10Be和26Ai揭示的合黎山西南部侵蚀速率初步研究

地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素 10Be 和 26Al 对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示：约 30 ka 以来，合黎山西南部的地表岩石侵速率约为 24 mm∙ka-1。这一结果与已见报道的其他基岩侵蚀速率值一致。这一结果与 Small et al 获得的非干旱地区的基岩侵蚀速率也基本一致，但是显著高于干旱的南极地区和半干旱的澳大利亚。10Be 和26Al 获得的侵蚀速率的良好一致性表明本研究中所用侵蚀模式的有效性。所得的侵蚀速率小于 Palumbo et al 测定的合黎山平均流域侵蚀速率（99 mm∙ka-1），原因解释尚待更多地点和样品的研究。<br style="line-height: normal; text-align: -webkit-auto; text-size-adjust: auto;" /

Separation of potential and kinetic electron emission from Si and W induced by multiply charged neon and argon ions

T he total secondary electron emission yields, gamma(T), induced by impact of the fast ions Neq+ (q = 2-8) and Arq+ (q = 3-12) on Si and Neq+ (q = 2-8) on W targets have been measured. It was observed that for a given impact energy, gamma(T) increases with the charge of projectile ion. By plotting gamma(T) as a function of the total potential energy of the respective ion, true kinetic and potential electron yields have been obtained. Potential electron yield was proportional to the total potential energy of the projectile ion. However, decrease in potential electron yield with increasing kinetic energy of Neq+ impact on Si and W was observed. This decrease in potential electron yield with kinetic energy of the ion was more pronounced for the projectile ions having higher charge states. Moreover, kinetic electron yield to energy-loss ratio for various ion-target combinations was calculated and results were in good agreement with semi-empirical model for kinetic electron emission

Size modification of Au nanoparticles induced by slow highly charged ions Ar-40(q+) irradiation

Size modification of Au nanoparticles (NPs), deposited on the Au-thick film surface and irradiated by slow highly charged ions (SHCI) 40Arq+ (3 6 q 6 12) with fixed low dose of 4.3 1011 ions/cm2 and various energy ranging from 74.64 to 290.64 keV at room temperature (293.15 K), was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The effect of projectile kinetic energy on the modified size of NPs was explored by an appropriate choice of the fixed process parameters such as ion flux, irradiation temperature, incident angle, irradiation time, etc. The morphological changes of NPs were interpreted by models involving collisional mixing, Ostwald ripening (OR) and inverse Ostwald ripening (IOR) of spherical NPs on a substrate. A critical kinetic energy as well as a critical potential energy of the projectile in the Au NPs size modification process were observed

X-ray emission of hollow atoms formed by highly charged argon and xenon ions below a beryllium surface

The X-ray emission induced by highly charged argon and xenon ions impinging on a beryllium surface is investigated. It is found that spectra of the X-ray induced by Ar-17,Ar-18+ interacting with the surface are very different from those of the X-ray induced by Ar-17,Ar-18+ interacting with residual gases. The result provides an experimental evidence for the existence of hollow atoms below the surface. Several unexpected X-ray lines are also found in the experiment. Firstly, K X-rays are observed when Ar16+ ions which initially have no K shell holes interact with the surface. Secondly, if there are more than 2 M shell vacancies at the initial time, strong M alpha alpha two-electron-one-photon (TEOP) transitions are found in the collisions of Xe-28+,Xe-29+,Xe-30+ ions with the surface

MEASUREMENT OF Be-10 CONCENTRATION OF MODERN FALLING DUST IN NORTHERN CHINA

Paleoenvironmental and paleogeomagnetic tracing studies from Chinese loess Be-10 have progressed in recent years (Zhou et al. 2007a,b, 2010). In this approach, Be-10 flux determined from sediment concentration and accumulation rate may be used to recover information about paleomonsoon rainfall rates as well as past variations in the geomagnetic field strength. However, these methods require that a correction be made for residual undecayed Be-10 in remobilized dust. To better understand the feature of the Be-10 signals related to the remobilized dust, we report the first observational study on Be-10 concentration of modern falling dust using the 3MV multi-element accelerator mass spectrometer (AMS) in the Xi&#39;an AMS Center. Ten samples collected at Ansai observation station (109 degrees 19&#39;E, 36 degrees 51&#39;N) in northern China from May 2008 to June 2009 are measured along with 3 chemical blanks. The results clearly show that the Be-10 content of modern falling dust is relatively uniform, with a mean value of 1.21 x 10(8) atoms/g, a measurement similar to that of Chinese loess (Zhou et al. 2007a) and to the value found in the study by Shen et al. (2009) on dust Be-10 falling near Dingbian, China (1.25 +/- 0.06 x 10(8) atoms/g). Despite the fact that modern dust flux is much higher in spring relative to summer in northern China, Be-10 concentration in falling dust remains fairly constant. In addition, we find that dust Be-10 concentration is roughly independent of the local precipitation changes. This feature might be considered as an analogue to improve our understanding on the fundamental information of the source component contained in loess Be-10 records and its spatial/temporal distribution features.</p

Be-10 signature of the Matuyama-Brunhes transition from the Heqing paleolake basin

We present a new 10Be record spanning the Matuyama-Brunhes (M-B) reversal from the Heqing paleolake basin in southern China. It provides a robust proxy for past geomagnetic variations that can be compared with paleomagnetic records. The M-B transition is identified as a pronounced maximum of authigenic 10Be/9Be ratio between 768.6 and 778.5 ka, that is consistent with all other available 10Be-proxy records from marine, ice and loess archives. However, it is offset by approximately 0–60 cm depth from the magnetic signature of the polarity transition recorded in the same sediments. We attribute this offset to the lock-in effect of the remanence acquisition process, which is similar to the phenomenon that exists in marine sediments. We suggest that after eliminating the climatic-hydrological signal, the Heqing sediments may be used as an archive for atmospheric 10Be production rate changes. The combination of magnetic remanence measurements and the cosmogenic 10Be allows for a more precise geochronology of geomagnetic polarity reversals

An outlook of heavy ion driven plasma research at IMP-Lanzhou

Since the successful completion of the cooling storage ring (CSR) project in China at the end of 2007, high qualitative heavy ion beams with energy ranging from keV to GeV/u have been available at the Heavy Ion Research Facility at Lanzhou (HIRFL). More than 10(9) 1 GeVlu C6+ particles or 10(8) 235 MeV/u Xe particles can be stored in the CSR main-ring and extracted within hundred nano-seconds during the test running, the beam parameters will be improved in the coming years so that high energy density (HED) conditions could be achieved and investigated there. Recent scientific results from the experiments relevant to plasma research on HIRFL are summarized. Dense plasma research with intense heavy ion beams of CSR is proposed here.National Natural Science Foundation of China 1040502

X-ray spectra induced by Xe-129(q+) impacting the metal surface

Using the slow highly charged ions Xe-129(q+) (q = 25, 26, 27; initial kinetic T-0 <= 4.65 keV/a.u.) to impact Au surface, the Au atomic M alpha characteristic X-ray spectrum is induced. The result shows that as long as the charge state of projectile is high enough, the heavy atomic characteristic X-ray can be effectively excited even though the incident beam is very weak (nA magnitude), and the X-ray yield per ion is in the order of 10(-8) and increases with the kinetic energy and potential energy of projectile. By measuring the Au M alpha-X-ray spectra, Au atomic N-level lifetime is estimated at about 1.33x10(-18) s based on Heisenberg uncertainty relation

Kinetic energy and charge state effects in the X-ray emission of Mo surface induced by Xeq+ (q=25, 29) ions

L-shell X-ray spectra of Mo surface induced by Xe25+ and Xe29+ were measured. The X-ray intensity was obtained in the kinetic energy range of the incident ions from 350 to 600 keV. The relationship of X-ray intensity with kinetic energy of the projectile and its charge state were studied, and the simple explanation was given