The Event Detection System in the NEXT-White Detector

This article describes the event detection system of the NEXT-White detector, a 5 kg high pressure xenon TPC with electroluminescent amplification, located in the Laboratorio Subterráneo de Canfranc (LSC), Spain. The detector is based on a plane of photomultipliers (PMTs) for energy measurements and a silicon photomultiplier (SiPM) tracking plane for offline topological event filtering. The event detection system, based on the SRS-ATCA data acquisition system developed in the framework of the CERN RD51 collaboration, has been designed to detect multiple events based on online PMT signal energy measurements and a coincidence-detection algorithm. Implemented on FPGA, the system has been successfully running and evolving during NEXT-White operation. The event detection system brings some relevant and new functionalities in the field. A distributed double event processor has been implemented to detect simultaneously two different types of events thus allowing simultaneous calibration and physics runs. This special feature provides constant monitoring of the detector conditions, being especially relevant to the lifetime and geometrical map computations which are needed to correct high-energy physics events. Other features, like primary scintillation event rejection, or a double buffer associated with the type of event being searched, help reduce the unnecessary data throughput thus minimizing dead time and improving trigger efficiency.

Performance of the missing transverse momentum triggers for the ATLAS detector during Run-2 data taking

The factor of four increase in the LHC luminosity, from 0.5 × 1034 cm−2s−1 to 2.0 × 1034cm−2s−1, and the corresponding increase in pile-up collisions during the 2015–2018 data-taking period, presented a challenge for the ATLAS trigger, particularly for those algorithms that select events with missing transverse momentum. The output data rate at fixed threshold typically increases exponentially with the number of pile-up collisions, so the legacy algorithms from previous LHC data-taking periods had to be tuned and new approaches developed to maintain the high trigger efficiency achieved in earlier operations. A study of the trigger performance and comparisons with simulations show that these changes resulted in event selection efficiencies of > 98% for this period, meeting and in some cases exceeding the performance of similar triggers in earlier run periods, while at the same time keeping the necessary bandwidth within acceptable limits.

Radio Phased Arrays for the Detection of Ultra-High Energy Neutrinos

Ground-based radio arrays offer a promising future for the measurement of ultra-high energy neutrinos, including the prospect of reducing the radio-detection energy threshold to a level necessary to overlap with the high-energy range probed by IceCube (~1016 eV). Here we describe a phased array of antennas and beamforming electronics, which serves as a highly sensitive and directional trigger system for nanosecond-scale plane wave impulses. A prototype in-ice phased array was successfully installed during the 2017/18 austral summer at the South Pole in collaboration with the Askaryan Radio Array (ARA). The trigger array is a compact string of 7 in-ice dipole antennas deployed at a depth of 200 m, whose signals are continuously digitized at the surface using 1.5 GSa/s ADCs with 7-bit resolution. We measure a 50% trigger efficiency on band-limited impulses with signal-to-noise ratios of 2.0 or smaller.