991 resultados para H 800 R425r
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In this paper, we present results of the synthesis of gold nanoclusters in sapphire, using Ar ion implantation and annealing in air. Unlike the conventional method of Au implantation followed by thermal annealing, Au was deposited on the surface of m- and a- cut sapphire single crystal samples including those pre-implanted with Ar ions. Au atoms were brought into the substrate by subsequent implantation of Ar ions to form Au nanoparticles. Samples were finally annealed stepwisely in air at temperatures ranging from 400 to 800 C and then studied using UV–vis absorption spectrometry, transmission electron microscopy and Rutherford backscattered spectrometry. Evidence of the formation Au nanoparticles...
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高速、大功率LED(≥3W)光源驱动电路是中子墙探测器光刻度系统的重要组成部分。本文简要介绍高速、大功率LED光源驱动电路的设计。该电路具有稳定性好、驱动脉冲前、后沿快,大电流脉冲输出等特点。内置信号源信号经过成形电路后,形成具有一定脉宽的快脉冲信号作为驱动信号,驱动信号上升时间tr<10 ns,下降时间tf<10 ns,其脉冲宽度分5档可调。该脉冲信号通过驱动电路控制输出电流开关,最大输出脉冲电流为800 mA,控制LED在额定功率下工作。该驱动电路最多可同时驱动六个大功率LED光源工作,目前已用于我所中子墙探测器阵列探测单元的初步刻度与测试。
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介绍了厚度为300-800μm,有效面积为50-113mm2的高阻GaAs单晶材料制备的核辐射GaAs探测器的研制工艺,测试结果。
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为了提高激光靶丸的阻气性能,用戊二醛对阻气层材料聚乙烯醇进行交联改性。在17份完全相同的10 mL质量分数3%的聚乙烯醇(PVA)和20μL浓盐酸混合溶液中,分别加入从300μL到1 700μL的戊二醛(GA),交联反应后,测量缩醛膜的阻气性能,并计算渗透系数。结果表明,随着缩醛膜中戊二醛含量的增加,缩醛膜渗透系数的变化规律是:从减小到增加到不变再到增加;当戊二醛的含量是800μL时,缩醛膜的渗透系数最小,阻气性能最好。
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采用激光跟踪仪及配套带软件Insight对兰州重离子加速器冷却储存环主环磁铁进行了安装和准直。首先建立全局坐标系,用来确定从源体到实验环各子系统的理论原点的位置;而各个子系统又分别以各自的理论原点为基础建立局部坐标系,用来安装定位本系统内的各个元件;对各个子系统中的每一个元件还采用了元件坐标系。准直测量时,先在每块磁铁上焊接8个测量基准;然后对磁铁上的基准进行测量,以确定其在元件坐标系中的位置;再架设激光跟踪仪,测量主环控制网点,恢复主环局部坐标系,根据元件在主环局部坐标系中的位置及理论坐标,计算出相关的变换参数;转入元件坐标系,采用激光跟踪仪及Insight软件显示实时测量坐标及其与理论值之差,其精度达到0.15mm。
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IEECAS SKLLQG
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IEECAS SKLLQG
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IEECAS SKLLQG
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着重报告了自行研制的轴向对称型BGO反康屏蔽探测器的基本结构、抑制原理及其抑制性能的测试结果。测得60Coγ射线源的康普顿抑制系数在能区100~300、300~800、800~1100keV范围内分别为2.3、4.1和4.6,且峰总比为37%(对相对效率为30%的HPGe探测器)。
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Single-crystalline Si (100) samples were implanted with 30 keV He2+ ions to doses ranging from 2.0x10(16) to 2.0x10(17) ions/cm(2) and subsequently thermally annealed at 800 degrees C for 30min. The morphological change of the samples with the increase of implantation dose was investigated using atomic force microscopy (AFM). It was found that oblate-shaped blisters with an average height around 4.0nm were found on the 2.0 x 10(16) ions /cm(2) implanted sample surface; spherical-shaped blisters with an average height wound 10.0nm were found on the 5.0 x 10(16) ions/cm(2) implanted sample surface; strip-shaped and conical cracks were observed on the sample He-implanted to a dose of 1.0 X 10(17) ions /cm(2). Exfoliations occurred on the sample surface to a dose of 2.0 x10(17) ions /cm(2). Mechanisms underlying the surface change were discussed.
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Based on the isospin- and momentum-dependent transport model IBUU04, the transverse momentum distributions of the free neutron-proton ratio in the Sn-132+(124) Sn reaction system at mid-central collisions with beam energies of 400/A MeV, 600/A MeV and 800/A MeV are studied by using two different symmetry energies. It is found that the free neutron-proton ratio as a function of the transverse momentum at the mid-rapidity is very sensitive to the density dependency of the symmetry energy especially at incident energies around 400/AMeV.
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Based on the isospin- and momentum-dependent transport model IBUU04, we calculated the reaction of the Sn-132+Sn-124 systems in semi-central collisions at beam energies of 400/A MeV, 600/A MeV and 800/A MeV by adopting two different density dependent symmetry energies. It was found that the proton differential elliptic flow as a function of transverse momentum is quite sensitive to the density dependence of symmetry energy, especially for the considered beam energy range. Therefore the proton differential elliptic flow may be considered as a robust probe for investigating the high density behavior of symmetry energy in intermediate energy heavy ion collisions.
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The double neutron-proton differential transverse flow taken from two reaction systems using different isotopes of the same element is studied at incident beam energies of 400 and 800 MeV/nucleon within the framework of an isospin- and momentum-dependent hadronic transport model IBUU04. The double differential flow is found to retain about the same sensitivity to the density dependence of the nuclear symmetry energy as the single differential flow in the more neutron-rich reaction. Because the double differential flow reduces significantly both the systematic errors and the influence of the Coulomb force, it is thus more effective probe for the high-density behavior of the nuclear symmetry energy.
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Using the isopin- and momentum-dependant hadronic transport model IBUU04, the effect of symmetry energy on the pi(-)/pi(+) ratio are studied. Our investigations are based on the calculations of the Sn-132+Sn-124 semi-central collisions at beam energies of 400/ A MwV, 600/ A MeV and 800MeV. It is found that both the transverse momentum and kinetic energy distributions of the pi(-)/pi(+) ratio are rather sensitive to the symmetry energy, especially around the Colomb peaks. The position of the coulomb peak is shown to be nearly indrpendant of beam energy. The sesitivity of the pi(-)/pi(+) ratio to the symmetry ebergy decreases as the beam energy increases from 600/ A MeV to 800/ A MeV.
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We investigate hard photon production of the near-collinear bremsstrahlung and a new process called the inelastic pair annihilation, fully including the LPM effect, in a chemically equilibrating quark-gluon plasma at finite baryon density, and find that the effect of the system evolution on the photon production and large contribution of the bremsstrahlung make the total photon yield of the two processes as a strongly increasing function of the initial quark chemical potential.