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一种微弱信号检测方法及其在束流诊断系统中的运用
No full text本文首先阐述了一种微弱信号检测方法-锁定放大方法,并在此基础上对采用外差式技术的锁定放大器进行了详细的分析,经实验室测试在输入正弦信号频率为5MHz时,其积分非线性为0.75%,最小检测幅度<10个μV。最后介绍了超外差式锁定放大器在我所CSR束流诊断系统中的运用
Inner structure of Spin(c)(4) gauge potential on 4-dimensional manifolds
No full textThe decomposition of Spin(c)(4) gauge potential in terms of the Dirac 4-spinor is investigated, where an important characterizing equation Delta A(mu) = -lambda A(mu) has been discovered. Here, lambda is the vacuum expectation value of the spinor field, lambda = parallel to Phi parallel to(2), and A(mu) the twisting U(1) potential. It is found that when), takes constant values, the characterizing equation becomes an eigenvalue problem of the Laplacian operator. It provides a revenue to determine the modulus of the spinor field by using the Laplacian spectral theory. The above study could be useful in determining the spinor field and twisting potential in the Seiberg-Witten equations. Moreover, topological characteristic numbers of instantons in the self-dual sub-space are also discussed.IPRS
UQGSS
GSRTA
National Natural Science Foundation of PR China
Australian Research Counci
Low conductance injection tubes for storage cell targets
No full textThe effect of adding internal fins to the injection tube of a storage cell target filled with a polarized atomic beam source has been studied. The tube conductance and the atomic beam intensity at the exit of the injection tube have been measured, observing an unexpectedly large beam loss. Simulations of the atomic beam reproduce the observed attenuation only when the non-zero azimuthal component of the atom's velocity is taken into account
Entrance-channel dependence of isospin effects on double n/p ratio in HIC
No full textWithin the hadronic transport model IBUU04, we investigate the effect of density-dependent symmetry energy on double neutron/proton (n/p) ratio of free nucleons in heavy ion collisions by taking four isotopic Sn+Sn reaction systems. Especially the entrance-channel asymmetry and impact-parameter dependence of the effect of symmetry energy are discussed. It is found that in both central and semi-central collisions the sensitivity of the double n/p ratio to the density-dependent symmetry energy is more pronounced in neutron-richer systems. Our results also indicate clearly that the effect of symmetry energy is stronger in central collisions than that in semi-central collisions
Photons from quark and hadron phases in Au plus Au collisions
No full textBased on a relativistic hydrodynamic model describing the evolution of the chemically equilibrating quark-gluon plasma system with finite baryon density in a 3+1-dimensional spacetime, we compute photons from the quark phase, hadronic phase and initial non-thermal contributions. It is found that due to the effects of the initial quark chemical potential, chemical equilibration and rapid expansion of the system, the photon yield of the quark-gluon plasma is strongly suppressed, and photons from hadronic matter and initial non-thermal contributions almost reproduce experimental data.Chinese Academy of Sciences KJCX3-SYW-N2
CAS Master Scholar Fund
National Natural Science Foundation of China 10605037
10610285
10405031
National Basic Research and Development Programme of China 2007CB81500
Hot Nuclear Matter Equation of State and Finite Temperature Kaon Condensation
No full textWe perform a systematic calculation of the equation of state of asymmetric nuclear matter at finite temperature within the framework of the Brueckner-Hartree-Fock approach with a microscopic three-body force. When applying it to the study of hotka on condensed matter, we find that the thermal effect is more profound in comparison with normal matter, in particular around the threshold density. Also, the increase of temperature makes the equation of state slightly stiffer through suppression of kaon condensation.National Natural Science Foundation of China 10575119
Knowledge Innovation Project of Chinese Academy of Sciences KJCX3-SYW-N2
European Commission CN/ASIA-LINK/008(94791
The influence of fractionation on cell survival and premature differentiation after carbon ion irradiation
No full textCarbon ion radiotherapy/Fractionated irradiation/R-BE/Premature terminal differentiation. To investigate the influence of fractionation on cell survival and radiation induced premature differentiation as markers for early and late effects after X-rays and carbon irradiation. Normal human fibroblasts NHDF, AG1522B and WI-38 were irradiated With 250 kV X-rays, or 266 MeV/u, 195 MeV/u and I I MeV/u carbon ions. Cytotoxicity was measured by a clonogenic survival assay or by determination of the differentiation pattern. Experiments with high-energy carbon ions show that fractionation induced repair effects are similar to photon irradiation. The RBE10 values for clonogenic survival are 1.3 and 1.6 for irradiation in one or two fractions for NHDF cells and around 1.2 for AG1522B cells regardless of the fractionation scheme. The RBE for a doubling of post mitotic fibroblasts (PMF) in the population is I for both single and two fractionated irradiation of NHDF cells. Using I I MeV/u carbon ions, no repair effect can be seen in WI-38 cells. The RBE10 for clonogenic survival is 3.2 for single irradiation and 4.9 for two fractionated irradiations. The RBE for a doubling of PMF is 3.1 and 5.0 for single and two fractionated irradiations, respectively. For both cell lines the effects of high-energy carbon ions representing the irradiation of the skin and the normal tissue in the entrance channel are similar to the effects of X-rays. The fractionation effects are maintained. For the lower energy, which is representative for the irradiation of the tumor region. RBE is enhanced for clonogenic survival as well as for premature terminal differentiation. Fractionation effects are not detectable. Consequently, the therapeutic ratio is significantly enhanced by fractionated irradiation with carbon ions.GSI, German
Single-electron capture in keV Ar15+...18++He collisions
No full textSingle-electron capture in 14 keV q(-1) Ar15+...18++He collisions is investigated both experimentally and theoretically. Partial cross sections and projectile scattering angle dependencies have been deduced from the target ion recoil momenta measured by the COLTRIMS technique. The comparison with close-coupling results obtained from a two-centre extension of the basis generator method yields good overall agreement, demonstrating the applicability of close-coupling calculations to collision systems involving highly charged ions in charge states up to 18+.FANTOM
German Academic Exchange Servic
Study on the count plateau, gas gain and energy resolution of the Micromegas detectors
No full text介绍了自行研制的Micromegas探测器的基本结构和工作原理. 在不同工作气体(Ar和CO2)配比条件下，利用55Fe放射源对该探测器的能量分辨、计数曲线和气体增益等特性进行了较为详尽的测试. 对相关结果进行了讨论
Formation mechanisms of small fragment ions in nanosecond laser induced fragmentation of C-60
No full textThe time of flight mass spectrometric technique was used to determine the initial mean kinetic energy of small fragment ions C-n(+) (n <= 11) produced from C-60 excited by 532 nm nanosecond laser pulses. The measured kinetic energy shows little variation with the fragment mass and the laser fluence in a broad range. Based on the assumption that C-30(+) is produced predominantly by a single electron emission followed by successive C-2 evaporation from hot C-60 in the nanosecond laser field, the formation of small fragments is interpreted as the complete breakup of the unstable C-30(+) cage structure. The interpretation is consistent with the previously observed results.National Natural Science Foundation of China 10605034
State Key Program of National Science of China 1043410