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X-Ray Polarimetry Workshop SLAC, Stanford, California 9-11 February 2004 |
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New Developments in Liquid Xenon Detectors and Prospects for a Compton Scatter Polarimeter
Elena
Aprile
Columbia University
age@astro.columbia.edu
K.L. Giboni, P. Majewski, K.Ni and M. Yamashita
The application of compact photomultiplier tubes (PMTs) immersed in liquid xenon (LXe) for efficient detection of its fast scintillation, has made possible to significantly improve the energy response to MeV radiation. Our recent measurements of the simultaneous charge and light signals produced in LXe by Cs-137, Na-22 and Co-60 gamma-rays give an energy resolution of 3.2 % (FWHM) at 1 MeV and at 1 kV/cm electric field. This is more than a factor of two better than the resolution measured from charge signals only, as it was the case for the time projection chamber on board the LXeGRIT Compton telescope prototype. Further improvement is expected with more efficient photon detectors and lower noise charge amplifiers. Another relevant result is the fast coincidence timing of 300 picosecond (FWHM) at 1 MeV, measured with the same PMTs in LXe. This opens the possibility of a TOF measurement for background reduction in a compact LXe Compton scatter polarimeter and imager. We estimate the polarization sensitivity of such instrument on a long duration balloon mission.
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For more information, contact
Jennifer Formichelli |
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