## **Core Concept**
Bragg's peak refers to the phenomenon where the energy loss of charged particles, such as protons or heavy ions, increases as they travel through a material, reaching a maximum at a specific depth. This concept is crucial in **particle therapy**, particularly in **proton therapy**, where it is utilized to target tumors with precision.

## **Why the Correct Answer is Right**
The correct answer, **Protons**, is right because Bragg's peak is a characteristic feature of proton beams as they interact with matter. Protons exhibit a unique property where their energy deposition increases as they approach the end of their range, resulting in a sharp peak of energy deposition at a specific depth. This allows for precise targeting of tumors while minimizing damage to surrounding healthy tissues.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Electrons do not exhibit a Bragg peak in the same way protons do. Instead, electrons deposit their energy more uniformly as they travel through tissue.
- **Option B:** Photons (such as those from X-rays or gamma rays) do not have a Bragg peak; their energy absorption in tissue is described by different principles.
- **Option C:** Alpha particles do exhibit a Bragg peak, but the question seems to focus on the application and specificity to **proton therapy**.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the **Bragg peak** allows for **conformal dose distribution** in proton therapy, making it highly effective for treating tumors located near critical structures. This precision reduces side effects and improves outcomes for patients with certain types of cancer.

## **Correct Answer:** . Protons