Previously we reported a simple algorithmic method of spectral determination method (SDM), which is based on the first principle that a gamma-ray spectrum obtained for a sample is a linear superposition of individual spectra of the radioactive nuclides included in the sample and demonstrated that the method is valid for gamma-ray determination. Here, we apply it to the spectra obtained by liquid scintillation counter (LSC). In LSC measurements quenching is generally observed, and we at first developed its correction method to standard spectra. The SDM code reported in the previous investigation is used to analyze the LSC spectra. Based on the analyses done by using the measured spectra, we concluded that the SDM method is valid in the LSC spectra similarly to the gamma-ray spectra studied in the previous investigation.

So far, we have developed the innovative radioactivity quantification technique of spectral determination method (SDM) and applied it to spectra measured with Ge, NaI detectors and liquid scintillation counter (LSC). In the present study we extended the SDM to apply to a unified spectrum composed of LSC and Ge detector, and the number of nuclides has been increased from 8 or 9 to 40. We selected 40 radionuclides from possible radionuclides included in nuclear debris and radioactive wastes in the environment which were produced by the nuclear accident in Fukushima in 2011. We prepared LSC and Ge standard spectra by direct measurements and simulation calculations utilizing the Geant 4.10.3 Monte Carlo simulation tool kit. The derived LSC and Ge spectra for each nuclide were unified to a single spectrum and the 40 sets of them were completed as a unified database. We studied the determination accuracy of the present analysis by examining a composed spectrum made of 40 radionuclides with equal intensities. The SDM result shows that the relative determination uncertainties of 35 nuclides are below 20%. It is also indicated that by removing 3 interfering nuclides the determination accuracy of the other 37 nuclides could be improved.

We propose a simple algorithmic method of spectral determination method (SDM) for gamma-ray determination, which is based on the first principle that a gamma-ray spectrum obtained for a sample is a linear superposition of individual spectra of the radioactive nuclides included in the sample. The SDM treats the whole spectrum including peaks and a continuum background due to Compton scattering and does not need the peak analysis, which has been most conventionally used so far. The SDM was demonstrated by using two separate detector setups with a NaI detector or a Ge detector. The first experiment utilized six mixed standard sources. The determination accuracy of the SDM has turned out to be reasonable as compared with that of the peak analysis. In the next experiment for standard samples of JSAC0731 and JSAC0785, both Ge and NaI results show that the deviation of the SDM results from the certified values is within reasonable uncertainties for C-137 and Cs-134. The present study demonstrates that the SDM is a reliable gamma-ray determination method with a simple procedure.

Gamma-gamma coincidence measurement utilized in gamma-ray spectroscopy experiments is well known to be effective for the improvement of signal-to-noise ratio in a gamma-ray spectrum. We study its applicability to the determination of long-lived radioactive nuclides in environmental samples. The gamma-ray simulation code Geant 4.10.2 was used. A conventional and effective detector system comprising five Ge detectors was assumed. We took up 38 nuclides which need to be determined for the evaluation of fission product leakage at the nuclear accident in the Fukushima nuclear power plants in Japan. Among them 12 nuclides emit gamma-rays and five nuclides of Co-60, Nb-94, Cs-134, Eu-152, and Eu-154 can be the objectives of the multiple gamma-ray detection methods. The simulation results indicate that the signal-to-noise ratio can be improved by a factor between 9.84 and 283, and the detection limit by a factor between 2.71 and 8.53 relative to the singles measurement, implying that the method can be well applied to the determination of the long-lived radioactive nuclides and will provide a quick and non-destructive analysis method.

We have proposed a machine learning model for efficient gamma-ray spectrometry for environmental recovery from the Fukushima Daiichi Power Plant Accident. In the present study, we focus on a radioactive nuclide identification by the machine learning in a screening measurement. A simple deep neural network having two hidden layer is proposed, and the identification accuracy is achieved more than 95% for single gamma-ray spectra.

Charged Particle Activation Analysis (CPAA) utilizing an 8-MeV proton beam has been studied for determination of 35 long-lived radioactive nuclides. We accumulated the reaction cross section and nuclear decay data by referring to nuclear database supplied by National Nuclear Data Center in Brookhaven National Laboratory. We also calculated the reaction cross sections by using statistical model code ALICE. By using the nuclear data, we have derived determination sensitivity of the radioactive nuclides relative to unit weight and specific radioactivity. The result indicates that several hardly measurable nuclides with long half-lives such as Cs-135, Pu-244, I-129, Sn-126, Mo-93, Pd-107, U-236, Cm-248, and Np-237 have high sensitivity. It may be concluded that CPAA can be applied to determination of several long-lived nuclei and will provide a quick and non-destructive analysis method.

This study investigated intermediate-spin states of $^{92}\mathrm{Zr}$ via the inverse reaction $^{9}\mathrm{Be}(^{86}\mathrm{Kr},3\mathrm{n})\phantom{\rule{0.16em}{0ex}}^{92}\mathrm{Zr}$. Seven transitions were newly observed, and a lifetime was extracted for the ${10}_{1}^{+}$ state by analysis of Doppler-broadened line shapes of decay $\ensuremath{\gamma}$ rays. A large $B(E2)$ value was obtained for the transition from ${10}_{1}^{+}$ to ${8}_{1}^{+}$, and the magnitude was comparable to that for the deformed excited configurations in $^{94}\mathrm{Zr}$ that have recently been established. A possible origin for such collectivity is discussed qualitatively based on a phenomenological deformed rotor model. Moreover, a multipletlike structure that fits into the systematics for $N=52$ even-$A$ isotones is revealed for the negative-parity yrast states.

Charged particle activation analysis (CPAA) is a rapid method with high accuracy which can analyze multi-elements simultaneously. Since multiple γ-ray detection method is expected to improve the detection efficiency and the signal-to-noise ratio, we study what design of the γ-ray detector array is the most suitable for CPAA. We take up four design candidates and investigated the responses by the radiation simulation code Geant 4. From the results, we have deduced the best design with 5 germanium detectors in close geometry. By inspecting the sensitivity in CPAA, the method is proved to be useful and applicable to 116 nuclides.

This study investigated intermediate-spin states of Zr-92 via the inverse reaction Be-9(Kr-86, 3n)Zr-92. Seven transitions were newly observed, and a lifetime was extracted for the 10(1)(+) state by analysis of Doppler-broadened line shapes of decay. rays. A large B(E2) valuewas obtained for the transition from 10(1)(+) to 8(1)(+), and the magnitude was comparable to that for the deformed excited configurations in Zr-94 that have recently been established. A possible origin for such collectivity is discussed qualitatively based on a phenomenological deformed rotor model. Moreover, a multipletlike structure that fits into the systematics for N = 52 even-A isotones is revealed for the negative-parity yrast states.

The neutron-induced fission cross section of 237 Np was experimentally determined at the high-resolution and high-intensity facility n TOF , at CERN, in the energy range 100 keV to 9 MeV, using the 235 U( n,f ) and 238 U( n,f ) cross section standards below and above 2 MeV, respectively. A fast ionization chamber was used in order to detect the fission fragments from the reactions and the targets were characterized as far as their mass and homogeneity are concerned by means of α spectroscopy and Rutherford backscattering spectroscopy respectively. Theoretical calculations within the Hauser-Feshbach formalism have been performed, employing the EMPIRE code, and the model parameters were tuned in order to successfully reproduce the experimental fission cross-sectional data and simultaneously all the competing reaction channels.

Charged particle activation analysis (CPAA) utilizing an 8 MeV proton beam has been studied for general elemental quantification. We accumulate the reaction cross section and nuclear decay data by referring to nuclear database supplied by National Nuclear Data Center in Brookhaven National Laboratory. By using the database we have derived determination sensitivity of single element samples for each nuclide. The result indicates that, while the determination sensitivity tends to decrease gradually as the target nucleus becomes heavy, the CPAA analysis is possible over the whole elements including the heavy nuclear region. It may be concluded that CPAA can be applied to most of the stable nuclei and is one of the alternative methods to neutron activation analysis.

Lifetime measurements were made for the nu h(11/2) band in Pd-101, which had been interpreted as a possible antimagnetic rotation band based on the comparison of I - omega behavior with the calculation of a semiclassical particle-rotor model in our previous study. Doppler broadened line shapes were analyzed for the decaying gamma rays in the band following the reaction Zn-68(Cl-37, 1p3n)Pd-101. The semiclassical particle-rotor model was modified to reproduce both the I - omega plot and the B(E2) behavior simultaneously for the antimagnetic rotation bands in Pd and Cd nuclei, for which B(E2) values had been measured so far. Reasonable agreements between the experiment and the calculation were obtained. It is concluded that the lower part of the nu h(11/2) band in Pd-101 can be interpreted as an antimagnetic rotor.