More or less. The difference is that, if they really wanted to, they could very thoroughly clean the notebook and take most of the contamination off. I’m guessing they won’t because a) It’s a historical artifact and they don’t want to risk damaging it, b) the contamination is so low-level that it’s not dangerous as long as you don’t lick it or something, and/or c) there’s a bit of a shock factor in watching a scientist’s notebook make a Geiger counter freak out.

So there’s four types of radiation: alpha, beta, gamma, and neutron. When you’re talking about radioactive materials, it’s almost exclusively the first three. In addition to the inherent danger of the object itself, there’s also the danger of radioactive contamination: not making other things radioactive, but shedding bits of themselves as dust and then that dust getting on other things, or getting ingested/inhaled by humans.

Active fission reactions, like what goes on in the core of a nuclear reactor (or perhaps messing around with some plutonium and a screwdriver), produce neutron radiation. Neutrons can make other things radioactive, via a process called “neutron activation”, whereby the neutrons bind to the material and change some of the atoms into radioactive isotopes.

I hope that helps, and feel free to ask me anything else about radiation. I have some education about it thanks to my job, and I’m always happy to help other people understand it more as well.