HIRFL剥离器后切束线物理设计

HIRFL is a tandem cyclotron complex for heavy ion. On the beam line between SFC and SSC, there is a stripper. Behind it, the distribution of charge states of beam is a Gauss distribution. The equilibrium charge state Q_0 is selected by 1BO2(a 50° dipole behind the stripper) and delivered to SSC. One of two new small beam line (named SLAS) after 1B02 will be builded in or der to split and deliver the unused ions of charge states (Q_0 ± n) to aspecific experimental area. Q_0 ± n ions are septumed and separated from initial(Q_0) ion beam by two septum magnets SM1, SM2. The charge state selected by SM1 will be Q_0 ± 1(6 ≤ Q_0 < 17), Q_0 ± 2(17 ≤ Q_0 < 33) and Q_0 ± 3 (Q_0 ≥ 33) forming a beam in one of the two possine new beam line with the stripping energy of (0.2 to 9.83 Mev/A), an emittance of 10π mm.mrad in the two transverse planes and an intensity ranging from 10~(11) pps for z ≤ 10 to some 10~5 pps for the heaviest element. Behind SM2, a few transport elements (three dipoles and seven qudrupoles) tra nsport Q_0 ± n beam to target positions T1, T2 (see fig. 1) and generate small beam spots (φ ≤ 4mm, φ ≤ 6mm). The optics design of the beam line has been done based on SLAC-75 (a first and second - order matrix theory). beam optics calculation has been worked out with the TRANSPORT program. The design is a very economical thinking, because without building a new accelerator we can obtain a lower energy heavy ion beam to provide for a lot of atomic and solid state physical experiments

荷能重离子在等效生物组织--液态水中的径迹结构及能量沉积分布研究

本文建立了生物组织中最重要成分--液态水中的重离子径迹结构Monte Carlo计算模型，用它来研究重离子径迹内的能量沉积分布。最终将计算结果同实验值或其它#dalta#射线理论计算结果进行了比较。另外，由模型的电子传输慢化部分或OREC和CPA程序计算得到的单电子径迹中的绝对和相对能量沉积频率结果来看，这些单径迹效应结果都支持了低能重离子注入造成深部生物效应的作用机理--软x射线机制。本文的目的在于建立细胞损伤强度和损伤范围与重离子参量之间的关系，从理论上探讨重离子生物效应的机理

重离子耗散反应激发函数振荡结构的实验研究

直到八十年代中期，人名才发现耗散反应激发函数中存在振荡结构这种新现象。通过对激发函数振荡结构能量自关联函数的研究是获得复合核能级宽度的一个重要手段，Brick推广了Ericson的复合核统计理论，并成功地用于分析耗散反应激发函数振荡结构的研究，提取相应的能量相关宽度Г。本文报道了19F+51V耗散反应激发函数振荡结构的实验研究结果，用能级部分重叠模型对角动量相干引起的截面涨落、能量自关联函数进行了计算分析。实验中采用ΔE-E粒子鉴别方法和飞行时间TOF测量技术队102.25Mev~109.5Mev19F+51V反应类弹产物同时进行电荷和质量鉴别。首次在各个元素、同量异位素（质量数A为常数）和同位素的耗散反应激发函数中观察到振荡结构，并进一步证实了反应产物的各个出射道之间存在着相关。检验了用小角度弹性散射计数做相对归一对激发函数振荡结构研究可能造成的影响。分别采用能量自关联函数方法和谱密度方法提取了各个激发函数的能量相关宽度Г，其值大小为~350kev，并与出射道的电荷数Z、质量数A和中质比N/Z有很大的依赖关系，表明出射产物与入射弹核的差别越打所需的反应时间久越长。首次得到了Г随N/Z值变化的趋势，Г随N/Z的分布为Gauss型，通过分析分布的宽度得到其大小随相互作用时间的增长而线性增大的结果，并进一步提取了电荷扩散系数，证实了反应系统已达到电荷平衡。Г的数值随出射角的增大有减小的趋势。双核系统的转动造成了Г随出射角的变化关系，实验提取的双核系统平均角速度发生了较强的阻尼。用能级部分重叠模型在适当的精度内对激发函数和能力自关联函数进行了模拟。计算分析说明入射道的动能大多数转化为双核系统的转动能，只有较少部分转化为双核系统的内禀激发能，双核系统被激发到能级密度不太大的区域，能级之间的部分重叠引起截面的振荡行为。入射道角动量的相互干涉、双核系统能级的部分重叠和出射道的相互关联使得耗散反应的激发函数表现出其特有的规律性。

SSC120KW高频发射机改进可行性方案研究

我所SSC120KW高频发射机是HIRFL（Heavy Ion Research Facility, LanZhou）的一个重要组成部分，长期的调机以及运行经验表明：两台发射机存在调机程序复杂运行不稳定、运行维护费用高等缺点。本论文讨论一种改进方案，并且介绍了大功率放大器的设计方法。 该方案采用国产电子管TH537作为功率放大管，槽路电感固定，采用一个可变电容调谐，另一个可变电容调整负载。槽路结构简单，调整方便，同时槽路元件较现在方案少，能节省建造和维护费用。论文中详细介绍了电子管特性的计算，槽路得设计方法，并对中和与消除寄生振荡的方法作了扼要的介绍。

HIRFL束流相位测量系统的研究和改进

兰州重离子研究装置（Heavy Ion Research Facility at LanZhou,HIRFL）是由一台1.7m扇聚焦回旋加速器（SFC）与一台能量常数K=450的分离扇回旋加速器（SSC）组成的加速器系统。束流相位测量系统式束流诊断系统中的一个重要部分，对等时场优化等具有十分重要的作用。HIRFL束流中心相位测量系统于1985年完成了桌面实验，但由于测量精度低，现场抗干扰能力差，一直未能投入使用。 本课题的目的就是找出原系统存在的问题，逐一解决，以便提高其可靠性与测量精度，达到设计要求。 在通过一系列的电子学部分改进和SSC中心相位探针改造之后，于1995年7月第一次测出了SSC中心束流相位。此后，逐步完善改进电子学硬件部分，同时全新设计了系统控制软件，提高了在SFC和SSC上束流相位的测量精度，终于使该系统达到了测量精度为±2.75°~±1.5°的水平。 本论文第一、二章阐述了束流中心相位测量原理和HIRFL束流中心相位测量系统的工作原理，这是本工作的基础和出发点。 在本论文的第三章中，分析了原系统中存在的主要问题。实践使用中可以看出原系统灵敏度低，抗干扰能力差，可靠性差，测量精度低。为了定量判断系统存在的问题，我们设计了自检系统。利用自检系统我们测出原系统测量精度为±6°，且检测出原系统sin，cos正交输出异常。同时测量了原系统多路开关串话量，大多数道与道之间高于最低要求的-40dB，最差只有-20dB，证明存在严重的道间干扰。 本文的第四章中，针对原系统的可靠性差和精度低的两个问题，采取了硬件与软件两方面的各种措施，对系统加以改进。首先，为了提高系统的可靠性，必须提高系统抗干扰能力。为此，我们进行了两个方面的工作，一是根据我们现有条件自行设计了一种新的电缆电子学长度校正方法，大大减少了电缆间相差（小于0.3°），从而有效地提高了系统的抗干扰能力。这种方法不但可以用来校正相同介质电缆，而且可以用来校正不同介质电缆的电子学长度。二是设计了新的信号预选器，其串话量达到约-70dB，并完善了电磁屏蔽，使其完全达到了设计要求。在改进硬件的同时，为了提高可靠性，重新设计了系统控制软件。新的软件测量数据可靠，漏报概率为10-3，操作简便直观，并易于发展。其次，我们工作的重点是提高测量精度。根据自检结果，我们采取了如下措施： （1） 通过对自检数据进行分析，并与理论分析比较，发现问题主要存在于90°移相电路中。而其后的检测证实了这一点。重新调整90°移相电路，并对90°电缆相移进行了精确的校正，从原81.5°校正为90.6°，从而使系统的精度从±6°提高到±4°。 （2） 通过自检数据和理论分析发现鉴相器存在输出增益不平衡，在解决问题之后使系统测量精度达到了±2.75°~±1.5°。 在本文的第五章中，对加速器运行时的中心束流相位测量结果进行了详细分析。结果证明，测量数据可靠，能正确反映出磁场变化情况，测量重复误差达到了±0.5°，从而说明改进后的中心束流相位测量系统性能良好，达到了设计指标。

SFC控制系统软件设计

兰州重离子研究装置（Heavy Ion ReSearch Facility at Lanzhou, HIRFL）是我们研究所得一个大型实验装置，它包括SFC和SSC两个加速器和两条束运线。本论文比较系统地介绍了HIRFL束流诊断系统的改造和SFC分布式控制系统的设计。 在第一章中，简单介绍了国际加速器控制系统的现状和HIRFL控制系统中存在的问题。在第二章一般性地阐述了描述束流品质的各个参数，这些参数的测量原理以及测量这些参数的装置。本论文的第三章详细叙述了HIRFL束流诊断系统的改造方法、过程和结果，结果准确可靠，人机界面非常友好，给调束带来很大的方便。第四章介绍了计算机网络的基本概念，描述了在选用TCP/IP协议的条件下，利用Socket（套接字）实现Windows环境下的实时网络通信的具体过程和步骤，其中参与通信的双方是以客户机和服务器的形式存在的。第五章讲述了SFC分布式控制系统的实现，并在实时网络通信的基础上完成了ECR源扫谱程序和I/O级的网络通信程序。 论文的最后一章，介绍了对HIRFL束运线进行优化控制的一个设想，利用系统辨识的方法可以得到束运线的数学模型，并提供了自适应控制的实现细节，这也是作者对实现HIRFL优化控制的一个愿望。

Systematic study of the transfer of amino acids across the water/1,2-dichloroethane interface facilitated by dibenzo-18-crown-6

Facilitated ion transfer reactions of 20 amino acids with di.benzo-18-crown-6 (DB18C6) at the water/1,2-dichloroethane (W/DCE) interfaces supported at the tips of micro- and nano-pipets were investigated systematically using cyclic voltammetry. It was found that there were only 10 amino acids, that is, Leu, Val, Ile, Phe, Trp, Met, Ala, Gly, Cys, Gln (in brief), whose protonated forms as cations can give well-defined facilitated ion transfer voltammograms within the potential window, and the reaction pathway was proven to be consistent with the transfer by interfacial complexation/dissociation (TIC/TID) mechanisms. The association constants of DB 18C6 with different amino acids in the DCE (beta(0)), and the kinetic parameters of reaction were evaluated based on the steady-state voltammetry of micro- or nano-pipets, respectively The experimental results demonstrated that the selectivity of complexation of protonated amino acid by DB18C6 compared with that of alkali metal cations was low, which can be attributed to the vicinal effect arising from steric hindrance introduced by their side group and the steric bulk effect by lipophilic stabilization.

Studies on charge transfer across the micro-liquid/liquid interface supported at a double-barrel micropipette

In this paper, the charge transfer across the micro-liquid/liquid interface supported at the orifice of a double-barrel micropipette, namely, a theta-pipette, is reported. Simple ion transfer(TMA(+)), facilitated ion transfer (potassium ion transfer facilitated by DB18C6), and electron transfer (ferrocene and ferri/ferrocyanide system) have been investigated by cyclic voltammetry. The experimental results show that a very thin aqueous film, linking both barrels filled with the aqueous solution and the organic solution respectively, can spontaneously be formed on the outer glass surface of such a double-barrel micropipette to construct a micro-liquid/liquid interface, which provides the asymmetry of diffusion field. Such device is demonstrated experimentally which can be employed as one of the simplest electrochemical cells to investigate the charge transfer across the liquid/liquid interface.

Charge transfer across the water/nitrobenzene interface by three-electrode system

A droplet of aqueous solution containing a certain molar ratio of redox couple is first attached onto a platinum electrode surface, then the resulting drop electrode is immersed into the organic solution containing very hydrophobic electrolyte. Combined with reference and counter electrodes, a classical three-electrode system has been constructed, Ion transfer (IT) and electron transfer (ET) are investigated systematically using three-electrode voltammetry. Potassium ion transfer and electron transfer between potassium ferricyanide in the aqueous phase and ferrocene in nitrobenzene are observed with potassium ferricyanide/potassium ferrocyanide as the redox couple. Meanwhile, the transfer reactions of lithium, sodium, potassium, proton and ammonium ions are obtained with ferric sulfate/ferrous sulfate as the redox couple. The formal transfer potentials and the standard Gibbs transfer energy of these ions are evaluated and consistent with the results obtained by a four-electrode system and other methods.

Investigation of proton transfer across the water/1,2-dichloroethane interface by o-phenanthroline using glass micro/nano-pipets and cyclic voltammetry

Facilitated proton transfer across the water/1,2-dichloroethane (DCE) interface supported on the tips of micro- and nano-pipets by o-phenanthroline (Phen) was studied by using cyclic voltammetry. The formed micro- and nano-liquid/liquid interfaces functioned as micro- and nano-electrodes under certain experimental conditions. The dependence of the half-wave potentials on the aqueous solutions acidities was studied and the ratio of association constants between Phen and proton in the aqueous and DCE phases was calculated by the method proposed by Matsuda et al.. The standard rate constant (k(0)) and the transfer coefficient (alpha) evaluated by using nano-pipets were equal to 0.183 +/- 0.054 cm/s and 0.70 +/- 0.09, respectively.

Application of acetone and dimethyl ether chemical ionization reagent gases to structural analysis

Acetone and dimethyl ether( DME) have been shown to be reagent gases of exceptional utitlity and versatility for the characterization of a variety of class of organic compounds. The fragmentation mechanisms of the adduct product ions, formed by ion/molceule reaction of the substrate with the ionized gases, have been studied and substantiated by experiments with acetone-d(6) and DME-d(6).

Investigation of the structures of the product ions produced via self-CI of acetone

The ion-molecule reactions in acetone were investigated which were induced under the chemical ionization. The structural information of the reaction products were obtained by using collision-induced dissociation (CID) technique performed at ion kinetic energies of 30eV.

Synthesis and spectroscopic studies of endohedral metallofullerenes Tb@C-2n

Endohedral metallofullerenes Tb@C-2n were synthesized and extracted with high-yield by K-H carbon-are evaporation and an effective pyridine extraction technique at high-temperature high-pressure. Laser-desorption-ionization time-of-flight (LD-TOF) mass spectrometry, X-ray photoelectron spectroscopy (XPS), solid-state fluorescent emission spectroscopy and gas phase derivation reaction with the self-chemical ionization mass spectrometric ion system of vinyl acetate were employed for studying the electronic structures, fluorescent properties and gas phase reactivities of metallofullerenes Tb@C-2n. The experimental results suggest that endohedral metallofullerenes Tb@C-2n would have the approximate structures of Tb3+@C-2n(3-) similar to other metallofullerenes, good fluorescent emission properties and active reactivities in gas phase ion-molecular reactions.

Gas phase derivatization of endohedral metallofullerenes R@C-82 and R-2@C-80 (R = Nd, Ce)

Endohedral metallofullerenes Ce@C-82, Ce-2@C-80, Nd@C-82 and Nd-2@C-80 undergo gas phase ion/molecule reactions with the ion system from self-chemical ionization of vinyl acetate, and exohedral derivatives are thus generated, A new heterocycle is formed from metallofullerenes and a C2H3O+ cation, Endohedral metallofullerenes show much higher reactivities than empty fullerenes during the association and the charge and proton transfer processes, The strong electron-donating character of endohedral metallofullerenes is due to their unique super-atom-like electronic structures. (C) 1997 by John Wiley & Sons, Ltd.

FORMATION OF [C60C5H5] ADDUCT CATIONS AND THEORETICAL-STUDY OF THE ISOMERS

We study here the reactions between C-60 and planar C5H5+ cations that lead to the formation of [C60C5H5](+) adduct cations in the chemical ionization source of the mass spectrometer. The structures, stabilities and charge locations of some possible isomers of [C60C5H5](+): sigma-adduct, pi-complex, [1,4]- and [1,2]-addition cations, are studied by AM1 semiempirical molecular orbital calculations. We find that the most stable is the sigma-addition cation. Another interesting and stable structure is the pi-complex cation which is bonded by the electrostatic interaction at the inter-ring distance of 1.589 Angstrom with the C-5v symmetry. The C5H5+ cyclopentadienium cation seems to be an ''inverted umbrella'' sitting on a five-membered ring of the C-60 cage.