Hiroki ROKUJO (Nagoya Univ.) for GRAINE collaboration

Balloon-borne Emulsion Gamma-ray Telescope

Gamma-Ray Astro-Imager with Nuclear Emulsion

GRAINE project

Galactic plane Galactic center

Gamma-ray souce

60MeV-2GeV

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

Telescope Detected sources

1990- 2001

EGRET spark chamber 271

2008- Fermi-LAT SSD tracker >3000

All-Sky Map via gamma-ray above 1 GeV

Galactic planeGalactic center

Gamma-ray souce

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

Nearby Galactic Center

Many sources & Extended diffuse gamma-ray

High-statistic → NEXT: Precise Observation

60MeV-2GeV

チャンドラ望遠鏡 0.5 秒角

Rotating Neutron Star(Crab pulsar)

Angular Resolutionx 1/4

■1999 Chandra(Δθ~0.5 arcsec)■1990 ROSAT (Δθ~2 arcsec)

Impact of High-Resolution Observation (An Example in X-ray Astronomy)

Impact of High-Resolution Observation (An Example in X-ray Astronomy)

チャンドラ望遠鏡 0.5 秒角

Improvement of Imaging Performance　　　→New discoveries are expected!!

Rotating Neutron Star(Crab pulsar)

Ring Structure

Clear Evidence!!Jet Structure

Angular Resolutionx 1/4

CentralObject

■1999 Chandra(Δθ~0.5 arcsec)■1990 ROSAT (Δθ~2 arcsec)

Gamma-ray

e+e-

Emulsion

Emulsion

Plastic base

0.3mm (0.002Xo)

GTRUU=UJIVNRQHO=WNJX=RK=H=SOHVJ

Nuclear Emulsion

Gamma-ray e+/-

e-/+

10micronMicroscopic view

Angular resolution

1film

2films3films

TotalFront

Back

SPring-8 LEPSUVSOR

Fermi-LAT (2008- )(P7SOURCE_V6)

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

GRAINE2011(Zenith : 0-47deg)

100MeV 1GeV 10GeV 100GeV

1mrad

1arcmin

New SUBARU

SPring-8

GRAINE 2011

UVSORNew SUBARU

EGRET (1991-2000)

OUR ENERGY REGION

Angular Resolution for Gamma Ray

New technique for GRAINEMulti-stage Shifter （Time stamper）

time

time

1UV?UVHLJ=UMNKVJT=

time

3rd-stage shifter

dxdx

dx

Emulsion Chamber

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

Consisting of emulsion film.Low momentum threshold~10MeV/cHigh reliability & efficiencyEnlargeableSimple, compact, light weight, high-vol. free, low consumption, dead-time free

2nd?UVHLJ=UMNKVJT=

Emulsion Gamma-ray Telescope

Timestamper Multi-stage shifter

Attitude monitor Star camera

e+e-

γ

Calorimeter Emulsion + metal plate

Converter Emulsion stack

>=CBPD*εtrans*εconv*εdet

◉Higher Angular Resol.◉Polarization Sensitive◉Large Aperture Area

10m2, ~2t

Detector development /preparation

Observation(balloon flight) several days - 1 week Recovery of detector

Scanning (2nd data taking)

AnalysisFlow of experiment

GRAINE project

GRAINE 2015 Aperture：0.38m2 11.5 h@36-37km

GRAINE 2011 Aperture：0.013m2 1.6 h@35km

2004- 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

2015(May.) 2nd Balloon-Exp. • establishment of experimental flow • demonstration of detector K.Ozaki et al., JINST 10, P12018 (2015) S.Takahashi et al. PTEP 2016, 073F01 + in prep. (technical paper)

2018(Apr.) 3rd Balloon-Exp. • Celestial source detection

2021- Start scientific observation w/10m2

Prepare12. May. 2015 @ABLS, Australia

8.Jun. 2011 @TARF, Japan

2nd-Data taking by Scanning System

GRAINE 2015scanned

41m2 in total

Latest System “HTS” developed in Nagoya

current speed 4000 cm2/h→25000cm2/h by next generation system

Flight data

2 mm x 2 mm of single film

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

Flight data

track connection plate by plate (colors indicate different plates)

Flight data

Flight data

select track starting intermediate with another partner track.

Flight data

select track starting intermediate with another partner track.

γe+e-

Flight data

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

Flight data

Gamma-ray Energy:176 MeV (Recon.)

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

Track 2 Momentum: 129 MeV/c (Recon.)

[MeV]trueE100 200 300

[MeV

]re

con.

E0

200

400

600

E/E

δEn

ergy

Res

olut

ion

0

0.2

0.4

0.6

Energy Resolution by converter(Simulation, max 20 plates)

EMC [MeV]

δE/E~20 %

E rec

on. [M

eV]

H.Rokujo, et al. in prep.

Film# of converter0 20 40 60 80 100

)29

cm×

Num

ber

of tr

acks

/eve

nts p

er p

roce

ss u

nit(1

3

1

10

210

310

410

510

610

Bottom← →Top

|<1.3)θAll B-tracks (|tanAfter elimination of penetrating tracksTracks starting from target filmGamma-ray candidates (with partner track)Events connected to bottom film

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

Detected event numberGRAINE2011157 eventsreliability 98%, partial analysis

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

x10000

All tracks

e-paircandidatesin each film

Recent Progress of GRAINE

Energy [MeV]0 50 100 150 200 250 300

- e+ e

→γ

Det

ecti

on E

ffic

ien

cy f

or

0

0.2

0.4

0.6

0.8

1

Events converting at plate#10

Events converting at plate#95

GRAINE 2011

Sele

ctio

n Ef

ficie

ncy

GRAINE2011

GRAINE2015 with Nagoya-gel film

■Selection Performance(MC)

Recent Progress of GRAINEH.Rokujo, et al. in prep.

Energy[MeV]210

]-1 )2

(g/

cm-1

MeV

-1 s

r-1

s-2

Dif

fere

nti

al F

lux[

cm

6−10

5−10

4−10Kinzer et al.(1974), 4.5 GVStaib et al.(1973), 4.5 GVValdez et al.(1970), 4.5 GVKinzer et al.(1974), 12 GVStaib et al.(1973), 12 GV

GRAINE 2011(50-300 MeV), 8 GV

This work, 8 GV

GRAINE2011

GRAINE2015

■BG measurement(atmospheric gamma rays)

Phase-resolved analysis for pulsars is capable.

Altitude & Track rate

s=4.9mm w/ 500mm/sec operationÆTime resolution 9.8msec

Hadron event on spike structure

GRAINE 2015, Flight data analysis, Timestamper

10cm

e.g. 89msec period of Vela pulsar

Simultaneity of hadron event tracks

15 min.Altitude

Posit

ion

Y

Position X

Anglescale

Analyzed by F.Mizutani

～～～～ ～～

CR (protons, etc.)

4.4 m

Extrapolated positions at the height of the launching plate

～～～～

25 cm

38 cmEmulsion Telescope

Detected gamma-rays

Launching Plate

17 cm

Demonstration of Gamma-ray Imaging during Balloon Observation

Aluminum 4.6 kg

17 cm

emulsion telescope

～～～～ ～～

CR (protons, etc.)

4.4 m

Extrapolated positions at the height of the launching plate

～～～～

25 cm

38 cmEmulsion Telescope

Detected gamma-rays

Launching Plate

17 cm

Extrapolated Position X [cm]40− 30− 20− 10− 0 10 20 30 40

Extra

polate

d Posi

tion Y

[cm]

40−

30−

20−

10−

0

10

20

30

40

Event

s in 5-

cm ra

dius

60

80

100

120

140

160

180

200

220Preliminary

]2) [cm2+Y2 (=X2R0 100 200 300 400 500 600

20−

0

20

40

60

80

100

120 Preliminary

Gamma-ray Image of the launching plate

Extrapolated Position X [cm]40− 30− 20− 10− 0 10 20 30 40

Extr

apol

ated

Pos

ition

Y [c

m]

40−

30−

20−

10−

0

10

20

30

40

Even

ts in

5-c

m r

adiu

s

60

80

100

120

140

160

180

200

220Preliminary

]2) [cm2+Y2 (=X2R0 100 200 300 400 500 600

20−

0

20

40

60

80

100

120 Preliminary

This result is the first demonstration with the whole of enlarged area.(So far, with a small area using accel. beam)

100-300 MeV

R2 distributionclear excess

H.Rokujo, et al. in prep.

]2 [cm2R0 100 200 300 400 500 600

0

50

100

150

200This work

0.0)×MC (angular res.

1.0)×MC (angular res.

1.5)×MC (angular res.

2.0)×MC (angular res.

100-300 MeV

Energy [MeV]100 150 200 250 300

]-1

MeV

-1 s-1

[cm

plat

eG

amm

a-ra

y flu

x F

8−10

7−10

6−10

This work

Simulation

Preliminary

H.Rokujo, et al. in prep.

R2 distribution

Gamma-ray fluxfrom the plate

～～～～ ～～

CR (protons, etc.)

4.4 m

Extrapolated positions at the height of the launching plate

～～～～

25 cm

38 cmEmulsion Telescope

Detected gamma-rays

Launching Plate

17 cm

Gamma-ray Image of the launching plate

Emulsion telescope has the good performance as expected.→Next: overall demonstration by detecting celestial gamma-ray sources

Summary & Prospects•GRAINE project - Precise observation by balloon-borne emulsion gamma-ray telescope - High angular resolution, Polarization sensitive, Large effective area - SNR, Galactic center/plane, un-ID sources, Polarimetry, Burst events •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 •Next balloon experiment - The goal is confirming the overall performance by detecting a celestial gamma-ray source(Vela pulsar). - Please go to the following Poster Sessions!! • Y. Nakamura: Preparation of emulsion films • K. Kuretsubo: Preparation of Multi-stage shifter