1. Test Results Of Gain Uniformity Measurements Heidelberg Chamber maximum deviation [%] L1C0#001 33,45 L1C0#002 25,94 L1C0#017 24,41 L2C0#001 16,76 L2C0#002 17,50 L2C0#003 22,49 L1C1#001 13,00 L1C1#010 14,05 L1C1#019 10,18

2. Chambers with worst results are also the very first chambers that have been built. Improvements have been done. For example thicker anode wire at the edge of the chamber. Absorption in the radiator. What are reasons for the bad results ?

3. One segment has additional fiber mat Gain or radiator structure? X-Ray Source E<8 keV

4. A sheet of paper attached to the radiator in every corner.

5. Full scans with different tube voltages, same chamber. 8 kV maximum deviation: 13,0 % 9 kV maximum deviation: 9,6 % 10 kV maximum deviation: 7,0 %

6. Measure at 10 kV? T. Lehmann C. Baumann High anode current ~5 muA Radiator structure may still dominate test results