用单板机获取穆斯堡尔谱数据

穆斯堡尔谱仪主要由振动子和驱动电路两大部分组成。驱动线路用来驱动振动子和控制谱仪的工作,振动子的驱动线圈和拾波线圈安放在磁钢系统的磁隙中,用弹簧片支撑。当参考信号为三角波时,振动子就按等加速度方式运动,其频率为7.03Hz。它是由115.2kHz石英晶体振荡器经两块7级二进制分频产生,在振动子上装有穆斯堡尔放射源~(57)Co,谱仪工作时,放射源~(57)Co放出的γ射线受到了振子振动速度的调制,在振子振动的周期内,不同时刻的速度值随时间线性增加。     

穆斯堡尔谱仪速度非线性测定的探讨

在穆斯堡尔谱仪中,驱动速度的质量指标主要在于它的稳定性和非线性。稳定性将在谱线宽度中反映出来,它主要取决于零电平漂移、参考信号幅度的微小不稳定以及驱动电路中放大单元的不对称漂移。而后二者通常在整个速度扫描中可以好于10~(-4)。速度的非线性是一个更重要的指标,它取决于速度参考信号的线性、反馈回路的增益以及拾波线圈响应的线性度(图1)。如果采用多道分析器,道址——道位置间的非线性关系也是一个重要的影响因素。而速度的非线性直接影响谱峰的位置,从而影响所得穆斯堡尔参数的精度。     

基于LabVIEW的虚拟穆斯堡尔谱仪

在LabVIEW平台上利用数据采集卡实现穆斯堡尔谱仪的速度驱动和脉冲计数功能,构成一台虚拟穆斯堡尔谱仪。谱仪操作界面友好,功能丰富,参数满足实验要求,已用于实际测量。     

双通道穆斯堡尔谱仪的两种接法

使用双通道穆斯堡尔谱仪同时测得两个穆斯堡尔谱是提高工作效率的一种有效途径。如果在通常的单通道穆斯堡尔谱仪的驱动器两端各加一个放射源,用两个探测器分别测取两个样品的穆斯堡尔谱,同时存储于一台多道分析器中,则组成了所说的双通道穆斯堡尔谱仪。如果使用带有透射窗的背散射探测器,使用一个放射源就可组成另一种形式的双通道穆斯堡尔谱仪,且有利于吸收谱与背散射谱同时测量。可见,把单通道穆斯堡尔谱仪改装     

穆斯堡尔谱仪速度非线性的测定探讨

在穆斯堡尔谱仪中,速度非线性是一个重要指标,它直接影响谱峰的位置,从而影响所得穆斯堡尔参数的精度。在我国国内,虽已对若干台穆斯堡尔谱仪作了鉴定,但对谱仪非线性指标的定义和测定方法尚欠明确。 速度非线性取决于速度参考信号的线性、反馈回路的增益以及拾波线圈响应的线性度。如果采用多道分析器,道址-道位置间的非线性关系也是一个重要的影响因素。 本文根据非线性定义探讨比较了各种测定方法,并提出采用下述方法进行测定的建议:     

幅度调制穆斯堡尔谱仪

穆斯堡尔谱仪通常采用多道多定标工作方式(时间型)。由于多道存储器需要一定的读写时间,当谱所需道数给定后,就有一个最大容许振动频率。本文介绍的幅度调制型穆斯堡尔谱仪,振动频率可不受上述因素的限制,以满足某些需要振动频率高达10～100kHz的实验需要。     

穆斯堡尔谱仪速度参考信号差误信号的计算机采集

通过计算机的声卡以及辅助电路把穆斯堡尔谱仪的速度参考信号和差误信号在计算机上实时采样分析，从而可以随时监控谱仪的运动情况，确保谱仪的工作质量。     

正弦波驱动的穆斯堡尔数据的抛物洛伦兹曲线最小二乘方拟合

目前,穆斯堡尔谱仪通常都采用三角波(等加速度)驱动方式,但是在某些特殊情况下,采用正弦波驱动也有突出的优点,本文给出了一种正弦波驱动时穆斯堡尔数据的抛物洛伦兹曲线的最小二乘方拟合方法。     

一个简单实用的计算机穆斯堡尔谱仪系统

介绍了一个简单实用的计算机穆斯堡尔谱仪系统。谱仪被设计成单宽ＮＩＭ插件,内部包含一个８０３１单片机用来管理整个谱仪的数据采集,该谱仪可同一台ＩＢＦＭＰＣ机或兼容性通过标准串行口相连,构成一个完整的谱仪系统。在这个系统中,使用者可通过主计算机键盘来控制谱仪进行穆斯堡尔谱和能谱的测量,利用主计算机的显示器进行实时显示和利用计算机的磁盘保存数据,在进行长时间测量时,主计算机可以随时脱机或联机而不会影响谱     

高计数率穆斯堡尔谱仪

本文论述了我们研制的高计数率穆斯堡尔谱仪,将它与常用穆斯堡尔谱仪作了比较,并利用512道,在道计数率超过20万次/h条件下,测量了磁带样品和考古样品的穆斯堡尔谱。     

四输入微计算机多道分析器

本文介绍一个能采集和分析四个512道γ谱的微计算机多道系统,该系统也可作一个2048道的脉冲幅度分析器使用,或用于多样品低本底液闪计数测量和数据处理。这里重点叙述多道部分的系统构成、工作原理、软件功能和性能指标。     

Design of 150kV bouncer modulator

The 150 kV bouncer modulator is designed to drive the 10 MW multi-beam klystron for the DESY TESLA Test Facility. The modulator is different from the 10 kV modulators previously built at Fermilab. First, the new 150 kV bouncer modulator has no transformer, so the modulator circuit is simplified and the output waveform is improved well. Second, the bouncer circuit has been changed to fit the output need, which is the most significant challenge. This paper gives the design of the 150 kV long pulse bouncer modulator.     

Multichannel acquisition system for high-resolution position-sensing silicon drift detectors

We present the design guidelines and the experimental characterization of a multichannel acquisition system that measures the amplitude and the time-of-arrival of the signal pulses delivered by position-sensing silicon drift detectors (SDDs). The readout system has been equally developed for multichannel SDDs and for controlled drift detectors (CDDs) intended for spectroscopic imaging of X-rays or charged particles. The analog section includes a very large scale integration (VLSI) front-end preamplifier and bias current generator for the on-chip JFET follower while the digital back-end is realized with 12 bit 100 MS/s 8-channel analog-to-digital converter (ADC) versa modular eurocard (VME) boards. Amplitude and time are measured by digitally processing each unipolar shaped pulse also in presence of a superposed background waveform. The VME modularity allows the expansion of the readout system up to 128 channels per VME crate. The overall linearity error is better than 0.05%, and the mean noise over all channels, expressed in terms of equivalent noise charge, is about 4 electrons r.m.s. The measured time resolution is 0.6 ns r.m.s. at a signal charge of 5000 electrons, corresponding to a position resolution of 2-3 /spl mu/m r.m.s. along the drift direction. The developed readout system has been used for X-ray imaging tests with CDDs at Sincrotrone Trieste.     

RX64DTH -a fully integrated 64-channel ASIC for a digital X-ray imaging system with energy window selection

We report on the multichannel IC (RX64DTH) designed for position sensitive X-ray measurements with silicon strip detectors and dedicated to medical imaging applications. This integrated circuit has a binary readout architecture with a double threshold allowing on selection energy window for measured signals. The design was realized in a 0.8 /spl mu/m CMOS process. The core of the RX64DTH IC consists of 64 readout channels. The single channel is built with four basic blocks: charge sensitive preamplifier, shaper, two independent discriminators, and two independent 20-bit counters. Each readout channel counts pulses which are above the low discriminator threshold and counts pulses independently above the high discriminator threshold. The energy resolution in such architecture is limited by the noise of a single channel and by channel to channel threshold spread. We present the noise and matching performance of a 384-channel module built with a silicon strip detector and six RX64DTH ICs. In the 384-channel module an equivalent noise charge of about 200 el. rms is achieved for the shaper peaking time of 0.8 /spl mu/s and strip capacitance of 3 pF. The deviation of discriminator thresholds for the whole system is only 87 el. rms. The obtained results show that the energy resolution and uniformity of analog parameters (noise, gain, offset) are sufficient for medical diagnostic applications such as dual energy mammography and angiography.     

空间单粒子翻转甄别与定位系统原理样机的设计及试验

单粒子翻转（SEU）是影响空间电子设备可靠性的重要因素,本文提出了一种SEU甄别与定位技术方法,研制了原理样机。硅探测器与辐照敏感器件在垂直方向相互临近安装,粒子入射到硅探测器的位置区域与目标辐照器件单粒子翻转的物理位置相对应。采用波形数字化技术实现了多道粒子甄别与能量信号测量,通过数据回读比较法实现了SRAM器件翻转逻辑定位检测。根据实验室测试和单粒子辐照试验结果,可探测高能粒子的LET≥6?06×10-3 MeV·cm2/mg,入射粒子的位置分辨率优于5 mm,最大计数率≥10 000 s-1,SRAM器件的SEU巡检周期时间分辨率为13?76 ms。通过掌握大容量SRAM型器件的SEU甄别与定位及其辐射环境感知能力,有助于提升空间电子设备的在轨工作性能。     

单光子时间分辨在线谱仪系统中的接口电路

本文介绍单光子时间分辨在线谱仪系统中的多道分析器与IBM PC/XT微型计算机接口的工作原理及控制程序。     

另一种多道脉冲幅度分析器死时间的数字测量方法

本文描述了一种多道分析器死时间的数字测量方法，与另一类似的测量方法作了详细的比较，实践表明，它是一种更简单适用的方法。     

Simulation calculation of 24kV long pulse TESLA modulator

1 Introduction output pulse is designed to meet the following speci- fications: The 24 kV long pulse modulator converts AC line Output voltage: 120 kVvoltage to pulsed high voltage in the 120 kV range to Output current: 138 Abe applied to the Thomson TH1801 multibeam kly- Pulse width: 1.7 msstron catho…     

束流均匀性测量前端读出电子学电路的设计

针对重离子治癌中的束流监测需要,用T型反馈电阻网络组成的电流-电压转换(IVC)电路将大面积二维位置灵敏平行板雪崩探测器( PPAC)输出的多路10pA～100 nA的微弱电流转换成-2V～-20 mV的电压信号,配合数据获取处理系统实现了近代物理研究所重离子治癌中的束流均匀性测量.实验表明该电路具有速度快、精度高等优...     

X-ray energy separation method using a CdTe semiconductor X-rayimaging sensor and photon counting method

A multichannel X-ray imaging sensor using a CdTe compound semiconductor radiation detector in photon counting mode was developed and tested for digital X-ray imaging and an X-ray energy separation capability. The X-ray imaging sensor was constructed of CdTe detector elements at a pitch of 0.25 mm. High band amplifiers, discriminators, and counters attached to each element formed the pulse counting circuit. Charge pulses generated by absorbed X-ray photons were directly counted and separated into two energy regions. Digitized X-ray images containing energy information were thus obtained. Using this sensor two separate X-ray images of different energy can be obtained simultaneously. A 256-channel X-ray imaging sensor was prepared and used to provide spatial resolution measurement for an X-ray charge. Low and high energy images of a hand phantom were thus obtained and both a soft tissue image and a bone image were produced using an energy subtraction method