Large Area 2π Proportional Detector - Model 43-135
Introduction

The Ludlum Model 43-135 is a large-area, 2π proportional detector designed for calibrating large-area alpha and beta sources. The windowless detector and gold-plated source tray are sealed together via heavy duty clamps, which permit operating at higher pressures (up to 0.2 MPa). This detector design is in use at the National Institute of Standards and Technology  (NIST), and has demonstrated superior beta response and counting statistics with uncertainties in the range of approximately 0.1%.