What are the two types of radiation that cannot escape the shielding in a nuclear gauge?

The correct choice identifies alpha and beta radiation as the types that cannot escape the shielding in a nuclear gauge. Both alpha and beta particles have relatively low penetrating power compared to other forms of radiation. Alpha particles, which are positively charged, are easily stopped by a sheet of paper or even the outer layer of human skin. Beta particles, which are negatively charged, can penetrate further than alpha particles but can still be stopped by materials such as plastic, glass, or a few millimeters of aluminum.

In a nuclear gauge, effective shielding materials are used to contain radiation, particularly ensuring that alpha and beta emissions do not pose a risk outside the device. Therefore, the materials used for shielding in nuclear gauges are designed to effectively block these types of radiation.

On the other hand, gamma and neutron radiation have higher penetrating abilities. Gamma rays can traverse through several centimeters of lead or concrete, which is why they require more substantial shielding. Neutron radiation is also more penetrating and typically requires materials rich in hydrogen, such as water or polyethylene, for adequate absorption. Similarly, X-rays can be somewhat penetrative and require careful consideration in shielding design but are not the focus of this question. Thus, alpha and beta are appropriately chosen as the two types of radiation that cannot escape