共查询到19条相似文献,搜索用时 93 毫秒
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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. 相似文献
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研究了形变效应对10.6MeV/u 84Kr+27Al反应中断前粒子发射的影响.发现通过测量的裂变前粒子多重性提取的裂变延迟时间将因此从20×10-21s减少到5×10-21s,表明增强的断前粒子发射有一部分来自形变效应的贡献. 相似文献
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57MeV/u 64Zn+27Al反应中集体流的研究 总被引:1,自引:0,他引:1
贺智勇 J.Peter J.C.Angelique G.Bizard R.Brou D.Cussol A.Kerambrun J.P.Patry R.Regimbart J.C.Steckmeyerr B.Tamain E.Vient G.Auger C.Cabot 《中国物理 C》1994,18(9):800-806
报道了利用4π带电粒子阵列测量的57MeV/u的64Zn轰击27Al反应中的集体物质流.各事件的碰撞参数分类采用平均平行速度方法,反应平面的确定采用横向动量分析方法.实验观察到在反应平面内的集体横向动量(边流参数)随着碰撞参数和粒子产物而变化. 相似文献
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We report (13)C-(27)Al double resonance experiments (REDOR and TRAPDOR) on several aluminum organic compounds with the aim of detecting (13)C-(27)Al dipolar couplings and distances in solids. The (13)C and (27)Al pulses are applied to the same probe channel because their resonance frequencies are in close proximity. The different possibilities of controlling the efficiency of the TRAPDOR approach (by varying the (27)Al RF amplitude and the MAS frequency) are investigated. The results indicate that TRAPDOR is superior to REDOR in resolving differences in (13)C-(27)Al distances when choosing the proper experimental conditions. Where known, the crystal structure data are in qualitative agreement with the distance information extracted from our experiments. The experiment should be very valuable in different fields of solid state chemistry, where the interaction of organic and inorganic sample fractions is of fundamental importance. 相似文献
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高岭土与针铁矿胶结样中27Al、29Si NMR谱与其原子电荷关系 总被引:3,自引:0,他引:3
由NMR谱实验得高岭土与针铁矿胶结样中27Al、29Si的化学位移较单一高岭土分别正移了2.7ppm和2.33ppm.由CNDO/2方法计算得到胶结样中Al、Si原子电行比高岭土分别减少了0.0787和0.0286.胶结样中Al、Si原子电荷的减少与27Al、29Si NMR谱化学位移相吻合,可以认为在高岭土与外铁矿的界面上形成了氢键而呈现胶结态. 相似文献
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Total reaction cross sections for the transfer reactions27Al(18O,16O)29Al,27Al(18O,17O)28Al and27Al(13C,12C)28Al are reported for center-of-mass energies between 13 and 20 MeV for18O projectiles and between 11 and 17.5 MeV for13C projectiles. The reaction products,29Al and28Al, beta decay to29Si and28Si, respectively, and the subsequentγ decays of29Si and28Si were measured. Due to the relatively long beta decay half lives, data were taken in a beam-off mode, resulting in very clean spectra. Total cross sections were calculated and compared with a theoretical model for barrier penetration proposed by C.Y. Wong. Differences between18O induced one and two-neutron total transfer reaction cross sections are discussed. 相似文献
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Ishida K Ozaki D Kamatsuka T Tou H Kyogaku M Kitaoka Y Tateiwa N Sato NK Aso N Geibel C Steglich F 《Physical review letters》2002,89(3):037002
We report (27)Al Knight shift ( (27)K) measurement on a single-crystal UNi(2)Al(3) that reveals a coexistence of superconductivity and a spin-density-wave (SDW) type of magnetic ordering ( T(SDW) = 4.5 K). The spin part of (27)K, (27)K(s), does not change down to 50 mK across the superconducting (SC) transition temperature T(c) approximately 0.9 K. In contrast with the isostructural compound UPd(2)Al(3) ( T(c) approximately 2 K), which was identified to be a spin-singlet d-wave superconductor, the behavior of (27)K strongly supports that UNi(2)Al(3) , like UPt(3) and Sr(2)RuO(4), belongs to a class of spin-triplet SC pairing state superconductors. 相似文献
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J. Csikai Zs. Lantos S. Sudár T. Chimoye T. Vilaithong N. Chirapatpimol 《Zeitschrift für Physik A Hadrons and Nuclei》1986,325(1):69-72
Cross sections for the reactions27Al(n, p)27Mg and28Si(n,p)28Al were measured by activation method between 13.40 and 14.83 MeV neutron energy. An accuracy of about 4% was achieved using the27Al(n, α)24Na reaction as a reference at 14.1 MeV where the relative excitation function has also been measured. Results obtained were compared to a recent compilation and that calculated by the Hauser-Feshbach model. Using the back-shifted level density formula and taking into account the contribution of the separated levels, the calculations were extended to the energy range from the threshold to 18 MeV. A structure was observed in the27Al(n, α)24Na reaction cross section curve around 14 MeV neutron energy. 相似文献
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We present here the first 3D homonuclear/heteronuclear correlation experiment applied to quadrupolar nuclei and making use of the sole scalar J-coupling. This experiment, based on the 2D-Homonuclear-Heteronuclear Single Quantum Correlation (H-HSQC) experiment, uses a relayed transfer from the (27)Al central transition to neighbouring (31)P spins and to the central transition of a second (27)Al. It confirms the correlation map characterizing the two (27)Al and the (31)P NMR signatures of (27)Al-O-(31)P-O-(27)Al chemically bonded molecular motifs. 相似文献
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Energy coherence widths of the dissipative products in the collision 27Al+27Al are extracted from measurement of the excitation functions. Then, the nuclear temperature T of the intermediate dinuclear system are determined, and discussed by using a concept of coherence rotation. 相似文献
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Two-dimensional 27Al multiple-quantum magic angle spinning (MQMAS) NMR experiments are used to study mixtures of bayerite (alpha-Al(OH)3) with either silicic acid (SiO2.nH2O) or silica gel (SiO2) that have been ground together for varying lengths of time. This mechanical treatment produces changes in the 27Al MAS and MQMAS NMR spectra that correspond to the formation of new Al species. Mean values of the quadrupolar interaction (PQ) and isotropic chemical shift (deltacs) are extracted from the two-dimensional 27Al NMR spectra for each of these species. The presence of significant distributions of both 27Al quadrupolar and chemical shift parameters is demonstrated and the effect of grinding duration on the magnitudes of these distributions is discussed. 相似文献
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Measurements of Cross Sections for the Reactions 27Al(N, P) 27Mg, 27Al(N, α)24Na and 27Al(N, α)24mNa in the Energy Region between 6,3 MeV and 8,3 MeV Using the activation method cross-sections for the reactions 27Al(n, α0)24Na, 27Al(n, α1)24mNa and 27Al(n, p)27Mg have been measured in the energy range 6.3 MeV to 8.3 MeV. Fast neutrons were produced at the Stuttgart University 4 MV Dynamitron via the reaction 9Be(α, n)12C irradiating 0.52 μm beryllium layers on high pressure water-cooled copper backings. The energy of the He-ions was varied between 1.86 MeV and 2.76 MeV, while the average current was 200 μAmp. The neutron flux has been measured with a 2″ × 2″ NE 213 liquid scintillator cell. 相似文献