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Experimental study on heavy ion single event effects in SOI SRAMs
No full textSilicon-on-insulator (SOI) technologies have been developed for radiation-hardened military and space applications. The use of SOI has been motivated by the full dielectric isolation of individual transistors, which prevents latch-up. The sensitive region for charge collection in SOI technologies is much smaller than for bulk-silicon devices potentially making SOI devices much harder to single event upset (SEU). In this study, 64 kB SOI SRAMs were exposed to different heavy ions, such as Cu, Br, I, Kr. Experimental results show that the heavy ion SEU threshold linear energy transfer (LET) in the 64 kB SOI SRAMs is about 71.8 MeV cm(2)/mg. Accorded to the experimental results, the single event upset rate (SEUR) in space orbits were calculated and they are at the order of 10(-13) upset/(day bit)
Theoretical Study on Inner Shell Electron Impact Excitation of Lithium
No full textCross sections for electron impact excitation of lithium from the ground state 1s(2)2s to the excited states 1s2s(2), 1s2p(2), 1s2snp (n = 2-5), 1s2sns (n = 3-5), 1s2pns (n = 3-5), and 1s2pnp (n = 3-5) are calculated by using a full relativistic distorted wave method. The latest experimental electron energy loss spectra for inner-shell electron excitations of lithium at a given incident electron energy of 2500 eV [Chin. Phys. Lett. 25 (2008) 3649] have been reproduced by the present theoretical investigation excellently. At the same time, the structures of electron energy loss spectra of lithium at low incident electron energy are also predicted theoretically, it is found that the electron energy loss spectra in the energy region of 55-57 eV show two-peak structures.National Natural Science Foundation of China 10774122
10876028
Specialized Research Fund for the Doctoral Program of Higher Education of China 20070736001
Technology and Innovation Program of Northwest Normal University NWNU-KJCXGC-03-2
Triton-He-3 relative and differential flows as probes of the nuclear symmetry energy at supra-saturation densities
No full textUsing a transport model coupled with a phase-space coalescence afterburner, we study the triton-He-3 (t-He-3) ratio with both relative and differential transverse flows in semicentral Sn-132 + Sn-124 reactions at a beam energy of 400 MeV/nucleon. The neutron-proton ratios with relative and differential flows are also discussed as a reference. We find that similar to the neutron-proton pairs, the t-He-3 pairs also carry interesting information regarding the density dependence of the nuclear symmetry energy. Moreover, the nuclear symmetry energy affects more strongly the t-He-3 relative and differential flows than the pi(-)/pi(+) ratio in the same reaction. The t-He-3 relative flow can be used as a particularly powerful probe of the high-density behavior of the nuclear symmetry energy.US National Science Foundation PHY-0652548
PHY-0757839
Research Corporation 7123
Texas Coordinating Board of Higher Education 003565-0004-2007
National Natural Science Foundation of China 10710172
10575119
10675082
10975097
MOE of China NCET-05-0392
Shanghai Rising-Star Program 06QA14024
SRF
SEM of China
National Basic Research Program of China (973 Program) 2007CB81500
Experimental study of the beta-delayed neutron decay of N-21
No full textThe first spectroscopic study for the beta decay of N-21 is carried out based on beta-n, beta-gamma, and beta-n-gamma coincidence measurements. The neutron-rich N-21 nuclei are produced by the fragmentation of the E/A=68.8 MeV Mg-26 primary beam on a thick Be-9 target and are implanted into a thin plastic scintillator that also plays the role of beta detector. The time of flight of the emitted neutrons following the beta decay are measured by the surrounding neutron sphere and neutron wall arrays. In addition, four clover germanium detectors are used to detect the beta-delayed gamma rays. Thirteen new beta-delayed neutron groups are observed with a total branching ratio of 90.5 +/- 4.2%. The half-life for the beta decay of N-21 is determined to be 82.9 +/- 7.5 ms. The level scheme of O-21 is deduced up to about 9 MeV excitation energy. The experimental results for the beta decay of N-21 are compared to the shell-model calculations.National Basic Research Program (973 program) of China 2007CB815002
National Natural Science Foundation of China 10775003
10475004
10735010
10775005
10875002
1082750
Analytic expressions for alpha particle preformation in heavy nuclei
No full textExperimental alpha decay energies and half-lives are investigated systematically to extract alpha particle preformation in heavy nuclei. Formulas for the preformation factors are proposed that can be used to guide microscopic studies on preformation factors and perform accurate calculations of the alpha decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei.Natural Science Foundation of China 10775061
10975064
10805016
Fundamental Research Fund LZULL200805
Chinese Academy of Sciences KJCX-SYW-N02
National Basic Research Programme of China 2007CB815004
DFG of German
Investigation of excited states in Mg-22 via resonant elastic scattering of Na-21+p and its astrophysical implications
No full textThe excited states in 22Mg have been investigated by the resonant elastic scattering of 21Na + p. A
4.0 MeV/nucleon 21Na beam was separated by the Center for Nuclear Study (CNS) radioactive ion beam
separator (CRIB) and then used to bombard a thick (CH2)n target. The energy spectra of recoiled protons were
measured at scattering angles of θc.m. ≈ 172◦
, 146◦, and 134◦, respectively. A wide energy-range of excitation
function in 22Mg (up to Ex ∼ 8.9 MeV) was obtained simultaneously with a thick-target method, and a state
at 7.06 MeV was newly observed. The resonant parameters were deduced from an R-matrix analysis of the
center-of-mass (c.m.) differential cross-section data with a SAMMY-M6-BETA code. The astrophysical resonant
reaction rate for the 18Ne(α,p)21Na reactionwas recalculated based on the present parameters. Generally speaking,
the present rates are much smaller than the previous ones
Study of the L-subshell X-ray production cross sections of Au by 20-50 MeV O5+ bombardments
No full text在北京13 MV串列加速器上利用20—50MeV O5+离子研究Au的L壳层X射线产生截面. 实验结果表明σ（Ll）/σ（Lα） ，σ（Lβ）/σ（Lα） 和σ（Lγ）/σ（Lα）与EＣＰSSR理论计算结果符合比较好.在实验中由于较高的能量,在能量点存在能移现象.国家自然科学基金（批准号：10774149）资助的课题
Isolated sub-30-as pulse generation of an He+ ion by an intense few-cycle chirped laser and its high-order harmonic pulses
No full textWe present an efficient method to generate a ultrashort attosecond (as) pulse when a model He+ ion is exposed to the combination of an intense few-cycle chirped laser pulse and its 27th harmonics. By solving the time-dependent Schroumldinger equation, we found that high-order harmonic generation (HHG) from He+ ion is enhanced by seven orders of magnitude due to the presence of the harmonic pulse. After optimizing the chirp of the fundamental pulse, we show that the cut-off energy of the generated harmonics is extended effectively to I-p+25.5U(p). As a result, an isolated 26-as pulse with a bandwidth of 170.5 eV can be obtained directly from the supercontinuum around the cut-off of HHG. To better understand the physical origin of HHG enhancement and attosecond pulse emission, we perform semiclassical simulations and analyze the time-frequency characteristics of attosecond pulse
Prematurely condensed chromosome fragments in human lymphocytes induced by high doses of high-linear-energy-transfer irradiation
No full textThis study provides a useful biodosimetry protocol for radiation accidents that involve high doses of
heavy particle radiation. Human peripheral blood lymphocytes (PBLs) were irradiated in vitro with high
doses (5–50 Gy) of charged heavy-ion particles (carbon ions, at an effective linear-energy-transfer (LET) of
34.6 keV/ m), and were then stimulated to obtain dividing cells. PBLs were treated with 100nMcalyculin
A to force chromosomes to condense prematurely, and chromosome spreads were obtained and stained
with Giemsa. The G2 prematurely condensed chromosome (G2-PCC) index and the number of G2-PCC
including fragments (G2-PCC-Fs) per cell for each radiation dose point were scored. Dose-effect relationships
were obtained by plotting the G2-PCC indices or G2-PCC-Fs numbers against radiation doses.
The G2-PCC index was greater than 5% up to doses of 15 Gy; even after a 30Gy radiation dose, the index
was 1 to 2%. At doses higher than 30 Gy, however, the G2-PCC indices were close to zero. The number of
G2-PCC-Fs increased steeply for radiation doses up to 30 Gy at a rate of 1.07 Gy−1. At doses higher than
30 Gy, the numbers of G2-PCC-Fs could not be accurately indexed because of the limited numbers of cells
for analysis. Therefore, the number of G2-PCC-Fs could be used to estimate radiation doses up to 30 Gy.
In addition, a G2-PCC index close to zero could be used as an indicator for radiation doses greater than
40 Gy
Faddeev-Jackiw canonical path integral quantization for a general scenario, its proper vertices and generating functionals
No full textWe generalize the Faddeev-Jackiw canonical path integral quantization for the scenario of a Jacobian with J=1 to that for the general scenario of non-unit Jacobian, give the representation of the quantum transition amplitude with symplectic variables and obtain the generating functionals of the Green function and connected Green function. We deduce the unified expression of the symplectic field variable functions in terms of the Green function or the connected Green function with external sources. Furthermore, we generally get generating functionals of the general proper vertices of any n-points cases under the conditions of considering and not considering Grassmann variables, respectively; they are regular and are the simplest forms relative to the usual field theory.National Natural Science Foundation of China 10875009
Beijing Natural Science Foundation 107200