Physics IA.

I'm currently in IBDP Y1, and now in the summer going onto Y2. I've decided that I wanted to start working on my physics and math IAs first, as I have the most time to reiterate and improve upon it. Being that this is the case, I spent some time searching for a good RQ. However, my Y1 teacher left in the last week of school, where we were supposed to do IA planning and start working on the first parts of it, so I've had and don't have any guidance as to how I should evaluate whether my IA idea is good enough. For those in a similar position/have been, do you have any advice as to how I can lock in an idea that is feasible before starting to write it?

If you feel up to it, here's my proposed RQ that I wanted to get feedback or advice on. I'm not asking for any feedback directly, but if you feel it's noteworthy, please let me know.

"How does lead shielding thickness x (mm), tested from 0 to 50 mm in 5 mm increments, affect the transmitted gamma-ray intensity I (counts s^-1) from a simulated cesium-137 source, as determined from a Monte Carlo attenuation model?"

P.S. This is for Physics HL.