In the news we've we've seen and heard this new term Millie Seaver.

It sort of used it as a unit of radiation, eh?

So what is it?

So we got our Millis Eve it unit.

And of course, not surprisingly amily.

Seaver.

It is one thousands off 11 secret, of course.

But what is this Eve it receive?

It is, if you like the human response, That's the important thing.

Is the human response to to radiation It contains all the information it needs about the type of radiation on the type of tissue.

In other words, where the radiation ends up with the physics of the of the measurement, in a sense, comes from our unit of Grey, Our unit of of Dose Andi.

The united ace is measured in one jewel per kilogram.

In other words, the energy that's deposited in literally one kilogram of tissue, which is probably around about that size.

To humanize the response, we clearly need to know about the effect of the radiation.

So the first thing to do is to multiply the dose in gray by a radiation factor on DDE.

If they're out of particles, particularly destructive.

We reallocate the factor of about 20 for gamma only a multiplier of one, because we know that an Alfa source is more damaging than the gamma source.

Actually, most of the gamma goes through you without being absorbed.

So it's whereas the alfa particles are going to get stopped very easily by your by your tissue.

That's liberating their energy.

We want our measurement deceiver to reflect how dangerous these thes particles are in some relative way.

So a doubt a particle is 20 times more dangerous than a gamma photons.

Clearly, we want to know where what sort of particulate waas, but we also need to know where it lands up now.

Radiation deposited in certain types of tissue, like Gonen, is the breast of thyroid and so on, and more likely to have a negative response on other words of development of cancer than than bone or something like that.

So we have to allocate different portion different Waiting's two different different tissues to reflect their likelihood of responding to radiation.

So we then multiply our Cleveland dose by another parameter, which gives us the effective equivalent dose on Here we are we've actually arrived at our arse.

Evert.

Our measurement notice.

It's still got the same fundamental unit joules per kilogram.

What does one Seaver it actually actually do to us?

Well, the one see vert given over a lifetime.

In other words, we add up our annual dose over many years or our little individual doses.

One Seaver would give us around about 5% chance of suffering from a fatal cancer.

So in other words, now we've We have humanized the unit into a probability when I say stress that it is only a probability of getting getting a fatal cancer.

Okay, so let's try and put this in some sort of some sort of context.

What?

You know what the quantity is actually a Seaver on.

The easiest way to do that is to just to think about our natural radiation dose.

In other words, the dose that comes from, um, gamma rays coming out of the rocks.

Very small cosmic rays coming out of coming out of the sky again.

Very small.

Actually.

The carbon on the potassium inside us also gives us our own gamma radiation.

And so if we had all these things together on DDE.

Assuming a sort of average UK type of figure, we end up with about 2.5 mil e c verts as the annual average dose for somebody in the UK Now, of course, you can see that you're likely to live long enough to actually receive receiver to radiation.

Unless, of course, you have a medical X ray or ah, lot of dental X rays, you would not be able to get Thio receiver.

So, really, the units of Seaver it are only really relevant for nuclear industry.

Clearly, the nuclear reactor that's gone wrong will generate a lot of radioactive material.

Certainly if it gets out into the environment with cesium.

For instance, of Gamma remit, I, Dean and sauna beater emitter on dhe thes could be taken up and in the body.

It could be breathed in and so on, and that will produce over a lifetime, quite a high dose or could produce quite a high dose.

So it's right that people are removed from the from the locality unless they're wearing protective protective equipment on taking appropriate appropriate precautions and so on.

Seaver.

It is really designed in terms of the units and probabilities as to to try and work out what lifetime doses do.

A long term doses lily with a very sudden and short days.

Then anything can happen.

In point of fact, if you get to the sort of level of 5 to 10 see votes in total, then we'll fight to 10 grey.

That is a sort of radiation dose that would make you seriously ill.

Onda Very unlikely to survive Still a scientific unit.

But in the end, we've got a certain uncertainty in the fact that somebody having a certain level of radiation one person is going thio get developed cancer.

One person, isn't it?

It's really the probability that that particle or that gamma photons actually did some damage to our d.

N A motor didn't go straight past that having any effect whatsoever.

But some of them will obviously cause damage.

On, of course, is a probability that that damage will actually go on to develop cancer.

And that's actually very, very low number.

Well, I thought I'd just go and show you a brief demonstration of how to measure how we measure gamma radiation.

You may have seen that garden mullah tubes and the little and counters that they were using to measure Seaver since Arnold Equivalent in camera.

So I'd like to just show you that Well, clearly, with radiation sources being very dangerous, we have to keep them under lock and key is gonna cover it.

And inside this box, you see right in the center of that, that box is a tiny dot and that's a cesium 137 that's producing radiation all the time.

Now it's in this box such that it's safe for me to handle.

Way got here is a is a gamma detector is going to detect the gamma radiation from the from the cesium.

It's a special crystal inside the sea inside, too.

Can there?

This is very similar device to the thing that people have been using.

Toe monitor, monitor radiation.

You might have seen people doing this.

This is this is a sort of instrument that they would have been using.

Okay, so what you're now seeing is the gamma particles being received on being counted.

Well, each one of those gamma photons is carrying a certain amount of send amount of energy.

And of course, we can adult that energy.

Assuming that it all ends up in one kilogram of tissue, then we can calculate the dose on dhe.

Therefore, the effective dose in Seaver's.

So effectively we've we've now counted the number of gamma particles that arriving at our detector.

Now, of course, what we don't know is where all the other particles were going in that cesium sample.

Because, of course, they're going in all directions.

So again we got we got to know something about the geometry of where the where the season particle is.

And so if it was on the skin, for instance, then clearly that's going to most of that.

Half of it is going to go into the skin.

If it's in the air somewhere, then clearly the gamma rays are going to go in all directions.

I'm only going to get a small part of that.

Well, what we got here is yet another method of measuring radiation somewhat simpler than the radiation method.

We've just seen the gamma counter, but this is sensitive to Alfa beater on gamma.

So if I then pick up in amorous IAM source, which is contained in this in this little container was in this little container, then I place it near my Geiger counter.

Then you see how close I have to get before this actually registers any sort of can on.

Really?

That shows us that the alpha particles coming out of here don't come.

Don't travel very far in there.

No effect there, really.

Lots of this.

The sort of radiation sources which we're allowed to use in teaching laboratories by their very nature are going to be very low levels off radiation.

They're enough to us to measure, but hopefully not enough for us to do any serious, serious damage with.

So this is this is off the scale in terms of microsieverts on it would have to stay there on my skin, for instance, for for quite some time before I got anywhere near a dangerous level.