High-Energy Radiation Phenomena from
Winter Thunderstorms and Lightning In Japan
Enoto et al., Nature 551, 481 (2017); Wada et al., GRL 45, 11 (2018)
Teruaki Enoto1, Yuuki Wada2, Yoshihiro Furuta3, Kazuhiro Nakazawa4, Takayuki Yuasa2, Kazuo
Makishima2, Mitsuteru Sato5, Yousuke Sato4, Daigo Umemoto2, Harufumi Tsuchiya3, Gregory S
Bowers6, Masashi Kamogawa7, Yoshitaka Nakamura8, Takeshi Morimoto9 and David Smith6(1) Kyoto University, (2) RIKEN, (3) JAEA, (4) Nagoya University, (5) Hokkaido University, (6) Univ of CaliforniaSanta Cruz, (7) Tokyo Gakugei Univ, (8) Kobe City College of Tech., (9) Kinki University,

Photo at Fukui, Japan by Otowa Electric Co., Ltd. / Masako Tanaka
17:00-17:15, 11 December, 2018@American Geophysical Union (AGU) fall meeting, Energetic radiation from lightning and thunderstorm I (Room 201)

Winter thunderstorm and lightning in Japan

low altitude (<1 km), powerful lightning, frequent positive discharge
Ideal for observing the high-energy atmospheric phenomena

Siberian
airmass

2017/2/6 15:00 JST
Himawari-8 / NICT
http://himawari8.nict.go.jp

WindA winter lightningdischarge in Japan(Fukui, Nov. 20, 2005)

Japanisland(C) Toshio Yoshioka andOtowa Electric Co., Ltd.

−GROWTH (Gamma-Ray Observationof Winter Thundercloud) project started
high-energy observations in 2006
(Tsuchiya, Enoto et al. 2007), and extended tomulti-point campaigns since 2015.

+++−+

Japan Sea
Siberia

Japan islandSupported by academic crowdfunding
学術系クラウドファンディングサイト academist (アカデミスト)

Original Return (Reward)
designed by Adachi design Lab.

Mug
Original T-shirt

日本海沿岸に住んでいたことがあり、冬季の雷を思い出しました。とても興味深い研究だと思います、応援しています。
Acknowledgement & USB

お二人のプロジェクトを見て、久しぶりにとてもわくわく
At the initial phase of our project, citizen supporters financially helped us through the academic
しました！今はささやかな資金貢献しか出来ませんが、私
crowdfunding. The donation gathered during the two month was ~$16k from 153 contributors. Thishas been used for prototype manufactures and preparing for power-plugs on the high school roofs.
もいつか、自分の専門分野を通じて科学技術に貢献できるよう仕事頑張ろうと思いました。がんばってください！！
Thank you for your support : )Since 2015, our project has been supported by the crowd funding “academist”, Grants-in-Aid for Young Scientists (A) Kakenhi
16H06006, the SPIRITS program of Kyoto University, and the joint research program of the ICRR, University of Tokyo.

Radiation detectors for mapping observations

A new stand-alone, low cost, and high-performance data acquisition (DAQ)
Boardsystem was developed; e.g., FPGA board of 4 channel 50 MHz, 12 bit ADC
data acquisitiondADC board

DC 4
ht and detection timeth FPGAquisition withRaspberry Pill-sized linux)
ion
possible
95 mm
95 mm
W
95,000JPY (~$1k)(Shimafuji Elec.)
Yuasa & Shimafuji Elec.

• Gamma-rays detected with BGO scintillators• Recorded with energy and GPS time tag• Waveform recording function is prepared• Environmental sensors (temperature, pressure, etc)
• Mobile data transfer & remote control• Compatible with CubeSats, and aiming at
distributing to citizen scientists

Front-endBoard
BGO scintillator

web camera(25x8x2.5 cm3)

PMT
DAQelectronics

cm20 cm

ADC board

45c
35m

Raspberry Pi

DAQ

water proof box(Detector FY2016)

Wada, Master thesis of the University of Tokyo, “Construction of the multi-point observation network for thundercloud gamma-rays”(ref) FPGA/ADC board specification http://ytkyk.info/blog/2016/09/04/growth-fpga-adc-board/ (C) T. Yuasa
MIS18-05

Radiation detectors for mapping observations

Board

data acquisition

Cost >$20 k

Cost ~$4 kEnoto

WadadDC 4ht and detection timeth FPGAquisition withll-sized linux)
ion possible
W
2006 December
Yuasa & Shimafuji Elec.

2016 October

Front-end
Board
BGO scintillator

web camera(25x8x2.5 cm3)

PMT
DAQelectronics

cm

20 cm

ADC board

45c35mRaspberry Pi

DAQ

water proof box(Detector FY2016)

Wada, Master thesis of the University of Tokyo, “Construction of the multi-point observation network for thundercloud gamma-rays”(ref) FPGA/ADC board specification http://ytkyk.info/blog/2016/09/04/growth-fpga-adc-board/ (C) T. Yuasa
MIS18-05

GROWTH collaboration observation sites
Multi-point observation of high-energy phenomena compared with moving
thunderstorms and radio measurements of lightning discharge processes.
20SuzuKomatsuToyamaMt. Norikura

Observed events

Kanazawa

Kashiwazaki

Short bursts (downward TGF)
Long bursts (gamma-ray glow)

15
105Mt. Fuji
Winter site
Summer site02006200820102012Year2014• 2006-2014: Only the Kashiwazaki site with 1-2 detectors• 2015-: Starting mapping observation campaigns increased detections• Developed at local high schools, universities, and private companies

2016Two types of high-energy radiation eventsLong burst

Short burst

gamma-ray glow

photonuclear reaction
100 msec

Lightning

1 minute• Bremsstrahlung gamma rays fromhigh-energy electrons accelerated
by electric fields in thunderstorms• 41 events since 2005 in total(13 events per year in 2017).

• Photonuclear reactions triggeredby downwad terrestrial gammaray flashes associated lighting.
• 14 events since 2005 in total(5 events per year in 2017).

See details: Wada, TE et al. arXiv:1811.06212

Detector B

Long burst (gamma-ray glow)
December 8, 2016, Komatsu city

Detector A

Detector B

Detector A

Detector B

See details: Wada, TE et al. arXiv:1811.06212

Detector B

Long burst (gamma-ray glow)
December 8, 2016, Komatsu city

tor B

Detector A

Detector B

Detector A

Detector B

See details: Wada, TE et al. arXiv:1811.06212

Detector B

Long burst (gamma-ray glow)
December 8, 2016, Komatsu city

Detector A

Detector B

Detector A

Detector B

See details: Wada, TE et al. arXiv:1811.06212

ctor B

Detector B

Long burst (gamma-ray glow)
December 8, 2016, Komatsu city

Detector A

Detector B

Detector A

Detector B

See details: Wada, TE et al. arXiv:1811.06212

Longburst at Science Hills Komatsu

・Extract Subtracted spectrum from Source (150 sec) andBackground (30 min in total).
・Fit response-resolved
December
8, 2016, Komatsu spectrum.
city40K

102~15000 photons detected(0.8-14.0 MeV)208Tl

1010

Count s-1 MeV-1

Counts s-1 MeV-1

3

1

1010-1−1

10−2

1010-3−3Source
Background
Subtracted
112 Energy (MeV) 5
Energy (MeV)

11Flux = 0.65 ± 0.05 cm-2 s-1(0.04-10 MeV)

1010-1−1

Photons cm-2 s-1 MeV-1

10103

Photons cm-2 s-1 MeV-1

Long burst (gamma-ray glow)

1010-2−2

Gamma-ray spectrum(background-subtracted,detectors response corrected)

1010-3 One
luminous
eventsF(E)=E-Γofexp(-E/Ecut)−3Total detected photon ~3,400 counts

cutinGROWTHExperiment.
Fx=0.65 cm-2 s-1 (0.04-10MeV)

Γ=0.31, E =3.6 MeV,

1010-4−41010112 Energy (MeV) 5
Energy (MeV)

1010We detecteda longburst
event
at ScienceHills Komatsu
gamma-raydetections
as a dense
cloud passed
above two
• Prolonged
detectors.
Theof
delay
is consistent
with a speedof the moving
consisting
gamma-raycontinuum
exceeding
10cloud.
MeV.

Originating
bremsstrahlungof accelerated
electrons.
gamma-rayspectrumextends above
20 MeV.
• Cutoff power-law
22 May 2017
JpGU+AGU Joint Meeting 2017 大気電気学 MIS18-05
Systematicanalysis
is now performed for all the gamma-ray glows•

compared with meteorological conditions (Matsumoto, Master thesis, 2019).
See details: Wada, TE et al. arXiv:1811.06212

Gamma-ray glow terminated with lightning
February 11, 2017, Suzu

70 km

0.2-7 MeVGROWTH

300 ms

0.3-20 MeV
GODOT

AEF

termination of gamma-ray glow
at the passage of discharge
Wada, Bowers et al., Geophys. Res. Lett., 48 (2018); See poster AE33A-3397

Gamma-ray glow terminated with lightning
February 11, 2017, Suzu
Strong E-field
accelerationsite of e-nearby lightning
discharge destroyed
acceleration site

Electrons
γ-raysradio
γ-ray and AEF
detectors

termination

LF network• Collaboration among gamma-ray radiation detections, atmosphericelectric field measurement, and radio measurement of lightning

Wada, Bowers et al., Geophys. Res. Lett., 48 (2018); See poster AE33A-3397

nstant of 40–60 milliseconds, and was followed by prolonged strong ‘undershoot’ (thassion
at about bursts:
0.511 megaelectronvolts,
which lasted fora which would never happe
Short
Photonucleear
reactions

Detectors
Monitoring stations

N100

1101n-–3lightning
4of

Ja

pa

2+Sea+17m

5Cs –1D9B
6A
871 km138.580º E

60
60

250

50
50
4040
30
30200

20
20138.606º E(~0.2 s)80

Gamma-rayafterglow
60

101000150−200−100-100

00

100

200

100 Time
200(s)

300

300

400

400

Time (ms)80

70 100300

lightning

500

500

600

40detector A(0.35-0.60 MeV)

60
50200

40

50

30

100
20

10138.593º E

detector C(>1.2 MeV)(~1 ms)lightning

102

70-1-1Counts s-1Counts per 10-msCounts(10 ms)ms)
bin Count(10103Downward
TGF

70

Relative enhancement

NN

300

8080毎秒のカウント数

NFebruary 6, 2017, Kashiwazaki
Three components: Lightning/TGF, Gamma-ray
afterglow, and e+/eline
bc00(~60 s)Positron20
annihilation
signal

0–100

05000
0 100 200
50 300 400100
100
時間 (秒)
Time (sec)Time (ms)–100 150
0 1
150Enoto, Wada et al., Nature (2017); Physics World, Top 10 breakthrough in 2017T

nstant of 40–60 milliseconds, and was followed by prolonged strong ‘undershoot’ (thassion
at about bursts:
0.511 megaelectronvolts,
which lasted fora which would never happe
Short
Photonucleear
reactions300

Detectors
Monitoring stations
Relative enhancement
103102NN

3lightning
4ofJapan-–++Se
a17m5Cs –1

D9B
6A
871 km138.580º E

250

2101

N100

1138.593º E

138.606º E

Counts per 10-ms bin

NFebruary 6, 2017, Kashiwazaki
LETTER RESEA
Three components: Lightning/TGF, Gamma-ray
afterglow, and e+/elinebc

80

200
60
150
40100

Extended Data Figure 6 | Observed annihilation spectrum andsimulated models. The background-subtracted spectrum in the delayedphase for detector A, accumulated over t = 11.1–62.8 s, is plotted, withblack crosses indicating ±1σ errors. The simulated model curves are50

overlaid, for assumed distances to the base of the positron-emitting cof 0 m (that is, the detector is within the cloud; red), 40 m (green), 80(blue) and 160 m (magenta). The models are normalized by the total
counts in the 0.4–0.6-MeV band.

20

Detection of the00
positronannihilation–100
100 200
300 400MeV–100 0 1
line0 at0.511
Time (ms)

Enoto, Wada et al., Nature (2017); Physics World, Top 10 breakthrough in 2017TPhotonuclear reactions triggered by lightning
downward TGF(initial spike)half-life 10 min

neutrino

nitrogenradioactive
isotopecarbonisotope

14N

13N

13C

proton 7
neutron 6

proton 6
neutron 7

atmospheric

γ-raysproton 7
neutron 7

fast neutron

photonuclear reaction

γ + 14N → 13N + npositronbeta-plus decay
13N → 13C + e+ + ν(p → n + e+ + ν)

fast neutron

positronGamma rays from neutron and positrons
fast neutron

positronatmosphericnitrogen 14N(n,p) reactionneutron capture

electron-positronannihilationelectroncarbon
isotopenitrogenisotope

14C

15N

semi-stable(half-life of 5730 years)
radiocarbon dating

promptgamma rays

gamma-ray afterglow

annihilation
gamma rays
at 0.511 MeV

delayed emission

New Event! Short burst just after long burst
January 9, 2018, Kanazawa
Gamma-ray glow terminated associated with photonuclear reactions

Wada, Enoto et al., submitted

New "long & short” associated Event
January 9, 2018, Kanazawa
Gamma-ray glow terminated associated with photonuclear reactions
Detector BPhotonuclear
reactionsGamma-ray glow

10 sec0.1 secWada, Enoto et al., submitted

Kanazawa Comprehensive Observation- On-ground gamma-ray multi-point observations simultaneous withatmospheric electric field and low-frequency radio measurements
negativechargerelativistic
electronacceleration

TGF
positivechargegamma-ray

Photonuclear
reactionsstrongelectric
field
lightning

Neutrondetection

Gamma-raybeam
Radiation
detector networkRadio
antennas

Expanding the project to citizen science- Main difficulty of the project is to ensure many observation sites- A new handy radiation detector (reasonable price, easy to run!)- A new organization “Kyoto Open Science Meetup” to support forcommunication among scientists and citizen supporters
Cloudmovingdirection
km10 cm

102018 version

Kanaiwa
obs. site

Kanazawa
UchinadaSummary

Selected as one of the Top 10 Physics Breakthroughsof 2017 by Physics World magazine, IOP Publishing Ltd• GROWTH collaboration started multipoint measurements ofhigh-energy atmospheric phenomena along Japan Sea.

Tsuchiya, Enoto et al. PRL (2007)• The number of detection of long bursts (gamma-ray glow) isincreasing (>41 events). We have started systematic study.

Matsumoto, Master thesis, in prep

• Termination of the gamma-ray glow was recorded with apassage of a lightning discharge.

Wada, Bowers et al., GRL (2018)• Photonuclear reactions by downward terrestrial gamma-ray
flashes have been detected as short bursts (14 events).

Enoto, Wada, et al. Nature (2017)• We have expanding our project to citizen science at Kanazawa
area. We detected the “short & long” burst event in this area.