Microphotoluminescence investigation of InAs quantum dot active region in 1.3 mu m vertical cavity surface emitting laser structure

Microphotoluminescence (mu-PL) investigation has been performed at room temperature on InAs quantum dot (QD) vertical cavity surface emitting laser (VCSEL) structure in order to characterize the QD epitaxial structure which was designed for 1.3 mu m wave band emission. Actual and precise QD emission spectra including distinct ground state (GS) and excited state (ES) transition peaks are obtained by an edge-excitation and edge-emission (EEEE) mu-PL configuration. Conventional photoluminescence methods for QD-VCSELs structure analysis are compared and discussed, which indicate the EEEE mu-PL is a useful tool to determine the optical features of the QD active region in an as-grown VCSEL structure. Some experimental results have been compared with simulation results obtained with the aid of the plane-wave admittance method. After adjustment of epitaxial growth according to EEEE mu-PL measurement results, QD-VCSEL structure wafer with QD GS transition wavelength of 1300 nm and lasing wavelength of 1301 nm was obtained.

~(19)F+~(27)Al耗散反应产物激发函数的长程关联

在中国原子能科学研究院的HI-13串列静电加速器上完成了19F+27Al耗散反应产物的激发函数测量。束流19F的入射能量从110.25MeV到118.75MeV,步长250keV,测量了实验室系+57°,+31°,-15°和-29°出射的类弹产物B,C,N,O,F和Ne的激发函数。观测到激发函数具有耗散反应的特征涨落结构,分析了激发函数之间的长程角度关联以及强烈的电荷数关联。

重离子弹性散射中的角分散研究

简要评述了重离子弹性散射角分散研究的内容、方法及物理意义。通过前角区重离子弹性散射产物微分截面的角分布测量,作出角分散图ln(dσ/dθ)-θ2。分析经典偏转函数,从而在实验上确定了反应系统的核虹角。在低能、重靶的重离子反应系统中,核虹角远小于擦边角。晕核及弱束缚核比稳定核具有更小的核虹角和更大的核相互作用范围。经典偏转函数的计算有助于提供一套光学势参数,以便于拟合弹性散射产物的微分截面。

小角度范围内弱束缚核~(17)F弹性散射微分截面的奇异行为(英文)

在兰州放射性束流线(RIBLL)上完成了17F／17O+208Pb的弹性散射微分截面角分布测量．分析了17F／17O弹性散射产物微分截面的对数(ln(dσ／dθ))随散射角平方(θ2)的依赖关系．结果表明,在所测量的角度范围内(6°-20°),17O的这一依赖关系可以用一条直线很好地拟合,而17F的这一依赖关系需要两条不同斜率的直线才能拟合．17F数据拟合中的这种斜率改变可能起因于17F的奇异结构．对其他实验组数据的分析支持以上的结论,即在一定的角度范围内,弱束缚核与稳定核相比,弹性散射产物微分截面的对数与散射角平方的依赖关系有明显的差异,这可以作为深入研究“晕核”和“皮核”的一个新探针．

~(19)F+~(27)Al耗散反应中双核系统的转动与形变

测量了19F+27Al耗散反应产物B,C,N,O,F和Ne的激发函数,入射束流的能量从110．25MeV 到118．75MeV,能量步长为250keV．从产物的能量自关联函数中提取了反应中所形成的中间双核系统的转动惯量,与相粘模型计算的刚体转动惯量相比较,结果表明形成的双核系统有大的形变．

~(19)F+~(27)Al耗散反应产物截面测量中的不重复性

在中国原子能科学研究院的HI-13串列静电加速器上完成了114MeV和118．75MeV的19F+27Al 耗散反应产物B,C,N,O,F,Ne,Na和Mg的微分截面测量．条形27Al同位素靶的大小尺寸为 10mm×50mm,平均厚度约67μg／cm2．固定入射束流19F的能量,通过移动靶位,先后轰击了靶上20个不同的位置．实验结果表明,在弹靶系统、入射能量以及探测系统都相同的多次独立的微分截面测量中,截面的涨落不呈现高斯型几率分布．截面测量的这种不重复现象难以用有限计数率的统计性质来解释．

(19)~F+(27)~Al耗散反应中双核系统的转动与衰变

测量了19F+27Al耗散反应产物B,C,N,O,F和Ne的激发函数,入射束流的能量从110.25MeV 到118.75MeV,能量步长为250keV.用能量自关联函数方法从激发函数中提取了各反应产物的平均衰变宽度,利用同时考虑反应中所形成的中间双核系统的转动特性和衰变特性而发展了的Ericson核反应统计理论,讨论了19F+27Al耗散反应中双核系统随时间的演化过程.

~(19)F+~(27)Al反应产物的角分布、角分散与耗散机制

完成了114MeV19F+27Al深部非弹性碰撞产物的角分布测量.分析了反应产物B,C,N,O,F,Ne,Na,Mg和Al的实验室系角分布,讨论了反应形成的中间双核系统随时间演化过程中角分布所表现出的耗散特点.从实验上提取了反应产物各元素的角分散参数并作了角分散参数的理论拟合,讨论了角分散参数的物理意义以及角分散参数与耗散反应产物的电荷数Z之间的依赖关系.

~(19)F+~(27)Al深部非弹性碰撞产物的角分布

完成了19F+27Al深部非弹性碰撞产物的角分布测量.初步分析了反应产物B,C,N,O,F,Ne,Na,Mg和Al的实验室系角分布,展现出深部非弹性反应机制的特点,显示了反应系统随时间的演化过程.

Cross-correlation of excitation functions for different fragments and different scattering angles in Al-27(F-19, x)y reactions

Excitation functions have been measured for different projectile-like fragments produced in Al-27(F-19,x)y reactions at incident energies from 110.25 to 118.75 MeV in 250 keV steps. Strong cross section fluctuations of the excitation functions are observed. The cross- correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle theta(cm) have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion Collision of Al-27(F-19,x)y.

Angular dispersion and deflection function for heavy ion elastic scattering

The differential cross sections for elastic scattering products of F-17 on Pb-208 have been measured. The angular dispersion plots of ln(d sigma/d theta) versus theta(2) are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nuclear rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.

Elastic scattering angular dispersion of weakly bound nucleus F-17

The differential cross-sections for elastic scattering of F-17 and O-17 on Pb-208 have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles, viz. angulax dispersion plot, shows clearly that there exists a turning point in the range of small scattering angles (6 degrees-20 degrees) for F-17 due to its exotic structure, while no turning point was observed for O-17. The experimental results have been compared with previous data of other groups. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering angular dispersion of weakly bound nuclei with halo or skin structure as compared with that of the stable nuclei. Therefore the fact that the turning point of the elastic scattering angular dispersion plot appears at small angle for weakly bound nuclei can be used as a new probe to investigate the halo and skin phenomenon.

Exotic behavior of elastic scattering differential cross-sections of weakly bound nucleus F-17 at small angles

The differential cross-sections for elastic scattering of F-17 and O-17 on Pb-208 have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles shows clearly that there exists a turning point in the range of small scattering angles (6 degrees-20 degrees) for F-17 having exotic structure, while no turning point was observed in the O-17 elastic scattering. The experimental results have been compared with previous data. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering differential cross-sections of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the fact that the turning point of the logarithms of differential cross-sections appears at small angle for weakly bound nuclei could be used as a new probe to investigate the halo and skin phenomenon.

Largely deformed dinuclear system formed in F-19+Al-27 dissipative collision

Excitation functions are measured for different charge products of the F-19+(27) Al reaction in the laboratory energy range 110.25-118.75MeV in steps of 250keV at theta(lab) = 57 degrees, 31 degrees and -29 degrees. The coherence rotation angular velocities of the intermediate dinuclear systems formed in the reaction are extracted from the cross section energy autocorrelation functions. Compared the angular velocity extracted from the experimental data with the ones deduced from the sticking limit, it is indicated that a larger deformation of the intermediate dinuclear system exists.