Some details of Katkus gamma ray altimeter with Cs-137 source

Kaktus is made by TsNII RTK, Tikhoretskiy pr. 21, St Petersburg, Russia (, +7-812-552-0110)

The location of the Cs source on the base of the Soyuz descent module

Design of Soyuz Priborno-Agregatniy Otsek (Instrument-Service Module)

Some links
Some information and diagrams

Some sources for Kaktus