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Surface morphological and compositional changes of GaN films induced by swift heavy-ion irradiations
No full textWurtzite GaN films irradiated at room temperature with 308 MeV Xe-129(35+) or 230 MeV Pb-208(27+) ions have been studied by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The three-dimensional AFM images showed that swellings of the GaN films were caused by the ion irradiations at very low fluences. In comparison with the Xe ions, the Pb ions led to a much more pronounced swelling. The XPS results indicated that after the Xe and Pb irradiations, the contents of Ga and N dangling bonds in the GaN increased, and the contents of Ga-O and N-O bonds in the surface layer also increased. In the case of the Pb irradiation, a peak associated with the defect of interstitial N was detected in the N 1s core-level spectrum, implying the formation of N-2 bubbles close to the GaN surface. However, no homonuclear Ga-Ga bond was found according to the related Ga 3d spectrum. The dramatic experimental results are discussed and the distinct difference of irradiation damages in GaN induced individually by the Xe and Pb ions is analyzed
The Effects of C-12(6+) Irradiation on Cell Cycle, Apoptosis, and Expression of Caspase-3 in the Human Lung Cancer Cell Line H1299
No full textIntroduction: We aimed to investigate the effects of C-12(6+) irradiation on the cell cycle and apoptosis as well as the associated mechanisms in the human lung cancer cell line H1299. Methods: After irradiation with different doses of C-12(6+) for varying lengths of incubation, the changes in H1299 cells were assayed by flow cytometry and the microculture tetrazolium test. The expression of caspase-3 was detected by immunocytochemistry, western blot, and reverse transcription-polymerase chain reaction (RT-PCR). Results: The G(2)/M phase was blocked after treatment with 1 and 2 Gy at the 12-hour time point, and the most obvious block of G(2)/M occurred after treatment with 2 and 4 Gy at the 24-hour time point in a dose-dependent manner. The apoptosis rate increased with increasing radiation dose and reached a peak after the cells were irradiated with 2 Gy and incubated for 48 hours. In addition, the RT-PCR, western blot, and ICC results showed that irradiation with C-12(6+) significantly increased the expression of caspase-3 compared with the control group (p < 0.05). Conclusions: Irradiation of H1299 cells with C-12(6+) induced apoptosis and significantly inhibited their growth through heavy ion irradiation-mediated activation of the caspase-3 pathway. Our results show that caspase-3 may play an important role in radiation-induced apoptosis through a p53-independent pathway
Effects of the magnetic field on the spallation reaction
No full textBased on the Boltzmann-Uehling-Uhlenbeck (BUU) transport model coupled with a<br />phase-space coalescence afterburner, the spallation reaction p+197Au at the incident beam energy<br />Ebeam =800MeV/nucleon is studied. We find that the number of test particles per nucleon has<br />minor effects on the neutron-to-proton ratio (n/p) of the produced heavier fragments while it<br />affects much their yields. The external strong magnetic field affects the production of heavier<br />fragments more than the n/p of produced fragments. The n/p of free nucleons is greatly affected<br />by the strong magnetic field, especially for the nucleons with lower energies.所长基金与国基1117521
A surprise in the 6Li(p,γ)7Be reaction at low energies
No full text<span style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">The astrophysical S-factor of </span><sup style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">6</sup><span style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">Li(p,γ)</span><sup style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">7</sup><span style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">Be shows at energies below 200 keV a sizable decline contrary to expectation, a surprise. This corresponds to the energy range, where the reaction is important for both primordial and stellar nucleosynthesis. This drop is not understood and may reflect a novel mechanism. The decline effect might influence the element abundances prediction in the Bing-Bang Nucleosynthesis (BBN) models. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.(22 refs)</span
Performance and operation of advanced superconducting electron cyclotron resonance ion source SECRAL at 24 GHz
No full textObservation of the Superheavy Nuclide (271)Ds
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">With the recent commissioning of a gas-filled recoil separator at Institute of Modern Physics (IMP) in Lanzhou, the decay properties of (271)Ds (Z = 110) were studied via the Pb-208(Ni-64, n) reaction at a beam energy of 313.3MeV. Based on the separator coupled with a position sensitive silicon strip detector, we carried out the energy-position-time correlation measurements for the implanted nucleus and its subsequent decay alpha's. One alpha-decay chain for (271)Ds was established. The.. energy and decay time of the (271)Ds nucleus were measured to be 10.644 MeV and 96.8 ms, which are consistent with the values reported in the literature.</span
Multiple ionization effect of Ta induced by heavy ions
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The M X-ray spectra of Ta induced by H+, He2+, Ar11+ and Xe20+ are measured in Heavy Ion Research Facility in Lanzhou. The intensities of M-gamma (M3N5) and M-alpha beta (M4,5N6,7), i.e. I-gamma and I-alpha beta, are also derived from the spectra. It is found that the intensity ratio of I-gamma/I-alpha beta increases with the increase of projectile atomic number. The results show that the M-3-subshell fluorescence yield omega(3) of Ta target is greatly enhanced, owing to multiple ionization effect in collision with heavy ions.</span