A 64-Channel Wide Dynamic Range Charge Measurement ASIC for Strip and Pixel Ionization Detectors

In this paper we report a 64-channel application specified integrated circuit (ASIC) for the readout of parallel plate strip and pixel ionization detectors. The detectors measure the intensity and the geometrical characteristics of a hadron beam for hadrontherapy cancer treatments. The ASIC is based on a current to frequency converter followed by a counter. It uses a charge balancing integration technique to obtain a dynamic range in excess of$10^5$with a nonlinearity of less than 1%. The ASIC has been designed in a CMOS 0.8$mu m$technology and it has been used for the readout of both strip ionization detectors for beam calibration and pixel detectors for beam monitoring during treatment. A new version of the chip in CMOS 0.35$mu m$technology which allows bipolar input currents has been designed and is currently under test.     

RG64—High Count Rate Low Noise Multichannel ASIC With Energy Window Selection and Continuous Readout Mode

We report on the performance of a low noise and high count rate readout ASIC with binary architecture and energy window selection for X-ray imaging applications using semiconductor detectors. The ASIC called RG64 is designed in 0.35 mum CMOS process and its total area is 3900times5000 mum². The core of RG64 consists of 64 readout channels. Each channel is built of a charge sensitive amplifier with a second order shaper of peaking time 75 ns, two independent discriminators with an 8-bit offset correction circuit and two independent 20-bit counters with RAM memory buffers. The ENC of the circuit reaches the value of about 126 el. rms with 1 pF input load and 5 mW power consumption per single channel. The mean gain in the multichannel ASIC is about 50 muV/el., with the dispersion from channel to channel of 0.9% (on one sigma level). The deviation of the effective threshold voltage spread for given energy can be reduced to less than 7 el. rms (calculated to the charge sensitive amplifier input). High count rate measurements have been performed up to 2 Mcps of average rate of input pulses, both for AC and DC coupled silicon strip detectors with X-ray photons of energy 8.04 keV. The RG64 can operate both in the continuous readout mode and in the readout mode separate from exposure.     

Semiconductor drift detectors for X- and gamma-ray spectroscopy and imaging

The semiconductor drift detectors (SDDs) show basic advantages, in terms of spectroscopic resolution and detection rate, with respect to other semiconductor detectors. These advantages are strictly related to the very low values of the output capacitance of these devices. In this paper the working principles and the performance of the SDDs are presented and the most recent devices (“droplet type” SDDs and monolithic arrays of SDDs) are introduced. The requirements of front-end electronics for the readout of the SDDs signals are then discussed and the most recent implementations (pulsed-reset preamplifiers, multi-channel ASIC readout circuits) are introduced. Some relevant applications of SDDs in the field of X-ray spectroscopy for material analysis and for nuclear physics experiments, and in the field of gamma-ray imaging, are presented as a conclusion.     

基于VME总线的高精度信号发生器的设计

北京谱仪(BESⅢ)的飞行时间读出电子学(TOF)对于时间信号的测量具有非常高的要求,需要对TOF时间测量电路进行严格的测试。本文介绍了用于该测试的高精度信号发生器的实现方案,该电路能够产生抖动(Jitter)小于23．623ps的脉冲信号和抖动小于12．265ps的40．000MHz时钟信号。同时,对设计中使用的关键性技术一高速高精度时钟电路和脉冲产生电路的设计进行了分析。     

Sampling Pulses for Optimal Timing

When extracting unknown band-limited pulses from sampled data, the Nyquist criterion defines the minimum sampling frequency. With well-defined pulse shapes and a stationary noise environment one can use matched filters to recover time and amplitude, but this is usually not the case with scintillation detectors. If the noise is not stationary other methods must be used. Our study investigates different timing strategies and how the timing precision depends on ADC resolution and sample rate. It also compares the timing precision with data obtained from an analogue setup. Pulses from an LSO crystal with photomultiplier readout are studied experimentally. Our best method gives in this case a 10% improvement in timing compared to a matched filter approach. Some simulation results are also reported     

Pulse Height Analyzer with Internal Storage for Space Use

A pulse height analyzer has been designed for space use which is able to handle input count rates in excess of 5 X 104 counts per second with low power consumption and very small size. It can operate in the temperature range of -15 to + 70°C and survive storage temperature from -55 to + 125°C. A parallel-serial, coincident current, wide-temperature-range, ferrite core memory of 256 channels, 16 bits per channel is provided. A digitizing rate of 0. 5 microsecond per channel plus an average 25.5 microsecond storage time is used. An internal, nonoverloading linear amplifier is provided to handle up to 100 millivolt negative pulses for full scale storage. Control logic is provided for external commands for power, accumulate, nondestructive readout, and destructive readout functions. All input-output logic levels are compatible with conventional integrated circuits. All components are run at a fraction of their ratings in order to obtain maximum reliability.     

Caliste 64, an Innovative CdTe Hard X-Ray Micro-Camera

A prototype 64 pixel miniature camera has been designed and tested for the Simbol-X hard X-ray observatory to be flown on the joint CNES-ASI space mission in 2014. This device is called Caliste 64. It is a high performance spectro-imager with event time-tagging capability, able to detect photons between 2 keV and 250 keV. Caliste 64 is the assembly of a 1 or 2 mm thick CdTe detector mounted on top of a readout module. CdTe detectors equipped with aluminum Schottky barrier contacts are used because of their very low dark current and excellent spectroscopic performance. Front-end electronics is a stack of four IDeF-X Vl.l ASICs, arranged perpendicular to the detection plane, to read out each pixel independently. The whole camera fits in a 10 times 10 times 20 mm³ volume and is juxtaposable on its four sides. This allows the device to be used as an elementary unit in a larger array of Caliste 64 cameras. Noise performance resulted in an ENC better than 60 electrons rms in average. The first prototype camera is tested at -10degC with a bias of -400 V. The spectrum summed across the 64 pixels results in a resolution of 697 eV FWHM at 13.9 keV and 808 eV FWHM at 59.54 keV.     

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.     

CMOS low-noise switched charge sensitive preamplifier for CdTe andCdZnTe X-ray detectors

CdTe and CdZnTe X-ray detector arrays for imaging and spectroscopy provide low capacitance current sources with low leakage currents. The optimal shaping time for low-noise operation is relatively high in CMOS analog channels that provide the readout for these detectors. The shaper is centered at lower frequencies, and thus the 1/f noise from the electronics is the main noise source that limits the resolution of the channel. The optimal dimensions of the input stage MOSFET are determined by this noise. In this paper a design criterion for the optimization of the resolution and the power consumption in a 1/f noise dominated readout is introduced. A readout based on CMOS switched charge sensitive preamplifier without feedback resistor has been designed and fabricated in the CMOS 2-μ low-noise analog process provided by MOSIS. This design provides high sensitivity and the possibility to integrate a large number of channels with low power consumption. Measurements of the performance of a first prototype chip are presented     

Event-driven timing system based on MRF cPCI hardware for HLS-II

Hefei Light Source(HLS)-II is a vacuum ultraviole(VUV) synchrotron light source. A major upgrade of the light source was finished at the end of 2014. The timing system was rebuilt using compact peripheral component interconnect(cPCI) event-driven hardware to meet synchronization requirements of the machine. In the new system, the c PCI event-driven products manufactured by the micro-research finland(MRF) Oy are employed to achieve about 100 output signals with different interfaces. Device supports and drivers developed for common Experimental Physics and Industrial Control System(EPICS) records are used to access the registers on the timing modules. Five c PCI-bus input/output controllers(IOCs) distributed in different areas of the light source host timing modules for various subsystems. The delay resolution of this system is 9.8 ns for most channels and 9 ps for the channels used for triggering the electron gun and the injection kickers. The measured rms jitter of the output signal is less than 27 ps. Using the bucket chooser, this system enables the HLS-II to fill the storage ring with any designated bunch pattern. Benefitting from this upgrade, brightness and performance of the light source are significantly improved.     

Investigation of a Multi-Anode Microchannel Plate PMT for Time-of-Flight PET

We report on an investigation of a mulit-anode microchannel plate PMT for time-of-flight PET detector modules. The primary advantages of an MCP lie in its excellent timing properties (fast rise time and low transit time spread), compact size, and reasonably large active area, thus making it a good candidate for TOF applications. In addition, the anode can be segmented into an array of collection electrodes with fine pitch to attain good position sensitivity. In this paper, we investigate using the Photonis Planacon MCP-PMT with a pore size of 10 μm to construct a PET detector module, specifically for time-of-flight applications. We measure the single electron response by exciting the Planacon with pulsed laser diode. We also measure the performance of the Planacon as a PET detector by coupling a 4 mm × 4 mm × 10 mm LSO crystal to individual pixel to study its gain uniformity, energy resolution, and timing resolution. The rise time of the Planacon is 440 ps with pulse duration of about 1 ns. A transit time spread of 120 ps FWHM is achieved. The gain is fairly uniform across the central region of the Planacon, but drops off by as much as a factor of 2.5 around the edges. The energy resolution is fairly uniform across the Planacon with an average value of 18.6±0.7% FWHM. While the average timing resolution of 252±7 ps FWHM is achieved in the central region of the Planacon, it degrades to 280±9 ps FWHM for edge pixels and 316±15 ps FWHM for corner pixels. We compare the results with measurements performed with a fast timing conventional PMT (Hamamatsu R-9800). We find that the R9800, which has significantly higher PDE, has a better timing resolution than the Planacon. Furthermore, we perform detector simulations to calculate the improvement that can be achieved with a higher PDE Planacon. The calculation shows that the Planacon can achieve significantly better timing resolution if it can attain the same PDE as the R-9800, while only a 30% improvement is needed to yield a similar timing resolution as the R-9800.     

快定时放大器

本文叙述了一种快定时放大器的结构，性能及实验结果以及在核物理实验中的应用，并对其工作原理进行了适当的分析。     

Timing Electronics and Fast Timing Methods with Scintillation Detectors

Time spectroscopy involves the measurement of the time relationship between two events. This paper reviews time pick-off techniques, practival time-pickoff circuits, and timing with scintillation detectors. A detailed comparison is made between leading-edge timing and constant-fraction timing. Typical timing resolution results are given for 60Co.     

基于APV25多通道读出电子学系统设计

介绍了基于APV25芯片的多通道读出电子学系统的设计方法,利用ASIC芯片与可扩展读出系统相结合,实现多通道信号的处理。在该系统中,基于PXI机箱的单个读出板可实现2 048路信号的读出及处理,并具有集成度高、低功耗、可扩展等优点。电子学测试结果表明,本系统电荷输入线性动态范围为0~12 fC,APV25等效输入噪声408 e,可适应大型物理实验微结构气体探测器、硅像素探测器等探测器的读出需求。     

Development of hybrid photon detectors with integrated siliconpixel readout for the RICH counters of LHCb

We report on the ongoing work towards a hybrid photon detector with integrated silicon pixel readout for the ring imaging Cherenkov detectors of the LHCb experiment at the Large Hadron Collider at CERN. The photon detector is based on a cross-focussed image intensifier tube geometry where the image is demagnified by a factor of 4. The anode consists of a silicon pixel array, bump-bonded to a fast, binary readout chip with matching pixel electronics. The developments and tests of full-scale prototypes with 80% active area are presented. Specific requirements for pixel front-end and readout electronics in LHCb are outlined, and recent results obtained from pixel chips applicable to hybrid photon detector design are summarized     

LaCl3:Ce3+闪烁体正电子湮没寿命谱仪

对国内最新研制出的LaCl3：Ce^3＋闪烁晶体时间特性进行了测试,用该种晶体尝试组建了正电子湮没寿命谱仪,时间分辨率达到了350ps。由于LaCl3：Ce^3＋探头在具有快速时间响应特性的同时还具有较高的能量分辨率,用该探头组建正电子湮没寿命谱仪将具有许多潜在的优势。     

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.     

Three-detector setup for PAL spectrometer based on DRS4 waveform digitizing board

A digital three-detector positron lifetime spectrometer was developed.It consists of a DRS4 waveform digitizing board and three La Br3scintillation detectors coupled to XP2020Q photomultiplier tubes.DRS4 waveform digitizing allows data sampling at up to 5 GSPS with high amplitude resolution,with good time scale linearity and stability.In the triple-coincidence,the new system could reach a 195 ps time resolution,which is better than the conventional analog apparatus with the same detectors.This spectrometer can be applied to the other scintillation timing measurements with picoseconds accuracy.     

用于In-BeamTOF-PET的时间校正系统

设计和构建了用于In-BeamTOF-PET时间校正的定时系统。该系统是由1对BaF₂( 40mm× 45mm)晶体耦合到光电倍增管XP2020Q和标准核电子学插件构成。经测试,系统对511keV γ射线测量的最佳符合时间分辨达576ps。对光电倍增管、信号读取方式、定时放大器以及甄别器等对该定时系统时间分辨的影响进行了测试分析。结果表明：从光电倍增管打拿级引出信号的读取模式的系统分辨率最佳;光电倍增管类型,尤其是它的上升时间和电子渡越时间对定时系统性能影响较大。光电倍增管的上升时间和电子渡越时间越短,其定时性能越好。系统的定时性能也与电子学插件的组合有关。     

Initial Beam Test Results from a Silicon-Strip Detector with VLSI Readout

Silicon detectors with 256 strips, having a pitch of 25 ?m, and connected to two 128 channel NMOS VLSI chips each (Microplex), have been tested in relativistic charged particle beams at CERN and at the Stanford Linear Accelerator Center. The readout chips have an input channel pitch of 47.5 ?m and a single multiplexed output which provides voltages proportional to the integrated charge from each strip. The most probable signal height from minimum ionizing tracks was 15 times the rms noise in any single channel. Two-track traversals with a separation of 100 ?m were cleanly resolved.