= Multiwire proportional chamber experiment
{title2=1968}
The original apparatus used $40\,\mu\mathrm m$ stainless-steel wires between meshes $7.5\,\mathrm{mm}$ away, flowing <argon> with organic <vapor>, negative mesh <voltage> and individual <electronic amplifiers>. A $5.9\,\mathrm{keV}$ <X-ray> source calibrated pulse height while <voltage> was varied.<The Use of Multiwire Proportional Counters to Select and Localize Charged Particles by Georges Charpak and others>[CERN manuscript §§1–2.1, Fig. 3]{ref}
A <coincidence circuit> defined a narrow <proton> or <pion> beam. Scanning it across wires tested localization; the response edge matched the beam width, limiting the inference. Distant counts were attributed to <accidental coincidences>. Separate <Electron> scans measured pulse delay versus position, comparing <gas> mixtures and pulse-height-dependent electronics.<The Use of Multiwire Proportional Counters to Select and Localize Charged Particles by Georges Charpak and others>[CERN manuscript §§2.3–2.4, Figs. 8–11]{ref}
Thresholds rejected small pulses, reducing <detection efficiency>. Wire-independence tests did not establish unlimited separation of overlapping tracks.<The Use of Multiwire Proportional Counters to Select and Localize Charged Particles by Georges Charpak and others>[CERN manuscript §§2.2–2.4]{ref}
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