Title: Half ALPACA and its sensitivity to sub-PeV gamma rays from the
Galactic Center
Presenter: Yoshichika Yokoe
oral/poster: oral
Abstract:
ALPACA is a project aimed at the wide field-of-view observation of
cosmic rays and gamma
rays with an 83,000 m^2 air shower array composed of approximately 400
surface scintillation counters
and a large underground muon detector array,
at an altitude of 4,740m near
the Chacaltaya mountain in Bolivia. After a prototype air-shower array
currently under construction, we plan to expand the array to ‘half
ALPACA’, which covers an area of 83,000 m^2 with roughly 200 surface
scintillation counters. Also,
we will　construct an underground muon
detector array with an area of 4,000 m^2 that allows us to dramatically
improve the sensitivity to gamma rays by discriminating gamma rays from
cosmic rays based on the number of muons　in air showers.
One of our main interests is the detection of gamma rays beyond 100
TeV
from　the Galactic center.　In 2016, H.E.S.S observed the diffuse
gamma-rays around the Galactic　center. This data suggests that a
cosmic-ray accelerator exists around it.
In this presentation, we report on the performance of half ALPACA,　
especially its sensitivity to sub-PeV gamma rays from the Galactic
center, based on our detailed MC simulations.