Balloon-borne Emulsion Gamma-ray Telescope

GRAINE projectGamma-Ray Astro-Imager with Nuclear Emulsion

Hiroki ROKUJO (Nagoya Univ.)for GRAINE collaboration

Gamma-ray Observation (GeV/sub-GeV region)
Detected

Telescope

19902001

2008-sources

EGRET

271

spark chamber

Fermi-LAT
SSD tracker

60MeV-2GeV>3000

All-Sky Map
via gamma-ray
above 1 GeV

Gamma-ray souce

Galactic plane

Galactic center

Gamma-ray Observation (GeV/sub-GeV region)
Nearby Galactic Center

60MeV-2GeV

Many sources &Extended diffuse gamma-ray
Gamma-ray souce

Galactic plane

Galactic center

High-statistic → NEXT: Precise Observation

Nuclear Emulsion

Microscopic view
10microne+/-Gamma-raye-/+:HFII4I>=JBFE;C4LB>M4F?4;4GC;J>
Gamma-ray
Emulsion

PlasticbaseEmulsion

e-e+

0.3mm
(0.002Xo)

Angular Angular
Resolution
for Gamma Ray
resolution
SPring-8 LEPSUVSORNew SUBARU
EGRET (1991-2000)

UVSOR
New SUBARUGRAINE 2011

GRAINE2011(Zenith : 0-47deg)

Fermi-LAT (2008- )(P7SOURCE_V6)

SPring-8

1mrad

Back
Total
Front

GRAINE (MC)emulsion film(70,180,70)

1arcmin

1film
2films3films100MeV

1GeV

10GeV

OUR ENERGY REGION

100GeVPolarimetryγ

Microscopic view of a pair creation

γY, EAzimuth  ωXemulsion

Up stream

293Pm
0.002Xo1Pm

TAC
base

Down stream
emulsionσ(ω)=σo{1+P・A・cos2(ω-S/2)}
P : degree of polarization
ω:  Azimuth
A : Amplitude (0.1 – 0.3)

depending on the kinematics

Polarization measurement
偏光with accel. J-ray beam
LEPS/SPring-8
EJ, Max.=2.4GeV

N (Z )^`

p 0 1  p1  cos 2(Z  p 2  90$ )Significant& consistent result with expectation.
有意で矛盾のない結果が得られた<P>=66%, modulation factor = 0.21+-0.09
K. Ozaki,
etS.al.,NIM A 833,11(2016)165
K. Ozaki,Takahashi
et al.,NIM A (Prep)

Emulsion Chamberdx

New technique for GRAINE

Multi-stage Shifter（Time stamper）
dx

Simple, compact, light weight, high-vol. free,
low consumption, dead-time free

dx

time

Consisting of emulsion film.
Low momentum threshold~10MeV/c
High reliability & efficiency
Enlargeable

S. Takahashi et al.
NIM A620(2010) pp.192-195

1IJ6IJ;@>4IAB?J>H4

2nd6IJ;@>4IAB?J>H4time
3rd-stage shiftertimeEmulsion Gamma-ray Telescope
Converter
Emulsion stack◉Higher Angular Resol.
◉Polarization Sensitive◉Large Aperture AreaγTimestamper
Multi-stage shiftere- e+Calorimeter

10m2, ~2t

Emulsion + metal plate

Attitude monitor
Star camera

5487D9*εtrans*εconv*εdet

Flow of experiment
Detector development/preparation
Observation(balloon flight)
several days - 1 week

AnalysisScanning(2nd data taking)Recovery of detector

GRAINE project

GRAINE 2011

Aperture：0.013m22004­ Development on ground
S.Takahashi et al. NIMA 620, 192 (2010)
K.Ozaki et al. NIMA 833, 165 (2016)

2011(Jun.) 1st Balloon-Exp.
• Checking Feasibility

H.Rokujo et al. NIMA 701, 127 (2013).
S.Takahashi et al. PTEP 2015 043H01

1.6 h@35km
8.Jun. 2011
@TARF,Japan

2015(May.) 2nd Balloon-Exp.
• establishment of experimental flow
• demonstration of detector

GRAINE 2015

K.Ozaki et al., JINST 10, P12018 (2015)
S.Takahashi et al. PTEP 2016, 073F01
H,Rokujo et al., PTEP (submitted)

Under Preparation

2018(Apr.) 3rd Balloon-Exp.
• Celestial source detection2021- Start scientificobservation w/10m2

Aperture：0.38m2
11.5 h@36-37km
12. May. 2015

@ABLS,Australia

Data taking by Scanning System
Latest System “HTS”
developed in Nagoya

GRAINE 2015
scanned41m2 in total
current speed 4000 cm2/h→25000cm2/h by next generation system

Flight data

2 mm x 2 mm of single ﬁlm

Flight data

emulsion ﬁlm records all charged particles.
density ~400 tracks/mm2

Flight data

track connection plate by plate(colors indicate diﬀerent plates)

Flight data

select track starting intermediatewith another partner track.

Flight dataγe-e+

reconstruct downstream tracks(Follow down for 95 plates in this event)0.6

Energy Resolution by converter(Simulation, max 20 plates)

recon.

Track 1
Momentum:
46 MeV/c (Recon.)

600400δE/E~20 %20000.40.2

1002000300
Etrue [MeV]

EMC [MeV]

Gamma-ray Energy:
176 MeV (Recon.)

Energy Resolution δE/E

Track 2
Momentum:
129 MeV/c (Recon.)
Erecon. [MeV]
E[MeV]

Flight data

Recent Progress of GRAINE
Number of tracks/events per process unit(13×9 cm2)

■Automatic γ→e+e− Selection for the whole of the chamber

All tracks
106105104e-paircandidates
in each film

103
All B-tracks (|tanθ|<1.3)

102After elimination of penetrating tracks
Tracks starting from target film
Gamma-ray candidates (with partner track)

10

Events connected to bottom film

10

←Bottom20

Detected event number

40
60
Film# of converter

GRAINE2011

157 events
reliability 98%, partial analysis

x10000

80

100
Top→

GRAINE2015~10^6 events
reliability 95%, almost full analysis (~75%)

Recent Progress of GRAINE■BG Flux Measurement(atmospheric gamma rays)

1

GRAINE2015
with Nagoya-gel film
0.8

0.6

GRAINE2011

0.4

Events converting at plate#100.2

Events converting at plate#95
GRAINE 20110050100150200250300
Energy [MeV]

Differential Flux [cm-2 s -1 sr -1 MeV -1 (g/cm 2)-1]

Detection
Efficiency for γ →e e
Selection
Efficiency+ -■Selection Performance(MC)Kinzer et al.(1974), 4.5 GV
Staib et al.(1973), 4.5 GV
Valdez et al.(1970), 4.5 GV
Kinzer et al.(1974), 12 GV
Staib et al.(1973), 12 GV

10−4

GRAINE 2011(50-300 MeV), 8 GVThis work, 8 GV

GRAINE2011
GRAINE2015

10−510−66070 80 90 100

200300400
Energy [MeV]F.Mizutani (Kobe Univ.)

Count Rate of Cosmic Ray
Launched

non-Vela mode

Start level ﬂight

Vela mode
Vela < FoVTrigger of Hadronic Interaction
EventbyTimingInformation
同時刻発生イベントを用いた時間分解能評価
27秒

3 mm x 3mm.

時刻が近い&
1点収束を要求
角度・運動量ごとにプロット約7.3倍の改善
同時イベントの時間分布を評価

For timing calibration source.
→Time resolution : 9.5 msec @ E>500MeV
26 msec @ E<200MeV

H.Kawahara (Nagoya Univ.)
GRAINE 2015, Flight data analysis, Converter+Timestamper

EJ>130MeV, tanTJ, zenith<0.5Preliminary

Hadronic Int. VTX image
by 2ndry gamma raysπ0→2γ
Vproj = 0.5deg (8mrad)

Angular resolution 0.7deg

Calibration sorce(direction, timing, energy, polarization, efficiency)

High J-ray imaging performance is being obtained.

# of J-ray events / (0.003)2

Calibration source
J-ray imaging performancefor gamma-ray
telescope
w/ hadron induced
J-ray events

Calibration source
J-ray imaging performancefor gamma-ray
telescope
w/ hadron induced
J-ray events

GRAINE 2015, Flight data analysis, Converter+Timestamper

Residual704030206010

π0→2γ500− 1004050 100 150 200 250 300
Invariant Mass [MeV]

30

yrna

DATA

Vproj = 0.5deg (8mrad)

Back Groundi
Angular resolution
0.7deggnm i

2010inluetrreP

00Calibration sorce(direction, timing, energy, polarization, efficiency)

dn
U

50

100

150

200
250300Invariant Mass [MeV]High J-ray imaging performance is being obtained.

# of J-ray events / (0.003)2

Preliminary

E80
J>130MeV, tanTJ, zenith<0.5

Demonstration of Gamma-ray Imaging
during Balloon Observation
17 cm

Cosmic rays

4.4 m

Extrapolated positions
at the height ofthe launching plate〜〜

LaunchingPlate(protons, etc.)γγγγ γγ〜〜〜 〜〜〜〜〜

emulsiontelescopecm
52Aluminum
4.6 kgDetected gamma-rays

38 cm

Emulsion Telescope

〜〜ng〜〜〜 〜〜〜〜〜

Preliminary

30

2180

10160

0140−10−30
Detected gamma-rays

38 cm

Emulsion Telescope200

20−20m5c

100-300 MeV−40−40① Number of events② Expanse of image−30−20−1001020
30
40
Extrapolated Position X [cm]

Events in 5-cm radius

4.4 m(protons, etc.)

220cm

Cosmic rays

Extrapolated positions
at the height of
the launching plate

40

1717 cm

Extrapolated Position Y [cm]Result of gamma-ray imaging of launching plate120
1008060

the first demonstration of gamma-ray imaging
of external gamma-ray sourcewith balloon-borne emulsion telescopeMC simulation
17 cm

Cosmic rays

4.4 m

Extrapolated positions
at the height of
the launching plate〜〜

25(protons, etc.)

γγγγ
γ γ
〜〜〜 〜〜〜〜〜• Incident particles•• 37 km @ Australia, Alice Springs
Zenith angle distributions• Spectrum,
calculated by HKKM model (thanks toP,α, e­/+,γM.Honda)• Target• Launching plate (Al) 4.6 kg• Shackles (Fe) 3.1 kg x 2• Geant4.10.01, QGSP̲BERTcm

Detected gamma-rays

38 cm

Emulsion Telescope• Output gamma-ray data

• Positions, angles, energies at detector

① Gamma-ray Flux
From Launching plate
17 cm

Cosmic rays

Extrapolated positions
at the height of
the launching plate〜〜

25〜〜〜 〜〜〜〜〜

Gamma-ray flux Fplate [cm-1 s-1 MeV-1]

4.4 m(protons, etc.)

10−6This work
Simulation

10−7cm10−8100
Detected gamma-rays

38 cm

Emulsion Telescope

150200250300
Energy [MeV]220

Preliminary

30200

20180

101600140−10120R−20100−30−40−4080−30−20−10010203040
Extrapolated Position X [cm]60

Angular resolution[deg]Expected angular resolution

Preliminary

200

100
80

x2.0
x1.5
x1.0

0.1
10100

300

Energy [MeV]1000

MC (angular res. ×0.0)

180

60
40160

20

MC (angular res. ×1.0)

0140

−200

100120200

300

MC (angular res. ×1.5)

400
500
600
222
R (=X +Y ) [cm2 ]x1.0(good)MC (angular res. ×2.0)

100
80

1

R2 distribution (MC)120

Number of gamma rays

40

Events in 5-cm radius

Extrapolated Position Y [cm]

② Expanse of gamma-ray image

60
40x1.5x2.0 (bad)2000100

200

300

400500600
R2 [cm2]

Number of gamma rays

② Expanse of gamma-ray image
200

This work
MC (angular res. ×0.0)

150

MC (angular res. ×1.0)
100x1.0(good)MC (angular res. ×1.5)
MC (angular res. ×2.0)

50x1.5x2.0 (bad)00100200300

400

500600R2 [cm2]

we conﬁrmed that the emulsion telescope had an excellent
angular resolution in the 100‒300-MeV energy region during
the observation, as expected.

GRAINE2015• Aperture area 3780cm2 [×30] (“high-sensitive film”, total area 48m2)• Flight time 14.4hour (11.5hour@36.0–37.4km) [×7]
• Established balloon exp. scheme & flow @ Australia• Total read out area 41m2 by HTS (First large scale trial)• S/N ratio of “high-sensitive film” [×20] ⇒ Data size reduced [×1/20]• Tracking efficiency of single film (.78 ➔ .97.7) ⇒ inefficiency [×1/10]• Data reduction load to detect gamma-ray event [×1/200]• Data processed overall effective aperture area 2830cm2 (total area 30m2)• Pointing accuracy of gamma-ray ≲ 1.0deg• Time resolution 9.8 msec [×1/10]• Limiting magnitude of the Star Camera 6.1 ➔ 7.5

Much improved from GRAINE2011

GRAINE Scientific observation roadmap
2018, Demonstration

2021–, Scientific flight

Approved
Alice Springs~0.4m2 aperture by JAXA
~18hours flight duration<~5g/cm2 altitude

Alice Springs
10m2 aperture>~36hours flight duration<~10g/cm2 altitude

Vela pulsar detection, Imaging,phase resolved analysis
Galactic diffuse & Geminga
detection/indication

Fundedby JSPS

Vela pulsar
Polarization observation (<50%)

Pioneering polarization
observation for highenergy g-rays

SNR W44 (<200MeV, >200MeV)
Precise spectrum measurement
High resolution imaging

Studying cosmic ray
sources

Galactic Center
Obs. with ~arcmin resolution

Resolving GeV g-rayexcess at galactic center

Test of fundamental symmetries beyond the Planck scale
Transient sources
Studying transientObs. w/ high sensitivity
sources & w/ ones& high photon stats
Search for g-ray correlation with Giant Radio Pulses from pulsars
Search for GeV g-ray Pair Halo Æ Constraints on IGMF

Emulsion Film Production
Conventional

Nagoya Univ.

New (under development)

中村(悠), isas17-sbs-6

エマルションフィルム

We are constructing faster and more uniform ﬁlm production.
飛跡検出効率

大幅な改善！！
95%※実際には気温の日変動があるた
め横軸の値はおよそ2倍になる
AgBr体積充填率45%,30%RH
AgBr体積充填率55%,22%RH

温度耐性試験結果
Study forthe performance ofis updated day by day.
•emulsion
2018年実験ではより安定性が高いフィル
ムに変更•
2015年実験に用いたフィルムよりも2倍潜像退行特性が改善
We
install emulsion ﬁlms which•
フィルムクオリティの向上による飛跡検出has
better long-term stability
効率の改善

to GRAINE 2018.

現像までの日数(@40℃)

Kobe Univ.

Multi-stageShifter
シフターフィルム実装デザインの改良

GRAINE2018 Model

Top View 従来のステージ

新型ステージ

805cm

101mm

126mm

253mm

固定段
reducing the materialsof the stage
1mm
to increase the low momentum track eﬃciency.

Side View

上段

1mm
中段

2mm

recovered in GRAINE 2015.

下段

GRAINE2021 Model

light-weight multi-stage shifter unit.

we plan to set 8 units on the balloon gondola

Pressure Vessel Gondola

Nagoya Univ.

To keep vacuum-packed
emulsion chambers
at observation altitudes

Inside of vessel

2015年モデル(球型)
GRAINE2015使用

7m
2018年モデル(繭型)

GRAINE2018使用予定

フルスケールモデル
1.25平米望遠鏡ユニット
8機搭載(全重量~2t)

Summary & Prospects• GRAINE project- Precise observation by balloon-borne emulsion gamma-ray telescope- High angular resolution, Polarization sensitive, Large eﬀective area

• 2015-Balloon experiment in AUS- Flight, Scanning, and Analysis were established.
- Achieved 9.8 ms of time resolution by multi-stage shifter.
- Demonstrated gamma-ray imaging performance @100-300 MeV as expected• Prospects- GRAINE2018 (scheduled in next April.)goal is conﬁrming the overall performance by detecting a• Thecelestial gamma-ray source(Vela pulsar).
• GRAINE2021:• Start Scientiﬁc Observations with 10-m Telescope• Polarimetry, SNR, Galactic center, un-ID sources, Burst events2