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991.
At the new high flux reactor FRM-II in Munich the accelerator MAFF (Munich accelerator for fission fragments) is under design.
In the high neutron flux of 1014 n/cm2 s up to 1014 neutron-rich fission fragments per second are produced in the 1 g U-235 target. Ions with an energy of 30 keV are extracted
from the ion source. In the mass separator two isotopes can be selected. One of the beams is used for low energy experiments,
the other one is injected into an ECRIS (or EBIS) for charge breeding to a q/A≥0.16. A gas filled RFQ cooler is used for emittance improvement. The subsequent LINAC delivers beams with an energy ranging
from 3.7 MeV/u to 5.9 MeV/u. New IH structures are being developed at the Munich tandem laboratory. A small storage ring is
planned in a further stage to recycle the fission fragments. A thin target foil can be placed into this ring, e.g., for synthesis
of super-heavy elements. The through-going beam tube has been installed in the heavy water tank of the reactor. Tests of the
target ion source in a special oven to test long term stability and safety tests were in progress. 相似文献
992.
J Ashenfelter 《Pramana》2002,59(5):713-717
The ESTU began operation in 1988 and achieved the design voltage of 20 MV in 1990. Since that time, improvements to the gas
handling system, negative ion injector, accelerator terminal and control system have greatly increased its capability and
reliability. Today, the ESTU can efficiently produce an extensive assortment of stable ions at wide-ranging energies in support
of low-energy nuclear physics. 相似文献
993.
Shahn Majid 《Communications in Mathematical Physics》2002,225(1):131-170
We construct noncommutative “Riemannian manifold” structures on dual quasitriangular Hopf algebras such as ℂ
q
[SU
2] with its standard bicovariant differential calculus, using the quantum frame bundle approach introduced previously. The
metric is provided by the braided-Killing form on the braided-Lie algebra on the tangent space and the n-bein by the Maurer–Cartan form. We also apply the theory to finite sets and in particular to finite group function algebras
ℂ[G] with differential calculi and Killing forms determined by a conjugacy class. The case of the permutation group ℂ[S
3] is worked out in full detail and a unique torsion free and cotorsion free or “Levi–Civita” connection is obtained with noncommutative
Ricci curvature essentially proportional to the metric (an Einstein space). We also construct Dirac operators in the metric background, including on finite groups such as S
3. In the process we clarify the construction of connections from gauge fields with nonuniversal calculi on quantum principal
bundles of tensor product form.
Received: 22 June 2000 / Accepted: 26 August 2001 相似文献
994.
Chris Quigg 《EPJ direct》2002,4(1):1-15
We study the branching ratio, CP-violating asymmetry, forward-backward asymmetry and the CP-violating asymmetry in the forward-backward asymmetry for the exclusive decay B → Kτ+τ− in the two Higgs doublet model with tree level flavor changing neutral currents (model III). We analyse the dependencies of these quantities on the neutral Higgs boson contributions and the CP parameter sinθ in the model III. We observe that to determine the neutral Higgs boson effects, the measurements of the forward-backward asymmetry and the CP-violating asymmetry in the forward-backward asymmetry for the decay B → Kτ+τ− are promising. 相似文献
995.
通过研究用自组装法制备的萘磺酸掺杂的纳米管结构聚苯胺(苯胺与萘磺酸的摩尔比分别为1∶025,1∶05,1∶1,1∶2,1∶3)的电阻率温度依赖关系(测量温区为80—300K),仔细分析聚苯胺的结构形貌特征,提出了变程跳跃隧道穿透混合模型:认为在萘磺酸掺杂的纳米管结构聚苯胺样品中,跳跃和隧穿两种机制同时起作用,载流子沿纳米管传导是变程跳跃过程起主要作用,而载流子在纳米管之间的传导是隧穿过程起主要作用.实验结果表明,不同浓度的萘磺酸掺杂对样品的低温电阻率的影响很大,随着掺杂浓度增加,载流子传导所需克服的能垒C0迅速减小,当掺杂接近饱和时,C0不再减小.实验中还研究了不同形貌对电阻率的影响,结果表明样品中纳米管所占比例的增大有利于载流子传导
关键词:
聚苯胺
纳米管
低温电阻率 相似文献
996.
A fiber Fabry-Perot interferometer (FFPI) sensor is formed with broadband (~3 nm, 3-dB bandwidth) fiber Bragg grating (FBG) mirrors. Repetitively modulating a distributed-feedback laser produces chirping that modulates the reflectance of the FFPI. Because the reflectance of the FBG mirrors varies with optical frequency, the fringes in the sensor reflectance modulation are distinguishable, making it possible to extend the sensor dynamic range versus that of a FFPI sensor with conventional wavelength-dependent mirrors. An ambient temperature is determined in the range from 25 to 170 degrees C with a resolution of 0.005 degrees C. 相似文献
997.
998.
描述了一种延长EPR波谱仪中速调管使用寿命的方法.根据这种方法,只要正确地调谐微波桥的工作状态和适当地调整功率电平器的功率校正电平.即使对于已经严重老化的速调管仍然可以继续使用一段时间,维持仪器的正常运行. 相似文献
999.
1000.
A physicochemical and fluid dynamic model is formulated for the numerical simulation of the flow field in a reactor for titanium
dioxide production, the turbulence motion is described by theKε equation, the governing equations are solved by the SIMPLER algorithm devised by Partankar and Spalding. The velocity, tmperature
and concentration fields are obtained for three cases: A) with chemical reaction and thermal insulation on the walls; B) with
chemical reaction and wall temperature is 450K; C) without chemical reaction and thermal insulation on the walls, and the
physicochemical numerical simulation for the titanium dioxide production has been done. The results of the paper can be used
as a theoretical guide for the engineers in the design of such reactors. 相似文献