Question

The effective neutron capture radius of a nucleus having a cross-section of 1.0 barn is:

[Given: $1barn=1.0\times {10}^{-24}c{m}^2$]

• A. $5.6\times {10}^{-13}cm$
• B. $4.3\times {10}^{-13}cm$
• C. $2.3\times {10}^{-11}cm$
• D. $5.6\times {10}^{-24}cm$

Answer 1

Answer: (A)

$5.6\times {10}^{-13}cm$

Given that,

$1.0barn=1.0\times {10}^{-24}c{m}^2={10}^{-28}{m}^2$

The area of a circle is given by $A=\pi r^2$

Hence,

$r=\sqrt{\frac{A}{\pi }}$

$r=\sqrt{\frac{(1.0\times {10}^{-24})c{m}^2}{3.14}}$

$r=5.6\times {10}^{-13}cm$