied from 500 to 8000 cps. The coincidence beta spectrum was stable and unperturbed by the gamma detection events for most measurements while notable perturbation was observed in the low energy region when the beta to gamma count ratio is very low.

Simultaneous quantitative analysis of 3H and 14C radionuclides in aqueous samples via artificial neural network with a liquid scintillation counter

Liquid scintillation counters are common instruments used in the measurement of pure beta-emitting radionuclides, and while they represent a conventional radiometric technique, they are still competitive for their potential to measure multiple radionuclides simultaneously. In this work, we propose an algorithm based on an artificial neural network (ANN) for the simultaneous analysis of the beta-ray spectra of 3H and 14C in dual beta-labeled samples using a liquid scintillation counter. We achieved percentage deviations below 5.0% using the proposed algorithm in 16 out of 18 cases, with RMSDs below 1.5% in 17 out of 18 cases. The trained ANN also produced activity ratios with high accuracy even while having to deal with highly fluctuating spectra. Results demonstrate that the rapid predictions with a short measurement time from our proposed ANN method are compatible with the calculated ones from previous studies that were obtained with long measurement times.

Measurement of 90Sr radioactivity in cesium hot particles originating from the Fukushima Nuclear Power Plant Accident.

A method for the determination of 134+137Cs and 90Sr in cesium hot particles (Cs-HPs) originating from the Fukushima Daiichi Nuclear Power Plant accident has been developed. The method depends on a response function that is calculated by PHITS code and fitted to the beta-ray spectrum measured with a Si-detector. The 134+137Cs radioactivity in the Cs-HPs was consistent with that measured by a Ge-detector, thus confirming the reliability of the method. The 90Sr/137Cs ratios, which ranged from 0.001 to 0.0042, were consistent with a 90Sr/137Cs inventory ratio for contaminated soil samples. That is, the extracted Cs-HPs contained 90Sr in the same ratio as that for the 90Sr/137Cs inventory ratio for the contaminated soils. The method is attractive in that the samples are unaltered, andthat no chemical separation techniques are required.

Constraints on the Active and Sterile Neutrino Masses from Beta-Ray Spectra: Past, Present and Future1

Although neutrinos are probably the most abundant fermions of the universe their mass is not yet known. Oscillation experiments have proven that at least one of the neutrino mass states hasmi> 0.05 eV while various interpretations of cosmological observations yielded an upper limit for the sum of neutrino masses ∑mi< (0.14 ‒ 1.7) eV. The searches for the yet unobserved 0νββ decay result in an effective neutrino massmββ< (0.2 ‒ 0.7) eV. The analyses of measured tritium β-spectra provide an upper limit for the effective electron neutrino massm(ve) < 2 eV. In this review, we summarize the experience of two generations of β-ray spectroscopists who improved the upper limit ofm(ve) by three orders of magnitude. We describe important steps in the development of radioactive sources and electron spectrometers, and recapitulate the lessons from now-disproved claims for the neutrino mass of 30 eV and the 17 keV neutrino with an admixture larger than 0.03%. We also pay attention to new experimental approaches and searches for hypothetical sterile neutrinos.

Improvement of Inventory and Leaching Rate Measurements of C-14 in Hull Waste, and Separation of Organic Compounds for Chemical Species Identification

ABSTRACTIn order to analyze the C-14 inventory and leaching rate for safety evaluation of transuranic waste disposal, it is necessary to establish an analytical method that can measure C-14 with sufficient precision [1]. Oxidative decomposition of organic compounds containing C-14 is carried out to absorb carbon dioxide (CO2) in an alkaline solution, which is mixed with a liquid scintillation cocktail, and the amount C-14 is quantified by measuring a beta ray spectrum with a liquid scintillation counter. It has been difficult to completely decompose carbon compounds in a sample, even to CO2, by using conventional oxidizing agents. In the work described here, we improved the method of oxidative decomposition used to completely decompose carbon compounds using peroxydisulfuric acid (K2S2O8). When C-14 in the form of CO2 was absorbed in a sodium hydroxide (NaOH) aqueous solution, only 80% of the actually used quantity was detected. Total organic carbon measurements showed that the entire quantity of CO2 was absorbed by NaOH. When NaOH aqueous solution was used, it was found that only the analytical value was 80%. The entire quantity of the actually used carbon could be measured by absorbing the CO2 in Carbo-Sorb®. An anion form and a neutral molecule exist in the organic compound released from activated metals. In order to identify organic compounds efficiently, fractionation into an anion and a neutral molecule and separation by high performance liquid chromatography (HPLC) are necessary. Here, we propose the combined use of an ion exchange resin and HPLC as an improved technique for identification of the chemical species.

Negatron Decay of 122Sb

A unique set of numerical values for six nuclear matrix elements, ∫σ·r, ∫γ5, ∫r, ∫α, ∫σ×r and ∫Bij, were found by means of the chi-square fit to the experimental data on the beta-ray spectrum and beta-gamma directional correlation in the cascade transition, 2−(1.4 MeV β−)2+(0.56 MeV γ)0+ of 122Sb, measured by Yamada and Hayashi. These matrix elements are also consistent with all other available data on this transition.

Search for the three-body photodisintegration of Be

We have searched for neutrons from the three-body photon-induced reaction {sup 9}Be+{gamma}{yields}{alpha}+{alpha}+n using bremsstrahlung produced by electrons from a 2-MV Van de Graaff on a gold target. The target was located within a block of beryllium surrounded by an array of {sup 3}He proportional counters embedded in paraffin. Based on energy and intensity calibrations of the accelerator and detector using the {sup 9}Be+{gamma}{yields}{sup 8}Be+n reaction, an upper limit of 93 nb (4{sigma}) was placed on the cross section for neutron production between the three-body and two-body thresholds. This value is substantially below a previous experimental result using photoexcitation by {sup 142}Pr gamma rays and also below an earlier theoretical estimate. Bremsstrahlung spectra from the gold target were also measured in a NaI(Tl) detector at electron energies from 1.7 to 2.0 MeV and angles of 0 deg. to 60 deg. with respect to the beam axis. An analysis of photons above the 1665-keV two-body threshold shows that bremsstrahlung due to beta rays between 1665 keV and the 2160-keV end point of the {sup 142}Pr beta-ray spectrum could account for the photoneutron yield in the three-body region that had previously been attributed to {sup 142}Pr gamma rays.

表計算ソフトを用いたべータ線エネルギースペクトルの計算

A spreadsheet software, Microsoft Excel, was used to calculate beta-ray spectra, which are necessary to obtain bremsstrahlung data for betaemitting nuclides. The results of the present calculation were compared with numerical data listed in ICRU Report 56, Appendix D.The calculated spectra for 14 nuclides among 36 nuclides of importance listed in ICRU Report were in good agreement, 20 showed slight discrepancy, and two, 204Tl and 210Bi, did not agree.Among the above-mentioned 20 nuclides, those which emit single beta-ray could be made to agree with ICRU data by multiplying a newly modified correction factor. For the remaining nuclides correction was not applied because no detailed information e.g. maximum energy and intensity of beta rays is given in ICRU Report.To calculate“|Γ (γ+ iy) |2” of the Fermi function in the formula of a beta-ray energy spectrum, two types of calculation were carried out: 1) direct calculation of infinite product and 2) calculation with approximation used in ICRU Report. The results of both calculations agreed well.

4. Beta-Ray Sources and Spectra

4. Beta-Ray Sources and Spectra

Appendix D: Calculated Beta-Ray Spectra

Appendix D: Calculated Beta-Ray Spectra

Appendix D: Calculated Beta-Ray Spectra

Appendix D: Calculated Beta-Ray Spectra

An atlas of selected beta-ray spectra and depth-dose distributions in lithium fluoride and soft tissue generated by a fast Monte Carlo-based sampling method

A method to generate depth-dose distributions due to beta radiation in LiF and soft tissue is proposed. In this method, the EGS4 Monte Carlo radiation transport code is initially used to generate a library of monoenergetic electron depth-dose distributions in the material for electron energies in the range of 10 keV to 5 MeV in 10 keV increments. A polynomial least-squares fit is applied to each distribution. In addition, a theoretical model is developed to generate beta-ray energy spectra of selected radionuclides. A standard Monte Carlo random sampling technique is then employed to sample the spectra and generate the depth-dose distributions in LiF and soft tissue. The proposed method has an advantage over more traditional methods in that the actual radiation transport in the media is performed only once for a set of monoenergetic cases and the beta depth-dose distributions are easily generated by sampling this previously-acquired database in a matter of minutes. This method therefore reduces the demand on computer resources and time. The method can be used to calculate depth-dose distribution due to any beta-emitting nuclide or combination of nuclides with up to ten beta components.

Atomic Effects in Tritium Beta Decay

The electron neutrino mass has been measured in several tritium beta decay experiments. These experiments are sensitive to a small neutrino mass because the energy release of the decay is small. But the very smallness of the energy release implies that the Coulomb interactions of the slowly moving emitted beta electron are relatively large. Using field theoretic techniques, we derive a systematic and controlled expansion which accounts for the Coulomb effects, including the mutual interaction of the beta ray electron and the electron in the final3He+ion. In our formulation, an effective potential which describes the long range Coulomb force experienced by the beta ray is introduced to ensure that our expansion is free of infrared divergences. Both the exclusive differential decay rate to a specific final3He+state and the inclusive differential decay rate are calculated to orderη2, whereηis the usual Coulomb parameter. We analyze the orderη2correction to the beta ray spectrum and estimate how it may affect the neutrino mass squared parameter and the endpoint energy when this corrected spectrum is used to compare with the experiments. We find that the effect is small.

Measurements of Beta Ray Spectra in CANDU Nuclear Generating Stations Using a Silicon Detector Coincidence Telescope

The measurement of beta ray spectra at various work locations inside nuclear generating stations operated by Ontario Hydro is described. The measurements were carried out using an advanced coincidence telescope spectrometer using silicon detectors only. The spectrometer is capable of measuring electron energies over the range 60 keV-2500 keV with close to 100% coincidence efficiency. Photon rejection is carried out by requiring a coincidence between either two or three silicon detectors. Monte Carlo calculations were then used to estimate beta correction factors for the LiF:Mg,Ti elements used in the Ontario Hydro thermoluminescence dosemeters. Averaging over all the measured beta correction factors for the 'skin' chip (100 mg.cm -2 ) results in a value of 2.73 ± 0.77 and for the extremity dosemeter (240 mg.cm -2 ) an average value of 4.42 ± 1.17 is obtained. These values are 57% and 120% greater, respectively, than the current values used by Ontario Hydro. In addition, beta correction factors for nine representative spectra were calculated for 40 mg.cm -2 and 20 mg.cm -2 chips and the results demonstrate the benefits of decreased dosemeter thickness. The average value of the beta correction factor, as well as the spread in the beta correction factor, decreases dramatically from 4.80 ± 2.1 (240mg.cm -2 ) to 1.29 ± 0.1 (20 mg.cm -2 ).

Monte Carlo Calculations of Electron Fluence Attenuation Coefficients for Photon General Cavity Theory

Application of photon general cavity theory requires knowledge of the electron mass attenuation coefficient, ß. One approach has been to adopt values of ß derived from the attenuation of beta ray spectra, which are based on a one-to-one correspondence between ß and the maximum energy of the beta ray spectrum. Other approaches are also available, so that, for 60Co generated electrons, for example, six different empirical expressions yield values of ß for LiF from a minimum value of 5.16 cm2.g-1 to a maximum value of 14.26 cm2.g-1. The results are reported of coupled photoelectron Monte Carlo calculations over a wide range of photon energies, 0.1 MeV < E < 1.4 MeV, and wall materials; Al, Cu, Cd and Pb. For the relatively low Z materials and over the energy range 0.3 MeV to 1.4 MeV, ß in LiF is given to within an accuracy of ±10% by the relation ß = 10.5 E-1.82 where E is expressed in MeV. ß is strongly dependent on Z so that for the high Z materials a simple power law relationship does not exist for any extended range of gamma ray energies.

Measurements of Beta Ray Spectra Inside Nuclear Generating Stations Using a Silicon Detector Coincidence Telescope: Skin Dose Beta Correction Factors for TL Elements

The measurement of beta ray spectra at various work locations inside nuclear generating stations operated by Ontario Hydro is described. The measurements were carried out using an advanced coincidence telescope spectrometer using silicon detectors only. The spectrometer is capable of measuring electron energies over the range 70-2500 keV with close to 100% efficiency. Over 40 beta ray spectra were measured at various work locations in three nuclear generating stations. Photon rejection is carried out by requiring a coincidence between either two or three detectors. Monte Carlo calculations were then used to estimate beta correction factors for the LiF:Mg,Ti elements used in the Ontario Hydro thermoluminescence dosemeters. Averaging over all the measured beta correction factors for the 'skin' chip (100 mg.cm -2 ) results in a value of 2.73 ± 0.77 and for the extremity dosemeter (240 mg.cm -2 ) an average value of 4.42 ± 1.17 is obtained. These values are 57% and 120% greater, respectively, than the current values used by Ontario Hydro. In addition, beta correction factors for nine representative spectra were calculated for 40 mg.cm -2 and 20 mg cm -2 chips, and the results demonstrate the benefits of decreased dosemeter thickness. The average value of the beta correction factor, as well as the spread in the beta correction factor, decreases dramatically from 4.80 ± 2.1 (240 mg.cm -2 ) to 1.29 ± 0.1 (20 mg.cm -2 ).

Monte Carlo calculations of monoenergetic electron depth dose distributions in LiF chips: skin dose correction factors for beta rays.

Monte Carlo calculations have been carried out for monoenergetic electrons from 0.1 to 4 MeV irradiating LiF chips in both perpendicular and isotropic geometry. This enabled the calculation of skin dose correction factors (beta factors) for typical beta energy spectra as measured with a beta-ray spectrometer at CANDU nuclear generating stations. The correction factors were estimated by averaging the depth dose distributions for the monoenergetic electrons over the experimentally measured beta-ray spectra. The calculations illustrate the large uncertainty in beta factors arising from the unknown angular distribution of the beta-ray radiation field and uncertainties in the shape of the beta-ray spectra below 500 keV.

Neutron pioneer

There are not very many of us left who can remember the 1920s, when the Cavendish Laboratory at Cambridge University was the leader in the nascent subject of nuclear science. Earlier in the century Rutherford and Bohr had established that the atom had a nucleus. At Manchester University, where this took place, theory and experiment went together smoothly. Chadwick finished his undergraduate work at Manchester University in 1911 and at the end of four years had his name on four research papers, two of them on his own. At the conclusion of the work for his MSc degree, in 1913, he was awarded an 1851 exhibition scholarship and used this to go to work in Germany with Geiger, who had also been at Manchester. With Geiger he made one of his major discoveries, the continuous beta-ray spectrum.

Analysis of Beta-Ray Data Important to Decay Heat Predictions

Recently obtained experimental total beta-ray spectra for 77 radionuclides created during fission of 235U are compared with predicted total beta-ray spectra based on beta-ray transition energies an...