Sampling FEE and Trigger-less DAQ for the J-PET Scanner

Abstract

In this paper, we present a complete Data Acquisition System (DAQ) together with the readout mechanisms for the J-PET tomography scanner. In general detector readout chain is constructed out of Front-End Electronics (FEE), measurement devices like Time-to-Digital or Analogto-Digital Converters (TDCs or ADCs), data collectors and storage. We have developed a system capable for maintaining continuous readout of digitized data without preliminary selection. Such operation mode results in up to 8 Gbps data stream, therefore it is required to introduce a dedicated module for online event building and feature extraction. The Central Controller Module, equipped with Xilinx Zynq SoC and 16 optical transceivers serves as such true real time computing facility. Our solution * Presented at Jagiellonian Symposium on Fundamental and Applied Subatomic Physics arXiv:1602.05251v1 [physics.ins-det] 17 Feb 2016 for the continuous data recording (trigger-less) is a novel approach in such detector systems and assures that most of the information is preserved on the storage for further, high-level processing. Signal discrimination applies an unique method of using LVDS buffers located in the FPGA fabric.

Monte Carlo N-Particle simulations of an underwater chemical threats detection system using neutron activation analysis

“…Otherwise the signal from sulphur could be masked by a significant number of counts from the hydrogen line of exactly the same energy. The acquisition system used for prompt γ-rays detection should be able to operate at high count rates in a short time period, up to 1 Mcps [33][34][35].…”

A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

“…The limitation on the source activity can be overcome by the J-PET due to the application of plastic scintillators that are characterized by about two orders of magnitude shorter duration of signals, thus decreasing significantly the pile-ups problems with respect to the crystal based detector systems. In addition, the improved angular resolution combined with the superior timing of the J-PET detector (by more than order of magnitude improved with respect to the crystal detectors) and with the possibility of the triggerless registrations [11, 12] of all kind of events with no hardware coincidence window allow suppression and monitoring of the background, due to misidentification of events and possible contribution from pick-off annihilations.…”

“…The J-PET detector is made of three cylindrical layers of EJ-230 plastic scintillator strips ( black ) with dimension of and Hamamatsu R9800 vacuum tube photomultipliers ( grey ). The signals from photomultipliers are probed in the voltage domain at four thresholds with the timing accuracy of 30 ps [10] and the data acquisition is working in the trigger-less mode [11, 12]…”

Time Calibration of the J-PET Detector

“…The measurement procedure was repeated for each of the 192 J-PET scintillator strips arranged in three cylindrical layers. Since the J-PET frontend electronics are able to probe signals at four different thresholds, and on both the leading and trailing edges [19,20] the calibration was done for times measured on each threshold of both signal edges. Collected data were analysed using the J-PET Framework software [18] w. r. t. the time calibration of each separate module (so called "A-B" synchronization) and w. r. t. the TOF between scintillators.…”