The MWPC has an active area of 40x38 mm^2. It is composed by three layers of 25 um gold wires. Each layer is at a distance of 2 mm from the next one and the wires are also placed at 2 mm distance. The innermost layer contains the anode wires where the charge is multiplied. The two outermost layers contain the cathode wires, where the ions from the charge avalanche are collected. These two layers are rotated by 90 degrees with respect to each other. The cathode wires in each dimension are interconnected by inductor and capacitor chains, allowing to determine the x and y coordinates of the position of the interaction from the time difference between the signals at each end of the delay lines. For the signal processing, the fast analog signals are discriminated and injected into CAMAC Time-to-Digital-Converter modules. A Labview software package was developed to reconstruct the images on-line. The position resolution for X-rays is 0.4 mm.
FIG. 1: First version of the MWPC prototype.
FIG. 2: Prototype chamber.
Fig. 3: Determination of the position resolution from the Edge Spread Function of the detector. Top row: An object with known size is imaged, providing an intensity profile. Bottom row: The edges of the object appear as steps in the profile. One of them is used to determine how sharp is the image. The resolution can be taken from the distance between the positions corresponding to 10% and 90% of the intensity (left side) or by measuring the full width at half maximum of the derivative of the edge (right side).
The accelerator and the laboratory are operated and upgraded in frame of the research funding grant "VdG Research infrastructure" by the Ministry of Education, Youth and Sports of the Czech Republic (Contract No. LM2015077).
Last update: January 2022