TARGET: A Digitizing And Trigger ASIC For The Cherenkov Telescope Array

The future ground-based gamma-ray observatory Cherenkov Telescope Array (CTA) will feature multiple types of imaging atmospheric Cherenkov telescopes, each with thousands of pixels. To be affordable, camera concepts for these telescopes have to feature low cost per channel and at the same time meet the requirements for CTA in order to achieve the desired scientific goals. We present the concept of the TeV Array Readout Electronics with GSa/s sampling and Event Trigger (TARGET) Application Specific Circuit (ASIC), envisaged to be used in the cameras of various CTA telescopes, e.g. the Gamma-ray Cherenkov Telescope (GCT), a proposed 2-Mirror Small-Sized Telescope, and the Schwarzschild-Couder Telescope (SCT), a proposed Medium-Sized Telescope. In the latest version of this readout concept the sampling and trigger parts are split into dedicated ASICs, TARGET C and T5TEA, both providing 16 parallel input channels. TARGET C features a tunable sampling rate (usually 1 GSa/s), a 16k sample deep buffer for each channel and on-demand digitization and transmission of waveforms with typical spans of ~100 ns. The trigger ASIC, T5TEA, provides 4 low voltage differential signal (LVDS) trigger outputs and can generate a pedestal voltage independently for each channel. Trigger signals are generated by T5TEA based on the analog sum of the input in four independent groups of four adjacent channels and compared to a threshold set by the user. Thus, T5TEA generates four LVDS trigger outputs, as well as 16 pedestal voltages fed to TARGET C independently for each channel. We show preliminary results of the characterization and testing of TARGET C and T5TEA.Comment: 6 pages, 8 figures, Proceedings of the 6th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2016

Oil spills and sea turtles: Documented effects and considerations for response and assessment efforts

Hydrocarbon (i.e. oil) extraction, transport, consumption, and pollution occur daily in marine environments, threatening vulnerable natural resources, habitats, and biodiversity. However, threats of episodic oil spills to imperiled marine species are not as well-studied as more acute, readily apparent threats such as incidental capture in fisheries and habitat degradation. We performed a global review of spill incident databases to evaluate reported effects of oil spills on sea turtles, which are flagship species of the world’s oceans. Our goals were to (1) summarize available information about oil spills and their effects on sea turtles; (2) identify major knowledge gaps; and (3) provide recommendations related to oil spills and sea turtles for managers, researchers, and conservation groups around the world. Over 2000 oil spill incidents of variable magnitude (range: ~20 to >1 million barrels) have occurred worldwide in the past 60 yr in areas where sea turtles are found, but resulting effects on sea turtles have been reported in less than 2% of those incidents. Further, evidence indicates that most effects are related to heavy external oiling, while chemical effects of oil exposure have not been well defined. We recommend that, where available, resources be prioritized to document co-occurrence of turtles and oil, the degree and nature of oil exposure, and mortality and reproductive losses to individual sea turtles and their populations caused by spills and spill response activities. These data will best inform assessments of the extent and magnitude of adverse effects of oil spills on sea turtles

TARGET 5: A new multi-channel digitizer with triggering capabilities for gamma-ray atmospheric Cherenkov telescopes

TARGET 5 is a new application-specific integrated circuit (ASIC) of the TARGET family, designed for the readout of signals from photosensors in the cameras of imaging atmospheric Cherenkov telescopes (IACTs) for ground-based gamma-ray astronomy. TARGET 5 combines sampling and digitization on 16 signal channels with the formation of trigger signals based on the analog sum of groups of four channels. We describe the ASIC architecture and performance. TARGET 5 improves over the performance of the first-generation TARGET ASIC, achieving: tunable sampling frequency from 1 GSa/s; a dynamic range on the data path of 1.2 V with effective dynamic range of 11 bits and DC noise of similar to 0.6 mV; 3-dB bandwidth of 500 MHz; crosstalk between adjacent channels 100 p.e. (assuming 4 mV per p.e.); and minimum stable trigger threshold of 20 mV (5 p.e.) with trigger noise of 5 mV (1.2 p.e.), which is mostly limited by interference between trigger and sampling operations. TARGET 5 is the first ASIC of the TARGET family used in an IACT prototype, providing one development path for readout electronics in the forthcoming Cherenkov Telescope Array (CTA). (C) 2017 Elsevier B.V. All rights reserved