Speaker
Description
MeV gamma-ray astronomy remains relatively underexplored, despite
extensive worldwide efforts to investigate this crucial energy range.
To address this challenge, we have demonstrated the high-performance
capabilities of an electron-tracking Compton camera (ETCC) during the
Sub-MeV/MeV gamma-ray Imaging Loaded-on-balloon Experiment (SMILE)
missions. The ETCC employs a gaseous time-projection chamber (TPC) as
the primary scatterer, surrounded by pixelated scintillator arrays
(PSAs) that function as absorbers. The gas TPC measures the momentum
vector of the recoil electron, while the PSAs simultaneously determine
the energy of the scattered gamma ray. This capability enables a
bijective reconstruction of both the direction and energy of the
incident gamma ray, which enhances the sensitivity compared to
classical Compton reconstruction that constrain the incident direction
only by a circular region. The SMILE-2+ experiment, which consisted of
a 26-hour balloon flight over Australia, successfully detected the
Crab Nebula and Galactic diffuse emissions around the Galactic Center
at a significance level exceeding 4\sigma. Following this achievement, we
have initiated the successor project, SMILE-3, to enable a more
detailed investigation of diffuse emissions. The detector design has
been upgraded to achieve a larger effective area and a wider dynamic
range, thereby increasing photon collection power. The first flight for
SMILE-3 is currently planned for early 2027. In this paper, we present
an overview of the SMILE-3 experiment and report the current status of
our R&D efforts.
| Collaboration(s) | SMILE-3 |
|---|
