A fast and flexible multichannel electron detector with parallel readout for photoelectron spectroscopy

To satisfy end user requirements for higher throughput and reliability in photoelectron spectroscopy, a new multichannel electron detector with discrete electronics has been designed and commissioned at Daresbury Laboratory. Count rate performance has been enhanced by the use of low resistance microchannel plates which amplify the electron pulses incident on the anode array. The low resistance microchannel plates are linear to 2.5 × 104 s−1 mm−2 for a bias voltage of 900 V per plate, providing more than an order of magnitude improvement in count rate performance over high resistance microchannel plates, microchannel plate outgassing in the ultra-high vacuum environment limits the scale of this improvement. A novel anode design maximizes the collection efficiency, while minimising crosstalk between channels (< 0.6% after discrimination) and provides up to 40 parallel channels on a 1 mm pitch. The collection efficiency is increased from 50% to 70% (for the present geometry) by applying a 50 V bias between the guard rail and electrodes on the anode. Each data collection channel comprises a fast current amplifier and discriminator, capable of a throughput of 2.5 × 107 s−1, and a 24 bit scaler. The integral non-linearity for flat-field illumination is better than 10% with no correction. The fast multichannel detection system gives a throughput enhancement of 10–20 on single-channel detection systems. It has also proved to be significantly better than previous multichannel detection systems with discrete electronics due to its high throughput, modular design and flexible structure.