CALETによる⾼エネル
ギーガンマ線観測
森正樹

⽴命館⼤学理⼯学部物理科学科
For the CALET collaboration
⾼エネルギー宇宙物理連絡会研究会

2020/03/02‐03

The CALET collaboration
O. Adriani25, Y. Akaike2, K. Asano7, Y. Asaoka9,31, M.G. Bagliesi29, E. Berti25, G. Bigongiari29, W.R. Binns32, M. Bongi25,P. Brogi29, A. Bruno15, J.H. Buckley32, N. Cannady3, G. Castellini25, C. Checchia26, M.L. Cherry13, G. Collazuol26,
K. Ebisawa8, H. Fuke8, T.G. Guzik13, T. Hams3, K. Hibino10, M. Ichimura4, K. Ioka34, W. Ishizaki7, M.H. Israel32, K. Kasahara31,J. Kataoka31, R. Kataoka17, Y. Katayose33, C. Kato23, Y.Kawakubo13, N. Kawanaka30, K. Kohri 12, H.S. Krawczynski32,
J.F. Krizmanic2, J. Link2, P. Maestro29, P.S. Marrocchesi29, A.M. Messineo27, J.W. Mitchell15, S. Miyake5, A.A. Moiseev3,M. Mori20, N. Mori25, H.M. Motz31, K. Munakata23, H. Murakami31, S. Nakahira9, J. Nishimura8, G.A De Nolfo15,S. Okuno10, J.F. Ormes25, N. Ospina26, S. Ozawa31, L. Pacini25, F. Palma28, V. Pal’shin34, P. Papini25, B.F. Rauch32,
S.B. Ricciarini25, K. Sakai3, T. Sakamoto1, M. Sasaki3, Y. Shimizu10, A. Shiomi18, R. Sparvoli28, P. Spillantini25, F. Stolzi29,
S. Sugita34, J.E. Suh29, A. Sulaj29, I. Takahashi11, M. Takita7, T. Tamura10, T. Terasawa7, S. Torii9,31, Y. Tsunesada19,
Y. Uchihori16, E. Vannuccini25, J.P. Wefel13, K. Yamaoka14, S. Yanagita6, A. Yoshida1, and K. Yoshida22
1) Aoyama Gakuin University, Japan2) CRESST/NASA/GSFC and Universities Space ResearchAssociation, USA
3) CRESST/NASA/GSFC and University of Maryland, USA
4) Hirosaki University, Japan5) Ibaraki National College of Technology, Japan6) Ibaraki University, Japan
7) ICRR, University of Tokyo, Japan
8) ISAS/JAXA Japan
9) JAXA, Japan10) Kanagawa University, Japan11) Kavli IPMU, University of Tokyo, Japan12) KEK, Japan
13) Louisiana State University, USA
14) Nagoya University, Japan
15) NASA/GSFC, USA
16) National Inst. of Radiological Sciences, Japan17) National Institute of Polar Research, Japan18) Nihon University, Japan
19) Osaka City University, Japan
20) Ritsumeikan University, Japan21) Saitama University, Japan
22) Shibaura Institute of Technology, Japan23) Shinshu University, Japan24) University of Denver, USA
25) University of Florence, IFAC (CNR) and INFN, Italy
26) University of Padova and INFN, Italy
27) University of Pisa and INFN, Italy28) University of Rome Tor Vergata and INFN, Italy
29) University of Siena and INFN, Italy30) University of Tokyo, Japan
31) Waseda University, Japan32) Washington University-St. Louis, USA
33) Yokohama National University, Japan34) Kyoto University, Japan2

CALET Payload
Kounotori (HTV) 5

CGBM (CALET
Gamma-ray
Burst Monitor)

FRGF (Flight Releasable
Grapple Fixture)

ASC (AdvancedStellar Compass)

Calorimeter
Launched on Aug. 19th, 2015
by the Japanese H2-B rocket

GPSR (GPSReceiver)

Emplaced on JEM-EF port #9
on Aug. 25th, 2015
(JEM-EF: Japanese Experiment
Module-Exposed Facility)
MDC (MissionData Controller)

JEM/Port #9・ Mass: 612.8 kg∙
JEM Standard Payload Size:
1850mm(L) × 800mm(W) × 1000mm(H)∙ Power Consumption: 507 W（max）∙ Telemetry:
Medium 600 kbps (6.5GB/day) / Low 50 kbps

CALET/CAL Detector
Fully active thick calorimeter (30X0) optimized for electron
spectrum measurements well into TeV region
448mm

Charge Detector

CHD

plastic scintillator hodoscope,absolute charge measurement(including charge zero)

ImagingCalorimeter

IMC

SciFi + tungsten plate (3X0),
reconstruction of arrival direction
and initial shower development

Total Absorption
Calorimeter
1TeV electron shower isfully contained in TASCTASCPWO hodoscope (27X0),
energy measurements and particle
identification

Cannady et al., ApJS 238:5 (2018)

Gamma Ray Event Selection= Electron Selection Cut + Gamma‐ray ID Cut w/ Lower Energy Extension

gamma‐ray

100 GeV Event Examples
electronCharge Z=0

Electromagnetic Shower
well contained, constant shower development

protonCharge Z=1Hadron Shower
larger spread 5

Effective Area and Sensitivity

Cannady et al., ApJS 238:5 (2018)

Effective area is estimated as a function of incident angle (dx/dz, dy/dz) and energy.
Maximum effective area is achieved at around 5 GeV, but lower energy is more
important for steep spectrum like E‐2.
LE‐ trigger: > 1 GeV
dy/dz

3‐10GeV average

HE trigger: > 10 GeV
CC Trackdx/dz

Mostly axially symmetric except
for FOV cut

Effective area as a function of energy. Four
representing zenith angle ranges are shown.

* LE‐ mode is activated when the geomagnetic latitude is below 20 and following
a CALET Gamma‐ray Burst Monitor (CGBM) burst trigger

6

Cannady et al., ApJS 238:5 (2018)

Point spread function (PSF)

Np：number of track
points used forreconstruction●Np=3 ●Np=4 ●Np=5●Np=6 ●Np=7―core―tail―core + tail7

Gamma‐ray candidates in CALET FOV
LE Trigger
60o
45o

Gamma‐ray candidates
in CALET FOV8Gamma‐ray candidates in CALET FOV
LE Trigger

JEM
60o
45o

CAL

Gamma‐ray candidates
in CALET FOV

TrussFish‐eye view of CALET FOV
9Mori, Asaoka et al., ICRC2019

Gamma‐ray skymap

LE‐ mode, from 2015 November to 2018 May(Contours show relative exposures)

Mori, Asaoka et al., ICRC2019

Gamma‐ray spectra

LE‐ mode
from 2015 November to 2018 May“On‐plane”: |l| < 80 & |b|< 8Cannady et al., ApJS 238:5 (2018)

Point Source Spectra: Sensitivity Validation
CALET Preliminary

The observed point source spectra are well consistent with
Fermi‐LAT’s parameterizations. Therefore, it was found thatcurrent selection criteria has a validated sensitivity.
12

CTA 102 (AGN) light curve

Preliminary

Flux [cm‐2s‐1]

LE trig (> 1 GeV)(2016/1/13

2016/7/31

2017/2/16

2017/9/4

2018/3/23

Red: CALET signal, Hatched: CALET upper limit (<10‐7cm‐2s‐1)
Blue: Fermi‐LAT

2018/10/9

2019/4/27)

Modified Julian Day
13

April 30, 2020

LIGO‐VIRGO observation 314

Mori, Asaoka et al., ICRC2019

Energy flux limit map for S190408an

10‐690% C.L. upper limit on S190408an energy flux in the energy region 1–10 GeV and time
window [T0‐60s, T0+60 s] shown in the equatorial coordinates. The thick cyan line shows
the locus of the FOV center of CAL, and the plus symbol is that at T0. Also shown by green
contours is the localization significance map of S190408an reported by LIGO/Virgo.

Mori, Asaoka et al., ICRC2019

CAL limits on electromagnetic emission(LIGO/Virgo O3)
from gravitational wave events
New!

†: LE‐Extended to 12‐SEP‐2019

CAL limits on electromagnetic emission(LIGO/Virgo O3)
from gravitational wave events†: LE‐Summary• CALET cosmic ray detector onboard the ISS has been monitoringcosmic gamma‐rays above 1 GeV since 2015 October.
• We have developed cuts to reduce secondary gamma‐ray
background produced in the various ISS structures, which
increase our event statistics significantly.
• Quality of gamma‐ray data has been checked by skymaps,
galactic plane spectra, and point sources.
• Searches for electromagnetic counterparts of gravitational events
upon triggers supplied by LIGO/Virgo interferometers during
their third observing run yielded upper limits on gamma‐rayemission.
• We continue observation at least until 2021, hoping for a furtherextension.