Darmstadtium is named after the German town of Darmstadt, which is where the big German
accelerator is situated. A letter arrived from Germany, from the institute
where they make all the elements from 107 up to 112. And all being well I want to go
and visit the institute so that we can actually see where these elements are being made.
So we’re in Darmstadt in Germany where they made 6 different super heavy elements and
I’m just going to show you how they did it.
So imagine that this tree here is a lead target full of atoms and here I’ve got the atom
of a lighter element, say copper or iron, and I throw it and it doesn’t stick and
you go on throwing and throwing, more and more. And eventually, after days perhaps,
they stick together and you make a big atom. This is one of your new elements. And the
atom flies off from the target to a detector, and when it gets to the detector you may still
be unlucky and it may all fall to bits. If you’re really lucky little bits fall off,
one particle after another. And if you do very clever measurements from the way that
these particles are formed you can work out what the original atom was. And so you can
say I’ve discovered a new element. Well this is a door to protect the people
outside from x-rays in the accelerator tunnel here, very important for the health of the
colleagues. How heavy is the door?
The door has a weight of approximately 70 tonnes because it’s filled with lead.
We’re finally here in the linear accelerator hall where they accelerate the ions. So the
ions start behind this wall, behind me, and they go down quite a narrow tube. So the tube
is quite narrow, about 30 millimetres diameter, and inside that there is the beam of ions.
So let’s walk along and see where the ions go.
By the time we get to here the ions are already travelling at 5% of the speed of light so
they accelerate enormously faster than a car or something like that, because they’re
so light. And when they get to here this is the so-called ‘stripper’, which strips
off more electrons so they can accelerate the ions even faster. So let’s keep going
and see where the experiment is. So as we go along the here the ions are going
faster and faster and faster all the time inside the tube.
So here we’re nearly at the end of the accelerator and the experiment is over there 30 metres
behind that wall. And we’ll go round and see it in a minute.
The ions here are accelerated and you can choose the speed. If you’re driving the
machine flat out they can go up to 20% of the speed of light. But that’s actually
too much energy for making the elements, so for the elements you settle for only 10% of
the speed of the light. And the way you make them go fast is by putting in energy from
radio waves. I’ve just been told by Ingo here from GSI that these radio waves really
are the same frequency as broadcasts and 20 years ago the American Forces Network, which
used to broadcast in Germany, used to increase their transmission power at 5 o’clock, when
the soldiers went for their tea, and they could notice this in the beam because all
their control circuits suddenly responded to the increased power of the radio station.
So now we go to the region which is usually closed during the experiment because they
have radiation inside. So now this is the place where the new elements are actually
produced. So here is the target amountage, the beam
is coming from here, from the accelerator, which you have just seen, along the tube here.
Then the beam is directed into the centre of the target and I can show you just such
a target wheel which we use here. Here you see such a target wheel which is mounted on
the axis of this motor here. Then it’s like this in the beam, the beam hits the targets
here, and the wheel rotates with about 1000 revolutions per minute. Here you see the original
of our target box, and all of the six elements which were made at GSI were made here in this
box. I will show you the biggest secret now. So
this is now our detector area. And here the ions are coming from the separator and they
are implanted into a silicone detector and this detector is now within this box and now
I will show you how it looks like and I will open the box.
I’m very excited, never seen anything like this before, so it’s really a real first
for me, I’ve never met anybody who’s discovered an element.
So now you see our secret. You see this is the main part for the identification and detection
of the elements. The beam comes from here and this detector is then mounted in this
direction here. The whole system is cooled to minus 20 degrees, and this gives us a much
better energy resolution. When a particle comes into the detector we measure the time
when it arrived and this can be done within a microsecond you will see. Then we measure
the energy of the particle which comes into the detector and we measure at which place
in the detector, and this we can do with the position of point one millimetre. Usually
this is hidden in the vacuum box and you don’t see it I just opened it to show it to you.
Do you feel like this is a piece of history? Certainly. Our first version which we had
is already in the museum in the Deutsches Museum in Bonn now. This is already a second
version and an improved one. Yes with the detector in the museum we saw
all the elements under 700, 800, 9. With this detector we saw under 10, 11 and 12.