A. Albert

Dark Matter Limits from Dwarf Spheroidal Galaxies with the HAWC Gamma-Ray Observatory

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field of view observatory sensitive to 500 GeV - 100 TeV gamma rays and cosmic rays. It can also perform diverse indirect searches for dark matter (DM) annihilation and decay. Among the most promising targets for the indirect detection of dark matter are dwarf spheroidal galaxies. These objects are expected to have few astrophysical sources of gamma rays but high dark matter content, making them ideal candidates for an indirect dark matter detection with gamma rays. Here we present individual limits on the annihilation cross section and decay lifetime for 15 dwarf spheroidal galaxies within the HAWC field-of-view, as well as their combined limit. These are the first limits on the annihilation cross section and decay lifetime using data collected with HAWC.

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

Abstract TARGETxa05 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. TARGETxa05 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. TARGETxa05 improves over the performance of the first-generation TARGET ASIC, achieving: tunable sampling frequency from 1xa0GSa/s; a dynamic range on the data path of 1.2xa0V with effective dynamic range of 11xa0bits and DC noise of ∼0.6xa0mV; 3-dB bandwidth of 500xa0MHz; crosstalk between adjacent channels 100xa0p.e. (assuming 4xa0mV per p.e.); and minimum stable trigger threshold of 20xa0mV (5 p.e.) with trigger noise of 5xa0mV (1.2 p.e.), which is mostly limited by interference between trigger and sampling operations. TARGETxa05 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).