Reaction Q value and threshold energy

[oksuz_]

In order to calculate the energy of a reaction's ejectile, we make use of the concepts of the conservation of energy and momentum along with the reaction Q energy. However, if there is a threshold energy with above zero, meaning Q value is negative, do we have to consider the threshold energy as we calculate the energy of the ejectile?

Thank you!

 

[mfb]

The energy of the incoming particles has to be high enough to meet this threshold, and the threshold energy enters the calculations.

 

[oksuz_]

If the incoming particle's energy is higher than the threshold energy, then we should consider the energy of the particle, not the threshold energy, should not we? And also Q-value enters the calculations, but it is, in this circumstances, negative. Am I right?

 

[mfb]

then we should consider the energy of the particle, not the threshold energy, should not we?

Both are relevant.

And also Q-value enters the calculations, but it is, in this circumstances, negative.

That is very closely linked to the threshold energy.