Internal volume of the MWPC is a cylinder 55 mm in height and 340 mm in diameter. The size of the position sensitive area of the MWPC is - 150x150 mm. The diameter of the entrance Be window is 120 mm. The support frame is installed on the window for compensation of internal gas pressure. X-ray calibrations sources, Fe-55 (5.89 keV) and source Cd-109 (22.1 keV), are integrated into the Ti body of the chamber beyond the entrance window zone over the sensitive area.
The system of electrode planes forms two layers. The first layer is position sensitive and spectrometric, the second one - only spectrometric. The second layer is also used for the anticoincidence system with the aim to reduce the charge particle background in the MWPC. All electrode planes are mounted on ceramics frames.
The first layer includes an amplification zone of 12 mm depth formed by the anode plane A and cathode planes K1 and K2 and two drift zones of 16 mm depth placed above and under the amplification zone. A second layer of 6 mm depth is formed by the anticoincidence plane AC and the grounded plane D. The second cathode is formed from the AC-layer at the bottom of the chamber. The AC-layer has only an amplification zone.
Tungsten-rhenium gold wire is used for the anode planes and has a diameter 20 mm. The wire pitch in both layers is 3 mm. Anode wires of each layer are combined in two groups and connected with preamplifiers. The guard wires have diameter 100, 150 and 200 mm and are placed on the edge of the electrode planes for smoothing the edge plane influence.
Cathodes K1 and K2 and drift D planes are made of wire with diameter 100 mm, pitch - 1 mm, material - Be bronze. The delay line on discrete elements is used for determination of coordinate x-ray photon detection.