===== Working with a current preamp =====
When we measure small currents (nanoAmps or even picoAmps) outside noise sources can interfer with the meausrement.

==== Shielding by Faraday cage ====

Because our lab is not underground and we have fluorescent lighting we have to shield experiments from EM radiation. We currently have the probe station inside a cooper mesh Faraday cage (purchased from TMC). To see if this Faraday cage is sufficient, try the following experiment inside the Faraday cage: 
  *measure current noise through an unshielded resistor, compare this to current noise through the same resistor when the resistor is packaged inside a solid-metal project box. 

[[http://www.twpinc.com/twpinc/control/category-price/~category_id=TWPCAT_11|Copper mesh supplier]]