Re: Balloon-Borne Instrument Collects Antimatter (fwd)

Robert J. Bradbury (
Wed, 18 Aug 1999 11:26:41 -0700 (PDT)

> Clint O'Dell <> wrote:

> I'm no physicist, but doesn't anti-matter and matter annihilate each other?

> How could you capture anti-matter that is floating around with matter?

The experiment used NASA's biggest (helium) balloon to take a Japanese instrument into the upper reaches of the atmosphere. The instrument detects anti-protons among the cosmic rays arriving from outer-space. Space is so empty that the anti-particles created in highly energetic events (supernovas, star collisions, etc), if they escape, can reach the Earth's atmosphere. When they (or the other non-anti-particles hit one of the air molecules they produce a cosmic-ray shower of particles. Most of these are absorbed before they reach the ground. The ones that hit you are part of the normal background radiation that to some degre is responsible for cancer.

[More than you wanted to know I bet... :-)]

Cosmic rays are mostly the nuclei of atoms that have been accelerated to high velocities with a few anti-protons thrown in. The experiment is trying to find "anti-helium" (since an anti-proton is effectively "anti-hydrogen"). Such a finding might be an indication that some galaxies could be composed entirely of anti-matter. If such a galaxy were to collide with a normal-matter galaxy the fireworks would be quite amazing.

The NASA press release is at: