Which of the following detects radiations by flashes produced on a phosphorscreen ?

Options

A. `GM` counter
B. Bubble chamber
C. Ionization chamber
D. Scintillation counter

Answer

To solve the question "Which of the following detects radiations by flashes produced on a phosphor screen?" we will analyze the given options one by one.

### Step 1: Understand the options
The options provided are:
1. GM counter
2. Bubble chamber
3. Ionization chamber
4. Scintillation counter

### Step 2: Analyze each option
- **GM Counter (Geiger-Muller Counter)**: This device detects radiation by ionizing gas within a tube and producing a measurable electrical pulse. It does not specifically mention detecting flashes on a phosphor screen.

- **Bubble Chamber**: This device is used to visualize the passage of charged particles through a superheated liquid. It does not produce flashes on a phosphor screen.

- **Ionization Chamber**: This device measures ionizing radiation by collecting charges produced by ionization in a gas. It does not involve a phosphor screen.

- **Scintillation Counter**: This device detects radiation by using a scintillator material that emits flashes of light (scintillations) when it absorbs ionizing radiation. These flashes are then detected by a photomultiplier tube or similar device.

### Step 3: Identify the correct answer
Based on the analysis, the correct answer is the **Scintillation Counter** because it specifically detects radiation by producing flashes on a phosphor screen.

### Final Answer:
The correct answer is **Scintillation Counter**.

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