Geomagnetic paleointensity dating of South China Sea sediments for the last 130 kyr

Relative paleointensity records from the northern South China Sea, northwest Pacific Ocean were studied in two gravity piston cores. Continuous mineral magnetic and paleomagnetic measurements were made using discrete sediment samples. Detailed rock magnetic parameters, such as thermomagnetic and high-field hysteresis data, indicate that pseudo-single domain magnetite in a narrow range of grain-size and concentration is the main contributor to the remanent magnetization. The uniform magnetic mineralogy meets the commonly accepted criteria for establishing relative paleointensity records. The relative paleointensity (RPI) curves were constructed by normalizing the natural remanent magnetization (NRM) with isothermal remanent magnetization (IRM), both in the 20-60 mT demagnetization state. Dating constraints have been provided by radiocarbon ages in the upper 400 cm of both cores. Furthermore, we have correlated our paleointensity records with NAPIS-75, S.Atlantic-1089, Sint-200 and NOPAPIS-250 to determine the chronological RPI framework for the South China Sea (SCS-PIS). Although some temporal offsets of paleointensity features between the different records have been recognized, their similar shape suggests that relative paleointensity on the 10(3)-10(4) year scale is globally coherent and can provide an age framework for sediments independent of delta O-18 ages.

808-nm fiber coupled module with a CW output power up to 130 W

A fiber coupled module is fabricated with integrating the emitting light from four laser diode bars into multimode fiber bundle. The continuous wave (CW) output power of the module is about 130 W with a coupling efficiency of around 80%. The output power is very stable after the temperature cycling and vibration test. No apparent power decrease has been observed as the device working continuously for 500 h.

短寿命缺中子同位素~(130,129,128)Ce的(EC+β~+)衰变

首次报道130Ce、129Ce和128Ce的(EC+β+)衰变纲图,其中包括核素的产生、核素的分离鉴别以及纲图的建立。着重补充了一些重要的技术细节,更新了129Ce的衰变纲图,并对这些纲图中涉及的物理问题进行了讨论。

A new OSL chronology for dust accumulation in the last 130,000 yr for the Chinese Loess Plateau

IEECAS SKLLQG

Did an extensive forest ever develop on the Chinese Loess Plateau during the past 130 ka?: a test using soil carbon isotopic signatures

IEECAS SKLLQG

~(130)Ce(EC+β~+)衰变研究及其放射化学分离

利用兰州SFC加速的16O束轰击同位素118Sn ,由熔合蒸发 4n反应产生目标核13 0 Ce。为了消除本底干扰并指定13 0 Ce核 ,采用溶剂萃取法对He - jet带传输系统从靶室传输出来的反应产物进行了离线分离与纯化。将目标核13 0 Ce从大量的靶材料、反应产物及母核中分离出来 ,快速制成薄源后在铅室中进行γ单谱测量及X -γ、γ -γ符合测量。从化学分离后的产物中观察到了半衰期为 2 2 .9min的 10 8条γ射线 ,其中 10 7条是新发现的 ,该活性被指定为13 0 Ce。在此基础上 ,进一步研究这些γ线的级联关系 ,建立了缺中子同位素13 0 Ce较完整的 (EC + β+ )衰变纲图。为118Sn(16O ,4n) 13 0 Ce反应体系建立的放化分离流程的分离时间仅 10min ,化学产额大于70 %。化学分离除去 98%以上的核反应生成的13 0 La ,对其它杂质的去污完全满足13 0 Ce(EC + β+ )衰变研究的要求。

~(130)Nd和~(140)Tb的EC/β~+衰变研究

利用能量为１７０ＭｅＶ左右的３６Ａｒ重离子束轰击９６Ｒｕ和１０６Ｃｄ浓缩同位素靶，分别生成缺中子同位素１３０Ｎｄ和１４０Ｔｂ．借助氦喷嘴带传输系统，用 Ｘ－γ和 γ－γ符合方法，分离鉴别了这两种核素，并进一步测定了它们的衰变性质．得到１３０ Ｎｄ的半衰期为（１３± ３）ｓ，首次建议了它的ＥＣ／β＋衰变纲图，推测了其子核１３０Ｐｒ的基态和低位能级的自旋宇称．修订了１４０Ｔｂ的原有极简单的ＥＣ／β＋衰变纲图并指认１４０Ｔｂ的基态自旋宇称为７＋．

缺中子~(130)Pm和~(128)Pr核的EC/β~+衰变研究

171MeV 36Ar束轰击96Ru靶由熔合蒸发反应生成了130 Pm和12 8Pr核 .由氦喷嘴快速带传输系统将反应产物送到低本底区 .基于X γ t,γ γ t符合测量 ,首次建立了130 Pm的 (EC + β+)衰变纲图 .重新研究了12 8Pr核的衰变 ,订正和补充了γ射线 ,建立了新的 (EC + β+)衰变纲图

A-130区核的高自旋态在束γ研究

通过~(109)Ag(~(19)F, ypxn)在束流为75MeV的熔合蒸发反应，使用带BGO康普顿抑制的高纯错探测器阵列进行γ-激发函数、γ-γ符合和γ-角分布的测量，研究了~(124,125)Ba，~(124,125)Cs的能级结构，共观察和鉴别出20个新能级，29条新γ跃迁。得到了~(124)Ba核的高自旋态能级结构纲图；并首次在A-130区实验观测到了建立在组态[γh_(11/2),g_(7/2)]上的第二个负宇称带。观测到~(124)Cs高自旋态能带结构及其向基态的γ跃迁，从而使其高自旋态能级的能量和自旋指定成为可能。在此基础上建立了~(124)Cs的能级纲图。把~(125)Ba建立在H_(11/2)中子支壳上的负宇称带和建立在g_(7/2)中子壳上的正宇称带分别延伸到了35/2和23/2~+态。而对~(125)Cs则观测到了一个新的集体性很强的带

PALEOMONSOONS OF CHINA OVER THE LAST 130,000 YEARS - PALEOMONSOON RECORDS

The characteristics of the modern monsoon climate of China may be used as clues for recognizing the records of paleomonsoon climate. The present paper deals primarily with the various paleomonsoon records of the last 130,000 years in the southeast monsoon area. These records mainly come from the following three fields: (i) the historical, (ii) the geological, including loess-paleosol sequence, deserts, lakes, snowlines, timberlines, the phenomena of continental desertization and so on, and (iii) the biological, presented by vegetation a.d mammals. Among these records, the loess-paleosol sequence in the Loess Plateau reflects a climatic history characterized by alternation of two different climatic periods when the Asian winter monsoon and summer monsoon showed pronounced effects on environment, respectively.