Recently, I attended a school on particle physics, and there was this particular hands-on session on building a small simple wire chamber and the wire chamber was filled with argon gas. The lecturer mentioned that the x-ray radiation (from a radioactive source placed to show how wire chamber works) will cause the electron to come out of argon through the photoelectric effect. I was confused with it, as it always occurs to me that photoelectric effect occurs on solid surfaces. As I asked, the lecturer explained that it is photoelectric effect and its not just normal ionization. He further explained that ionization occurs at the outermost shell while photoelectric effect occurs in the K-shell with a high electric field (The main characteristics?, he was a Japanese lecturer and I can't really understand well with his accent [no offence intended]). If he said that an electron coming out from a cloud of gas that escaped from the force to pull the electron back to the gas is the photoelectric effect, it would make much more sense to me but it wasn't the case.
And a Vietnamese postgrad participant (Again, the accent was too strong for me to understand [no offence intended]) also explained to me that if with more energy, we won't have the photoelectric effect, we would have Compton and pair production. This boggles me for a while now, and essentially I have few questions:
- Is it true that Photoelectric effect occurs in gas?
- If so, is there a way to differentiate photoelectric effect and other electron-producing effects?
- Does photoelectric effect consider as ionization too? (Since the atom becomes an ion anyway)
- Is there anymore reference or materials more on photoelectric effect in gas?
- Lastly, won't it be easier outermost electron to escape than the core electrons, since x-ray have so high energy + the outermost shell have low ionization energy?