1. CALET-CALによる ガンマ線観測初期解析
早大理工研，早大先進理工A，CRESST/USRA/GSFCB, 神奈川大工C，JAXAD,青学大理工E, 名大ISEEF
浅岡陽一，鳥居祥二，小澤俊介A ，山口優幸A, 赤池陽水B，清水雄輝C ，田村忠久C ， 中平聡志D, 吉田篤正E, 坂本貴紀E, 川久保雄太E, 山岡和貴F, 他CALETチーム
2017/3/18 春の物理学会 @ 大阪大学
18aK21-1

2. CALET System Overview (CAL) (*) JEM stands for Japan Experiment Module
x-ray to soft-gamma-ray transient
(*) JEM stands for Japan Experiment Module

3. 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)
Imaging Calorimeter
IMC
SciFi + tungsten plate (3X0),
reconstruction of arrival direction and initial shower development
Total Absorption Calorimeter
TASC
PWO hodoscope (27X0),
energy measurements and particle identification
1TeV electron shower is fully contained in TASC

4. CALET-CAL Shower Imaging Capability (MC)
gamma
electron
pion
we can use the shower shape difference to separate electrons and protons and proton rejection factor of ...
gamma-rays can be identified by requiring zero charge at incidence.
Proton rejection power of 105 can be achieved by taking advantage of shower imaging capability of IMC and TASC
Angular resolution of ~0.2o for 10GeV gamma rays

5. CALET Scientific Objectives
While CALET is optimized for observation of TeV electrons, the instrument is sensitive to gamma-rays, protons and nuclei.
Science Objectives
Observation Targets
Nearby Cosmic-ray Sources
Electron spectrum in trans-TeV region
Dark Matter
Signatures in electron/gamma energy spectra
Origin and Acceleration of Cosmic Rays
p-Fe over several tens of GeV, Ultra-heavy ions
Cosmic-ray Propagation in the Galaxy
B/C ratio up to several TeV/nucleon,
Diffuse gamma-ray observation up to TeV
Solar Physics
Electron flux below 10 GeV
Gamma-ray Transients
X-rays/Gamma-rays in 7 keV－20MeV in CGBM and GeV gamma-rays in CAL

6. Overview of CALET Trigger System

7. ISS Orbit and CALET Operations

8. Accumulation of Observational Live Time
HE Trigger
LE Gamma-Ray Trigger
1.42e6/7.44e6 = 19%
Live time fraction of 85% achieved
Now more than hours!
From 2016/08, 19% of total live time is covered by LE gamma-ray trigger

9. Objectives of CALET Gamma-Ray Observation
Diffuse Component => High energy region
Galactic
Extragalactic
Point Source
Calibration of pointing accuracy
Confirmation of angular resolution
Cross check of energy measurements/efficiency
Transient Object
GRB
Gravitational wave
Other transients

10. Objectives of CALET Gamma-Ray Observation
Diffuse Component => High energy region
Galactic
Extragalactic
Point Source
Calibration of pointing accuracy
Confirmation of angular resolution
Cross check of energy measurements/efficiency
Transient Object
GRB
Gravitational wave
Other transients
Statistics is the KEY
We will focus on this topic by utilizing 10,000 hours of flight data

11. Gamma Ray Event Selection
= Electron Selection Cut + Gamma-ray ID Cut w/ Lower Energy Extension
100 GeV Event Examples
gamma-ray
electron
proton
Charge Z=0
Charge Z=1
Electromagnetic Shower
Hadron Shower
well contained, constant shower development
larger spread

12. Gamma Ray Event Selection
= Electron Selection Cut + Gamma-ray ID Cut w/ Lower Energy Extension
100 GeV Event Examples
gamma-ray
electron
proton
Charge Z=0
Charge Z=1
E<10GeV: Maximum Energy Deposit in CHD
Reconstructed Energy [GeV]
CHD Maximum Energy Deposit [MIP]
MC: Gamma-Ray
MC: Proton
Electromagnetic Shower
Hadron Shower
well contained, constant shower development
larger spread

13. Gamma Ray Event Selection
= Electron Selection Cut + Gamma-ray ID Cut w/ Lower Energy Extension
100 GeV Event Examples
gamma-ray
electron
proton
Charge Z=0
Charge Z=1
E>10GeV: Maximum Energy Deposit in CHD and IMC associated w/ Track
MC: Gamma-Ray
MC: Proton
well contained, constant shower development
larger spread

14. Sensitivity Improvements
Larger acceptance
requires CHD and TASC-X1
to avoid too much energy leakage, 2cm margin is required at TASC-X1
Accurate energy reconstruction
geometry conditions are sub-divided in terms of leaking energy
energy correction factor is estimated in each sub-divided geometry condition.

15. LE Trigger (w/ Enlarged Acceptance)
PRELIMINARY

16. FOV cut
FOV cut is very important to avoid secondary gamma-rays especially in LE region
LE Trigger
blue circles: 45 deg and 60deg.
by JAXA

17. LE Trigger (w/ FOV cut) PRELIMINARY Crab Geminga CTA102 (transient)
Vela
Exposure is limited to low latitude region => |declination| > 60 is hardly seen.

18. LE Trigger (October 2016) PRELIMINARY Geminga CTA102 (transient)
Exposure is limited to low latitude region => |declination| > 60 is hardly seen.

19. LE Trigger (November 2016) PRELIMINARY Geminga CTA102 (transient)
Exposure is limited to low latitude region => |declination| > 60 is hardly seen.

20. LE Trigger (December 2016)
PRELIMINARY
Geminga
CTA102 (transient)

21. LE Trigger (January 2017)
PRELIMINARY
Geminga
CTA102 (transient)

22. LE Trigger (in Galactic Coordinate)
PRELIMINARY

23. comparison with fermi
TO BE REVISED

24. comparison with diffuse model
TO BE REVISED

25. comparison with fermi
TO BE REVISED

26. comparison with diffuse model
TO BE REVISED

27. HE Trigger in Galactic Coordinates
PRELIMINARY
VELA
Vela and Crab are identified.

28. comparison with fermi

29. comparison with diffuse model

30. finer binning

31. comparison with fermi

32. comparison with diffuse model

33. Summary & Prospects
Using the full set of CALET data from Oct to Feb. 2017, gamma-ray analysis was performed and gamma-ray sky was obtained in LE and HE trigger mode.
Geminga, Crab, Vela, and AGN flare (CTA-102) are clearly identified.
Sensitivity was confirmed to be consistent with diffuse expectation.
Significant sensitivity improvements in lower and higher energy region is expected
tracking in LE
gamma-ray identification in HE
Automated pipeline to search for gamma-ray transient was also developed and is being implemented.

34. backup

35. Objectives of CALET Gamma-Ray Observation
Diffuse Component => High energy region
Galactic
Extragalactic
Point Source
Calibration of pointing accuracy
Confirmation of angular resolution
Cross check of energy measurements/efficiency
Transient Object
GRB
Gravitational wave
Other transients

36. 探索感度

37. GRB Simulation
データはできている
Quaternion の扱いに問題
フラックスと検出できたことを示す

38. CGBMトリガーによる他観測と同期したGRB観測(19回)
MDCTime Date GRB
2015/11/07 20:24:54.771
GRB151107B
2015/12/10 00:59:20.485
GRB151210B
2015/12/12 01:32:04.734
GRB151212B
2015/12/25 19:09:10.34
GRB151225A
2015/12/27 05:13:48.86
GRB151227B
2015/12/31 10:37:53.15
GRB151231A
2016/01/01 00:43:54.044
GRB160101A
2016/01/06 22:45:34.70
GRB160106A
2016/01/07 22:20:43.20
GRB160107A
2016/01/18 01:25:56.902
GRB160118A
2016/02/23 09:58:59.51
GRB160223B
2016/03/16 13:45:16.79
GRB160316A
2016/03/24 15:58:37.99
GRB160324A
2016/04/08 06:25:37.40
GRB160408A
2016/04/19 15:16:35.41
GRB160419A
2016/04/22 11:59:08.28
GRB160422A
2016/05/08 14:32:31.73
GRB160508A
2016/05/09 08:58:51.21
GRB160509A
2016/05/25 10:54:20.251
GRB160525C

39. 内容(案) CALET Observation Summary GRB counterpart search
Statistics
Operation Mode HE
LE gamma ray
Calibration
GRB counterpart search
感度評価 w/ GRB simulation (田中)
探索結果
(semi) Real Time Search System (山口)
Improvement
CC Track => diffuse (佐藤)

40. CGBMトリガーによる他観測と同期したGRB観測(19回)
MDCTime Date GRB
2015/11/07 20:24:54.771
GRB151107B
2015/12/10 00:59:20.485
GRB151210B
2015/12/12 01:32:04.734
GRB151212B
2015/12/25 19:09:10.34
GRB151225A
2015/12/27 05:13:48.86
GRB151227B
2015/12/31 10:37:53.15
GRB151231A
2016/01/01 00:43:54.044
GRB160101A
2016/01/06 22:45:34.70
GRB160106A
2016/01/07 22:20:43.20
GRB160107A
2016/01/18 01:25:56.902
GRB160118A
2016/02/23 09:58:59.51
GRB160223B
2016/03/16 13:45:16.79
GRB160316A
2016/03/24 15:58:37.99
GRB160324A
2016/04/08 06:25:37.40
GRB160408A
2016/04/19 15:16:35.41
GRB160419A
2016/04/22 11:59:08.28
GRB160422A
2016/05/08 14:32:31.73
GRB160508A
2016/05/09 08:58:51.21
GRB160509A
2016/05/25 10:54:20.251
GRB160525C

41. HE Trigger Events

42. HE Trigger Events

43. HE Trigger Events

44. E>30GeV

45. E>30GeV

46. E>30GeV

47. E>30GeV

52. CALET Gamma Rays Candidates w/ HE Trigger