Question

The rest mass of the deuteron, ${}_1^{2}H,$ is equivalent to an energy of $1876MeV$, the rest mass of a proton is equivalent to $939MeV$ and that if a neutron to $940MeV$. A deuteron may disintegrate to a proton and a neutron if it:

• A. emits a $\gamma$-ray photon of energy $2MeV$
• B. Captures a $\gamma$-ray photon of energy $2MeV$
• C. emits a $\gamma$-ray photon of energy $3MeV$
• D. Captures a $\gamma$-ray photon of energy $3MeV$

Answer 1

The correct option is D Captures a $\gamma$-ray photon of energy $3MeV$

$\begin{array}{c}\text{Given,}\\ {\text{Rest mass of}}_1^{2}H\left(deutron\right)=1876Mev\end{array}$

$\begin{array}{c}{\text{Rest mass of}}_1^{1}H\left(proton\right)=939Mev\end{array}$

$\begin{array}{c}{\text{Rest mass of}}_0^{1}n\left(neutron\right)=940Mev\end{array}$

${}_1^{2}H\to {}_1^{1}H+{}_0^{1}n$

$\begin{array}{c}(\text{Qvalue)}=\text{Enerey of product - Energy of reactent}\\ =(939+940)-1876\end{array}$

$\left(Q\text{-value}\right)=3Mev$

$\begin{array}{c}\text{Hence energy of product side is higher than}\\ \text{energy of reactant side by}3\text{ev.}\end{array}$

$\begin{array}{c}\text{So, Reactant side will captare}\gamma \text{ray of Energy}\\ 3Mev\\ \text{So, our option (D) is correct}\end{array}$