(Left) The circuit diagram for the low noise, high-gain transimpedance
amplifier. The gain is set by R3; the values depicted give a gain of 2.2 × 108 V/A.
Optional damping is via capacitor C1. The output signal is carried on differential
outputs V+0 and V-0 by two BNC cables with screens connected to the enclosing copper
Faraday cage, which also serves as a housing and mount for all the components above
the upper viewport.

(Right) The layout of the printed circuit board for our transimpedence amplifier and photodiode
is shown in Figure A1. There are six independent voltage nets in the circuit, these are:
the 0 V ground plane which is also V-0; +9 V; -9 V; the photodiode anode; V+0 and the
junction of R1, R2 and R3. The right hand side of R3 is connected to the ground plane.
The anode track to pin 2 of the operational amplifier was kept short and is completely
surrounded by the ground plane, making a guard ring.