Expected performance of a hard X-ray polarimeter (POLAR) by Monte Carlo simulation

Xiong, S. L.; Produit, N.; Wu, Bobing

doi:10.1016/j.nima.2009.04.033

Cited by 20 publications

(19 citation statements)

References 35 publications

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“…We assumed for POLAR the same limits on θ used throughout the paper, that is θ min = 0 and θ max = π, and evaluated f = 0.70. A technique proposed for deriving the polarization when the photons are incident off-axis is to divide the measured modulation curve by that measured or derived from simulations for unpolarized photons impinging from the same incident direction (Xiong et al 2009). Such an "off-axis normalized" modulation curve is supposed to recover the cosine square dependency so that the subsequent analysis to derive the angle and the degree of polarization can proceed as that for on-axis radiation.…”

Section: Discussionmentioning

confidence: 99%

On the Operation of X-Ray Polarimeters With a Large Field of View

Muleri

2014

ApJ

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The measurement of the linear polarization is one of the hot topics of High Energy Astrophysics. Gas detectors based on photoelectric effect have paved the way for the design of sensitive instruments and mission proposals based on them have been presented in the last few years in the energy range from about 2 keV to a few tens of keV. As well, a number of polarimeters based on Compton scattering are approved or discussed for launch on-board balloons or space satellites at higher energies. These instruments are typically dedicated to pointed observations with narrow field of view telescopes or collimators, but there are also projects aimed at the polarimetry of bright transient sources, like Soft Gamma Repeaters or the prompt emission of Gamma Ray Bursts. Given the erratic appearance of such events in the sky, these polarimeters have a large field of view to catch a reasonable number of them and, as a result, photons may impinge on the detector off-axis. This changes dramatically the response of the instrument to polarization, regardless if photoabsorption or Compton scattering is involved. Instead of the simple cosine square dependency expected for polarized photons which are incident on-axis, the response is never purely cosinusoidal and a systematic modulation appears also for unpolarized radiation. We investigate the origin of these differences and present an analytic treatment which proves that actually such systematic effects are the natural consequence of how current instruments operate. Our analysis provides the expected response of photoelectric or Compton polarimeters to photons impinging with any inclination and state of polarization.

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Section: Discussionmentioning

confidence: 99%

On the Operation of X-Ray Polarimeters With a Large Field of View

Muleri

2014

ApJ

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“…• in Monte Carlo simulations (Xiong et al 2009;McConnell et al 2009;Gunji et al 2014). These degradations in the modulation factor can be theoretically canceled out by the above two steps, and therefore we need a multipurpose polarimeter that measures all the required information, such as the three-dimensional direction of the scattered photons and the arrival direction and energy of the incident photon for each event.…”

Section: Basic Principles Of Compton Polarimetrymentioning

confidence: 99%

Imaging Polarimeter for a Sub-MeV Gamma-Ray All-sky Survey Using an Electron-tracking Compton Camera

Komura

Takada

Miyamoto

et al. 2017

ApJ

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X-ray and gamma-ray polarimetry is a promising tool to study the geometry and the magnetic configuration of various celestial objects, such as binary black holes or gamma-ray bursts (GRBs). However, statistically significant polarizations have been detected in few of the brightest objects. Even though future polarimeters using X-ray telescopes are expected to observe weak persistent sources, there are no effective approaches to survey transient and serendipitous sources with a wide field of view (FoV).Here we present an electron-tracking Compton camera (ETCC) as a highly-sensitive gamma-ray imaging polarimeter. The ETCC provides powerful background rejection and a high modulation factor over a FoV of up to 2π sr thanks to its excellent imaging based on a well-defined point spread function. Importantly, we demonstrated for the first time the stability of the modulation factor under realistic conditions of off-axis incidence and huge backgrounds using the SPring-8 polarized X-ray beam. The measured modulation factor of the ETCC was 0.65 ± 0.01 at 150 keV for an off-axis incidence with an oblique angle of 30• and was not degraded compared to the 0.58 ± 0.02 at 130 keV for on-axis incidence. These measured results are consistent with the simulation results. Consequently, we found that the satellite-ETCC proposed in Tanimori et al. (2015) would provide all-sky surveys of weak persistent sources of 13 mCrab with 10% polarization for a 10 7 s exposure and over 20 GRBs down to a 6 × 10 −6 erg cm −2 fluence and 10% polarization during a one-year observation.

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“…It is capable of detecting ∼ 10 GRBs/yr with minimum detectable polarization (MDP) ≤ 10%. 47 The Astrosat mission, launched in September 2015, has a cadmium zinc telluride (CZT) imager 48 with the capability to make time resolved polarisation measurements for 5-6 GRBs per year. 49 Off-axis angle (degrees) The left panel of Figure 4 shows the expected sensitivity of e-ASTROGAM for the detection of GRBs in the 0.2-2 MeV energy range, as a function of the off-axis angle θ off−axis .…”

Section: +31mentioning

confidence: 99%

e-ASTROGAM mission: a major step forward for gamma-ray polarimetry

2017

J. Astron. Telesc. Instrum. Syst

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Abstract. e-ASTROGAM is a gamma-ray space mission proposed for the fifth Medium-size mission (M5) of the European Space Agency. It is dedicated to the study of the non-thermal Universe in the photon energy range from ∼0.15 MeV to 3 GeV with unprecedented sensitivity, angular and energy resolution, together with a groundbreaking capability for gamma-ray polarimetric measurements over its entire bandwidth. We discuss here the main polarization results expected at low energies, between 150 keV and 5 MeV, using Compton interactions in the e-ASTROGAM instrument, from observations of active galactic nuclei, gamma-ray bursts, microquasars, and the Crab pulsar and nebula. The anticipated performance of the proposed observatory for polarimetry is illustrated by simulations of the polarization signals expected from various sources. We show that polarimetric analyses with e-ASTROGAM should provide definitive insight into the geometry, magnetization and content of the high-energy plasmas found in the emitting sources, as well as on the processes of radiation of these plasmas.

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Expected performance of a hard X-ray polarimeter (POLAR) by Monte Carlo simulation

Cited by 20 publications

References 35 publications

On the Operation of X-Ray Polarimeters With a Large Field of View

On the Operation of X-Ray Polarimeters With a Large Field of View

Imaging Polarimeter for a Sub-MeV Gamma-Ray All-sky Survey Using an Electron-tracking Compton Camera

e-ASTROGAM mission: a major step forward for gamma-ray polarimetry

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