Brewster window and windowless resonant spectrophones for intracavity operation

We report a new design for an acoustically resonant spectrophone well suited for intracavity operation with widely tunable lasers. Operation with Brewster angle windows or in a windowless mode is possible, and high quality factors (560 and 509, respectively) are achieved. Windowless operation permits continuous monitoring of ambient air. We discuss factors limiting the sensitivity, ∼10⁻⁷ cm⁻¹, and present a double chopping scheme capable of significantly reducing the acoustical background encountered in windowless operation. The sensitivity of the spectrophone's performance to misalignment is also examined.     

A plug‐and‐measure diagnostic tool for flux,resolution and beam size of a soft X‐ray beamline

A compact multi‐functional diagnostic tool has been installed for commissioning beamlines at the Taiwan Light Source. For a photon beam, the instrument can measure the photon flux, energy resolution and beam size, consecutively with a photodiode or gold mesh, a windowless gas cell and a movable fluorescence screen viewport. Two gratings with ruling densities of 350 and 1000 lines mm^?1 and dispersing photons of energies from 80 to 1200 eV were calibrated with a photon flux of 10¹¹ photon s^?1 at slit openings of 50 µm × 50 µm; a maximum resolving power of greater than 10000 was certified with an absorption spectra of gaseous samples. Pressure differences over four orders of magnitude were achieved between the ion chamber and the flux measurement chamber with a single capillary differential pumping stage. A sequence of beam profiles was measured by moving continuously in the vicinity of the nominal focal positions. This tool is useful in commissioning or trouble‐shooting at most beamlines in a synchrotron facility.     

Measurement of 4He(12C,16 O)γ Reaction in Inverse Kinematics

A cross section measurement employing a direct ¹⁶O detection method for the reaction energies from E _cm = 2.4 to 0.7 MeV is planned at Kyushu University Tandem Laboratory. To perform this experiment and to obtain quantitative information about the cross section to within an error of 10%, we have developed several instruments, including a blow-in type windowless gas target and a ionization chamber. A target thickness of 24 × 3.9 Torr cm was achieved using the developed gas target. The particle identification was successfully performed by using the energy deposit in the ionization chamber. Experiments were performed at E _cm = 2.4 and 1.5 MeV using the developed instruments and the cross sections were obtained.     

ADS无窗靶件自由界面流动非稳态特性研究

加速器驱动次临界系统(ADS)无窗靶件设计的重点之一,是研究冷却剂自由界面形成和控制机理。本文使用水作为模拟工质,对无窗靶件模型的自由界面非稳态特征进行了实验研究并进行了数值模拟。采用激光诱导荧光方法对自由界面流场进行了可视化研究,得到了高雷诺数下的自由界面和可视化流场信息。可在高雷诺工况流场中可观察到大尺度非稳态涡结构,随着自由界面的波动,涡结构表现出几种典型的瞬态特征。采用大涡模型(LES)湍流模型结合自由界面追踪方法(VOF)对无窗靶件实验工况进行了数值模拟,计算能较好地模拟实验中所得的流场现象和界面特征。     

ADS无窗散裂靶件水模拟实验研究

散裂靶件作为加速器和次临界堆芯的耦合部件,是ADS系统相关研究最主要的组成部分之一。无窗靶巧妙地利用了液体的自由液面特性,避免了质子束对结构材料直接轰击,是一种很有前景的散裂靶靶件形式。采用水作为实验工质搭建了一套无窗散裂靶水模拟实验台架,该实验系统覆盖了无窗散裂靶水模拟实验所需的流量及压力条件,采用粒子图像测速仪(PIV) 对自由界面的流场进行可视化观察与分析,得到了自由界面的基本表征参数之间关系和可视化界面的流场信息。结果表明,无窗靶自由液面的位置和形状受到回路整体流量、压力和靶件几何尺寸的影响。As the coupling component between accelerator and subcritical core, the spallation target is of crucial importance to the operation safety of the whole system. Hence, the spallation target is one of the most important parts in ADS corresponding researches. Due to lifetime limitation of material, the windowless target which has a stable free surface attracts more and more attention. The present paper deals with the experimental investigation on the free surface behavior in an approximately 1:1 size windowless target model using water as test fluid. We can get the flow and pressure conditions of windowless spallation target water simulation experiment from the platform. The free surface and eld visualization were obtained by particle imaging velocimetry. The  results show that the position and  flow pattern of the free surface depend on experimental pressure, flow velocity and geometry of the target.     

Construction and cosmic-ray test of the new inner drift chamber for BESIII

A new inner drift chamber has been built which can replace the aged part of the BESIII drift chamber when needed. The design of the new inner drift chamber can minimize the ineffective area in the very forward and backward region and hence reduce the background event rate. With this design, the new inner drift chamber is expected to have a longer lifetime and improved performance due to the lower occupancy. The endplates and the cylinder were machined with high precision. Wire stringing was performed after the mechanical structure was assembled, and good quality of wire stringing was ensured by measurement of the tension and leakage current of the wires. After completion of the physical construction of the new chamber, a cosmic-ray test was carried out to test its performance. The results of the cosmic-ray test show that the new inner chamber achieves a spatial resolution of127 μm and a d E/dx resolution of 6.4%, which satisfies the design specifications.     

Photoenhanced deposition of silicon oxide thin films using a novel windowless internal nitrogen discharge lamp

This paper reviews the production of silicon oxide thin films using a novel photoenhanced deposition technique incorporating a windowless nitrogen discharge lamp contained within the deposition vessel. This process has the potential to produce better semiconductor/insulator interfaces than those produced using conventional RF glow discharge techniques, since there is no damage to the growing film surface from energetic ions produced in the glow discharge plasma. The use of an internal lamp obviates the need for a window between the lamp and reaction chamber and thus overcomes the problems of attenuation of short wavelength ultraviolet radiation by the window. All the ultraviolet output of the lamp can now directly couple into the reaction gases, so the need for sensitising agents is also removed. Thin films of silicon oxide have been deposited onto single crystal silicon wafers from nitrous oxide-silane gas mixtures. The physical properties are comparable to those of high quality insulator films deposited by plasma enhanced techniques. The results of electrical measurements indicate that this material is of sufficiently high quality to be used as a low temperature deposited gate dielectric for thin film devices. To confirm this, thin film transistors (TFTs) have been fabricated using the material (and an active layer of amorphous silicon deposited in the same system) and characteristics of these TFTs are also presented.     

铸铁蒸发器水室结构的参数化有限元分析

铸铁蒸发器水室常开有大直径管孔,且铸造结构复杂,无法使用常规设计。运用V isual Basic 6.0对AN-SYS进行二次开发,实现了铸铁水室结构的参数化有限元设计。该设计平台有效地提高了设计效率和设计精度,为铸铁蒸发器水室结构的安全评定提供了有效手段。     

Study of a multi-wire proportional chamber with a cathode strip and delay-line readout

The design principle for a multi-wire proportional chamber with a cathode strip and delay-line readout is described. A prototype chamber of a size of 10 cm ～ l0 cm was made together with the readout electronics circuit. A very clean signal with very low background noise was obtained by applying a transformer between the delay-line and the pre-amplifier in order to match the resistance. Along the anode wire direction a position resolution of less than 0.5 mm was achieved with a 55Fe-5.9 keV X ray source. The simple structure, large effective area and high position resolution allow the application of a gas chamber of this kind to many purposes.     

Intensities of γ- and X-rays in the125I decay

Total number of X- and γ-rays per decay equal to 1·4785±0·009 was determined by means of the coincidence measurement in the windowless 4π scintillation counter. The coincidence measurement with Si(Li) and scintillation counters gave P_Kω_K = 0·685±0·012.     

用于软X射线光谱探测的双MCP近贴单幅相机

研制了一种双MCP近贴单幅相机,相机用于软X射线光谱探测.采用开放式无窗结构,利用第一块通道板进行选通, 有效探测面积Φ26mm.相机时间分辨率5ns,静态空间分辨率 25 lp/mm,动态空间分辨率7 lp/mm,控制电路固有延时小于20 ns.主要介绍了该相机的结构、工作原理、快门脉冲发生器电路、应用情况及其性能特点.     

Sensitivity and systematics of KATRIN experiment

The KArlsruhe TRItiumNeutrino experiment (KATRIN) will measure a “kinematical” electron antineutrino mass upper limit up to 0.2 eV/c². The experimental setup based on an electrostatic spectrometer with adiabatic magnetic collimation and windowless gaseous tritium source is briefly described. This sensitivity to the neutrino mass could be reached with a 10-m-diameter spectrometer after three years of data taking. Several major sources of the systematic errors are discussed.     

Polymer photoablation under windowless VUV hydrogen or helium discharge lamp

In this work, the photoablation of PolyPhenyl-Quinoxaline (PPQ) films is investigated by using the vacuum ultraviolet (VUV) incoherent emission (λ<160nm) from a novel windowless hydrogen (or helium) discharge lamp. A tentative explanation of the film etching process is given through the photochemical reactions which take place in the polymer under VUV illumination.     

HL-2M装置5 MW中性束加热束线离子源放电室研制

为了给HL-2M装置建设一条5 MW中性束加热束线,开展了中性束加热用热阴极弧放电离子源放电室的研制。这条中性束束线包含4套80 kV/45 A/5 s离子源,放电室的设计指标为850 A/5 s。首先采用CST软件中的电磁工作室对特定几何结构的放电室会切磁场进行了模拟计算,得到了会切磁场分布,验证了会切磁场布局的合理性。针对放电室加工工艺和实验过程中局部拉弧等问题,对放电室结构进行了不断改进。放电室侧壁由40列会切磁体改为7圈环形磁体,阴极灯丝结构从灯丝板结构最终改为陶瓷可伐结构,并且在放电室和加速器之间增加了陶瓷屏蔽。在阴极板结构放电室和阴极陶瓷可伐结构放电室内都获得了正常的弧放电。最终定型的放电室采用周边7圈环形会切磁体和陶瓷可伐结构。在定型的放电室内达到了5 MW中性束束线离子源弧放电的指标。弧放电时间接近5 s,最大弧放电电流达到1 000 A。     

膨胀腔类超材料的传递损失研究*

声学超材料及结构已被广泛研究,其超结构通常利用3D打印技术实现,当结构刚度较小或者面积较大时,由声固耦合所导致的声学效果与设计不符的情况广泛存在。本文针对含有膨胀腔类的超材料,研究了声固耦合对其声学性能的影响,采用有限元计算结合阻抗管实验的方法,得到其传递损失,分析了声固耦合现象对传递损失的影响。结果表明：薄壁膨胀腔结构的作用频率范围与只考虑声学理论计算的设计不符,声固耦合现象对传递损失产生显著影响;采用增加膨胀腔壁厚、减少膨胀腔内径或选择金属材料的方式,都可以使得声固耦合现象对传递损失的影响减小;仿真结果与实验结果基本吻合。该研究结果说明：对于膨胀腔类超材料,当刚度较小或者面积较大时,对其进行声固耦合分析是完全必要的。     

合肥光源BPM真空室位移监测系统

 合肥光源(HLS)电子储存环的束流水平轨道存在缓慢漂移现象,导致轨道水平漂移的主要原因是同步光热效应导致束流位置检测器(BPM)真空室水平移动。为抑制这种现象而研制的合肥光源BPM真空室位移监测系统,利用光栅位移传感器实时监测全环24个BPM真空室的位移,并将数据反馈至HLS控制系统,由控制系统对BPM的轨道测量值进行实时修正,从而提高了慢速轨道反馈系统有效性。     

Development and investigation of a metal ion source for accelerators

The design and operation of a new spray-type metal ion source are described. The source is built around a plasma emitter containing metal ions and using a two-step glow discharge with double plasma compression. The necessary temperature of electrons in a discharge chamber is reached by distributing the discharge power without heating. The design of the discharge chamber is optimized. The first set of experimental data for the mass-and-charge composition of a beam generated by this source is presented.     

New possible laser media in the UV and XUY in high current heavy ion beam induced plasmas

Mixtures of rare gases with alkali-metal vapour were excited by a high power argon ion beam in a windowless gas target system. Narrow emission continua were observed in the vacuum ultraviolet region between 60 and 200 nm. The observed emission was assigned to the decay of a new class of excited ionic molecules Rg⁺ A formed by the combination of a rare gas ion Rg⁺ with an alkali atom A. These excimer-like ions are of great interest for possible short-wavelength lasers, because the ground state consisting of a rare gas atom and an alkali ion is only weakly bound. The observed decay energies and fine structure splittings agree well with the prediction of calculations. A summary of previous results is presented.Supported by the German Government Department for Research and Technology (BMFT), Bonn, Germany.     

First direct measurement of the total cross-section of 12C(α,γ)16O

The total cross-section of ¹²C(α,γ)¹⁶O was measured for the first time by a direct and ungated detection of the ¹⁶O recoils. This measurement in inverse kinematics using the recoil mass separator ERNA in combination with a windowless He gas target allowed to collect data with high precision in the energy range E = 1.9 to 4.9 MeV. The data represent new information for the determination of the astrophysical S(E) factor.     

Electronically controlled high intensity reverberation chamber

The problems associated with the operation of an aerodynamically-operated reverberation chamber, led to an investigation into the possibility of building an electronically-controlled reverberation chamber. The requirement of the chamber was specifically to operate at 150 dB, as per any required spectrum shape between 150–7000 Hz, with some possibility of control outside this range. In this paper the design and construction specifications and results are discussed, mainly from the practical viewpoint.