On the Detection of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math>-Ray Polarization by Pair Production

Berlin, T. H.; Madansky, L.

doi:10.1103/physrev.78.623

Cited by 41 publications

(29 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…nature is reflected in the probability distribution of the azimuthal scattering angle. In the pair domain, the polarization information is given by the distribution of azimuthal orientation of the electron-positron plane (as discussed since the 1950s; see, e.g., [29,147,150]). e-ASTROGAM will be able to perform for the first time at these energies polarization measurements thanks to the fine 3D position resolution of both the Si Tracker and the Calorimeter, as well as the light mechanical structure of the Tracker, which is devoid of any heavy absorber in the detection volume.…”

Section: Line Sensitivitymentioning

confidence: 99%

The e-ASTROGAM mission

et al. 2017

View full text Add to dashboard Cite

e-ASTROGAM ('enhanced ASTROGAM') is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV -the lower energy limit can be pushed to energies as low as 150 keV, albeit with rapidly degrading angular resolution, for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and the promise of eLISA.

show abstract

Section: Line Sensitivitymentioning

confidence: 99%

The e-ASTROGAM mission

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Additionally, the conversion azimuthal angle of the electron and the positron with respect to the flight direction of the incident photon can in principle enable the measurement of the polarisation fraction and the polarisation angle of the source [11]. With the low-density detectors presently under development, the track directions can be measured with enough precision before multiple scattering ruins the azimuthal information carried by the pair [12].…”

Section: Introductionmentioning

confidence: 99%

γ-ray telescopes using conversions to e+e− pairs: event generators, angular resolution and polarimetry

Bernard

2017

Astroparticle Physics

View full text Add to dashboard Cite

We benchmark various available event generators in Geant4 and EGS5 in the light of ongoing projects for high angular-resolution pairconversion telescopes at low energy. We compare the distributions of key kinematic variables extracted from the geometry of the three final state particles. We validate and use as reference an exact generator using the full 5D differential cross-section of the conversion process. We focus in particular on the effect of the unmeasured recoiling nucleus on the angular resolution. We show that for high resolution trackers, the choice of the generator affects the estimated resolution of the telescope. We also show that the current available generator are unable to describe accurately a linearly polarised photon source.

show abstract

“…Berlin and Madansky obtained the expression for a linearly polarized photon [25], that was later expressed in Bethe-Heitler notation by May [26], and after a correction by a factor of 2 as indicated by [67], is:…”

Section: Bethe-heitler Polarization Asymmetry At Thresholdmentioning

confidence: 99%

“…Measuring γ-ray linear polarization by pair production was first suggested by Yang [24] and the full polarized differential cross section was given by Berlin [25] and May [26] (an exhaustive review can be found at Ref. [27]).…”

Section: γ-Ray Polarimetry With Pairs: Techniquesmentioning

confidence: 99%

γ-Ray polarimetry with conversions to e+e− pairs: Polarization asymmetry and the way to measure it

Gros

Bernard

2017

Astroparticle Physics

View full text Add to dashboard Cite

We revisit the measurement of the polarization fraction, P , and the measurement of the polarization angle of partially linearly-polarized gamma rays using their conversion to e + e − pairs in the field of a nucleus. We show that an inappropriate definition of the azimuthal angle, ϕ, used to reference the orientation of the final state degrades the precision of the measurement of P , by comparison to the optimal case where the bisector angle of the electron and of the positron momenta is used. We then focus on the lowest part of the energy spectrum, below ≈ 10 MeV, where a large part of the statistics lie for a cosmic source. We obtain the value of the polarization asymmetry, A, of pair conversion at threshold and we show that in the case where the correct expression is used for ϕ, the measured value of A tends to the limit.

show abstract

On the Detection ofγ-Ray Polarization by Pair Production

Cited by 41 publications

References 3 publications

The e-ASTROGAM mission

The e-ASTROGAM mission

γ-ray telescopes using conversions to e+e− pairs: event generators, angular resolution and polarimetry

γ-Ray polarimetry with conversions to e+e− pairs: Polarization asymmetry and the way to measure it

Contact Info

Product

Resources

About