Gamma- r ay Imaging with a L ar ge mic r o- T PC and a Sc - - PowerPoint PPT Presentation

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Gamma- r ay Imaging with a L ar ge mic r o- T PC and a Sc intillation Came r a Kyoto University dept. of physics Cosmic-ray group K. Hattori Contents 1. MeV gamma-ray astronomy 2. Principle of Compton Imaging 3. -PIC (Micro Pixel

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SLIDE 1

22/2/2007 11th Vienna Conference on Instrumentation

Gamma- r ay Imaging with a L ar ge mic r

  • - T

PC and a Sc intillation Came r a

Kyoto University dept. of physics Cosmic-ray group

  • K. Hattori

Contents

  • 1. MeV gamma-ray astronomy
  • 2. Principle of Compton Imaging
  • 3. μ-PIC (Micro Pixel Chamber) with a large detection area

+ GEM (Gas Electron Multiplier) Micro-TPC with a large detection volume

(Time Projection Chamber based on μ-PIC)

  • 4. Performance of Compton camera

5.Summary

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22/2/2007 11th Vienna Conference on Instrumentation

De te c tio n Se nsitivity in

the X/ gamma- r ay

band

keV MeV GeV TeV

All-sky survey

1mCrab EGRET Air Cherenkov GLAST(2007) ～１°

Sensitivity(ergs cm-2 s-1)

MeV band COMPTEL (CGRO) INTEGRAL MeV band ∙ ∙ ∙ ∙ ∙ Low sensitivity

Our Goal 10 times as high sensitivity as that of COMPTEL

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22/2/2007 11th Vienna Conference on Instrumentation

incident gamma-ray liquid scintillator Recoil electron

energy loss, location, time

NaI(Tl) scintillator Scattered gamma-ray

Energy loss, location, time

1.5m 1.7m

Princ iple o f Classic al Co mpto n I maging

Photon ∙ ∙ ∙ ∙ ∙ main interaction in MeV band Compton scattering

  • G. Weidenspointner’ et al.,
  • 2001. A&A 368, 347.

signal background Distribution of TOF (time-of-flight)

Recoil electrons are not tracked The origin of a single event can be restricted by the “event circle” The gamma-ray originated at the point of overlap low background rejection power

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22/2/2007 11th Vienna Conference on Instrumentation

Princ iple o f Advanc e d Co mpto n Came ra

base d o n Mic r

  • Pixe l Chambe r

(μ-PIC)

mic r

  • - T

PC (gas de te c to r) e ne r gy and tr ac k

  • f a re c o il e le c tro n

Ange r c ame r a sc intillation de te c tor

NaI (T l)(surro unding mic ro -T PC) e ne rgy and po sitio n o f a sc atte re d gamma-ray

gas de te c tor le ss c ollisions the dir e c tion of r e c oil e le c tr

  • n

→le ss e r

r

  • r

2-dimensional imaging gaseous detector

1photon : r e c onstr uc te d c omple te ly e ne r gy and dir e c tion

High bac kgr

  • und

r e je c tion powe r

Having tracks of recoil electrons… Unnecessary to use a TOF value and a collimator

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22/2/2007 11th Vienna Conference on Instrumentation

400μm 10cm

2-dimensional imaging gaseous detector electrode pitch 400μm

μ –PI C (Mic ro Pixe l Chambe r)

Stable operation @gas gain ~ 6000

Max gas gain ～ 15000

position resolution ~120μm

Electric field

prototype of Compton camera based on a μ-PIC with a detection area of 10 cm ×10 cm

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22/2/2007 11th Vienna Conference on Instrumentation

GEM (Gas Electron Multiplier) F.Sauli(1997)

  • perated @ low gas gain(~10)

30 cm

400μm

De ve lo pme nt o f large μ-PI C

Goal 10 times as high sensitivity as that of COMPTEL To attain goal….. prototype (10 cm × 10 cm) is not enough

large μ-PIC with a detection area of 30 cm ×30 cm gain max : 7,000 stable gas gain : 2,000

To detect Compton events · · · · · detection of recoil electrons using the micro-TPC Energy loss of recoil electrons ～ 2 ~ 3 × MIPs (Minimum Ionizing Particle)

required gas gain 2×104 (We have not achieved because of discharge) μ-PIC Another electron multiplier is necessary

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22/2/2007 11th Vienna Conference on Instrumentation

140μm 70μm Cu (5μm) 10MΩ

electron cloud

dr ift plane GE M

μ- PIC

polyimide (50μm)

  • HV
  • HV

10MΩ

  • HV

14.5c m 0.41kV/ c m 0.5c m 2kV/ c m

Standard GEM design GEM was installed just above the μ-PIC

Mic ro -T PC base d o n μ-PI C and GE M

28 cm 23cm

GEM

segmented GEM (8 segments) to reduce capacitance and thus damage caused by discharge 23 cm × 28 cm (limited by material size) Scienergy Co. Ltd, Japan A charged particle runs in the micro-TPC and makes electron clouds, and then electorn clouds are pre-amplified by the GEM and then the μ-PIC

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22/2/2007 11th Vienna Conference on Instrumentation

Pe rfo rmanc e o f μ–PI C and GE M

Maximum gas gain

  • f 5×104

Stable gas gain 2×104 using Ar-C2H6(90:10) gas 1atm μ-PIC 2×103

×

GEM 10

103 104

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22/2/2007 11th Vienna Conference on Instrumentation

Mic ro -T PC was ke pt in the se ale d ve sse l

The micro-TPC was set in a aluminum vessel filled with Ar-C2H6(90:10) gas to a pressure of 1 atm sealed for the duration of the measurements.

from μ-PIC to pre-amplifiers

Sealed vessel

Anode:768ch + cathode:768ch →Signals from the μ-PIC are sent via the printed boards 256ch per board

μ-TPC

30cm 15cm

drift cage vessel printed board Outside μ-PIC pre

  • amplifier
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22/2/2007 11th Vienna Conference on Instrumentation

DAQ syste m

ASD (amplifie r

  • shape r
  • disc r

iminator )

mic r

  • - T

PC VME F ADC 100MHz 8c h ×3

VME Me mor y Boar d

anode 768 ch cathode 768h 1536 ch digital

32bit

Position e nc oding module (100MHz F

PGA) summed analog (8ch)

21cm 11cm Recording anode and Cathode coincident positon and the timing Recording summed analog signals

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22/2/2007 11th Vienna Conference on Instrumentation

Pe rfo rmanc e o f the mic ro -T PC(1)

Gain uniformity rms 13.9 % 10cm ×10cm μ-PIC 5% Energy resolution Irradiation of 133Ba with the whole detector direct X-ray (31 keV) the peak of copper fluorescent X-rays at 8.0 keV, generated at the GEM and the μ-PIC by the original X-rays from 133Ba the energy resolution was worse at 59.5 keV It might be due to the saturation of the ASD chips gain 2.3×104 gain 2.3×104

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22/2/2007 11th Vienna Conference on Instrumentation

Pe rfo rmanc e o f the mic ro -T PC(2)

30cm

30cm 15cm

2 2 detector 2 diffusion 2 detctor

) ( ) ( l D l + = + = σ σ σ σ mm 37 . mm, 51 .

detector

= = D σ l:drift length

30cm Two plastic scintillators were used in coincidence for cosmic muon trigger Position resolution Difference between hit points and tracks obtained from fitting Total gas gain of 5×104

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22/2/2007 11th Vienna Conference on Instrumentation

Co mpto n Came ra

  • Position resolution < 11mm(FWHM)
  • Effective Area (No image distortion) ~30x30cm2
  • Energy Resolution 7.4%(FWHM)@662keV,11.2%(FWHM)@80keV
  • Dynamic range 80keV-1.5 MeV

37cm

6x6 = 36PMTs

Anger camera scintillation detector for scattered gamma-rays A large NaI(Tl) crystal and 6×6PMTs

source

γ γ e-

Anger camera

μ-TPC encoder ASD

45cm

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22/2/2007 11th Vienna Conference on Instrumentation

Pro to type o f Advanc e d Co mpto n Came ra

x 012345678910 y 1 2 3 4 5 6 7 8 9 10 z 1 2 3 4 5 6 7 8 9 10

Classical Compton telescope

  • 50
  • 40
  • 30
  • 20
  • 10

10 20 30 40 50

  • 50
  • 40
  • 30
  • 20
  • 10

10 20 30 40 50

1625 events (smoothing) Event Circle

x 012345678910 y 1 2 3 4 5 6 7 8 9 10 z 1 2 3 4 5 6 7 8 9 10

  • 50
  • 40
  • 30
  • 20
  • 10

10 20 30 40 50

  • 50
  • 40
  • 30
  • 20
  • 10

10 20 30 40 50

150 events (smoothing)

Electron-tracking telescope SPD~40o

Event Arc

Imaging Quality (662keV two sources ) Imaging Quality (662keV two sources )

We have developed Prototype of Compton Camera based on 10cm×10cm μ-PIC Line source I-131 (364 keV)

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Pe rfo rmanc e o f Co mpto n Came ra(1)

Typical recoil electron tracks Irradiating 137Cs (662 keV) based on 23 cm×28 cm ×15cm micro-TPC Typical Compton event

137Cs (662 keV)

Eμ-PIC : 78.02 keV Escinti : 615.9 keV Recoil electron Scattered gamma-ray Reconstructed gamma-ray Micro-TPC Anger camera

137Cs source

30cm 30cm 15cm

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22/2/2007 11th Vienna Conference on Instrumentation

Pe rfo rmanc e o f Co mpto n Came ra(2)

137Cs 662 keV

using data with reconstructed energy 610 keV ~ 760 keV 137Cs (1 MBq) ×2 137Cs (1 MBq) 137Cs (1 MBq) 43cm point source ~45 cm from micro-TPC

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22/2/2007 11th Vienna Conference on Instrumentation

Pe rfo rmanc e o f Co mpto n Came ra(3)

ARM (Angular Resolution Measure) Concerned with the angle between the scattered gamma-ray and the recoil electron SPD (Scatter Plane Deviation) Determination accuracy of the plane formed By the scattered gamma-ray and the recoil electron Error concerned with the reconstructed direction of a Incident gamma is determined event by event Well fitted by Lorentzian ARM = 9.95˚ (FWHM) SPD = 159˚ (FWHM)

137Cs (662 keV)

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22/2/2007 11th Vienna Conference on Instrumentation

Summary & F uture Wo rks

  • Micro-TPC based on 23cm×28cm GEM

and 30cm×30cm μ-PIC effective volume 23cm×28cm×15cm

Gain uniformity rms 13.9 % energy resolution FWHM 37.5% (31.0 keV)

  • Large Compton camera

recoil electron tracks were successfully obtained point source imaging using 137Cs (662 keV)

ARM 9.96˚ (FWHM) SPD 159˚ (FWHM)

  • Future Works

Imaging using source with various energy (350 keV ~ a few MeV) To obtain better position resolution of scattered gamma-rays….. Anger camera ( < 11mm FWHM ) → Pixel scintillator ( < 3mm FWHM)

  • Goal FWHM

500 keV ARM 7˚ SPD 40 ˚ 1 MeV 5 ˚ 20 ˚

5cm 16×16 pixels

13mm 3 mm

PMT (H8500)

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22/2/2007 11th Vienna Conference on Instrumentation

Me V gamma-ray Astro no my

Nucleosynthesis

Supernova: nuclear line from radioisotope Galactic disk: long-time decay radioisotope

Particle Acceleration

AGN Jet, Gamma-ray pulsar Gamma-ray burst、Solar flare

Strong Gravity

Black hole: accretion disk・π0decay・Primordial

Structure and Evolution of Universe

Extragalactic diffuse background

Origin and Propagation of cosmic-ray

Galactic diffuse emission