Cd Sheets Research Articles

Au@CdO core/shell nanoparticles synthesized by pulsed laser ablation in Au precursor solution

Au@CdO core/shell nanocomposite was prepared using Pulsed Laser Ablation in Liquids (PLAL) via one step-process. A nanosecond pulsed laser (Nd:YAG, λ = 1064 nm) was used to ablate Cd sheet immersed in HAuCl4 solution. The surface plasmon resonance (SPR) using UV–vis absorption spectroscopy was employed to monitor the fast changes occurring in the NP colloidal solutions upon interaction between Cd sheets and Au precursor. The structure of the as-prepared samples was confirmed by high resolution transmission electron microscope (HRTEM) analysis and energy dispersion X-Ray spectroscopy (EDX) analysis. A mechanism for the growth of Au@CdO core/shell nanocomposite was given.

Effects of texture on anisotropy of mechanical properties in annealed Mg–0.6%Zr–1.0%Cd sheets by unidirectional and cross rolling

Effects of texture on anisotropy of mechanical properties in annealed Mg–0.6%Zr–1.0%Cd sheets by unidirectional and cross rolling were investigated. The results show that both sheets exhibit typical basal texture and obvious anisotropy. Compared with the unidirectional rolling sheet, a weaker basal texture and more scattering rotated grains are obtained by cross rolling within the sheet plane. Meanwhile, the crossing rolling sheet exhibits lower mechanical properties anisotropy than the unidirectionally rolled one. Taking into account of prismatic 〈a〉 slip and basal 〈a〉 slip as the dominant deformation mechanism for the unidirectional and cross rolling sheets respectively, the effects of texture on anisotropic behavior of both sheets could be explained by the microscopic crystal plasticity theory. Furthermore, the decreased anisotropy in annealed sheet by cross rolling is likely attributed to the weakened basal texture which originated from the specific geometry of cross rolling.

Neutron total cross-section measurements with the 6Li-ZnS(Ag) scintillator (BC702) employing a neutron and noise separation technique

The neutron total cross-section of natural Dy has been measured in the energy region from 0.01 to 100 eV by using the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and a timeof- flight path with an 11-m length. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.5 cm has been used as a neutron detector, and a metallic Dy plate has been used for the neutron transmission measurement. The background level has been determined by using notch filters of Co, Ta, and Cd sheets. In order to reduce the gamma rays from bremsstrahlung and from neutron capture, we have employed a neutron-gamma separation system based on their different pulse shapes.

Design of an epithermal neutron beam for BNCT in thermal column of Tehran research reactor

Abstract The potential of the thermal column of Tehran Research Reactor (TRR) to provide epithermal neutron beam for Boron Neutron Capture Therapy (BNCT) has been investigated using Monte Carlo simulation. A Beam Shaping Assembly (BSA) has been designed and optimized to meet BNCT neutron beam criteria recommended by International Atomic Energy Agency. The suggested BSA configuration in cylindrical geometry consists of 20 cm Al as a moderator, 35 cm Pb as a reflector, two 5 cm Bi slabs as gamma shield, and two 2 mm Cd sheets as thermal neutron filters. The results show that epithermal neutron flux at the exit of the BSA can be 0.65 × 10 9 n/cm 2 s. In-phantom dose analysis indicates that the designed neutron beam can be used for treatment of deep-seated brain tumors in acceptable time.

Growth of CdS nanocrystallites on graphene oxide Langmuir–Blodgett monolayers

Large area GO–Cd composite Langmuir–Blodgett monolayers were transferred onto Si substrate by introducing Cd2+ ions into the subphase. The changes in the behaviour of the Langmuir monolayer isotherm in the presence of Cd2+ ions are attributed to changes in the microstructure and density of the GO sheets on the subphase surface. The uptake of Cd onto the GO monolayers and the effect of subsequent sulphidation were investigated by AFM, FTIR, Raman, XPS and HRTEM techniques. The incorporation of Cd into the GO monolayers causes some overlapping of sheets and extensive formation of wrinkles. Sulphidation of the GO–Cd sheets results in the formation of uniformly distributed CdS nanocrystallites on the entire basal plane of the GO monolayers. The de-bonding of Cd with oxygen functional groups results in a reduction of the wrinkles. The GO sheets function primarily as a platform for the interaction of metal ions with oxygen functionalities and their structure and characteristic features are not affected by either uptake of Cd or formation of CdS.

Measurement of neutron cross sections and resonance parameters of 169Tm below 100 eV

The neutron total cross-sections of thulium (169Tm) were measured in the neutron energy region from 0.01 eV to 100 eV by using the time-of-flight method at the Pohang Neutron Facility, which consists of an electron linac, a water-cooled tantalum target with a water moderator, and a 12 m time of flight path. Two thulium plates with different thicknesses were used for the neutron transmission measurement. The background level was determined by using a notch-filter of Co, In, and Cd sheets. The present measurement was compared with the previous ones, and a new set of resonance parameters of 169Tm isotope was obtained from the transmission rate by using the SAMMY code, with a comparison with the recommended parameters by Mughabghab.

Measurement of the Neutron Total Cross Sections of Natural Palladium by Using Pulsed Neutrons at Pohang Neutron Facility

The neutron total cross-sections of palladiums are measured in the neutron energy region from 0.1 eV to 500 eV by using time of flight method at the Pohang Neutron Facility. The Pohang Neutron Facility consists of an electron linac, a water-cooled tantalum target with a water moderator, and a 12 m long time-of-flight path, and is producing pulsed neutron beam from 65 MeV electron as 10~15 Hz repetition rate. The neutron detector is using a 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm. Natural palladium metal plates with 5 × 5 cm2 in area and 0.5 mm, 1 mm in thickness, are used for the neutron transmission measurement. The background level is determined by using a notch-filter of Co, In, and Cd sheets. The measurements are compared with other measurements and the evaluated data in ENDF/B-VII.0.

Evaluation of N50 neutron slab monitor detection efficiency with TRIPOLI-4.3 Monte Carlo code

Monte Carlo code TRIPOLI-4.3 has been used to evaluate the N50 neutron slab monitor detection efficiency benchmark organised by the non-destructive assay (NDA) working group of European Safeguards Research and Development Association (ESARDA). The lattice geometry of TRIPOLI-4.3 was applied to simplify the modelling of the N50 monitor, which consists of four 3He tubes embedded in a high-density polyethylene (HDPE) moderator. Using additional HDPE slabs and/or Cd sheets, 10 geometry configurations with different states of moderation were considered in this study. Two cross section libraries from ENDF/B-VI.4 and JEF2.2 and three representations of the 252Cf fission spectrum were investigated and the calculation experiment (C/E) ratios were discussed. The perturbation option was used in order to study the sensitivity to the HDPE density. The S(alpha,beta) thermal scattering in HDPE was also tested to quantify its impact on the N50 detection efficiency calculations.

Measurement of Neutron Total Cross Section of Ag and Sm at Pohang Neutron Facility

The neutron total cross section of natural Ag and Sm has been measured in the energy region from 0.1 eV to 100 eV by the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and an 11 m long time-of-flight path. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm has been used as a neutron detector and metallic plates of Ag and Sm samples have been used for the neutron transmission measurement. The background level has been deterrnined by using notch-filters of Co, In, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and that from neutron capture, we have employed a neutron-gamma separation system based on their different pulse shapes. The present measurements are in general agreement with the previous ones and the evaluated data in ENDF/B-VI. The resonance parameters of Ag isotopes (107Ag and 109Ag) have been extracted from the transmission data by using the SAMMY code.

Measurement of Thermal Neutron Capture Cross Section and Resonance Integral of the 237Np(n, γ)238Np Reaction

The thermal neutron capture cross section (σ0) and the resonance integral (I 0)of 237Np have been measured by an activation method to supply basic data for the study of transmutation of nuclear waste. The neutron irradiation of 237Np samples have been done at the Research Reactor Institute, Kyoto University (KUR). Samples of 237Np were irradiated between two Cd sheets or without a Cd sheet. Since 237Np has a strong resonance at the energy of 0.49 eV, the Cd cutoff energy was adjusted at 0.358 eV (thickness of the Cd sheets: 0.125 mm). A high purity Ge detector was employed for activity measurement. The reaction rate to produce 238Np from 237Np was analyzed by the Westcott's convention. Results obtained were 141.7±5.4 barns for σ0 and 862±51 barns for I 0 above 0.358 eV of 273Np. By setting the Cd cut-off energy at 0.358 eV considering the resonance at 0.49 eV, a smaller value of σ0 was obtained in this work than the values reported by the previous authors.

Measurement of neutron total cross-section of Dy at Pohang Neutron Facility

Abstract The neutron total cross-section of natural Dy has been measured in the energy region from 0.025 eV to 100 eV by the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and a time-of-flight path with an 11 m length. A 6Li–ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.5 cm has been used as a neutron detector and a metallic plate of Dy sample have been used for the neutron transmission measurement. The background level has been determined by using notch-filters of Co, Ta, and Cd sheets. In order to reduce the gamma rays from a Bremsstrahlung and that from a neutron capture, we have employed a neutron-gamma separation system based on their different pulse shape. The present measurements are in general agreement with the previous ones and the evaluated data in ENDF/B-VI. The resonance parameters of Dy isotopes (161,162,163Dy) have been extracted from the transmission data by using the SAMMY code and compared with the previous ones.

Characteristics of the Kyoto University Lead Slowing-down Spectrometer (KULS) coupled to an electron linac

A lead slowing-down spectrometer coupled to a 46 MeV electron linear accelerator (linac) was installed at Research Reactor Institute, Kyoto University (KURRI). The size of this Kyoto University Lead Slowing-down Spectrometer (KULS) is 1.5 × 1.5 × 1.5 m 3 , and it is covered with Cd sheets 0.5 mm thick. One of the eleven experimental holes in the KULS is covered with 10 to 15 cm thick bismuth layers to suppress high energy capture gamma-rays from lead. The characteristics of this KULS have been experimentally obtained and the results are compared with the predicted values by Monte Carlo calculations using the MCNP code. 1) The slowing-down constant K in the relation E = K t 2 between the neutron slowing-down time t and energy E is 190±2 (keV μ s 2 ) for the bismuth hole and 156±2 (keV μ s 2 ) for an ordinary lead hole, respectively. The K values agree with the calculated ones. 2) The measured energy resolution ΔE E at full-width-at-half-maximum (FWHM) was about 40% for both holes, while the calculated values were lower by about 10% than the measured ones in the relevant energy region. 3) The neutron energy spectrum from 0.01 eV to 20 MeV and the spatial distribution of neutrons in the KULS were measured by the foil activation method. The angular neutron spectrum perpendicular to the linac electron beam was also obtained experimentally in the energy range from a few eV to about 10 MeV by the neutron time-of-flight (TOF) method. The measured results are compared with the calculated ones in which we have used the three evaluated nuclear data JENDL-3, ENDL-85 and ENDF/B-IV for lead. Through the comparison a check on the nuclear data has been performed.