Trigger and readout system for the Ashra-1 detector

Ashra-1 Collaboration

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Highly sophisticated trigger and readout system has been developed for All-sky Survey High Resolution Air-shower (Ashra) detector. Ashra-1 detector has 42 degree diameter field of view. Detection of Cherenkov and fluorescence light from large background in the large field of view requires finely segmented and high speed trigger and readout system. The system is composed of optical fiber image transmission system, 64x64 channel trigger sensor and FPGA based trigger logic processor. The system typically processes the image within 10 to 30 ns and opens the shutter on the fine CMOS sensor. 64x64 coarse split image is transferred via 64x64 precisely aligned optical fiber bundle to a photon sensor. Current signals from the photon sensor are discriminated by custom made trigger amplifiers. FPGA based processor processes 64x64 hit pattern and correspondent partial area of the fine image is acquired. Commissioning earth skimming tau neutrino observational search was carried out with this trigger system. Addition to the geometrical advantage of the Ashra observational site, the excellent tau shower axis measurement based on the fine imaging and the night sky background rejection based on the fine and fast imaging allow zero background tau shower search. Adoption of the optical fiber bundle and trigger LSI realized 4k channel trigger system cheaply. Detectability of tau shower is also confirmed by simultaneously observed Cherenkov air shower. Reduction of the trigger threshold is appeared to enhance the effective area especially in PeV tau neutrino energy region. New two dimensional trigger LSI was introduced and the trigger threshold was lowered. New calibration system of the trigger system was recently developed and introduced to the Ashra detector.

Original languageEnglish
Title of host publicationProceedings of the 33rd International Cosmic Rays Conference, ICRC 2013
PublisherSociedade Brasileira de Fisica
ISBN (Electronic)9788589064293
Publication statusPublished - 2013
Externally publishedYes
Event33rd International Cosmic Rays Conference, ICRC 2013 - Rio de Janeiro, Brazil
Duration: 2013 Jul 22013 Jul 9

Publication series

NameProceedings of the 33rd International Cosmic Rays Conference, ICRC 2013


Other33rd International Cosmic Rays Conference, ICRC 2013
CityRio de Janeiro


  • High energy neutrino

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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