A NEW GAS ELECTROLUMINESCENT DETECTOR FOR SYNCHROTRON RADIATION EXPERIMENTS

D.A. Goganov, A.A. Schultz

Bourevestnik,Inc. 68 Malookhtinsky pr., St.Petersburg 195272 Russia

Keywords: Electroluminescent detector, energy resolution, rise-time analyser.

A completed work on further construction and characteristic improvement of sealed off gas electroluminescent detector (DELG) of X-ray radiation is reported. For a detector with a homogeneous interelectrode field and a working window square of 150mm² the spectrometric characteristics in the range 2-30 kev and loading interval from 0.1c^-1 to 10⁵c^-1 were improved. The filling-gas pressure was increased up to 2atm in order to reach an objective of increasing the registration efficiency in region above 20 kev. As a result registration efficiency of industrial DELG samples reached 70% for Mok were improved. The filling-gas pressure was increased up to 2atm in order to reach an objective of increasing the registration efficiency in region above 20 kev. As a result registration efficiency of industrial DELG samples reached 70% for Mok-time analyser it became possible to separate the impulses which correspond to quanta absorbed in the electroluminescence region that ten times improved the peak/valley ratio for quanta with energy above 20 kev (peak/valley value became 500 instead of 50 for AgKa line). Detector own background for CuKa line was successfully declined to 0.02c^-1. Detection unit short-time stability based on DELG and PMT was increased up to < 0.3 % at loading change from 10²c^-1 to 5x10⁴c^-1 at the expense of introducing three LEDs with individual light brightness regulation into the structure.

For providing registration of loadings which are significantly over 10⁵c^-1 a canal for current measuring by a gas detector at the current signal output from the second grid was introduced. As a result starting from the 10⁵c^-1 loading current measuring for MnKa line is performed to within 1% at a ten second exposition. When loadings are above 10⁶c^-1 measuring accuracy is determined by the registration statistics.

Thus, we managed to build a detection unit for registration range from 10^-1c^-1 to 10¹⁰c^-1 while in the range from 0.1 to 8x10⁴c^-1 at unit entrance the impulse registration with high energy resolution as well as current measuring in the range from 2x10⁴c^-1 to 10¹⁰c^-1 are performed simultaneously. The unit is supposed to be used in experiments with synchrotron radiation at small-angle scattering as well as in EXAFS-spectroscopy.