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Radiation measurement at underwater environment helps to get a better understanding on sedimentation, geological structure, radiation monitoring, and so on. However, reports about radiation of natural underwater environment are rare, especially in situ gamma radiation measurement. Two gamma spectrometers are going to be used in underwater in situ radiation measurement. Aiming at different scientific goals, the spectrometers can develop multiple kinds of measurements, including dose and energy spectrum of gamma rays. In this article, a compatible data acquisition (DAQ) system is proposed. The DAQ provides features of readout, visualization, data process algorithm, and file input and output. To benefit from high reusability and low coupling, the Model-View-ViewModel (MVVM) pattern is adopted in the DAQ system. With an application layer protocol based on Modbus, the DAQ can be fully compatible with different spectrometers. Besides supporting of real-time control, the DAQ system also provides a way to program the spectrometers to execute an unmanned mission, so that the spectrometers can load a timetable from a built-in flash memory and run automatically. [ABSTRACT FROM AUTHOR]

The compressed baryonic matter (CBM) experiment will investigate the quantum chromodynamics phase diagram at high net baryon densities and moderate temperatures. CBM time-of-flight (TOF) system is composed of super modules containing high-performance multigap resistive plate chambers (MRPCs). During the mass production, each super module assembled with MRPCs needs quality evaluation, which includes time measurement and data readout. Read out electronics encounter the challenge of reading data from a super module at a speed of about 6 Gb/s. In this paper, a read out method based on peripheral component interconnect express (PCIe) over optical fiber is proposed for CBM-TOF super module quality evaluation. The digitized data from super module will be concentrated at the front-end electronics and then be transmitted to a PCIe switch module (PSM) over optical fiber using PCIe protocol. The PSM is directly plugged into the motherboard via vertical edge card connector at the back-end data acquisition server. With this readout method, a high-speed transmission rate can be reached. Furthermore, a PSM can receive data from several super modules simultaneously, which is important to improve the evaluation efficiency. This readout method simplifies the architecture of readout electronics and supports long-distance transmission between front end and back end. [ABSTRACT FROM AUTHOR]

The time-of-flight system in the Compressed Baryonic Matter experiment is composed of super modules that are based on multigap resistive plate chambers for high-density and high-resolution time measurement. To evaluate the quality of detectors during mass production, a distributed data readout system was developed. Furthermore, a related data acquisition (DAQ) software was developed under Linux operating system to test and verify the feasibility of the utilized distributed data readout method. In this paper, the DAQ software focused on data collection, event building, status monitoring, and system control. Laboratory tests confirmed the function of the DAQ software for super module quality control and showed that the overall data transfer rate of a single data transmission path can reach up to ~550 Mb/s. [ABSTRACT FROM AUTHOR]

The time-of-flight (TOF) system in the compressed Baryonic matter (CBM) experiment is comprised of super modules and used for charged hadron identification. Each super module contains several multigap resistive plate chambers (MRPCs) for high-precision time measurements. The quality of each super module should be evaluated to ensure that the detectors achieve the targeted performance. In this paper, the quality evaluation electronics for super modules based on the peripheral component interconnect eXtensions for instrumentation platform is proposed. The discriminated MRPC signals are digitized by the time-to-digital converter (TDC). Then, the digitized time data from a super module are aggregated at the TDC readout motherboard and are transmitted to the data readout modules (DRMs) via optical links. Finally, the DRMs relay the digitized data to the data acquisition system through the Gigabit Ethernet ports in parallel. The laboratory test results indicate that the quality evaluation electronics achieve a time resolution better than 20 ps. The initial cosmic ray tests with the MRPC detectors have also been conducted to confirm the performance of the quality evaluation system. Based on the results, the evaluation system can subsequently be used for quality evaluation of the CBM-TOF super module. [ABSTRACT FROM AUTHOR]

A supermodule assembled with multiple resistive plate chamber detectors is a component of time-of-flight (TOF) system for the compressed baryonic matter (CBM) experiment. Before the supermodules are applied to CBM-TOF, their quality needs to be evaluated. The readout electronics is confronted with a tremendous challenge of transmitting data at the maximal speed of 6 Gb/s. In this paper, the readout method for the CBM-TOF supermodule quality evaluation is presented. A parallel architecture based on the Gigabit Ethernet is designed to meet the requirement for data transmission rate. First, the data are sent from the front-end electronics to four readout module groups via optical fibers at the maximal rate of 1.5 Gb/s per fiber. Next, the data are further distributed to 16 parallel daughter readout models so that the maximal data throughput of each daughter readout module is 375 Mb/s, within its capacity of 550 Mb/s. Finally, the readout daughter modules send data to the data acquisition software through the standard Gigabit Ethernet. The proposed readout method has the advantage of good scalability, so it can meet different requirements for variable data rate. The preliminary test result shows that each of four parallel readout groups can transmit data at the speed of 1.6 Gb/s, which indicates that the overall readout system can meet the requirement for the maximal data-transmission speed of 6 Gb/s. [ABSTRACT FROM AUTHOR]

At the China spallation neutron source-white neutron sources (CSNS-WNS), the BaF2 (barium fluoride) detector array in planning is designed for neutron capture cross section measurements with high accuracy and efficiency. Once proton beam collides with the spallation target, the neutrons will fly from the target to specimen surrounded by BaF2 array and produce cascaded $\gamma $ rays eventually. The time of flight (TOF) corresponds to the neutron energy. To identify $\gamma $ signals from the high $\alpha $ -particle background, pulse shape discrimination (PSD) technique is usually used according to the ratio of fast to slow component in the signal. Waveform digitization is a valid supporting technology for PSD. In order to precisely obtain the wave and time information carried by detector signal, and to maximally cover the signal dynamic range, a universal digitizer with 1 GSps sampling rate and 12-b resolution has been designed based on a 3U PXIe platform in this paper. Besides waveform digitization, this customized digitizer also measures TOF precisely based on the digitized waveform data and technique of time-to-digital converting on field-programming gate array. Test results show that this digitizer can achieve good static and dynamic performance. The specification of effective number of bits is better than 9.43 b within 198 MHz. Digitizer proposed in this paper can meet the requirements for BaF2 spectrum at CSNS-WNS. [ABSTRACT FROM AUTHOR]

The “in programming barium fluoride (BaF2) detector array” is one of the experiment facilities at China Spallation Neutron Source-White Neutron Sources, which is designed for the measurement of neutron capture cross section with high accuracy. It consists of 92 crystal elements with completely $4\pi $ solid-angle coverage, which needs 92 analog channels and 92 digitization channels for data acquisition. Accordingly, the readout electronics is comprised with four distributed readout PXIe crates, containing 46 field digitization modules (FDMs). Each FDM supports two valid channels for signal digitizing. In this paper, evaluation software is designed for evaluating the performance of BaF2 readout electronics. It focuses on evaluating the performance of data transmission, waveform digitizing, and working status monitoring. Test results show that the evaluation software can correctly acquire and assemble data from the BaF2 readout system and evaluate the analog digital converter (ADC) performance under ADC test mode. FDMs in the readout system can also be monitored and controlled by this software in real time. [ABSTRACT FROM AUTHOR]

Time-to-digital converter (TDC) implemented in field programmable gate array (FPGA) has been developed for years and obtained superior performance. In an application with large amount of channels, tradeoff must be weighed between performance and cost if TDC is implemented in FPGA. Massive channels with high event rate also lead to big challenges for high data rate transmission in real time. Thus, it has great significance to develop time digitizers that accommodate high data rate with satisfying resolution and cost. In this paper, a TDC prototype with sandwich structure implemented in low-cost FPGA is presented. It contains 320 time measurement channels (ten TDC daughter cards) and can be used as digitizer for evaluating super module detectors in compressed baryonic matter time-of-fight experiment. Gigabit transceiver integrated in FPGA is utilized to support over 1-Gb/s data rate of a single TDC daughter. Preliminary tests show rms of leading edge measurement is better than 15 ps, and that of TOT measurement implemented by a single channel is better than 28 ps. [ABSTRACT FROM AUTHOR]