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MeV Gamma Ray Nuclear Astrophysics Yesterday: Science and Observations Today: Instrumentation. (Krause 2004). Steven Boggs UC Berkeley Department of Physics. Nuclear Gamma-Rays. Atmosphere is opaque at these energies. Gamma-ray interactions. Index of refraction ~1.0000

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Krause 2004

MeV Gamma Ray Nuclear Astrophysics

Yesterday: Science and Observations

Today: Instrumentation

(Krause 2004)

Steven Boggs

UC Berkeley

Department of Physics


Krause 2004

Nuclear Gamma-Rays

Atmosphere is opaque at these energies.


Gamma ray interactions

Gamma-ray interactions

Index of refraction ~1.0000

Penetration ≥ cm into materials

Standard mirrors & lenses don’t work


Krause 2004

Gamma Ray Detectors

  • Solid State

  • good/excellent resolution (<2%)

  • may require cooling

  • finer position resolution

  • more channels/power

Liquid Xe

NaI, CsI, BGO

  • Scintillators

  • high Z

  • large volume

  • room temperature

  • moderate/poor resolution (3-10%)

Si Semiconductor

CZT Semiconductor

Ge Semiconductor


The radiation environment

The Space Radiation Environment

Sun through solar flares: photons, charged particles

Radiation belts:

Trapped protons (SAA) & resulting activation, electrons

  • Cosmic rays:

    • Photons

    • Protons (& activation)

    • Alphas

    • Ions

    • Electrons

    • Positrons

Secondaries induced by cosmic-ray interaction with upper atmosphere:

Albedo photons, neutrons, electrons, positrons

The radiation environment


Krause 2004

Compton Gamma-Ray Observatory

(1991-2000)

COMPTEL

(0.8-30 MeV)

OSSE

(50 keV – 10 MeV)

BATSE

(20-600 keV)

EGRET

(20 MeV – 30 GeV)


Krause 2004

Spectroscopy, no Imaging

“light bucket”

Galactic Center Positrons

(Purcell et al., 1993)



Krause 2004

Coded Aperture Imaging

pinhole camera….

with lots of pinholes

  • Good for:

  • point sources

  • photons that stop in the mask (<0.2 MeV)


Krause 2004

INTErnational Gamma-Ray Astrophysics Laboratory (launched October 2002)

IBIS

(15 keV-10 MeV)

JEM-X

(3-35 keV)

E/DE ~ 10, Df ~ 20’

E/DE ~ 500, Df ~ 2º

SPI

(30 keV-8 MeV)

OMC

(500-600 nm)


Krause 2004

IBIS/INTEGRAL October 2002)

ISGRI: 128x128 CdTe array (4x4x2 mm3)

PICsIT: 64x64 CsI array (8.4x8.4x30 mm3)


Ibis galactic plane survey

IBIS Galactic Plane Survey October 2002)

(Bird & Walter 2004)


Krause 2004

SPI/INTEGRAL October 2002)

19 Ge detectors


Krause 2004

SPI Positron Map October 2002)

(Weidenspointner et al., 2008)


Krause 2004

Compton Gamma-Ray Observatory (1991-2000) October 2002)

COMPTEL

(0.8-30 MeV)

OSSE

(50 keV – 10 MeV)

BATSE

(20-600 keV)

EGRET

(20 MeV – 30 GeV)


Krause 2004

COMPTEL - Compton Imaging October 2002)

cos  = 1+mc2(1/E2-1/E)

COMPTEL Detectors

D1: 4188 cm2 liq. scint.

D2: 8620 cm2 NaI

DE: 5-8% (FWHM)

DX ~ DY ~ 2 cm (1s)

DZ ~ 3 cm (1s)

Dt ~ 0.25ns

COMPTEL Performance

0.8-30 MeV

E/DE ~ 9-14 (FWHM)

Df ~3º

Aeff < 20 cm2

FOV ~ 1str

(Schoenfelder et al., 1993, ApJS 86, 657)


Krause 2004

26 October 2002)Al (1.809 MeV), ~1Myr

(Oberlack et al., 1996; Pluschke et al., 2001)


Krause 2004

Compton Telescopes: Then & Now October 2002)

  • ACT Enabling Detectors

  • 1 mm3 resolution

  • DE/E ~ 0.2-1%

  • 10-20% efficiency

  • background rejection

  • polarization

3 decades…

  • CGRO/COMPTEL

  • ~40 cm3 resolution

  • DE/E ~ 10%

  • 0.1% efficiency


Krause 2004

Overview of the October 2002)Nuclear Compton Telescope

A balloon-borne g-ray spectrometer, polarimeter & imager

Steven Boggs, UCB

NCT Collaboration: Berkeley, NTHU, NCU, NSPO, NUU, LBNL, CESR


Krause 2004

Nuclear Compton Telescope October 2002)

balloon payload

  • Heart of NCT:

  • Cross Strip 3-D GeDs

  • 37x37 strips

  • 2-mm pitch

  • 15-mm thickness

  • 81000 mm3 volume

  • 1.6 mm3 localization

  • ~2.1-keV noise resolution


Krause 2004

3D GeD Design October 2002)

(Luke et al. 1992, 1994)


Krause 2004


Krause 2004

60 October 2002)Co Laboratory Tests

1.173, 1.333 MeV

1.173 MeV processed image


Krause 2004


Krause 2004

The 2005 balloon flight from Fort Sumner October 2002)

Impressions from the NCT 2009 Balloon flight


Krause 2004

BGO shield October 2002)

Pre-Amps

lN2 dewar


Krause 2004

Rotor October 2002)

Differential GPS

Solar Panels

Electronics Bay

Detector

CSBF SIP


Krause 2004

  • 4D sin October 2002) = n 

  • Alternate layers of high/low Z materials

  • ex. W/Si

  • D ~ 25 Å (technological limit)

  • < 1 Å (0.18 Å @ 68 keV)

  • ~ 30’

    f ~ 10 m


Krause 2004

SN 1987A in the LMC October 2002)

~110-4 M

(Suntzeff et al.1992; Diehl & Timmes 1998)

Blue supergiant (~20 M, 6 M He core) (Arnett et al., 1989)

Spherical models predict 44Ti < 1000 km/s

56Ni mixed out to ~3000 km/s (0.7 keV at 68 keV)

(Motizuki & Kumagai 2004)


Krause 2004

Bragg Scattering October 2002)

  • 2D sin  = n 

  • Use a crystal to bend (“focus”) the -rays

  • D ~ 1 Å (crystal spacing)

  • < 1 Å (0.014 Å @ 0.847 MeV)

  • ~ 10’

    f ~ 60 m


Krause 2004

Laue Lens: Focusing October 2002)g-rays

von Ballmoos et al., CESR, Toulouse