X-ray Polarimetry - INAF-IASF-Roma

X-ray polarimetry with a micropattern
Time Projection Chamber
High efficiency Not an imager
Black 2007
The photons enter along Z, the readout strips run also along Z. The GEM multiply the
charge. The charge is then collected by the 1-d strip detector. The signal in each strip is
connected to a waveform digitizer and by using its timing characteristics the information the
other coordinate is derived.
TThis method allows for decoupling the drift length that blurs the image and decreases the
modulation factor from the absorption depth that controls the efficiency. Since the origin of
the time is not known the TPC is not an imager.
Paolo Soffitta The Extreme and Variable High Energy Sky Chia Laguna 19-21/09/2011