TY - GEN
T1 - MeV gamma-ray observation with a well-defined point spread function based on electron tracking
AU - Takada, A.
AU - Tanimori, T.
AU - Kubo, H.
AU - Mizumoto, T.
AU - Mizumura, Y.
AU - Komura, S.
AU - Kishimoto, T.
AU - Takemura, T.
AU - Yoshikawa, K.
AU - Nakamasu, Y.
AU - Matsuoka, Y.
AU - Oda, M.
AU - Miyamoto, S.
AU - Sonoda, S.
AU - Tomono, D.
AU - Miuchi, K.
AU - Kurosawa, S.
AU - Sawano, T.
N1 - Funding Information:
This study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (Grant numbers 21224005, 20244026, 23654067, 25610042, 15K17608, 16K13785, 16H02185), a Grant-in-Aid from the Global COE program "Next Generation Physics, Spun from Universality and Emergence" from the MEXT of Japan.
Publisher Copyright:
© 2016 SPIE.
PY - 2016
Y1 - 2016
N2 - The field of MeV gamma-ray astronomy has not opened up until recently owing to imaging difficulties. Compton telescopes and coded-aperture imaging cameras are used as conventional MeV gamma-ray telescopes; however their observations are obstructed by huge background, leading to uncertainty of the point spread function (PSF). Conventional MeV gamma-ray telescopes imaging utilize optimizing algorithms such as the ML-EM method, making it difficult to define the correct PSF, which is the uncertainty of a gamma-ray image on the celestial sphere. Recently, we have defined and evaluated the PSF of an electron-tracking Compton camera (ETCC) and a conventional Compton telescope, and thereby obtained an important result: The PSF strongly depends on the precision of the recoil direction of electron (scatter plane deviation, SPD) and is not equal to the angular resolution measure (ARM). Now, we are constructing a 30 cm-cubic ETCC for a second balloon experiment, Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment: SMILE-II. The current ETCC has an effective area of ∼1 cm2 at 300 keV, a PSF of ∼10° at FWHM for 662 keV, and a large field of view of ∼3 sr. We will upgrade this ETCC to have an effective area of several cm2 and a PSF of ∼5° using a CF4-based gas. Using the upgraded ETCC, our observation plan for SMILE-II is to map of the electron-positron annihilation line and the 1.8 MeV line from 26Al. In this paper, we will report on the current performance of the ETCC and on our observation plan.
AB - The field of MeV gamma-ray astronomy has not opened up until recently owing to imaging difficulties. Compton telescopes and coded-aperture imaging cameras are used as conventional MeV gamma-ray telescopes; however their observations are obstructed by huge background, leading to uncertainty of the point spread function (PSF). Conventional MeV gamma-ray telescopes imaging utilize optimizing algorithms such as the ML-EM method, making it difficult to define the correct PSF, which is the uncertainty of a gamma-ray image on the celestial sphere. Recently, we have defined and evaluated the PSF of an electron-tracking Compton camera (ETCC) and a conventional Compton telescope, and thereby obtained an important result: The PSF strongly depends on the precision of the recoil direction of electron (scatter plane deviation, SPD) and is not equal to the angular resolution measure (ARM). Now, we are constructing a 30 cm-cubic ETCC for a second balloon experiment, Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment: SMILE-II. The current ETCC has an effective area of ∼1 cm2 at 300 keV, a PSF of ∼10° at FWHM for 662 keV, and a large field of view of ∼3 sr. We will upgrade this ETCC to have an effective area of several cm2 and a PSF of ∼5° using a CF4-based gas. Using the upgraded ETCC, our observation plan for SMILE-II is to map of the electron-positron annihilation line and the 1.8 MeV line from 26Al. In this paper, we will report on the current performance of the ETCC and on our observation plan.
KW - balloon experiment
KW - Compton telescope
KW - MeV gamma-ray astronomy
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U2 - 10.1117/12.2232171
DO - 10.1117/12.2232171
M3 - Conference contribution
AN - SCOPUS:85003726527
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Space Telescopes and Instrumentation 2016
A2 - Bautz, Marshall
A2 - Takahashi, Tadayuki
A2 - den Herder, Jan-Willem A.
PB - SPIE
T2 - Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Y2 - 26 June 2016 through 1 July 2016
ER -