The level structure of 184Os from 184Ir decay and 185Re(p, 2nγ) in-beam spectroscopy

Levels of ¹⁸⁴Os populated in the decay of 3.1 h ¹⁸⁴Ir and in the ¹⁸⁵Re(p, 2nγ) reaction have been investigated. The measurements included γ-ray singles, β⁺ ray endpoint, conversion coefficient, β⁺-γ coincidence and detailed γ-γ coincidence determinations. The results have established an extensive ¹⁸⁴Os level scheme, which includes well developed ground state, γ-vibrational and K = 3 octupole bands and which accommodates all the intense transitions observed in both the radioactivity and in-beam γ-ray measurements. Deviations of the level energies in the K^π = 0⁺and K^π = 2⁺ bands and of the interband reduced transition probabilities from the predictions of the strong-coupling model are discussed in terms of the rotationvibration interaction, and the systematics of the octupole vibrational excitations in even-mass W and Os nuclei are reviewed. It is concluded that the ¹⁸⁴Ir ground state configuration has a spin of 5, and that it contains large admixtures of K = 0 or K = 1 character.     

A study of the (n, α) reactions induced by 18 MeV neutrons in 151Eu, 151Eu, 159Tb, 16SHo and 169Tm

The energy spectra of α-particles emitted in the ${}^{151}\text{Eu(n}\text{, α)}{}^{148}\text{Pm}\text{,}{}^{153}\text{Eu(n}\text{, α)}{}^{150}\text{Pm}\text{,}{}^{159}\text{Tb(n}\text{, α)}{}^{156}\text{Eu}\text{,}{}^{165}\text{Ho(n}\text{, a)}{}^{162}\text{Tb and}{}^{169}\text{Tm(n}\text{, α)}{}^{166}\text{Ho}$ reactions have been measured at a neutron energy of 18.15 MeV. For the ${}^{165}\text{Ho(n}\text{, α)}{}^{162}\text{Tb}$ reaction the α-particle angular distribution has been measured as well. The results have been analysed in terms of statistical, pre-equilibrium and knock-on models.     

Ratio of the ternary to binary fission induced by thermal and resonance neutrons in 239Pu

Measurements were performed of the ratio of ternary to binary fission (T/B) in ²³⁹Pu by neutrons in the energy region from 0.020 eV to 50 eV. The ternary and binary fission time-of-flight spectra were recorded at a 8.1 m flightpath at the Geel Linac with large gold-silicon surface-barrier detectors on both sides of a 1 mg/cm² double-faced ²³⁹Pu target. From these time-of-flight spectra the ratios of the areas of the strongest isolated resonances in ternary and in binary fission were calculated; moreover in the region 0.02–1 eV ratios were calculated for about 40 zones throughout the spectrum. The T/B ratio does not vary significantly in the energy region below 1 eV; this is not the case in the region 1–50 eV, where the T/B value for the 15.5 eV resonance is significantly larger than for the other resonances. These T/B values seem to be correlated with the resonance spin J and with some other fission characteristics.     

Determination of 13CO2/12CO2 Ratio by IRMS and NDIRS

Abstract

Breath tests using ¹³C-labelled substrates require the measurement of ¹³CO₂/¹²CO₂ ratio in breath gas samples. Next to isotope ratio mass spectrometry (IRMS), which is very sensitive but also complex and expensive, alternatively isotope selective nondispersive infrared spectrometry (NDIRS) can be used to determine the ¹³CO₂/¹²CO₂ ratio in expired breath. In this study we compared NDIRS- with IRMS-results to investigate whether the less expensive and very simply to operate NDIRS works as reliable as IRMS. For this purpose we applicated 1-¹³C-Phenylalanine to patients with advanced liver cirrhosis and healthy volunteers and took duplicated breath samples for IRMS and NDIRS at selected time points. Our data show a good correlation between these two methods for a small number of samples as required for simple breath tests. Longer series, where repeated measurements are required on the NDIRS instrument lead to a decreasing correlation. This indicates the superiority of IRMS concerning ¹³CO₂-kinetics over longer time periods.     

The mass and kinetic energy distributions in the fission of 237Np, 232Th, 238U, 235U and 209Bi induced by 110 MeV electrons

Fission of ²³²Th, ²³⁷Np, ²⁰⁹Bi, ²³⁵U and ²³⁸U induced by 110 MeV electrons has been studied by means of surface barrier detectors. The resulting mass and kinetic energy distributions are presented. Comparison with the liquid drop model predictions shows reasonable agreement in the case of ²⁰⁹Bi. The data are analysed in terms of a two component model of fission and the mean total kinetic energies of the components are shown to depend linearly on $\text{Z}{}_1\text{Z}{}_2\text{(A}{}_1{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{+ A}{}_2{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{)}$. Interesting differences are found when the present results are compared with the recent photofission experiments of Areskoug et al. and features in both sets of data correlate with changes of fragment deformation implied by the calculations of Wilkins et al.     

Determination of the static quadrupole moment of the first 2+ states of 122Te, 124Te,and 130Te by heavy-ion coulomb excitation

A Coulomb excitation experiment has been performed on the first 2⁺ states of ¹²²Te, ¹²⁴Te and ¹³⁰Te. The relative excitation probabilities of the first 2⁺ states were measured at backward and forward projectile scattering angles. Particle-γ coincidences were used to identify the inelastic events. The data were analyzed with the aid of the Winther-deBoer multiple Coulomb excitation program. Separate γ-ray angular distribution measurements were made as a function of target recoil velocity to determine the influence of the deorientation effect. The projectile and bombarding energy were chosen to minimize the effect on the experiment of higher state interference due to Coulomb excitation of the first 2⁺ state via the second 2⁺ state. For positive higher state interference the extracted quadrupole moments of the first 2⁺ states are Q₂₊ = ?0.43 ± 0.08 b, ?0.49 ± 0.08 b and ?0.08 ± 0.08 b for ¹²²Te, ¹²⁴Te and ¹³⁰Te respectively. These results and other measurements of Q_2⁺ for the doubly even Te isotopes are used to discuss the model dependent calculations of Q_2⁺.     

Analysis of 226Ra, 232Th and 40K in soil samples for the assessment of the average effective dose

The activity concentrations of the natural radionuclides namely ²³⁸Ra, ²³²Th and ⁴⁰K are measured for soil samples collected from different locations of Faridkot and Mansa districts of Punjab. HPGe detector, based on high-resolution gamma spectrometry system is used for the measurement of activity concentration. The range of activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the soil from the studied areas varies from 21.42 Bq kg⁻¹ to 40.23 Bq kg⁻¹, 61.01 Bq kg⁻¹ to 142.34 Bq kg⁻¹ and 227.11 Bq kg⁻¹ to 357.13 Bq kg⁻¹ with overall mean values of 27.17 Bq kg⁻¹, 95.22 Bq kg⁻¹ and 312.76 Bq kg⁻¹, respectively. Radium equivalent activities are calculated for the analyzed samples to assess the radiation hazards arising due to the use of these soil samples in the construction of dwellings. The absorbed dose rate calculated from activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K ranges between 9.87 and 18.55, 38.01 and 88.68 and 9.40 and 14.79 nGy h⁻¹, respectively. The total absorbed dose in the study area ranges from 61.10 nGy h⁻¹ to 112.86 nGy h⁻¹ with an average value of 84.80 nGy h⁻¹. The calculated values of external hazard index (H _ex) for the soil samples of the study area range from 0.36 to 0.68. Since these values are lower than unity, according to the Radiation Protection 112 (European Commission, 1999) report, soil from these regions is safe and can be used as construction material without posing any significant radiological threat to population. The corresponding average annual effective dose for indoor and outdoor measured in the study area are 0.42 mSv and 0.10 mSv respectively.      

Determination of the ratio of soot refractive index function E(m) at the two wavelengths 532 and 1064 nm by laser induced incandescence

A new method is proposed to measure the ratio of the refractive index function of soot particles E(m) at the two fixed wavelengths: 532 and 1064 nm. Using a non-intrusive, in-situ laser based technique, the ratio E(m,1064 nm)/E(m,532 nm) can be determined by comparing laser induced incandescence (LII) intensities at 532 and 1064 nm excitation wavelengths. The method consists of selecting laser energies that insure the equality of the LII signals in the low fluence regime under given conditions. Such equality is consistent with the fact that the soot particle will have reached the same temperature independently of the laser wavelength, i.e. the soot particle has absorbed the same energy. As the absorbed energy is proportional to the laser irradiance times E(m), the measurement of the laser energies required to insure perfect concordance of the LII intensities (spatially and temporally) serves to deduce the ratio E(m,1064 nm)/E(m,532 nm). The method is demonstrated in an acetylene/air flame, validated against extinction measurements performed by cavity ring-down spectroscopy (CRDS) by using laser radiations at 532 nm and 1064 nm and finally applied to different flame conditions. PACS 78.20.Ci; 78.90.+t; 81.05.Uw; 42.62.-b     

北航沙河校区土壤中40 K、238 U、232 Th相对含量的实验测量

环境中天然伽马射线主要来源于40K以及钍系、铀系和锕系.通过探测伽马射线来识别放射性核素并得到它们的相对含量,是核科学与核技术中的一个重要方法.利用高分辨的高纯锗探测器,北航以及国内部分高校已开设了鉴别环境中放射性核素的实验.在此基础上,本文进一步利用特征γ射线与递次衰变规律,对北航沙河校区土壤中的40 K、238 U...     

采用高信噪比电磁诱导透明谱测定~(85)Rb原子5D_(5/2)态的超精细相互作用常数

基于~(85)Rb原子5S1/2-5P3/2-5D_(5/2)阶梯型能级系统(780 nm+776 nm),利用高信噪比的电磁诱导透明谱对~(85)Rb原子5D_(5/2)态超精细分裂进行测量.其中,频率校准是通过位相型电光调制器和共焦法布里-珀罗腔共同实现的.通过测量~(85)Rb原子5D′5/2态(F′=5),(F′′=4)及(F′′=3)之间的超精细分裂,我们确定了~(85)Rb原子5D_(5/2)态的磁偶极超精细相互作用常数(A=-(2.222±0.019)MHz)和电四极超精细相互作用常数(B=(2.664±0.130)MHz).     

The asymptotic S- to D-state ratio of the deuteron- and triton-wave function determined by empirical continuation of the 2H(d,p)3 tensor polarization

By continuing the ²H($\text{d}$, p)³H, E_d = 13.0 MeV tensor polarizations to the forward and backward transfer poles it was possible to determine the corresponding $\text{G}{}_2\text{G}{}_0$ values for the deuteron (0.0268 ± 0.0007) and triton (0.048 ± 0.007).     

Determination of binary systems based on light elements by the ratio of the Compton and Rayleigh scattering intensities

A generalization of the Compton method for determining elements with a low atomic number Z from 1 (H) to 9 (F) by the ratio of the intensities of incoherent (Compton) and coherent (Rayleigh) scattering is proposed. The generalization takes into account not only the dependence of this ratio on the effective atomic number of the scatterer material but also the momentum transfer variable x = . The new method is based on the application of calibration function of obtained by measuring scattering spectra at two values of x₁= 0.831 Å⁻¹ and x₂= 1.297 Å⁻¹ with a WDXRF spectrometer. The elemental atomic numbers and their concentrations of binary compounds with unknown compositions are determined by the solution of a system of linear equations. Coefficients of the equations are calculated from the measured ratios for the test sample and the regularization solution for the corresponding calibration. The experiments have been carried out for standard samples of single-component, binary and triple stoichiometric compounds based on H, Li, Be, B, C, O and F. The identification of these elements was found to be possible in the absence of a relationship between the positions of scattering peaks and the composition of the sample, and a qualitative and quantitative analysis of the composition of the material was carried out as part of the solution of a single inverse problem.     

Determination of carbon isotope ratios of methanol and acetaldehyde in air samples by gas chromatography-isotope ratio mass spectrometry combined with headspace solid-phase microextraction

Isotopic signatures of atmospheric methanol and acetaldehyde have the potential to improve our ability to quantitatively assess their importance in atmospheric chemistry. However, isotopic measurements of atmospheric methanol and acetaldehyde and their individual source and sink processes have been limited. In this study, we examined gas chromatography-isotope ratio mass spectrometry combined with headspace solid-phase microextraction to measure the carbon isotope ratios of methanol and acetaldehyde in air samples. The method enabled us to determine carbon isotope ratios with a precision (1 standard deviation) of±0.6 ‰ for 20 ml of air sample containing more than 3 ppm of methanol and±0.7 ‰ for 20 ml of air sample containing more than 2 ppm of acetaldehyde. Moreover, the applicability of this method to determine isotope ratios of methanol and acetaldehyde emitted from detached plant leaves was demonstrated.     

In situ radiation measurement and estimation of U/Th ratio to reflect on the uranium bearing potential zone in metamorphic rocks of Mahendragarh district, Haryana

Gross gamma radiation survey was carried out using Nal(Tl) scintillator based portable gamma ray spectrometer (PGRS) around areas of Gaonri, Dholera, Pachnota and Meghot in Mahendragarh district, Haryana. Geologically the area forms part of north Delhi fold belt comprising calc-silicate, quartz biotite schist, impure marble, quartzite and pegmatite rocks. Equivalent uranium (eU₃O₈) concentration in ppm was estimated in situ on a regular grid pattern of 500 m (E-W) × 1000 m (N-S) and grab samples were collected at grid locations for analyzing in the laboratory for estimating the contents of eU₃O_s Ra_eq, ThO₂ and %K. A comparison with the laboratory analysed grab samples for eU₃0₈ data and in situ radiation measurements shows a good match of the two sets of data. The in situ measurements indicate higher concentration of eU₃O₈ in Chapra Bibipur in northeastern most corners, Maghot area in central part, Gaonri in western part and Pachnota in southwestern part of the study area. As index to uranium favorability, U(Ra_eq)-Th contour map (prepared using Surfer software with Krieging interpolation method for this grid size) based on the data on grab samples was generated which show three major clusters of relatively high U-Th ratio. The blocks delineated are enriched in sodic mineral albite which support albite hosted uranium mineralization potential in metamorphic rocks in Haryana.      

Determination of the Li/Nb ratio in lithium niobate by means of birefringence and Raman measurements

Two optical methods for the determination of the Li/Nb ratio in lithium niobate (LiNbO₃) are discussed. Data for the optical birefringence method are presented, they cover the entire composition range in which LiNbO₃ can be fabricated and a wide spectral region. The line-widths of lattice modes have been measured by means of Raman scattering as a function of the Li/Nb ratio for single crystals with polished and rough surfaces.     

通过HSQC和1H,13C-COSY叠合增强二维谱分辨率的方法

通常二维谱F₁维分辨率较差,F₂维分辨率较好. 即HSQC实验¹³C维度分辨率较差,¹H维度分辨率较好. 而¹H, ¹³C-COSY实验¹³C维度分辨率较好,¹H维度分辨率较差. 提出一种通过HSQC和¹H, ¹³C-COSY叠合,取较弱的值储存并显示的方法增强分辨率,采用Bruker Topspin软件AU程序实现. 该方法在不明显增加采样时间的情况下,可显著增强分辨率,信噪比也没有降低. 同时抑制了F₁噪声. 处理后,谱图美观清晰.     

Effect of Fe/Pb molar ratio on the structure,magnetic and dielectric properties of PbFe12O19 nanoparticles

In this paper, lead hexaferrite (PbFe₁₂O₁₉) nanoparticles were synthesized by sol-gel method. In order to prepare PbFe₁₂O₁₉ nanoparticles, the metal nitrates with Fe/Pb?=?8, 10, 11, 12, 14 ratios and citric acid were used. The structure, morphology, magnetic, and dielectric properties of PbFe₁₂O₁₉ nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), vibrating sample magnetometer (VSM) and LCR meter. XRD results revealed that the samples with Fe/Pb?≤?10 and Fe/Pb?>?10 have single-phase hexaferrite and hematite (α- Fe₂O₃) structures, respectively. As a result, the sample with Fe/Pb?=?10 is single-phase and shows the highest values of the saturation magnetization and remanence magnetization. We found that the values of dielectric constant (ε′) and dielectric loss (ε″) increase with an increase in the Fe/Pb molar ratio from 8 to 12 and then decreases with an increase of Fe/Pb molar ratio to 14. The variation of ac conductivity (σ_ac) with frequency ranging from 1?kHz to 200?kHz showed that electrical conductivity in these ferrites is mainly due to the electron hopping mechanism.     

A spectroscopic study of water vapor isotopologues H2O, H2O and HDO using a continuous wave DFB quantum cascade laser in the 6.7 μm region for atmospheric applications

A quantum cascade spectrometer was used in the laboratory to study H₂¹⁶O, H₂¹⁸O and HDO line intensities near 6.7 μm. The spectral region ranging from 1483 to 1487 cm⁻¹, which is suitable for the in situ laser sensing of these isotopologues in the atmosphere, was investigated using a continuous-wave distributed feed-back quantum cascade laser. Eight lines of water vapor isopologues were studied—one line of the ν₂ band of H₂¹⁶O, one line of the 2ν₂-ν₂ band of H₂¹⁶O, two lines of the ν₂ band of H₂¹⁸O and four lines of the ν₂ band of HDO were carefully revisited. The measured intensities were thoroughly compared to relevant molecular databases and other experimental and calculated results. We also observe that the H₂O, D₂O, HDO equilibrium constant agrees excellently with previously determined values.     

ICP法测定超临界水氧化设备腐蚀液中铜、铬、铝、镍、钛

采用光谱法研究了超临界水氧化设备腐蚀液中Cu,Cr,Al,Ni和Ti元素的含量,分析判断不锈钢设备腐蚀状况及其因素。结果表明,超临界设备不锈钢材料主要成分元素Cr在超临界水中有不同程度的溶解,并且溶解程度随温度和压力升高而增大。     

Theoretical insight into the influence of molecular ratio on the binding energy and mechanical property of HMX/2-picoline-N-oxide cocrystal,cooperativity effect and surface electrostatic potential

Molecular dynamics method was employed to study the binding energies and mechanical properties of the selected crystal planes of the energetic/nonenergetic 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)/2-picoline-N-oxide cocrystal in different molecular ratios. The solvent effect in HMX:2-picoline-N-oxide (1:1) was calculated, and the cooperativity effect was discussed in HMX···HF/CH₄···2-picoline-N-oxide by using the M06-2X and MP2(full) methods at the 6-311++G^** basis set. The density, oxygen balance and detonation velocity were calculated. The results indicate that HMX/2-picoline-N-oxide prefers cocrystalising in the 1:1, 2:1 and 3:1 molar ratios, in which the cocrystals own the highest binding energy and best ductility. The cooperativity effect is present in the cyclic complex with CH₄, while the anti-cooperativity effect is found in the HF complex. Thus, in order to obtain stable HMX/2-picoline-N-oxide cocrystal, the solvent with low dielectric constant should be chosen, as is in accordance with the result from solvent effect. The reduced density gradient (RDG) and surface electrostatic potential analysis confirms the cooperativity effect and reveals the nature of decreased sensitivity in complex (or cocrystal). The cocrystals in the molar ratios of 5:1–10:1 could be satisfactory in view of explosive properties.