J/ApJS/156/69 MGGPOD Monte Carlo suite (Weidenspointner+, 2005)
MGGPOD: a Monte Carlo suite for modeling instrumental line and continuum
backgrounds in gamma-ray astronomy.
Weidenspointner G., Harris M.J., Sturner S., Teegarden B.J., Ferguson C.
<Astrophys. J. Suppl. Ser., 156, 69-91 (2005)>
=2005ApJS..156...69W 2005ApJS..156...69W
ADC_Keywords: Gamma rays ; Spectroscopy ; Models
Keywords: gamma rays: observations - instrumentation: miscellaneous -
line: identification - methods: data analysis - methods: numerical
Abstract:
Intense and complex instrumental backgrounds, against which the much
smaller signals from celestial sources have to be discerned, are a
notorious problem for low- and intermediate-energy γ-ray
astronomy (∼50keV-10MeV). Therefore, a detailed qualitative and
quantitative understanding of instrumental line and continuum
backgrounds is crucial for most stages of γ-ray astronomy
missions, ranging from the design and development of new
instrumentation through performance prediction to data reduction. We
have developed MGGPOD, a user-friendly suite of Monte Carlo codes
built around the widely used GEANT (ver. 3.21) package, to simulate ab
initio the physical processes relevant for the production of
instrumental backgrounds. These include the build-up and delayed decay
of radioactive isotopes as well as the prompt de-excitation of excited
nuclei, both of which give rise to a plethora of instrumental
γ-ray background lines in addition to continuum backgrounds. The
MGGPOD package and documentation are publicly available online
(http://sigma-2.cesr.fr/spi/MGGPOD/). We demonstrate the capabilities
of the MGGPOD suite by modeling high-resolution γ-ray spectra
recorded by the Transient Gamma-Ray Spectrometer (TGRS) on board Wind
during 1995. The TGRS is a Ge spectrometer operating in the 40keV-8MeV
range. Because of its fine energy resolution, these spectra reveal the
complex instrumental background in formidable detail, particularly the
many prompt and delayed γ-ray lines. We evaluate the successes
and failures of the MGGPOD package in reproducing TGRS data and
provide identifications for the numerous instrumental lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 145 254 Identified lines; blends of identified lines
table6.dat 103 65 Blends containing unidentified lines
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See also:
http://sigma-2.cesr.fr/spi/MGGPOD/ : MGGPOD Home Page
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 6 F6.1 keV TGRS Transient Gamma-Ray Spectrometer line energy
8- 14 F7.5 ct/s CRate Count rate
16- 43 A28 --- Trans Transition identification (G1)
45- 50 F6.1 keV Energy ? Laboratory energy
52- 54 A3 --- React Reaction type (G2)
56-120 A65 --- Comm Additional Comments
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 6 F6.1 keV TGRS Transient Gamma-Ray Spectrometer line energy
8- 14 F7.5 ct/s CRate Count rate
16- 57 A42 --- Trans Transition identification (G1)
59- 61 A3 --- f_Energy Approximate flag on Energy
62- 67 F6.1 keV Energy ? Nominal energy
69- 71 A3 --- React Reaction type (G2)
73-102 A30 --- Comm Additional Comments
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Global Notes:
Note (G1): K and L are atomic sub-shell binding energies in cases of
electron capture (EC).
Note (G2): Reaction type, defined as follows:
a = β-decay after activation;
s = spallation followed by prompt de-excitation;
n = (n,γ) or (n,n') followed by prompt de-excitation;
r = natural radioactivity.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 01-Jun-2005