# Neutron Isomerie

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1. Apr 15, 2015

### Garlic

Hello everyone,
Can a hadron be in an excited stage? If yes, can neutrons -the element- neutronium have a nuclear isomer in a metastable stage, making it have a longer half life?

2. Apr 15, 2015

### Orodruin

Staff Emeritus
Yes, but hadrons with the same quark content but different internal configuration will generally be listed as separate hadrons.

Excited states generally have shorter half-lives than the ground states.

3. Apr 15, 2015

### Garlic

[QUOTE="Excited states generally have shorter half-lives than the ground states.[/QUOTE]

I understand, but aren't some Isomers of an Atom (Sodium-22m for example) have longer half live, and the letter "m" is put in order to indicate that it is an Isomer with a higher half life?

4. Apr 15, 2015

### Orodruin

Staff Emeritus
The m means that it is more stable than you would typically expect. It does not mean that it is more stable than the ground state. For example sodium 22 has a half life 2.6 years while sodium 22m has a half life of roughly 250 ns.

5. Apr 15, 2015

### Garlic

Okay. Thank you..

6. Apr 15, 2015

### Staff: Mentor

There are nuclear isomers with a longer half-life - most notably 180mTa where no decay has been observed so far (half-life > 1015 years) while the ground-state has a half-life of just 8 hours.

Single hadrons don't show such metastability. If they can decay via the strong or electromagnetic interaction they do so within ~10-20 seconds. If they can decay via the weak interaction only they live longer, but apart from the neutron "longer" still means pico- to nanoseconds.

7. Apr 18, 2015

### vanhees71

Here's the explanation for this astonishing phenomenon. It's a drastic example for the application of selection rules:

http://en.wikipedia.org/wiki/Nuclear_isomer#High_spin_suppression_of_decay

Another drastic change in halflife of a beta-decaying nucleus can be due to the Pauli effect, the socalled bound-state beta decay. A nice example is Re187. This isotope as a neutral atom has a half-life of about $40 \cdot 10^{9} yr$. As measured in the storage ring at the heavy-ion research center in Darmstadt (GSI), the half-life of a Re187 ion is only about 33 yr! The reason is that the beta-decay electron cannot be emitted easily in the case of the atom with all its electrons around, because it's energy is such that it would have to end up in an occupied atomic state.

That's pretty important in astrophysics, as you can read here:

http://www.euroschoolonexoticbeams.be/site/files/nlp/LNP651_contrib5.pdf