Study of neutron response for two hybrid RPC setups using the GEANT4 MC simulation approach

The present article describes a detailed neutron simulation study in the energy range 10^-10 MeV to 1.0 GeV for two different RPC configurations. The simulation studies were taken by using the GEANT4 MC code. Aluminum was utilized on the GND and readout strips for the （a） Bakelite-based and （b） glass-based RPCs. For the former type of RPC setup the neutron sensitivity for the isotropic source was Sn = 2.702 × 10^-2 at En = 1.0 GeV, while for the latter type of RPC, the neutron sensitivity for the same source was evaluated as Sn = 4.049 × 10^-2 at En = 1.0 GeV. These results were further compared with the previous RPC configuration in which copper was used for ground and pickup pads. Additionally A1 was employed at （GND＋strips） of the phosphate glass RPC setup and compared with the copper-based phosphate glass RPC. Good agreement with sensitivity values was obtained with the current and previous simulation results.     

Effect of Zr Addition on Glass-Forming Ability and Magnetic Properties of Fe-Nd-Al-B Alloys Prepared by Suction Casting

The microstructure and magnetic behaviors of the Fe-Nd-Al-B alloys prepared by suction casting with zirconium addition are investigated. With the small amount of zirconium addition, the magnetic properties of the alloys change from hard magnetic property to soft magnetic property. The proper addition of Zr （6%） not only improves the glass forming ability, but also suppresses the crystallization. From the scanning electron microscopy of the [（Fe0.53Nd0.37 Al0.10 ）0.96B0.04]94Zr6 alloy and the local average elemental compositions determined using energy dispersive spectroscopy analysis, the amorphous phase with a composition of Fe47Nd38Al12Zra in the alloy can be observed. The bulk amorphous Fe47Nd38Al12Zr3 alloy is prepared by suction casting exhibiting good glassforming ability and soft magnetic behavior.     

Efficient Fibre Amplifiers Based on a Highly Er3＋/Yb3＋ Codoped Phosphate Glass-Fibre

Highly Er3＋ /yb3＋-codoped single-mode phosphate glass fibre is fabricated by the rod-in-tube technique. The performances of high-concentration Er3＋ /yb3＋-codoped phosphate glass fibre amplifiers are investigated and discussed. An efficient optical fibre amplifier with a gain of 12.6 dB based on a 3.0 cm long Era＋ /ybe＋-codoped phosphate glass fibre is demonstrated under a dual-pump configuration with two 976 nm fibre-pigtail laser diodes, which make it attractive for compact Er3＋-doped fibre amplifiers. The obtedned noise figures of signal wavelength from 1525 to 1565nm are less than 6.0dB. Gain saturation behaviour at 1535nm is also investigated, and the obtained saturation output power is larger than 10 dBm.     

振转耦合振子实验研究

介绍一个非常有趣的物理演示实验——振转耦合振子实验.弹簧振子实际上是一个具有两个振动模式的振动系统,两振动模式之间存在着耦合,振动能量将从一种模式向另一模式转移.在共振条件下可以实现能量在两模式之间的来回完全转移.     

用激光分子束外延在玻璃衬底上生长La0.67Sr0.33MnO3薄膜

采用激光分子束外延技术,在玻璃衬底上制备了La_067Sr_033MnO₃ （LSMO） 薄膜,X射线衍射测量结果表明在玻璃衬底上生长的LSMO薄膜沿c轴择优取向生长.在外磁场3 T和88, 220, 300 K条件下,LSMO薄膜的磁电阻变化率分别达到-378%, -268%和-607%.实验结果表明,在廉价的玻璃衬底上制备大面积和具有应用价值的锰氧化物薄膜是可行的. 关键词： 锰氧化物薄膜 玻璃衬底 外延生长     

掺铒碲酸盐玻璃中的协作上转换能量转移

研制了组分为TeO₂-ZnO-Na₂O(TZN)和TeO₂-ZnO-La₂O₃(TZL)掺铒碲酸盐玻璃,测试了碲酸盐玻璃中Er³⁺离子⁴I_13/2能级荧光特性.结果发现,在较高的Er³⁺离子掺杂浓度下,碲酸盐玻璃的荧光强度随着Er³⁺离子掺杂浓度的提高而减小.分析表明,对于除     

掺杂有机染料的铅锡氟磷酸闪烁玻璃及其在伽马激发下的发光

制备了掺杂有机染料芪420的铅锡氟磷酸盐杂化闪烁玻璃(lead tin fluorophosphates,简记为PTFP),测量其玻璃转变温度为75℃,染料在玻璃中的荧光发射峰位为446nm.测量了几种掺杂浓度的闪烁玻璃在⁶⁰Co源1.25MeV伽马射线激发下的发光,并和同样厚度的有机闪烁体ST401的发光进行比较,约为ST401发光的1%—2%. 关键词： 铅锡氟磷酸 闪烁玻璃 芪420 伽马     

Sherrington-Kirkpatric自旋玻璃模型的非平衡态性质

通过动力学蒙特卡罗模拟对Sherrington-Kirkpatric （SK）自旋玻璃模型进行研究. 结果表明,弱场下自旋玻璃的磁化率在转变点非常陡峭,而比热容则呈现比较宽的转变. 同时,也成功地模拟了自旋玻璃体的年龄效应和记忆效应. 通过模拟发现,不同的弛豫时间对系统的能量影响很大,这直接导致了年龄效应和记忆效应;各向同性的SK模型不能给出实验中的交换偏移现象. 关键词： 自旋玻璃 记忆效应 年龄效应 磁化率     

高压作用下相分离液体玻璃转变的分子动力学研究

采用分子动力学模拟方法,研究了二元混合液体在不同外压作用下的相分离与玻璃转变过程,计算了相分离液体在玻璃转变过程中的结构和动力学特征.研究发现,外压会促进相分离的产生,并提高玻璃转变温度,会使β弛豫出现的温度更高、存在的时间更长,导致系统扩散性降低.同时还发现,相分离液体的玻璃转变过程存在微观不均匀现象. 关键词： 相分离 玻璃转变 分子动力学模拟 外压影响     

晶粒尺寸对Bi0.2Ca0.8MnO3电荷有序的影响

利用溶胶-凝胶法制备了平均晶粒尺寸在38—1500 nm的系列Bi_0.2Ca_0.8MnO₃多晶样品,研究了它们的结构、电输运性质和磁性.研究结果表明,随着晶粒尺寸的减小,电荷有序逐渐消失、最后被完全压制,导致低温下出现自旋玻璃态.利用马氏体相变图像和表面效应解释了相关现象. 关键词： 钙钛矿锰氧化物 电荷有序 马氏体相变 自旋玻璃