GERO: a general SCA-based readout ASIC for micro-pattern gas detectors with configurable storage depth and on-chip digitizer

The paper presents GEneral ReadOut (GERO), a general readout ASIC based on a switched capacitor array for micro-pattern gas detectors. It aims at providing general readout electronics for low-to-medium event-rate gas detectors with high sampling frequency, configurable storage depth, and data digitalization. The first prototype GERO chip integrates 16 channels and was fabricated using a 0.18-lm CMOS process. Each channel consists of a sampling array working in a ping-pong mode, a storage array with a 1024-cell depth, and 32 Wilkinson analog-todigital converters. The detailed design and test results are presented in the paper.

Corrosion behavior of electrodeposited Ni with normal and bimodal grain size distribution

The corrosion behavior of electrodeposited Ni with normal and bimodal grain size distribution was investigated.The microstructure of samples was researched by SEM,EBSD,TEM and XRD.The corrosion behavior was studied by potentiodynamic tests and electrochemical impedance.Nanocrystalline Ni with(100)and(111)textures was prepared by an electrodeposition method.The Ni samples with different grain size distributions and twins were then obtained by heat treatment of nanocrystalline Ni at different temperatures.The effect of grain size on corrosion behavior of the sample depends on the ability of the environment to passivate.In the case where passive film forms on the sample surface,the corrosion resistance of the sample increases with decreasing grain size.Conversely,the corrosion resistance decreases with decreasing grain size when there is no passivation.The corrosion behavior of samples with bimodal grain size distribution obeys the rule of mixture.

Offset-free DC-coupled analog frontend circuit for high-dynamicrange signals

The analog frontend(AFE)coupling circuit is a crucial processing element for data acquisition systems based on analog-to-digital converters(ADCs).Currently,high-speed and high-resolution ADCs are predominantly designed with differential input stages.Conventional highspeed ADC drivers are mainly AC-coupled by employing transformers(Baluns)or fully differential amplifiers(FDAs)with blocking capacitors.However,the results of this study indicate that a certain degree of DC offset error exists and manifests itself as the baseline error in the presence of power dividers connecting several DC-coupled channels that implement high-dynamic-range(HDR)signal conditioning.The study involves a theoretical analysis and explanation of the baseline offset error.The offset error can potentially lead to unexpected out-of-range issues for sampling devices,including high-speed ADCs and switched capacitor array ASICs.High-performance FDAs are adopted,and an offset-free DC-coupled AFE circuit is proposed to address the aforementioned issue using twostage amplification and a resistive attenuator.The proposed methodology is verified via circuit simulations and hardware design.Thus,the baseline offset problem can be accurately solved using the proposed circuit by minimizing the neglectable error.The proposed circuit facilitates improvements in the high-precision measurement of HDR signals in many nuclear physics experiments and some applications in the DC-coupling scheme with FDAs involving resistive power dividers.

Design and offline processing of an ultrafast digitizer based on internal cascaded DRS4

In this paper, we present an ultrafast digitizer utilizing the DRS4 switched capacitor array applicationspecific integrated circuit to achieve an ultrafast sampling speed of at most 5 GS/s. We cascaded all eight channels(sub-channels) of a single DRS4 chip for increased storage depth. The digitizer contains four DRS4 chips, a quadchannel analog-to-digital converter,a controlling fieldprogrammable gate array, a PXI interface, and an SFP+connector. Consequently, each DRS4 channel has a depth of 8192 points and a vertical resolution of 14 bits. The readout sequences should be broken into several segments and then reordered to obtain the correct sequential data sets, and this offline procedure varies in different readout modes. This paper describes the design and implementation of the hardware;in particular, the respective processing procedures are described in detail. Furthermore, the offset error is calibrated and corrected to improve the precision of the captured waveform in both single-channel and highresolution modes.

Timing analysis of the black hole candidate EXO 1846–031 with Insight-HXMT monitoring

We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.

In-situ synchrotron high energy X-ray diffraction study of spontaneous reorientation of R phase upon cooling in nanocrystalline Ti_(50)Ni_(45.5)Fe_(4.5)alloy

This study investigated a peculiar phenomenon of self-reorientation of thermally formed R phase in nanocrystalline Ti_(50)Ni_(45.5)Fe_(4.5)by means of in-situ syn-chrotron high energy X-ray diffraction(HE-XRD).Two samples with different average grain sizes of 40 and 90 nm were investigated.R phase in the 40-nm grain size sample was found to self-reorient gradually upon cooling,whereas the same phenomenon did not occur in the 90-nm grain size sample.This self-reorientation process is attributed to the development and evolution of an internal stress anisotropy caused by the second order continuous lattice distortion of R phase upon further cooling in the small nanograined matrix,which lacks the self-accommodation mechanism for internal stress cancellation.