I am reading the book The Greatest Story Ever Told ... So Far by Lawrence Krauss, and I came across this in chapter 9:
In 1930 Bothe and his assistant Herbert Becker observed something completely new and unexpected. While bombarding beryllium nuclei with products of nuclear decay called alpha particles (already known to be the nuclei of helium), the two observed the emission of a completely new form of high-energy radiation. This radiation had two unique features. It was more penetrating than the most energetic gamma rays, but like gamma rays, the radiation was composed of electrically neutral particles so that it did not ionise atoms as it passed through matter.
I found the last part confusing:
... It was more penetrating than the most energetic gamma rays, but like gamma rays, the radiation was composed of electrically neutral particles so that it did not ionise atoms as it passed through matter.
My understanding was (and my web searching seems to corroborate this), that gamma rays DO ionise atoms as they pass through matter -- which is why they're so damaging to organisms. But this passage seems to state that gamma rays DO NOT ionise atoms as they pass through matter? Or is this passage specifically referring to certain types of atoms such as lead?
I would greatly appreciate it if people could please take the time to clarify this.