The INTEGRAL Mass Model – TIMM

Ferguson, C.; Barlow, E. J.; Bird, A. J.; Dean, A. J.; Hill, A. B.; Shaw, S. E.; Stephen, J. B.; Sturner, Steven J.; Tikkanen, Tuomo; Weidenspointner, G.; Willis, D. R.

doi:10.1051/0004-6361:20031403

Cited by 26 publications

(26 citation statements)

References 4 publications

(4 reference statements)

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“…These Compton scattered photons having lost only a small amount of energy contribute considerably to the continuum just below the line, which is of particular importance for the line shape calculations. We made therefore Monte-Carlo simulations with the code MGGPOD (Weidenspointner et al 2005) using the detailed SPI mass model (Sturner et al 2003) coupled to the TIMM model (Ferguson et al 2003) for the other parts of the spacecraft for gamma-ray energies corresponding to the lines observed at 1.37, 1.63, 1.78, 2.223, 4.4, 6.1 and 7 MeV. Monoenergetic beams of a projected area of 10 098 cm 2 centered at the Ge-detector array with 10 7 photons for each energy were generated in the simulations to obtain the spectral response for the lines of interest.…”

Section: Discussionmentioning

confidence: 99%

Properties of the energetic particle distributions during the October 28, 2003 solar flare from INTEGRAL/SPI observations

Kiener¹,

Gros

Tatischeff³

et al. 2005

A&A

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Analysis of spectra obtained with the gamma-ray spectrometer SPI onboard INTEGRAL of the GOES X17-class flare on October 28, 2003 is presented. In the energy range 600 keV-8 MeV three prominent narrow lines at 2.223, 4.4 and 6.1 MeV, resulting from nuclear interactions of accelerated ions within the solar atmosphere could be observed. Time profiles of the three lines and the underlying continuum indicate distinct phases with several emission peaks and varying continuum-to-line ratio for several minutes before a smoother decay phase sets in. Due to the high-resolution Ge detectors of SPI and the exceptional intensity of the flare, detailed studies of the 4.4 and 6.1 MeV line shapes was possible for the first time. Comparison with calculated line shapes using a thick target interaction model and several energetic particle angular distributions indicates that the nuclear interactions were induced by downward-directed particle beams with alpha-to-proton ratios of the order of 0.1. There are also indications that the 4.4 MeV to 6.1 MeV line fluence ratio changed between the beginning and the decay phase of the flare, possibly due to a temporal evolution of the energetic particle alpha-to-proton ratio.

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Section: Discussionmentioning

confidence: 99%

Properties of the energetic particle distributions during the October 28, 2003 solar flare from INTEGRAL/SPI observations

Kiener¹,

Gros

Tatischeff³

et al. 2005

A&A

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“…We thus performed Monte Carlo simulations using the INTEGRAL mass model previously described by Ferguson et al (2003) and improving it through the inclusion of a more detailed IBIS mass model (Laurent et al 2003). We validated our approach by comparing the results obtained for the detection of sources within the instrument FoV with the predictions of the PICsIT responses based on the most recent instrument calibrations provided by the instrument team.…”

Section: A3 Picsitmentioning

confidence: 99%

INTEGRAL IBIS, SPI, and JEM-X observations of LVT151012

Savchenko

Bazzano

Bozzo

et al. 2017

A&A

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During the first observing run of LIGO, two gravitational wave events and one lower-significance trigger (LVT151012) were reported by the LIGO/Virgo collaboration. At the time of LVT151012, the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) was pointing at a region of the sky coincident with the high localization probability area of the event and thus permitted us to search for its electromagnetic counterpart (both prompt and afterglow emission). The imaging instruments on board INTEGRAL (IBIS/ISGRI, IBIS/PICsIT, SPI, and the two JEM-X modules) have been exploited to attempt the detection of any electromagnetic emission associated with LVT151012 over three decades in energy (from 3 keV to 8 MeV). The omni-directional instruments on board the satellite, i.e., the SPI-ACS and the IBIS/Veto, complemented the capabilities of the IBIS/ISGRI and IBIS/PICsIT for detections outside their imaging field of view in order to provide an efficient monitoring of the entire LVT151012 localization region at energies above 75 keV. We did not find any significant transient source that was spatially and/or temporally coincident with LVT151012, obtaining tight upper limits on the associated hard X-ray and γ-ray radiation. For typical spectral models, the upper limits on the fluence of the emission from any 1 s counterpart of LVT151012 ranges from F γ = 3.5 × 10 −8 erg cm −2 (20-200 keV), within the field of view of the imaging instruments, to F γ = 7.1 × 10 −7 erg cm −2 (75-2000 keV), considering the least favorable location of the counterpart for a detection by the omni-directional instruments. These results can be interpreted as a tight constraint on the ratio of the isotropic equivalent energy released in the electromagnetic emission to the total energy of the gravitational waves: E 75−2000 keV /E GW < 4.4 × 10 −5 . Finally, we provide an exhaustive summary of the capabilities of all instruments on board INTEGRAL to hunt for γ-ray counterparts of gravitational wave events, exploiting both serendipitous and pointed follow-up observations. This will serve as a reference for all future searches.

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“…A computer model of the INTEGRAL spacecraft written in the GEANT 4 toolkit (Agostinelli et al 2003) was used for simulations in this work. This model was developed from the GEANT 3 INTEGRAL Mass-Model (TIMM) (Ferguson et al 2003) originally used to assess the background recorded by the instruments onboard INTEGRAL. The model contains an accurate representation of the SPI instrument, including the mask and veto elements.…”

Section: Model Simulationmentioning

confidence: 99%

Polarisation studies of the prompt gamma-ray emission from GRB 041219a using the spectrometer aboard INTEGRAL

McGlynn

Clark

Dean

et al. 2007

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Context. Linear polarisation in gamma-ray burst prompt emission is an important diagnostic with the potential to significantly constrain models. The spectrometer aboard INTEGRAL, SPI, has the capability to detect the signature of polarised emission from a bright γ-ray source. GRB 041219a is the most intense burst localised by INTEGRAL with a fluence of 5.7 ×10 −4 erg cm −2 over the energy range 20 keV-8 MeV and is an ideal candidate for such a study. Aims. Polarisation can be measured using multiple events scattered into adjacent detectors because the Compton scatter angle depends on the polarisation of the incoming photon. A search for linear polarisation in the most intense pulse of duration 66 seconds and in the brightest 12 seconds of GRB 041219a was performed in the 100-350 keV, 100-500 keV and 100 keV-1 MeV energy ranges. It was possible to divide the events into six directions in the energy ranges of 100-350 keV and 100-500 keV using the kinematics of the Compton scatter interactions. Methods. The multiple event data from the spectrometer was analysed and compared with the predicted instrument response obtained from Monte-Carlo simulations using the GEANT 4 INTEGRAL mass model. The χ 2 distribution between the real and simulated data as a function of the percentage polarisation and polarisation angle was calculated for all three energy ranges. The degree and angle of polarisation were obtained from the best-fit value of χ 2 . Results. A weak signal consistent with polarisation was found throughout the analyses. The degree of linear polarisation in the brightest pulse of duration 66 s was found to be 63 +31 −30 % at an angle of 70 +14 −11 degrees in the 100-350 keV energy range. The degree of polarisation was also constrained in the brightest 12 s of the GRB and a polarisation fraction of 96 +39 −40 % at an angle of 60 +12 −14 degrees was determined over the same energy range. However, despite extensive analysis and simulations, a systematic effect that could mimic the weak polarisation signal could not be definitively excluded. Conclusions. Our results over several energy ranges and time intervals are consistent with a polarisation signal of about 60% but at a low level of significance (∼2σ). The polarisation results are compared with predictions from the synchrotron and Compton drag processes. The spectrum of this GRB can also be well fit by a combined black body and power law model which could arise from a combination of the Compton and synchrotron processes, with different degrees of polarisation. We therefore conclude that the procedure described here demonstrates the effectiveness of using SPI as a polarimeter, and is a viable method of measuring polarisation levels in intense gamma-ray bursts.

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The INTEGRAL Mass Model – TIMM

Cited by 26 publications

References 4 publications

Properties of the energetic particle distributions during the October 28, 2003 solar flare from INTEGRAL/SPI observations

Properties of the energetic particle distributions during the October 28, 2003 solar flare from INTEGRAL/SPI observations

INTEGRAL IBIS, SPI, and JEM-X observations of LVT151012

Polarisation studies of the prompt gamma-ray emission from GRB 041219a using the spectrometer aboard INTEGRAL

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