Redesigning O Neill cylinders

Andrei Costea wrote:

I am curios about any improvements I can bring...
for example I will tell you that I don`t have a serious shield for alfa,
beta and gama particles..

I reply:

Alpha (helium nuclei) and Beta (electron) radiations are easily dealt
with: beta travels only a few feet in air and is stopped by almost any
solid matter - normal clothes work reasonably well. Alpha is even less
penetrating.

It's the gammas that cause problems (these are high energy
electromagnetic waves beyond X-ray frequencies) along with cosmic "rays"
- nuclear particles travelling at near light-speed, formed both in the
sun and from further sources across the galaxy. Neither of these are
much affected by shielding in the way alpha and beta particles are. On
Earth, these high-energy radiations tend to hit particles in the
atmosphere and cause cascades of secondary particles that reach the
ground, to add a few percent to our natural background radiation.

In space habitats, the general rule of thumb appears to be "add enough
solid shielding to equal the amount of atmospheric shielding we have on
the ground". Since the atmosphere has a scale height of about 7.4km, and
a surface density of 1.2 kg/m3, we require about 9000 kg per square
metre of shielding to equal this. In practical terms, that's a depth of
3-4m of concrete/slag/etc.

While that mass might make us baulk (one completed International Space
Station equals only 45 square metres of shielding) it does allow
large-sized pressure vessels such as the O'Neill designs to doubly
benefit from the sheer amount of material to construct them.

Andy Goddard