Lowest energy neutrino transmutations

[snorkack]

What are the lowest energy transmutation caused by a neutrino and an antineutrino respectively?

 

[Simon Bridge]

probably the transmutation of the neutrino into itself.
you should be able to answer this for yourself - what are the possible transmutations?
what would be the "energy of the transmutation"?

 

[snorkack]

With neutrino, the reaction should be
n+nue->p+e, right?
Therefore the lowest energy transmutation due to a neutrino should be the reverse of the lowest energy electron capture.

Which nucleus, of all nuclei, has lowest energy of electron capture?

Detecting antineutrinos should be much harder:
p+antinue->n+e+ should have a huge energy threshold
while p+antinue+e->n should be improbable because 1) it takes 3 particles at the start and 2) because there is only 1 particle at the end, it should be hard to dispose of excess energy.

 

[mfb]

p+antinue->n+e+ should have a huge energy threshold

Not huge compared to typical neutrino energies. But you can do this in a nucleus like tritium, where it can be threshold-free.

while p+antinue+e->n should be improbable because 1) it takes 3 particles at the start and 2) because there is only 1 particle at the end, it should be hard to dispose of excess energy.

Right.

 

[snorkack]

Where can data of electron capture energies be found systematically presented?

It seems that lowest energy electron capture should be the 163-Ho/163-Dy system... about 2,6 keV needed. What are the other low energy electron captures?

Not huge compared to typical neutrino energies? Typical neutrino energies should be couple hundred keV. The reaction p+p->d+e++nue has just about 400 keV energy, and that has to be divided between the neutrino and positron. So much of the time the neutrino should not have the 232 keV to transmute gallium 71.
So - are there any isotopes besides dysprosium 163 whose transmutation energy is lower than the 232 keV of gallium 71?

 

[mfb]

163 Ho/Dy and Tritium are well-known for their low transition energies, the neutrino mass experiments use them for this reason.

There are multiple websites with nuclear data, they all have different advantages and disadvantages.

 

[snorkack]

I´m puzzled why Ga-71 is used in radiochemical detection. There should be many ways to lose Ge-71 and its radiation, and even if caught the timing, energy and direction information is lost.

Ga-71 is commonly used to produce blue photons. So why not detect neutrinos with a gallium 71 nitride crystal? Any neutrino interacting with it should produce holes and electrons in the semiconductor and emit a number of photons easily detected.
Would a gallium nitride blue flash incorporate clear information of the direction of the incoming neutrino?

 

[Vanadium 50]

Gallium is used because the germanium can be chemically extracted easily - for example, by making germane gas - and the atoms of germanium counted. These experiments are not done in real time: they take a ~month-long exposure, remove and count the germanium, and repeat.