Physical design of scanning gantry for proton therapy facility

A proton therapy facility based on a linac injector and a slow cycling synchrotron is proposed. To achieve effective treatment of cancer, a scanning gantry is required. The flexible transmission of beam and high beam position accuracy are the most basic requirements for a gantry. The designed gantry optics and scanning system are presented. Great efforts are put into studying the sensitivity of the beam position in the isocenter to the element misalignments. It shows that quadrupole shift makes the largest contribution and special attention should be paid to it.     

Longitudinal RF capture and acceleration simulation in CSNS RCS

China Spallation Neutron Source (CSNS) is a high power proton accelerator-based facility. Uncontrolled beam loss is a major concern in designing the CSNS to control the radioactivation level. For the Rapid Cycling Synchrotron (RCS) of the CSNS, the repetition frequency is too high for the longitudinal motion to be fully adiabatic. Significant beam loss happens during the RF capture and initial acceleration of the injection period. To reduce the longitudinal beam loss, beam chopping and momentum offset painting methods are used in the RCS injection. This paper presents detailed studies on the longitudinal motion in the RCS by using the ORBIT simulations, which include different beam chopping factors, momentum offsets and RF voltage optimization. With a trade-off between the longitudinal beam loss and transverse incoherent tune shift that will also result in beam losses, optimized longitudinal painting schemes are obtained.     

Longitudinal RF capture and acceleration simulation in CSNS RCS

China Spallation Neutron Source (CSNS) is a high power proton accelerator-based facility. Uncontrolled beam loss is a major concern in designing the CSNS to control the radioactivation level. For the Rapid Cycling Synchrotron (RCS) of the CSNS, the repetition frequency is too high for the longitudinal motion to be fully adiabatic. Significant beam loss happens during the RF capture and initial acceleration of the injection period. To reduce the longitudinal beam loss, beam chopping and momentum offset painting methods are used in the RCS injection. This paper presents detailed studies on the longitudinal motion in the RCS by using the ORBIT simulations, which include different beam chopping factors, momentum offsets and RF voltage optimization. With a trade-off between the longitudinal beam loss and transverse incoherent tune shift that will also result in beam losses, optimized longitudinal painting schemes are obtained.     

纤维素衍生物手性固定相对戊唑醇对映体的拆分

戊唑醇是三唑类杀菌剂,作用机理为抑制麦角甾醇的生物合成。戊唑醇的化学名称为(R,S)-1-(4-氯苯基)-4,4-二甲基-3-(1H-1,2,4-三唑-l-基甲基)戊醇,结构如图l。它的分子结构中含一个手性碳,具有一对对映异构体。     

苯并咪唑衍生物的微波辅助合成研究

开展了邻苯二胺与4-甲基苯甲醛、4-硝基苯甲醛及4-二甲氨基苯甲醛反应生成苯并咪唑衍生物的微波辅助合成研究。用高效液相色谱法(HPLC)测定其产率。结果表明:相同反应时间,在微波辅助条件下,生成苯并咪唑衍生物的反应产率均较常规加热条件下增大,并且芳醛对位上取代基吸电子能力越强,反应产率越高。     

Y2BaCuO5粒子在准单畴超导块材中的分布及其对磁悬浮力的影响

熔融织构准单畴YBCO超导块材中的Y2 BaCuO5(Y-211)相粒子可以起到增强材料磁通钉扎力的作用.实验发现,顶部籽晶诱导生长熔融织构YBCO超导块材中的Y-211粒子分布呈不均匀性.Y-211相粒子在近籽晶处密度较低,而在样品底部则密度较高,并且呈现Y-211粒子团聚现象.通过优化Y-211相粒子在母体中的分布,可以有效提高YBCO块材的磁悬浮力.实验研究结果表明,Y-211相粒子在母体中的分布越均匀,且Y-211粒子平均粒径越小,则块材的磁悬浮力则越大.     

Y2BaCuO5相含量对准单畴YBCO块材生长及其性能的影响

本文采用Y-123 Y-211合成粉体作为前驱物粉体,利用顶部籽晶熔融织构技术制备了最大顶角间距为34 mm正六边形YBCO准单畴块材,研究了Y-211含量对准单畴块材生长过程,以及对成材样品磁浮力性能的影响.实验结果发现:Y-211摩尔含量为30%样品的最大磁悬浮力明显高于Y-211含量为40%的样品.实验结果还发现,在同一烧结程序下,Y-211含量为40%样品出现单畴区未完全生长状态,而Y-211含量30%样品则呈现完全生长状态.这一结果可以解释两样品之间磁悬浮力性能的差异,而造成这一结果的原因可能是不同Y-211含量样品单畴区的起始生长温度不同所致.     

基于多指标约束的鲁棒故障检测方法

针对存在模型不确定性和测量噪声的线性动态系统，研究了其鲁棒故障检测问题。通过H_性能指标和无故障时残差的稳态方差约束反映对干扰影响的抑制，采用肌性能指标刻画对故障的灵敏度，将故障检测滤波器的设计描述为一个多指标约束问题，并利用线性矩阵不等式方法进行了求解。最后，在一种应用捷联惯性导航设备的车载卫星天线稳定跟踪系统中进行了仿真研究，结果表明，这种方法能够有效提高系统的故障检测精度。     

气相色谱-质谱同时测定猪肉中3种巴比妥药物残留

建立了固相萃取-气相色谱-质谱同时分析猪肉中3种巴比妥类药物残留量的方法。对猪肉样品的乙腈提取、C18固相萃取柱净化和碘甲烷甲基化条件进行了优化。采用HP-5毛细管柱分离,电子轰击电离源质谱选择离子模式(SIM)检测(巴比妥m／z126,169,183,184;异戊巴比妥m／z169、170、184、226;苯巴比妥m／z175、232、245、260;dwell time80s),外标法定量(定量离子m／z分别为169、169和232)。3种巴比妥药物的添加标准曲线线性回归系数均在0．99以上;线性范围2．5～50μg/kg,回收率为65％～112％,相对标准偏差5．4％～17．2％,检出限均为1μg/kg。     

顺式、反式氯氰菊酯和烯唑醇对映异构体的手性拆分

将纤维素-三(3,5-二甲基苯基氨基甲酸酯)(CDMPC)涂敷于氨丙基硅胶上制备成高效液相色谱(HPLC)手性固定相,对手性农药顺式、反式氯氰菊酯和烯唑醇对映异构体在正相条件下进行了手性拆分。分别以正己烷和石油醚为流动相,考察改性剂的含量;在正己烷流动相条件下考察了色谱柱长度、温度对拆分效果的影响。试验结果显示,改性剂含量的减少、长色谱柱及降低温度均有利于对映体的分离。该手性固定相对顺式、反式氯氰菊酯具有非常强的立体选择性,对烯唑醇也有较好的拆分能力。