کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5486762 1523338 2017 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
γ-Ray polarimetry with conversions to e+e− pairs: Polarization asymmetry and the way to measure it
موضوعات مرتبط
مهندسی و علوم پایه فیزیک و نجوم نجوم و فیزیک نجومی
پیش نمایش صفحه اول مقاله
γ-Ray polarimetry with conversions to e+e− pairs: Polarization asymmetry and the way to measure it
چکیده انگلیسی
We revisit the measurement of the polarization fraction, P, and 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.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Astroparticle Physics - Volume 88, February 2017, Pages 30-37
نویسندگان
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