複選題
18. In a Compton scattering experiment, the spectrum of scattered X-rays displays two distinct peaks: a modified peak at wavelength $\lambda'$ and an unmodified peak at the incident wavelength $\lambda$. The Compton shift is defined as $\Delta \lambda = \lambda' - \lambda$. Which of the following statements regarding this experiment are correct?


(A) The modified peak is due to scattering from loosely bound electrons.

(B) The Compton shift $\Delta \lambda$ is independent of the wavelength $\lambda$ of the incident X-ray.

(C) The Compton shift $\Delta \lambda$ is always smaller than or equal to zero ($\Delta \lambda \leq 0$).

(D) The Compton shift $\Delta \lambda$ depends strongly on the atomic number $Z$ of the target material.

(E) The Compton shift $\Delta \lambda$ varies with the scattering angle $\theta$.