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Question #43706
The Question
In a theoretical statistical model of beta decay, the probability density of emitting a non-relativistic beta particle of mass with kinetic energy is given by , where is the endpoint kinetic energy, is a normalization constant, and is a very large integer () representing the phase space degrees of freedom.
To account for the wave nature of the beta particle, a quantum suppression factor is introduced. is defined as the ratio of the nuclear volume to the spherical volume associated with the electron's de Broglie wavelength (i.e., ).
The modified quantum probability density is , where is another normalization constant. Let and be the most probable kinetic energies of the beta particle in the classical and quantum models, respectively. What is the limiting value of the ratio for ?
Options
- A.
1.5
- B.
2.5
- C.
3.5
- D.
4.0
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Intuition_Breaker
Train your brain to resist "obvious" answers that are designed to deceive your intuition.
Concepts Behind This Question
Energy Distribution in Beta Decay|De Broglie Wavelength Scaling|Approximation (Binomial)
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to integrate quantum mechanical wave properties into a classical statistical mechanics phase-space distribution.
The primary trap lies in the De Broglie wavelength scaling: students often incorrectly assume (relativistic) instead of (non-relativistic), which leads to an incorrect suppression factor and a wrong ratio of 4.0.
Furthermore, the problem forces the use of the exponential limit approximation (derived from the binomial expansion).
Students who fail to recognize this will be bogged down in heavy algebraic differentiation (math bloat), increasing the likelihood of calculation errors.
Finally, a common structural mistake is applying but forgetting to multiply it by the original classical density prefactor , leading to an incorrect ratio of 1.5.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Nuclei - Class 12 |
| Concept | Energy Distribution in Beta Decay |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |