Shell or Solid for Buckling Analysis?

[elkcorn]

Hello:

I have a question regarding the selection of element type.

My initial geometry is a boom with a rectangular cross-section (thickness=0.25 in., side=20in,
length=300 in.) In addition, my main objective is to perform "buckling analysis".

My question is: Do I need to use shell element or solid element (brick)?

Any help would be greatly appreciate.

Thank you.