Trigger-less readout of the PANDA electromagnetic calorimeter

Abstract

The PANDA collaboration at the future FAIR facil ity at Darmstadt, Germany, will employ antiproton annihilations to investigate resonances in the charmonium mass region. In order to gain high flexibility for physics event selection, a readout system without hardware trigger, i.e. a trigger-less data acquisition system will be employed and is currently being de veloped. The event-selection is based on high-level reconstructed information, e.g. invariant mass, secondary vertices, and time correlations, which may be contributed from all sub-detector systems. Prototypes of the PANDA Electromagnetic Calorimeter have been exploited to verify the desired event-selection approach. The prototype readout system includes a dedicated Sampling ADC (SADC), data concentrator (DCON) and compute-node (CN) modules. An optical link connects several SADC digitizers to a DCON module from where the data are streamed to the CN network. Data, collected by the SADCs are processed on line in FPGAs by a feature-extraction algorithm. This processing technique guarantees a dead-time free operation and allows including an on-line pile-up recovery process for single detector counting rates up to 1 MHz.The prototype of the readout-chain has been evaluated using pulse generators and high-energy photon beams; the proper event correlation could be verified. The applied FPGA has been irradiated with protons to demonstrate its applicability in the radiation environment of the PANDA experiment.

Advances in nuclear detection and readout techniques

“…Except for the VTRx and the VTRx+, several optical modules used in physics experiments have been developed, such as a 5 Gbps compact parallel optical engine proposed by the Ohio State University [481], a dual-channel VCSEL driver LOCld-130 designed in 130 nm CMOS technology [482], a 20 Gbps PAM4 VCSEL driving ASIC for detector front-end readout [483], a 14 Gbps optical transceiver ASIC (LDLA14) fabricated in a 55 nm CMOS technology for NICA [484], and so on.…”

Technical design report for the $\overline{{\rm{P}}}\mathrm{ANDA}$ Barrel DIRC detector

“…A very important requirement for event building and reconstruction is the synchronization of the clocks of all subdetectors. This is provided by the SODANETframework [91].…”

Online cluster-finding algorithms for the PANDA electromagnetic calorimeter

“…In the simulation, these parameters are set to the values that were determined in the experiment: N = 1.667 and τ decay = 68.7 ns. A time-window, t active , is defined for each waveform from the expected pulse length, which is about 700 ns [82]. The waveforms are then convoluted with other waveforms when their respective time windows overlap, and if they lie within the same detector element, allowing the creation of a pile-up signal.…”