Theoretical analysis of double-differential neutron emission cross sections for n+^(56)Fe reactions at incident energies of 7-13 MeV

The double-differential neutron emission cross sections for n＋^56Fe reactions at incident energies of 7 -13 MeV at different angles are calculated by the UNF （abbreviation for unified, 2009 Version） code, which is based on the unified Hauser-Feshbach and exciton model. The results indicate that the higher the incident energies, the better the results, although there are some discrepancies between the calculated results and the measured data for natural iron. These discrepancies are analyzed in detail in this paper. In addition, the calculated results are also compared with the evaluated results of ENDF/B VII.0 and JEFF-3.1.1 near the angle of 90° at incident energies of 8.17 and 11.5 MeV, respectively.

Effects of temperature and input energy on a quasi-three-level emission cross section of Nd^(3+):YAG pumped by a flashlamp

The influence of temperature and input energy on the fluorescence emission cross section of Nd3＋ ：YAG crystal is studied. The stimulated emission cross sections of quasi-three-level systems are determined in a temperature range from -30 to 60 ℃ and an input energy range from 18 to 75 J. The cross section is found to be decreased when the temperature and the input energy are increased. This is attributed to the thermal broadening mechanism of the emission line. This study is relevant for the development of laser design.

Preparation and Optical Properties of Er^(3+)-Doped Gadolinium Borosilicate Glasses

Er^(3+)-doped Gd_2O_3 -SiO_2 -B_2O_3 -Na_2O glasses were prepared, and formation range of glass of Gd_2O_3 -SiO_2 -B_2O_3 system was experimentally obtained. It is found that the glass phase can be formed only when the content of SiO_2 is 0～50%(molar fraction), Gd_2O_3 is 0～30%(molar fraction) and B_2O_3 is above 20%(molar fraction) in this glass system. The glass can also be obtained but becomes translucent at the contents of 60%(molar fraction) SiO_2 and 30% Gd_2O_3 , or at the contents of 60%(molar fraction) SiO_2 and 30%(molar fraction) B_2O_3. There is no glass phase formed in other glass components. Glass forming ability for Gd_2O_3 content of 10%, was characterized by the value of β, the parameter of crystallization tendency, which is 0.32～1.76, obtained from the differential thermal analysis. The absorption and emission cross section, the J-O parameters Ωt_((2,4,6)) and radiative transition probabilities were calculated by using the theory of McCumber and Judd-Ofelt. The emission properties at 1.5 μm of the samples are discussed with the product of full width at half maximum and stimulated emission cross section. It can be seen that the value of the FWHM×σ_e^(peak) product in the prepared glass is more than those of germanate, silicate and phosphate glasses. Furthermore, the maximum value of the product among these glasses reported in this work is close to that of oxyfluoride silicate glass. Therefore, the Er^(3+)-doped gadolinium borosilicate glass in this paper is a candidate for broadband erbium doped fiber amplifiers.

Spectral Parameter Study on Tm^(3+) in Na_5Tm(WO_4)_4 Crystal

On the basis of the obtained intensity parameters Ω λ(λ =2,4,6) of Tm 3+ in the Na 5Tm(WO 4) 4 crystal, we performed calculations on the radiative transition probability, radiative lifetime, branching ratios and stimulated emission integrated cross sections between the two excited J manifolds of Tm 3+ , and discussed potentiality for the usage of this crystal as a laser material.

Optical-transition properties of the Nd^(3+) ion in KLu(WO_4)_2 crystal

Optical absorption and emission intensities of Nd3+ ion in KLu(WO4)2 crystal were investigated. Based on the Judd-Offelt theory, we calculated the following spectral parameters: phenomenological intensity parameters Ω2=5.567×10–20, Ω4=3.597×10–20, and Ω6= 3.800×10–20 cm2. The radiative lifetime of levels 4F3/2 was 182.58 μs. The fluorescence branching ratio for the transition 4F3/2→4I11/2 was 46.98%. In addition, the radiative transition probabilities AJ,J’, oscillator strengths PJ,J’ and the values of inte...