Marie Curie’s notebooks are still radioactive due to the presence of radium-226, which has a half-life of about 1,600 years. To make her notebook non-radioactive or significantly reduce its radioactivity, the following methods could theoretically be used:

1. Chemical Removal or Neutralization:

   • Chemical Extraction: This involves using chemicals to extract the radioactive elements from the paper. This process would be complex and potentially damage the paper.
   • Neutralization: This would involve converting the radioactive materials into stable, non-radioactive elements. However, there are no practical methods currently available for neutralizing radium in situ.

2. Encapsulation:

   • Instead of making the notebook non-radioactive, it could be permanently encapsulated in a material that blocks radiation, such as lead-lined containers or specialized glass. This wouldn’t make the notebook safe to handle without protection, but it would contain the radiation.

3. Decay Time:

   • Given the long half-life of radium-226, waiting for the radioactivity to decay to safe levels is impractical since it would take thousands of years for the radioactivity to diminish significantly.

4. Advanced Radiation Mitigation Techniques:

   • There are experimental methods like targeted transmutation, where the radioactive elements are bombarded with particles to induce decay into stable elements. This is highly theoretical and not feasible with current technology for something as delicate as a notebook.

Practically, due to the historical and scientific value of Marie Curie’s notebooks, they are preserved and stored in controlled environments where they can be studied safely using appropriate radiation protection measures. The best approach currently is to handle and store them with care rather than attempting to decontaminate them.