Cosmic ray shielding for electronics on Earth There are plenty of topics discussing cosmic ray shielding, but they all put emphasis on spacecraft shielding, where things like radiation and mass are a big problem.
So I decided to ask a question from a purely "particle physics" perspective.
Evidently, cosmic rays and their byproducts are the predominant cause of soft errors, or single bit errors, meaning that they are well able to penetrate the atmosphere, building walls and fairly thick metal equipment racks, with enough energy to flip a bit.
But on the other hand, the prevalence rapidly increases with altitude, meaning that the atmosphere does a decent job of absorbing most of those or significantly diminish their potential. Which leads me to suspect that there is a significant dynamic range to those particles, if the atmosphere is capable of absorbing most but those that manage to get through are still energetic enough to penetrate dense materials and cause damage.
Which brings up the question, what kind of materials provide the best kind of shielding of electronic equipment from that radiation? And how much of it. Considering that outside the context of spacecraft mass is not that much of an issue.
I've read that dense materials are good at scattering them into less energetic particles and hydrogen rich materials are good at absorbing them. I happen to have 4mm thick lead sheets and 20 mm thick PVC panels, so I am wonder whether a lead/pvc/lead/pvc sandwich will be effective at it, or will it take something more heavy duty?
 A: Low background particle-physics detectors (neutrino experiments, proton decay experiments, neutrino-less double beta decay experiments, etc.) are put underground exactly to obtain shielding from secondary cosmic muons (and their tertiary effects like neutron spallation). 
A few hundred meters water equivalent (MWE) is considered "shallow", a thousand or so MWE is middle depth, and you aren't into serious "deep" territory until you have at least a couple thousand MWE. There is precisely nothing you can do to a case or room that provides an interesting level of shielding.
Which is why you don't find anyone talking about the subject.

This is same physical fact that makes cosmic muon tomography useful for looking at the interior structure of volcanoes and big man-made piles of rock.
A: The cosmic rays that reach us are muons. They are very penetrating: first the atmosphere (equivalent to 10 meters of water). At sea level about 1 muon per cm$^2$ per minute. Still with a  highly relativistic kinetic energy of a few GeV.
Then the concrete of the building. They penetrate tens of meters into the ground. So your lead sheet won't make much of a difference.
