Some Superconducting Magnets at IMP

Some superconducting magnets research at IMP (Institute of Modern Physics, CAS, Lanzhou) will be described in this paper. Firstly, a superconducting electron cyclotron resonance ion source (SECRAL) was successfully built to produce intense beams of highly charged heavy ions for Heavy Ion Research Facility in Lanzhou (HIRFL). An innovation design of SECRAL is that the three axial solenoid coils are located inside of a sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. Some excellent results of ion beam intensity have been produced and SECRAL has been put into operation to provide highly charged ion beams for HIRFL since May 2007. Secondly, a super-ferric dipole prototype of FAIR Super-FRS is being built by FCG (FAIR China Group) in cooperation with GSI. Its superconducting coils and cryostat is made and tested in the Institute of Plasma Physics (IPP, Hefei), and it more 50 tons laminated yoke was made in IMP. This super-ferric dipole static magnetic field was measured in IMP, it reach to the design requirement, ramping field and other tests will be done in the future. Thirdly, a 3 T superconducting homogenous magnetic field solenoid with a 70 mm warm bore has been developed to calibrate Hall sensor, some testing results is reported. And a penning trap system called LPT (Lanzhou Penning Trap) is now being developed for precise mass measurements.

Dynamic Measurement System for Dipoles of RCS for CS

A dynamic measurement system was developed by the Institute of Modern Physics (IMP) for the dipole prototype of Rapid Cycle Synchrotron (RCS) of China Spallation Neutron Source (CSNS). The repetition frequency of RCS is 25 Hz. The probe is a moving arc searching-coil, and the data acquisition system is based on the dynamic analysis modular of National Instrument. To get the error of high order harmonics of the field at basic frequency, the hardware integrator is replaced by a high speed ADC with software filter and integrator. A series of harmonic coefficients of field are used to express the varieties of dynamic fields in space and time simultaneously. The measurement system has been tested in Institute of High Energy Physics (IHEP), and the property of the dipole prototype of RCS has been measured. Some measurement results and the repeatability of system are illustrated in this paper.

Prototype of the Superferric Dipoles for the Super-FRS of the FAIR-Project

The FAIR China Group (FCG), consisting of the Institute of Modern Physics (IMP Lanzhou), the Institute of Plasma Physics (ASIPP, Hefei) and the Institute of Electric Engineering (IEE, Beijing) developed and manufactured in cooperation with GSI, Germany a prototype of a superferric dipole for the Super-Fragment-Separator of the FAIR-project [1]. The dipole magnets of the separator will have a deflection radius of 12.5 m, a field up to 1.6 T, a gap of at least 170 mm and an effective length of more than 2 meters to bend ion beams with a rigidity from 2 T . m up to 20 T . m. The magnets operate at DC mode. These requirements led to a superferric design with a yoke weight of more than 50 tons and a maximum stored energy of more than 400 kJ. The principles of yoke, coil and cryostat construction will be presented. We will also show first results of tests and measurements realized at ASIPP and at IMP.

165Er的高自旋态研究

利用能量为42MeV和45MeV的9Be束流轰击160Gd自支撑靶，通过160Gd(9Be,4n)165Er熔合蒸发反应研究了165Er核的高自旋态结构。基于实验测量结果，扩展了基于ν5/2−[523]和ν5/2+[642]准粒子组态的转动带，观测到了连接这两条具有不同宇称的转动带的强电偶极跃迁。利用跃迁分支比，提取了带间电偶极跃迁的约化跃迁概率，并讨论了强电偶极跃迁与八极关联之间的关系。提取了ν5/2−[523]和ν5/2+[642]转动带的顺排角动量和能级能量旋称劈裂值，并进行了简单讨论。 High-spin states of 165Er have been studied using the 160Gd(9Be, 4n)reaction at beam energies of 42 and 45 MeV. The previously known bands based on the ν5/2−[523] and ν5/2+[642] configurations have been extended to high-spin states, and electric-dipole transitions linking these two opposite parity bands were observed. Relatively large B(E1) values have been extracted experimentally from the branching ratios, and were attributed to octupole softness. Alignment and signature splitting in energies in the ν5/2−[523] and ν5/2+[642] bands have been extracted and discussed briefly. 熔合蒸发反应;高自旋态;电偶极跃迁;八极关联

165Er的高自旋态研究

利用能量为42MeV和45MeV的9Be束流轰击160Gd自支撑靶，通过160Gd(9Be,4n)165Er熔合蒸发反应研究了165Er核的高自旋态结构。基于实验测量结果，扩展了基于ν5/2−[523]和ν5/2+[642]准粒子组态的转动带，观测到了连接这两条具有不同宇称的转动带的强电偶极跃迁。利用跃迁分支比，提取了带间电偶极跃迁的约化跃迁概率，并讨论了强电偶极跃迁与八极关联之间的关系。提取了ν5/2−[523]和ν5/2+[642]转动带的顺排角动量和能级能量旋称劈裂值，并进行了简单讨论。 High-spin states of 165Er have been studied using the 160Gd(9Be, 4n)reaction at beam energies of 42 and 45 MeV. The previously known bands based on the ν5/2−[523] and ν5/2+[642] configurations have been extended to high-spin states, and electric-dipole transitions linking these two opposite parity bands were observed. Relatively large B(E1) values have been extracted experimentally from the branching ratios, and were attributed to octupole softness. Alignment and signature splitting in energies in the ν5/2−[523] and ν5/2+[642] bands have been extracted and discussed briefly. 熔合蒸发反应;高自旋态;电偶极跃迁;八极关联

HIRFL-CSRm二极磁铁测量

本文从磁场测量的一般方法出发，简要介绍了磁场测量的基本理论和HIRFL-CSR（兰州重离子加速器冷却储存环）的二极铁积分测磁装置。测量装置主要包括探测线圈、积分器、步进电机驱动卡、步进电机、移动小车等。从HIRFL-CSR主环H型二极磁铁的设计要求出发， 根据积分测量的基本原理，着重介绍了CSR主环二极磁铁磁场分布测量、分散性测量、传递函数测量的方法、数据处理的方法和过程、及最后的测磁结果。为了提高测量结果的精度，使用了相对测量的方法，另外在分散性测量的论述中，用数学方法对相对测量进行了推导。在磁场分布性的测量中，根据测磁数据分析计算了磁场的高阶分量和二级铁的等效偏转角度随电流变化的结果。在测量分散性的过程中，对磁场垫补以达到CSR工程要求的方法和磁场特性了研究。在特殊磁铁的测量中，对调整线圈的磁场垫补的作用进行了测量。在CSRm二极铁的测量中，测磁的误差被给出， 且符合工程要求。

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

Autler-townes splitting in the multiphoton resonance ionization spectrum of molecules produced by ultrashort laser pulses

We report for the first time the proper conditions to observe Autler-Townes splitting (ac-Stark splitting) from vibrationally coherent states belonging to the different electronic terms of a diatomic molecule. Wave packet dynamics simulations demonstrate that such a process is feasible by multiphoton resonance ionization of the molecule Na-2 with a single ultrashort intense laser pulse. With the ultrahigh time resolution of a femtosecond laser pulse, one can directly measure the absolute value of the transition dipole moment between any kinds of molecular states by this kind of Autler-Townes splitting, which is a function of the internuclear distance R.

The modification of self-assembled monolayer on indium tin oxide as cathode in inverted bottom-emitting organic light-emitting diodes

Self-assembled monolayers (SAMs) of a series of p-substituted benzoyl chlorides were formed on indium tin oxide as the cathode for the fabrication of inverted bottom-emitting organic light-emitting diodes (IBOLEDs). The studies on the efficiency of electron injection and device performances showed that the direct tunneling of electron and the formation of dipole associated with the monolayer-forming molecule lead to significant enhancement in electron injection. Consequently, the device efficiency is greatly improved.

The morphology control of pentacene for write-once-read-many-times memory devices

We realized write-once-read-many-times (WORM) memory devices based on pentacene and demonstrated that the morphology control of the vacuum deposited pentacene thin film is greatly important for achieving the unique nonvolatile memory properties. The resulted memory devices show a high ON/OFF current ratio (10(4)), long retention time (over 12 h), and good storage stability (over 240 h). The reduction of the barrier height caused by a large interface dipole and the damage of the interface dipole under a critical bias voltage have been used to explain the transition processes.

Chemical Bonding and Electronic Structure of 4d-Metal Monosulfides

Bond distances, vibrational frequencies, dissociation energies, electron affinities, ionization potentials and dipole moments of the title molecules in neutral and charged ions were studied by use of density functional method. Ground states for each molecule were assigned. The calculated bond distance decreases with the increasing of atomic number of 4d metals, reaches minimum at RhS, then increases. For cationic molecules, the calculated bond distance decreases to the minimum at MoS+, then increases. The calculated vibrational frequency decreases from YS(YS+) to PdS(PdS+) for both neutral and cationic molecules. The bond ionic character decreases from YS(YS+) to PdS(PdS+) for neutral and cationic molecules. The bonding patterns are discussed and compared with the available studies.

Efficient inverted top-emitting organic light-emitting diodes using ultrathin MoO3/C-60 bilayer structure to enhance hole injection

Efficient inverted top-emitting organic light-emitting diodes with aluminum (Al) as both the cathode and semitransparent anode are investigated. It is found that introduction of the ultrathin molybdenum trioxide (MoO3)/fullerene (C-60) bilayer structure between the low work function Al top anode and the hole-transporting layer dramatically enhances the device performance as compared to the devices with sole MoO3 or C-60 buffer layer. The ultraviolet photoemission spectroscopy and x-ray photoelectron spectroscopy indicate that the hole injection barrier between Al anode and hole-transporting layer is effectively reduced via strong dipole effect at Al/MoO3/C-60 interfaces with its direction pointing from Al to C-60.

Realization of negative differential resistance and switching devices based on copper phthalocyanine by the control of evaporation rate

We have observed, respectively, a negative differential resistance (NDR) and switching conduction in current-voltage (I-V) characteristics of organic diodes based on copper phthalocyanine (CuPc) film sandwiched between indium-tin-oxide (ITO) and aluminum (Al) by controlling the evaporation rate. The NDR effect is repeatable which can be well, controlled by sweep rate and start voltage, and the switching exhibits write-once-read-many-times (WORM) memory characteristics. The traps in the organic layer and interfacial dipole have been used to explain the NDR effect and switching conduction. This opens up potential applications for CuPc organic semiconductor in low power memory and logic circuits.

Write-Once Read-Many-Times Memory Based on a Single Layer of Pentacene

We realized an organic electrical memory device with a simple structure based on single-layer pentacene film embedded between Al and ITO electrodes. The optimization of the thickness and deposition rate of pentacene resulted in a reliable device with an on/off current ratio as high as nearly 10(6), which was two orders of magnitude higher than previous results, and the storage time was more than 576 h. The current transition process is attributed to the formation and damage of the Interface dipole at different electric fields, in which the current conduction showed a transition from ohmic conductive current to Fowler-Nordheim tunneling current. After the transition from ON- to OFF-state, the device tended to remain in the OFF-State even when the applied voltage was removed, which indicated that the device was very promising for write-once read-many-times memory.

Electronic structures and chemical bonding in diatomic ScX to ZnX (X = S, Se, Te)

Bond distances, vibrational frequencies, electron affinities, ionization potentials, dissociation energies, and dipole moments of the title molecules in neutral, positively, and negatively charged ions were studied using density functional method. Ground electronic state was assigned for each molecule. The bonding patterns were analyzed and compared with both the available data and across the series. It was found that, besides ionic component, covalent bonds are formed between the metal s, d orbitals, and the p orbital of S, Se, and Te. For neutral and cationic molecules, the covalent character increases from ScX to CrX and from FeX to CuX with an exception of decrease at MnX and ZnX, while for anionic molecules, the trend is not obvious. For both neutral and charged molecules, the sulfides have the shortest bond distance and largest vibrational frequency, while tellurides have the largest bond distance and smallest vibrational frequency. For neutral and anionic molecules, the dissociation energy of sulfides is the largest, that of tellurides is the smallest, while this only remains true for cationic molecules from ScX+ to FeX+.