X-ray Polarimetry - INAF-IASF-Roma

For a non focal plane experiment to arrive to a large area for sensitive polarimetry with
also energy resolution by using Compton scattering, a subdivided and two phase
polarimeter [scatterer (low-Z) and absorber (high-Z)] must be devised.
Single PM tube for each 5 cm x 5 cm x 4 cm
NA102 scatterer and 7 cm x 1 cm x 9 cm NaI(Tl)
absorber
25 %, Modular implementation
Phoswich-type collimator. Field of View of 14.5 o
Gunji et al., 1994
MDP = 7 % in 5.5 hours in 30-700 keV for Crab
• The apparatus is divided in an array of small detecting units
in form of a fiber-like scintillators.
• A photon scattered by a low Z-fiber-like scintillator pass
across a number of similar fibers until is absorbed by a high-
Z fiber. A good sensitiviity can be reached.
Single cell: 37-plastic scintillator fibers (2mm large)
pins, 5 cm thick, 24-semi-exagonal sticks (CsI or
the faster YAP). The system is made by replicas of
such cells. (Costa et al., 1993, 1995)
•Far-away fibers are fed to a single channel of a multi-wire PM
tube to detect coincidence events.
• = 50% . MDP = 1.6 % in 20-200 keV in 5.5 hours for Crab
A = 1000 cm 2 .
• MDP sensitive the low energy threshold.
Paolo Soffitta The Extreme and Variable High Energy Sky Chia Laguna 19-21/09/2011