Superheavy Elements: The End of the Periodic Table

good mid morning good mid morning back who's here who's been to all four science lectures amazing, good to see you welcome to Livermore at the Bankhead theater and thank you for coming to the last of the four science presentations on Saturday Lawrence limore National Laboratory produces these science series with the help of local educators, as this is the last of the Saturday science series. I would like to thank Mr. Dick Dick Farnsworth, Limore Laboratory Science Education Program Manager, for providing these teachable moments as well. Many thanks to the staff, videographers and those who make these performances possible, so let's say a big thank you today.

Our topic is Super Heavy Elements, Search for the End of the Periodic Table, doesn't that sound like a title of a movie where a boastful scientist wearing a hat and a whip searches an Ikea store for a very special heavy piece of furniture. Well, maybe not, but here to talk to you about heavy

elements

is Dr. Ken Moody, chief scientist of radiochemistry at Lawrence Livermore. National Laboratory and Dean Ree, teacher of physics and biology at Tracy High School Liver Dean received his bachelor's degree in physics with a double minor in astronomy from the University of Massachusetts in 2002 and upon completion of his bachelor's degree, Dean decided to move to California and try his hand at teaching and has been doing so ever since.

Thank you Dean for becoming a professor and for inspiring our future scientists. Dr. Moody has been a member of the Livermore laboratory staff since 1985 and specializes in heavy element science and radiochemical separations. He received his Ph.D. in nuclear chemistry from the University of California at Berkeley in 1983. I'm sure that in the world of heavy

elements

, Dr. Moody is considered a rock star. If you had a band, it would be called The Heavy Elements and in this one that's the name of the group he's a core member of at the Livermore lab, which makes Dr. Moody cool: he's the co-discoverer of six elements and more. of three dozen heavy isotopes and has received the first prize in nuclear physics from The Joint Institute. for nuclear research so let's start with the lecture and please leave it for Ken and Dean thank you hello good morning uh thank you for coming uh I know when the weather is as nice as this it's really a shame to be inside so we'll try I don't want to go on a lot today um I'm talking about super heavy elements look at the end of the

periodic

table

probably the first thing we should do is talk about what a super heavy element is in the late 1960s there was when when.

The

periodic

table

ended with a much lower number of elements than it ends now. There was a further prediction that beyond the heaviest known element was a collection of elements that could have very unusual properties, including very, very long half-lives. , we call them Super heavy elements at that time were considered almost unattainable. This has been the focal point of my life for the last 30 years and for about 10 years we had some success and I will talk about that today. This topic actually lives at an interesting intersection between the physics of nuclei and the chemistry of radioactive substances.

As a result, there is a lot of basic information that we need to convey and, in fact, it killed much of the time. Last time, so bear with us, we'll get to the things that I think you know completely interesting. The part we will talk about today is that we will understand the relationship between atoms and elements, and between nuclei and isotopes. Let's talk about how new items were produced in the past and how they are produced now. We are going to talk about how the periodic table can be used to predict the properties of elements that have not yet been produced.

It has been discovered and we will talk about things that could eventually lead to the end of the periodic table. This image is actually an example of what you can do when you pay artists in Russia in dollars. In fact, you can get some. Quite an amazing piece of art and this is an image of a heavy element scientist looking through the end of the periodic table at the fundamentals of nature. It's also like a really pretty picture. Well, when I was in high school in 1969, sitting in my science class. this was the periodic table okay the periodic table ended at element 104 which was a fairly recent discovery in fact element 104 was written in bread on the table by the teacher he told us we might as well memorize it because there would be there will never be any more elements uh, I don't want to sound like I was speaking out of ignorance, I was actually very up to date at the time, it was thought that the end of the periodic table was probably around element 104 105, so uh, let's talk about how the periodic table.

In reality, it all began at the beginning of the 19th century, when it was noticed that certain chemical properties were repeated. Ok, it started with a fellow named Dober Riner in 19 or 1825, he noticed that this group of three elements. Chlorine, Potassium and Calcium When you put all the known elements on a line increasing the weight, these three elements represent halogens, alkali metals and alkaline earths. Halogens are elements that react with metal to produce salts that are generally soluble. Alkali metals like potassium are uh metals. which react violently with water and make soluble bases alkaline earth, such as calcium, react slowly with water and produce bases that are not necessarily as soluble.

It was observed that the same group of three halogens, alkali metals, alkaline earth metals, is repeated in bromine, rubidium and stone, chlorine and Bromine has very similar chemical properties. Potassium. Ridium has very similar chemical properties. It was also noted that iodine, cesium and barium, iodine is a halogen, cesium is an alkaline earth metal, barium is an or sorry, cesium and alkali metals, bariums and alkaline earth metals, many similarities between the calcium and stone. and barium, in 1871 Dimitri Mev decided to rearrange the elements from one to n by putting the elements that had similar chemical properties in the same vertical row and when he did he noticed some pretty surprising things, everything connected vertically, they all had similar chemical properties to everything.

Otherwise, in your vertical column, for example, copper, silver and gold, they are all connected vertically, those are all the metals of the coins. One of the things that was particularly important to us, because what Mle did was at the time when 61 elements were known, we know there was a lot more than that, he predicted places where he thought there should be elements that were not yet known and then he They found. I think the most important thing for him was that he saw that under the aluminum there was a space where something should be and he predicted the presence of an element and four years later gallium was found, so let's go back to 1969.

Here is the periodic table again in 1969 There are the halogens, including a couple that Menab didn't know about. Well, everyone is in a The vertical line actually the properties of halogens allowed Professor SRA and Berkeley to discover atin, which is element 85 according to the chemical properties of iodine. The next group is hydrogen and alkali metals. I didn't highlight alkaline lands, but yes. Note that when we go from halogens to alkali metals, we skip the noble gases in between. Mev didn't know about the noble gases that hadn't been discovered yet, it doesn't affect the result, but it's interesting. who didn't notice there are groups in the periodic table these are the representative elements that are sometimes called P block elements, you don't actually have to worry about the letters in front of the block, that's spectroscopic nomenclature, that's the way people talks about things that are not worth going into nowadays these are the transition metals which are a kind of elements sometimes called D block elements down here are the F block elements which are the lanides and actinides now again um Mena did not know about most of these elements and so did not include them in his periodic table.

This is called the 18 column version of the periodic table. Actually, if you divided the periodic table into groups three and four somewhere here and spread it out and stuck the lanthanides and actinides in there you would have the 32 column version of the periodic table. We usually do it this way because in 32 columns it becomes too unwieldy, it's an awkward shape, so the 1969 periodic table is the roadmap to chemical behavior. Scientists use the periodic table to discuss or understand how elements combine, how elements mix, the chemical properties they operate with and one of mle's real big victories in the periodic table was when element 104 was discovered. which has very similar chemical properties to halium, which is the element right above it on the periodic table, so let's talk about some basics again.

I'll try not to beat this to death, many of you have. You've probably already seen some of this in your science classes, uh, when this came up before, I was amazed because I didn't know that electrons were going to move. You could be completely mesmerized by, uh, okay, the smallest piece of an item it contains. that maintains all the properties of that element is the atom, okay, the word atom comes from the Greek word meaning indivisible, of course, now we know that atoms have structures in the old days, they thought they were drops. The interesting thing is that Mendelevium or Mev emerged. with a periodic table uh without any knowledge of the structure of the atom at all it was completely observational uh the atoms formed protons and neutrons that reside in the nucleus, which is a very small volume at the end of the center of the atom most of an atom is empty space electrons that have a negative charge Circle the atom electrons weigh approximately 12,000 times the weight of protons and neutrons, so most of the mass is concentrated right in the center, okay, electrons occupy again the large space The volume that is maintained in the atom by the attraction between protons and electrons several times today during the talk you will have to remember that electrostatic attraction two equal charges repel two opposite charges attract each other so the attraction between electrons and the protons are what keep the electrons from flying away, well, an ion, those of you who are making your notes, is an atom that has gained or lost an electron, if I add an electron to this atom, it becomes an negative ion because electrons have a negative charge if you remove an electron and it becomes a positive ion.

This can happen in a physics experiment where things are passed through an arc. It can also be made in the test tube with chemical processes. Well, again, Menal didn't know about the structure. of the atom uh uh, the periodic table actually acted as a kind of testing ground for atomic theories for about 50 years until the advent of quantum mechanics, when the entire structure of the periodic table could be explained by simple rules. We're not going now. Today I'm going to beat quantum mechanics because to be honest I don't really understand it all completely, but the rules define how many electrons are allowed at particular energy levels in the atom, you can't exceed a certain number of electrons in an atom . energy level if you add another electron beyond that number it has to go to an external orbital so sodium and potassium are two examples of alkali metals they are completely filled electron shells so sodium actually It looks a lot like a neon atom with an extra electron. because it has one more proton you need one more electron to counteract the nuclear charge, potassium is very similar to argon, it has 18 electrons in a closed configuration and the 19th electron to balance the nuclear charges outside the internal electric charges tends to shout the load. that the outer electron sees from the nucleus the outer electron is out there there are a lot of negative aspects between it and the nucleus and it makes it look like it's seeing a charge, that's why sodium and potassium have very similar chemical properties.

They both love to lose an electron in a chemical reaction, becoming a positive ion and looking an awful lot like a noble gas. The chemistry of these elements is actually dominated by reactions in which an electron is lost to become a positive Lon. We've talked about atoms now now we have to get into Nuclear Physics a little bit here, nuclei and isotopes. Well, the number of protons in the nucleus controls the number of electrons around the nucleus because everything is electrostatic, neutrons do not participate in that process. To any meaningful extent, if I have a hydrogen atom that has a proton in the nucleus or a hydrogen atom has a proton and a neutron in the nucleus, the chemical properties are the same because the electrons gain and lose control of the chemistry. and the number ofElectrons are controlled by the number of protons, so these are the three known isotopes of hydrogen, regular hydrogen, sometimes called prodium, here we call it hydrogen, dyum, which is a proton and a neutron, tridium, which is a proton and two neutrons, the prodium and the dyum, are stable. isotopes, meaning they have never been observed to decay.

Tridium is a radioactive isotope that decays to helium 3 with a half-life of about 14 years and we'll talk about the half-life in a minute. Each element has a certain number of stable isotopes, sometimes it is none, for example none of the elements heavier than bismuth have a stable isotope some of them have very long lived isotopes but none are stable there are 81 elements that have at least one stable isotope gold has a single stable isotope either 79 protons 79 protons in the nucleus makes it gold 118 neutrons and neutrons make it a stable isotope of gold if it has 119 neutrons it is still an isotope of gold and has the properties chemistries of gold but now it's a radioactive isotope because it's unstable upon decay element 10 has 10 stable isotopes it's the record holder if you were an element you'd like to be really competitive with tin okay so it's unstable.

Isotopes that are not stable are unstable and are radioactive. Radioactive decay is an unstable nucleus trying to achieve a stable configuration spontaneously. changing to a stable form uh we talked about that half-life concept. We have a demo for you in just a second. Here the half-life is the time it takes for half of the atoms in a sample to convert from one form to another. things have long half-lives some things have short half-lives, you might think that radioactive isotopes are something you don't need to worry about, but in reality radioactivity in nature is everywhere, there are primordial isotopes that are in nature because They have very short half-lives. very long half-lives, for example, uranium has a half-life of 4 billion years, it has been here since the universe was created, the element potassium in nature consists of three isotopes, two of them are stable, one of them is radioactive, so if you do it.

If you eat foods that contain a lot of potassium, like a banana, you are actually eating a radioactive substance and if you put a banana next to a sensitive measuring instrument, you can see the radioactive decay of the banana, so those of you who like them bananas, I apologize for ruining your dining experience. There are shorter Liv things that exist in nature, for example radium 226. Radium 226 has a half life of 1600e, it hasn't been around since the beginning of time, it's there because uranium has been there since the beginning of time. time disintegrates and keeps it alive.

There are also radioactive products like burum 7 and carbon 14 that are constantly being created in the atmosphere by cosmic ray bombardment, so nuclear reactions are going on overhead all the time right now. Well, let's do a half-life demonstration and I'll turn it over to Mr. Reese. Okay, so Dr. Moody just told us about radioactive atoms, basically atoms that decay into another form. I would like to do a demonstration here. uh I need a volunteer for this um this young lady in the gray sweater would you like to come thank you um so today's demonstration will involve M&M's which are fun um these M&M's will represent Adams come on how are you doing? to Mr.

Reese what's your name Cassandra Brown Cassandra nice to meet you um let's take a look at this so we get these M&M's right and why don't you help me here I'm going to have to I'm going to get You're involved in this let's turn over all these M&M's to Let the M's face up. Well, now I've counted them. There are 40 real M&Ms here, um, and if the M is face up, that basically means it's a radioactive atom. At this point what happens is these atoms break down over time and become a new type of atom, so take this cup and go ahead and take those 40 M&Ms face up and put them in the cup and I'm going to?

You have to shake that cup and basically that's going to mean that time is happening, so time is just happening and running and what's going to happen is that because of this random nature of radioactive decay, some of those atoms, the ones that have the m facing up, will they disintegrate? I'm not going to do it, so let's go ahead and pour them back into the plate and now what we need to do is remove everything that doesn't have an M face up and you can go ahead and put them back in this cup so that everyone who they have the M upside down, those in our little analogy here have radioactively decayed into something different, so I'm going to help you here just to speed this up, okay, and then what we're going to do is count how many of these M's, we have these radioactive atoms left. , so it looks like we have 2 4 6 8 10 12 14 16 18 22, so we start with 40 M&Ms that were all radioactive, we are left with 22 M&Ms that are radioactive and we could continue. go ahead and repeat the process again so pick them up and put them in the cup and as you can see progressively our sample size will get smaller because radioactive decay changes the radioactive atoms to a stable form but some of the radioactive atoms that he knows remain. behind Okay, go ahead and pour that in, okay and let's do the same thing, take all the ones that are face down, take them out of the sample and we'll see how many we have left. 2 4 6 8 10 12, okay, so we went from 40 to 22 to 12, you can imagine it's going to get smaller now, so one thing I want to emphasize is that this term half-life means how long it took for half of your M&Ms to become a stable atom. go from radioactive to stable, so in our little experiment after a uh, you know, throwing the cup away, we were at 22, not exactly the half-life, so the breakthrough time occurred long enough to create a lifetime half, our half life would be somewhere. between the first full cup and the second full cup that we dump on the plate, okay, so I just want to thank Cassandra for coming here.

Thank you very much and you can treat yourself, you can bring them back to your seat and enjoy. M&M's, if you like it here, you should have them sometimes, when you have a student up here, you do that, you shake, you pick up 40 and you get 36 or something funny, funny, how funny, how does that work, um, okay, there are several kinds of radioactive decay I'm not going to go over all of them with you, but some that are important for our talk are, on this slide, a beta decay, if I have an isotope that has too many neutrons, it has a stable configuration.

It has too many neutrons which make it radioactive. You will want to convert one of those neutrons into a proton by emitting an electron. It's called beta decay, so when a neutron turns into a proton, it becomes more positively charged and has to lose a negative charge. and the electrons emitted by the atom, this is particularly important to us because this is one of the ways that you can actually synthesize new elements beyond the end of the natural elements if I have an isotope of uranium and I add neutrons to it until already it is not this one. stable or no longer has a very long life, it undergoes beta decay when the neutron is converted from a neutron to a proton.

I mean, you have created element 93, which is a path to new elements. We call beta decay the indirect route. Beta decay processes now dominate. For light elements, when you like lead and it's heavier, then you start to have competition with beta decay from alpha decay. Alpha decay is actually a response of the nucleus to having too many protons crammed into a small space, well, protons packed against protons is very, very, it's very difficult to do. I mean, you're pushing a lot of positive charge, a lot of repulsive material together in a small volume mediated by neutrons, but eventually it can't work anymore and in order to get rid of the charge and become more stable in alpha decay, A helium nucleus that has two protons and two neutrons will be ejected, so not only do two elements become lighter, but four units of mass are reduced, so here we have an image on the left of Plutonium isotope that emits an alpha particle.

Plutonium is element 94. Uranium is element 92. So when you have emitted the two protons in the alpha particle, you have gone from 94 to 92, something that is not on the display graph and is also very important for our discussion and it relates to the periodic table in 1969 is that when you get to element 9798, the spontaneous fion becomes important, at that point you have packed so many protons into a small space that the nucleus simply wants to split into two more or less equal . sizes that will eventually be the end of the periodic table Is the fusion process okay?

So is there an end? In 1969, my chemistry teacher, who was aware of the latest nuclear theory, knew that if the nucleus was just a mass of charge, a mixture of protons. and neutrons, then the Kulum repulsion or electrostatic repulsion between the protons would cause the periodic to end up at element 104 or 105. It would not be possible to put more positive charge on the nucleus. Well, nuclei are not blobs, although the electrons we discussed above have shell structure certain configurations of electrons those associated with noble gases are very, very stable they are very, very resistant to chemical processes the nucleus actually also has a shell structure of shell a certain number of protons and neutrons are allowed at certain energy levels those nuclei are resistant to nuclear processes such as fission There are rules that control how many protons can be in a shell.

Well, when these nuclei were discovered, it was not known why they had additional stability. They couldn't explain their nuclear properties so they called the proton numbers the magic numbers we don't understand them we're going to call them magic the name has stuck even though we know what causes it now we still call them magic numbers okay let's wait that the magic numbers are the same as the The atomic numbers of the noble gases are probably not the reason because in an atom and electrons you have a negatively charged central potential that revolves around it, in the nucleus you do not have a central potential, the charge is distributed between all the nucleons, so the structure is completely different and therefore the magic numbers are actually not the same as the noble gas numbers, so here again, sorry to be stuck in 1969 , but some know that it was my best year.

I say, uh, wow, there are the atomic numbers of the noble gases on the right side of the box, here are the magic numbers. Well, in 1969, these were the known magic numbers: oxygen, calcium, nickel, tin, lead, one of the reasons why tin is so good. and it has all those stable isotopes and it is the envy of all the other elements it is because it is a magic number that everyone thinks of when they think of stability, they often think well of lead, the reason why lead is so stable is because it has a magic number of protons well, nuclear theory around 1969 was finally able to calculate and understand the effects that result in the magic numbers, so the next logical step is to understand the magic numbers, where is the next one and it turns out to be 114 protons?

Okay, so people understood. I'm really excited about this holy smoke, maybe the periodic table doesn't end where it is, maybe it can extend to element 114. The question is, although the theory was able to predict the magic number, it didn't. did, how far did the ex effect extend? generally speaking, on several elements or focused entirely on one particular place my old boss at Berkeley liked to show pictures of uh Mountain, so he put this on it. Okay, the effect around element 114 is like Half Doome and is only restricted around the element. 114 or is more like Mount Kilamanjaro, where it spreads over many elements because the effect is Wide.

He liked to use Mount Diablo, but I couldn't find a picture, so now let's begin our journey. Let's start our journey to create new items. Let's go back to 1940. Well, here's the periodic table for 1940. The first thing you might want to notice is that those elements are not where they were in 1969, the reason they were. It was so difficult to discover element 93 in the early days for two reasons: one is the only mistake Menal made in 1871 was that he placed those elements in that place on the periodic table when they really belonged to the Rare Earths, now he could probably be forgiven. so because we didn't know lanthanides existed at the time he put them where he thought they should go he saw some similarities between uranium and thorium and the elements immediately above them the other thing that affected our ability to find neptunium Element 93 was that When people bombarded uranium with neutrons, instead of producing one or two new radioactivities, they generated dozens of radioactivities.

Nobody could understand it if you stood back andYou looked at the chemical literature from that time, the explanations they gave were that they were crazy. I mean they just didn't make any sense. The problem was that uranium, having many protons, is very prone to fission. If you tickle it a little and excite it like you do when you pump a neutron into it, it will do it. they fall apart and make fission products, so actually people were misidentifying fission products as new heavy elements for about five or six years before someone at OT Han and Eliza Miter discovered that what was happening was that nuclear energy was envisioning and they discovered the fission process.

When elements 93 and '94 were first produced chemically, they were not isolated because, again, neptunium, which was in the wrong place, does not look much like the element above the river, so a chemical based on the chemistry of the river was not successful in recovering neptunium and Plutonium is nothing like osmium, they are not, there is no similarity, which is why one of the great radiochemists of all time, Stan Thompson, discovered what what was happening and was able to identify and develop chemical processes for neptunium and plutonium. and around the same time, 1945, after the amorium and curium were discovered, they were moved here to their current location, which is where they reside today, so it was necessary between 1871 and 1945 to replace it to correct a small error that Mev had committed in the original formulation. from the periodic table, okay, so we want to put neutrons into a nucleus, we want to create new heavy elements through Beta decay in the best direct source of neutrons, it's a nuclear reactor, uh, when I'm in a room with a kind of reactor. we will get into discussions about this graph and that is because one type of reactor is interested in the type of fusion reactor it wants fion fion produces neutronsneutrons produce more fusion, that is how the reactor operates and generates energy, so it believes that the 64% going into fion products is a good thing and you think the 36% going into capturing and producing heavy elements is a bad thing, well of course. he's completely wrong heavy elements Rock, okay, so anyway, you can see that the process is very, very inefficient.

When I make plutonium, I lost 64% of my material split to make plutonium isotopes while capturing neutrons to make p240 and make P2 41. At various places along the way I compete with vision again when I get to plutonium 241, plutonium 242 , plutonium 243, finally in pu 243, I did an activity that beta decays, so a neutron decays to a proton and element 94 becomes element 95, a new element. Element 95 captures neutrons until a beta decay isotope is produced at that point. The neutron decays into a proton. Curium is produced. You can see that the process is very, very inefficient, although when I get to the California isotopes only 3/10 percent of the things that react survive the fission process and have become California isotopes.

The heaviest element that can be produced in a reactor. Very, very small quantities of the element 100 firium can be produced. Well, the reason is that there are no beta emissions. Fermium isotopes you get, you go into the fermium, you decay through them, eventually you find a very short lived fission activity and it all ends up in the fission products, that's the end so I always have to put uh because because someone always asks what are the practical applications of these things, so let's talk about reactor isotopes here for a minute. Well, we all know that the uses of plutonium are nuclear fuel.

One thing you may not know is that plutonium isotopes are not visible. They can also be used for energy production due to the heat of decay. This is a plutonium-238 top wafer that glows red due to the energy released in its alpha decay, so it is actually red hot. They are used in a very small volume. um electric. generators, the heat source is used to produce electrical power, if you ever get a chance to see one of those, it's completely creepy, it's like the creepiest thing you've ever seen, okay, amorium element 95 amarium 95 element 95, is probably found in most In your homes, smoke sources and detectors ionize smoke particles by bombarding them with radiation from a smoke source.

There is an isotope of curium that is used in the same way as plutonium-238 in thermal electrical generators. California element 98 is probably the Holy Grail of applications it can. Use it for many different things, the neutrons that come from the fission of californium are actually used in medical treatments of various types, they are used in radiography and large scale engineering and will reduce a source of californium completely. when they are drilling for oil to see if neutrons scatter from hydrogen isotopes in the oil. Well, at this point, anything heavier than this I have no practical applications for, they are all designed to expand our knowledge of nuclear energy. structure and and atomic theory uh, new knowledge is always a good thing, we will always end up using it, uh, the example I like to give is, uh, I was at a talk once many, many years ago when someone asked a guy from NASA why we went. to the moon, what the hell, what the hell was the purpose of going to the moon and his response always stuck with me?

He said, well, you know, I can't really defend going to the moon, but to get there we had to invent Teflon, okay? At this point I can't point out Teflon to you in this topic, so from now on forget about Teflon, it's very very pure research, but knowledge is always a good thing and hopefully one day we will find Teflon. Well, items 99 and 100 actually weren't. produced in reactors, they were produced in the nuclear explosion, they were discovered in the rubble of the microphone test in 1952. We saw in that bar graph some previous graphs that in reactors neutrons are captured slowly and occasionally beta decay is reached that it takes you to the next element of the tire and then you continue capturing and the process in a nuclear explosion, which is also a large source of neutrons, is completely different because all the neutrons are delivered in a very, very short period of time, so instead of capturing, capture by disintegration.

Decay you have capture capture capture capture cap capture and then beta and then Decay Decay Decay Decay Decay uh, unfortunately, while it was useful in discovering einsteinium and fermium again, the path ends at element 100, you can't go higher than that , so at that point you have to abandon the indirect process of neutron capture followed by Beta decay and go to the direct process where you actually have to put protons into the nucleus to make its atomic number increase and create a new element . This is very difficult because the protons have the same charge as the nucleus you are trying to put them in so they repel each other.

Okay, there is a repulsive force between them, so you have to accelerate the protons to a very, very high energy to overcome the barrier. They collide with the protons and Fus to create the new elements, so we're going to do a demonstration of the accelerator for you at this point, okay Mr. Ree, so I guess at some point maybe if you pay attention to news or something So, you've heard the word particle accelerator, um, and some people wonder, why would you want to accelerate particles in the first place? and, uh, Dr. Moody was just talking about it to create these heavy elements.

You have to take positive nuclei and two positive things want to repel each other and you have to make them go very, very, very fast and hit them together so that they combine and overcome that force of repulsion, that force that makes two positive things want to. to separate you have to overcome that by having enough energy at the moment of impact to get the nucleus to combine to form a heavier element, so this device here was actually designed specifically for this talk and built for this talk by a gentleman by the name of Tom Crabtree, who is in the audience with us today, here he is, if you could defend us, thank you.

I would like to recognize his hard work. He's a retired technologist from Lawrence Limore National Laboratory and now also volunteers at the Discovery Center, so he built this, and you know, he was inspired by an idea that actually came from YouTube. We were looking at other types of homemade particle accelerators and just as a note, this is not something you can imagine. I want to try to build in your own house. This is something that professionals should build. There are energy sources involved and they can be dangerous. But yeah, we were lucky enough to have one built, so let me talk to you.

In this regard, first of all, the particle that will be accelerated is a pingpong ball, it doesn't look like a pingpong ball because it has been encoded with a metallic paint and, do you know one thing you know about metals? Yeah, what's good? That's true, if they have moving charges, they could be attracted to the magnets. What else happens to the metals that make them up? Yeah, you know, yeah, so metals are good conductors of electricity and they have loose outer electrons. Okay, that's one thing. What makes metals metals is that they have loose outer electrons, so you have this source of energy in this punch bowl, and as you look inside, you can see that there are some positive bands and some negative bands, and the positive bands attract electrons. from this.

You know, metal, coated ball, so the electrons will be attracted to the positive band and removed, and when they leave, guess what charge, the pingpong ball becomes positive and now it's still next to a positive band, so which the two positives will repel each other, which will push this. The ball in one direction will also bring it closer to the negative rail and now again you still have the positive pingpong ball, but it is being attracted towards a negative rail because opposites attract and once it gets to the negative rail, they are actually the electrons. it comes back to the surface and it becomes negative there and then it repels the negative band and it keeps getting pushed and pulled and pushed and pulled so let me show you how this works so you can see it and there.

It's so just by feeding this and creating a voltage, this just wants to move in circles and if this was a particle and a particle accelerator, you would have a really high voltage, you would make this move very fast, like at close speeds. approach the speed of light and then you would smash it into another heavy atom and hope that the two positive nuclei have enough strength so that when they collide they create larger positive nuclei and that is how you can discover heavier elements. Okay, yes, high voltage. Okay, can we look at the graphs again?

Well, part of the problem is overcoming this potential barrier that Mr. Ree was talking about. You have to hit these cores hard. What happens then is that you are forced to do it. produces a nucleus that has a very, very high level of arousal. You can think of it as heat. If you throw two drops of liquid at each other, they basically boil because you threw them with so much force. Because fission resistance decreases as the core charge increases and increases, the probability that the products you are making will survive decreases, for example, in the experiments that were carried out from 19 69 to about 19 well. say 19 from the 1950s to 1969, when these reactions were used to form the atom, the isotopes of elements 101 to 104, element 104, we can actually produce several atoms per minute in a bombardment of charged particles in a particle accelerator, maybe that doesn't ring a bell.

I like it a lot, but if you go to element 106 you can only generate several atoms in one hour and if you go to element 108 you can only generate several atoms in one day. Now we are trying to assault the island of stability at element 114 and if we move forward a little bit, we actually have to launch 10 to 18 particles at a target that is a million trillion particles for one of them to survive the fission process. and produce the new element that interests us. It takes many, many, many days. maybe weeks to generate 10 to 18 particles and accelerate them and deliver them to a target so that it doesn't become an atom of this stuff very often, that's why these experiments are so difficult, there is actually also a tendency to increase The charge during the half-life of things will get shorter, of course, we hope that the effect of the magic number 114 will counteract this to some extent, from 1970, when my favorite periodic table ended, until 1996, six elements from 105 to 112 were produced in various laboratories throughout the world.

At that point, it became obvious to the world that it was time to think about storming the shores of the island of stability centered on element 114. Now I'm going to talk a little about those experiments here, so a super heavy element has to start. with heavy element target materials to do these experiments, actuallyWe start with isotopes of plutonium, amorium and curium, we bombard them with heavy ions to produce heavier elements, so you first have to produce the target materials in a reactor using the processes we talked about. This is the high flux reactor at Oak Ridge they are taking out a target that has been irradiated to mercury for about 18 months.

You can see by the blue glow that it is very intensely radioactive. They manipulate it under a puddle of water. Well, after that you have to do it. take that goal and you have to separate the things that interest you. Remember there are a lot of fionic products there, so the image on the left is an ion exchange column. An ion exchange material is a material that has a certain chemical substance. attraction towards certain elements you choose your ion exchanger in this case the curium is stuck to the resin the fission products drip down and collect in a cone below so you can see from the blue glow that the fission products are very intensely radioactive this Image is taken through 6 feet of water to protect the chemical operator from this thing, curium itself, when beta particles from fission products hit, glows bright orange, which is kind of like what you see there At the top of the column, there is a water jacket. around that which cools it because the reactants tend to boil due to radioactivity, nothing is as interesting as trying to do a chemical separation in something where all the solutions are boiling while you're trying to work with them anyway, after that the Curium itself is not terribly radioactive, you can move it to a glove compartment and handle it only as respiratory correction protection.

I include the picture there just to show that I didn't always have white hair. Maybe that's why I have white hair. I don't have it. You know, okay, after you've purified the material, you have to craft it into a target. That's the image on the right. It's a curie lens that was used in the production of the 116 um element in this country when we make pictures for scale, we'll put a pencil in or we'll put in a quarter for some reason in Russia they always put a wrist watch in the photo. I don't know why, but after taking the photo, the guy put his wristwatch back on and left. for lunch, the curium target is irradiated with ions from the cyron u400, so this is the large version of the Atron punch arc accelerator that Mr.

Ree showed you. Calcium ions are delivered. Calcium has a nuclear charge of 20 uh. Curium has a nuclear charge of 96, 20 and 96 forms Element 116, which was what we were trying to do in the experiment. The products fly out of that target and are separated in flight by a recoil separator so you can see the targets. There, the beam hits the edge of the target, which rotates, so if you think aium Target is exciting, think aurum Target rotating at high speed. The reason the lens rotates is to distribute heat over a large area that we are working on right at the edges. of what materials can remain here when we do these experiments, the products we want are separated by the separator are diverted to an array of detectors.

In the image on the right there is an amorium target for an element 115 experiment that is inserted into the gas-fed separator. two guys with face masks and Vladimir without his face mask uh, the detector system looks like this uh, the detector is actually a very cool part, the products fly through the separator, particles 10 to 18 that we don't want deflect to a From the side that the particle we want is sent to the detector, the detector can see the impact. It can measure an energy signal from the product passing through the separator and hitting the detector. The detector also sees the radioactive decay of the products that are produced.

If the stability island concept is correct, then what you expect to see is an impact followed by an alpha decay, perhaps followed by several alpha decays until alpha has decayed from the edge of the island of stability into the sea of ​​instability where all fission, so our signature of something new is fission impact alpha alpha alpha and that's actually what we finally saw, so the whole process is demonstrated quite well in this movie if I can figure out how to do it here yes, so hold on to your seats. discovery of the new

superheavy

element element 117 a target made of the element burkum is placed in the u400 cyclotron of the Joint Institute for Nuclear Research in Dubna Russia calcium ions are accelerated at high speed towards the target burkam atoms calcium ions They bombard the burkam radioactive target for 150 days as they approach the target, only one of the billions fuses with the target to create element 117 at this point, the newly created element 117 travels through a separator and stops at a detector the experiment produced six atoms of element 117 during the 150 days of operation at detector element 117 decays to heavy element 115 to heavy element 113 and so on, finally the nucleus of the fish finally splits into two lighter elements .

Well, I thought it was completely cool, you'll have to forgive me. I'm not a Mac guy, this takes me a minute, okay, I'm an old man, take your blank plastic on the plane and draw your view graphics while you go to the conference with a pen, okay, so in the last 12 years we have In fact, we have produced six new elements, so we have Stadium R gum and cerium which were discovered in the German GSI laboratory, followed by 113 to 18, which are our discoveries working with the dubna laboratory. You can see that the half-lives of these things are Well, don't get me wrong, it's very exciting.

I mean, these things don't work. They decay by alpha decay, so there is an island of stability. Well, the disappointing thing is that we were expecting days or weeks of half-life to be able to do easy chemistry. experiments we can still think about doing chemistry experiments, but it is very, very difficult, you have to do things quickly, okay, and we are developing techniques to do it. One thing I must emphasize is that these are the half-lives of the isotopes. Of these elements that we have created now, one thing I have not talked about is that there is also a magic number of neutrons that is close, we do not know how to make these elements with the magic number of neutrons, but when we calculate Somehow, we hope Let these things have longer half-lives and perhaps higher production rates so that we can produce more than a few atoms per week.

Can you think about doing chemistry when you have a sample that has only one atom? atom in it, okay, we showed this in support of our discovery of element 5, the isotope of element 115 that we made decays through a series of Fast Alpha decays to an isotope of dubnium element 105 which has a half-life of about 20 hours , okay, we can only create about one atom of 115 each day or so, the atom of element 115 is collected, it is allowed to decay into dubnium and at that point the chemistry is done in the 20 hour activity quite frequently with a single atom, so how do you design a dubnium? chemistry, well, you have to go back to your old friend, the periodic table.

I hope you are sticking to the periodic table. Okay, dubnium is at the end of group five, okay, which includes vadium, niobium, tanum. Okay so tanum is actually our model element for designing a chemistry to isolate dubnium so we performed the experiment uh you see the guys there uh putting the amorium target in the chemical apparatus uh when I go to Russia I can wear that hat uh It's amazing anyway uh the lightning comes in and hits The target products come out of the target and are collected in a copper block. The copper block collects everything, it doesn't separate at all.

Everything that is produced in the reaction hits the copper block every day. Well, element 115 passes through there. As soon as it hits the copper block, it disintegrates and accumulates the 20-hour isotope 105. We take the copper block. We machine the surface of the copper block, which is where the products we want are. We put it in that Teflon container at the top right. and we do chemistry and that's my old friend Jerry holding a test tube with about five drops of an acid and an atom of element 105 that we know because we then plated it and put it in a radiation counter and watched a fion decay. we can do chemistry in a single atom, okay, why is this interesting to us?

Part of the reason we're interested in this is that we're starting to see signs that the periodic behavior predicted by Mev is starting to break down and the reason is because of Albert Einstein Albert Einstein was the guy who ruined every branch of science , the guy was, he was just, he was an incredible irritant to everyone who thought they understood everything, that they knew what they were doing, the problem with these elements is that, uh, the nuclear charge increases the speed of the electrons around the nucleus. closer to the nucleus they also have to increase more nuclear charge more attractive charge more speed is required to keep them in their orbits for element 14 14 those electrons are moving close to 90% of the speed of light strange things happen as they you approach the speed of light one of them is that the mass of things tends to start expanding when the mass of the electron expands the electron travels closer to the nucleus it actually penetrates the nucleus slightly the detection of the nuclear charge changes the chemical properties of the element, maybe you can forgive the menal change because I mean it was long before relativity, okay, but at this point, as we look at the periodic table and predict that, to design an experiment with the element 114, we must I need to design an experiment for lead.

Chemical calculations are currently being made that indicate that element 114 may actually be closer to radon. Okay, if you're creating an atom every day or so of an isotope of element 114 and it has a half-life from that. table that we saw of 3 seconds and you don't know anything about its chemical properties to design an experiment, you are talking about something that is really very difficult to do, so one of the ways you can do this is to automate the process like To the extent If possible, this is an area where, as I know having spoken to all of you, you will now become heavy element chemists and I can retire.

Here is your problem. Well, every day or so we make a Element 114 has a half-life of 3 seconds, so you can't collect it in a block of copper and machine it because when it hits it it starts to break down as soon as it's produced, so what you have What to do is every few seconds. you have to do a chemistry of element 114 and try to detect the atom and hope that the product you finally make lives through your chemistry when it is produced, so you actually have to do the chemistry thousands of times to be able to see a single atom .

It breaks down at some point in some chemical process, okay, that's very difficult, so the philosophical point you have to keep in mind is if I'm doing Chemistry 114 on a sample with no element 114 atoms and that counts as Element 11 chemistry 14 I I I don't know, so now we're going to talk about the end of the periodic table, so here's the periodic table, uh, elements 113 and 118 to 118, our experiments are recent experiments. You can see element 118 in the This picture of things is expected to be like radon, but we know from Albert Einstein that it could actually be element 114.

Strange things are happening up there. Other interesting things. We're talking about doing an experiment to try to find element 119 if you were designing. a chemistry experiment for element 119, which would you use as a model element for chemistry? You would probably correctly choose francium 87 or cesium 55 because they are in the same column. What will be really cool is when we finally get to trying to do element 122, which is the second member of what are called super actinides, which has no column to enter at that point, the 18, which is actually 32, will be becomes 50 and there's no element on top, that's the first member of the G. block of elements, we have no idea what their chemical properties are, that's going to be totally and totally cool, a whole new class of chemical compounds, like that To end this I want to talk, I just want to introduce the team, uh, the team that discovered. plutonium was four people, okay, these experiments are considerably more complicated, we work with a lot of people at the Joint Institute for Nuclear Research in Russia, we have collaborators at the Oak Ridge laboratory, the University of Nevada, Las Vegas, Vanderbilt University , so thank you very much.