Materials that are transparent to alpha particles?

[Sven Andersson]

A mica window is used on Geiger counters. The thin mica is supposedly very transparent to alphas. But are there other materials? Extremely thin metal foils?

 

[mfb]

Nothing is perfectly transparent (apart from vacuum), but in general very thin foils let most particles pass through. You need a material with sufficient stability which puts a lower limit on thickness.

 

[Vanadium 50]

Nothing is transparent to alphas. All you can do is use materials that can be made very thin.

 

[KarenRei]

You can see some (limited) alpha cross sections here:

http://www.nndc.bnl.gov/sigma/index.jsp?as=1&lib=endfb7.1&nsub=10

 

[PietKuip]

Maybe graphene is an idea? Or a few layers of graphene?

 

[KarenRei]

When you say "transparent", what you do you mean exactly? Low total cross section (including scattering), low cross section for nuclear reactions in general, low cross section for specific nuclear reactions, ...?

And is there a particular alpha energy that you're looking at?

Again, I recommend checking out and comparing the alpha cross sections at Sigma. They don't have a lot of elements, but they have most of the light ones, which are probably going to be your best bet.