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Radiation is Everywhere with Dr. Marcos Turqueti

It’s a good thing we are still fascinated by it, because it’s everywhere and there is no escape!  In this weeks Fireside Chat with the Xperts, hosts Megan Bergsma and Dr. Bill Cardoso absorb a minimal dose of radiation while exploring the topic with Dr. Marcos Turqueti of Lawrence Berkeley National Lab (LBL).  Dr. Turqueti helps us better understand the radiation all around us, and its effects on electronics, among other things.

This discussion provides an overview of the types and sources of radiation, as well as some of its effects.  Among the more interesting and vexing challenges this bombardment of radiation can cause in electronics are single-event upsets (SEUs).  Understanding such phenomenon is especially important for medical device manufactures and automakers, as well as others, making high-reliability products.

This one is sure to get some synapse firing.  Once things calm down, we hope you’ll reach out with any questions.  Register for upcoming Fireside Chats with the Xperts and view our archives here.


 

Transcript:

Megan Bergsma:
All right. Welcome to another fireside chat. I’m your guest host, Megan Bergsma, and we have our CEO, Dr. Bill Cardoso, with us today, and for our guest speaker is Dr. Marcos Turqueti. Thanks for joining us, Doctor.

Dr. Marcos Turqueti:
You’re welcome.

Megan Bergsma:
All right. So do you want to introduce yourself and your work at LBL?

Dr. Marcos Turqueti:
Sure. So I work here as a research engineer, and I do most of my work on radiation detectors and high energy physics detectors, so it is special detectors. Usually, I design what’s called the front end electronics, but I deal with the sensors, too, and we go as far as going to the digital signal processing of these signals that these particles and radiation generate. So that’s what my work is, and let’s say our clients is high energy physics experiments and Homeland Security.

Dr. Bill Cardoso:
Can you share with us some interesting projects you’re working on right now? Of course, for public consumption; no secrets.

Dr. Marcos Turqueti:
Yeah. No, absolutely. Let’s say, for example, there’s two that comes to my mind right now. So one project is to detect something that’s called a double battery gate. Okay? That is a interesting thing. That’s the opposite of the other project in the sense that this project happens under a mountain in Italy. Okay? So there is a laboratory there that is located there exactly because of the low background radiation. Okay? So this project is to try to detect these very rare events. Okay? So we have background radiation around us, and these would cause false positives on the detectors. So we shield everything. So we are inside this mountain, right? It also protect against these cosmic rays that are high energy particles that comes from outer space, right? So we are inside this mountain shielded.

Dr. Marcos Turqueti:
The project even had a shield that’s very interesting. It’s made with these lead bricks that come from … that was used on as ballasts on these old Roman ships. Right?

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
And the reason why is because this lead has been under the ocean for thousands of years.

Dr. Bill Cardoso:
Wow.

Dr. Marcos Turqueti:
So the lead’s not activated; it’s not been bombarded by the environmental radiation, right? And the other, and we have some parts called PRISM. This is for Homeland Security. This, for example, is it can be used for many applications. Right now, we have prototype being used in Fukushima to survey in the area. So, basically, it has a lidar that creates a three-dimensional map of the area, and then we have a gamma detector, a gamma array, made with this CZT crystals that are sensitive to gamma rays. So it basically do this map. It tells you where the radiation is and what elements are, right? So they’re using that.

Dr. Marcos Turqueti:
One interesting thing is there is a village there that was evacuated, so nobody lives anymore there. And when they surveyed the house, usually there’s no radiation inside. But if you had a leak in the roof where the water infiltrated, there is where they are seeing radiation.

Dr. Bill Cardoso:
Wow. So it’s fascinating, right? So in one experiment, you basically are using a whole mountain as a shield?

Dr. Marcos Turqueti:
Yeah.

Dr. Bill Cardoso:
Detectors. On the other one, you’re looking for radiation out there in Fukushima.

Dr. Marcos Turqueti:
That’s right.

Dr. Bill Cardoso:
So that’s something that not a lot of people know, but radiation is all around us, and there’s radiation everywhere. You mentioned background radiation. Can you go over what types of radiations are out there and how we see them in our daily lives?

Dr. Marcos Turqueti:
Sure. Absolutely. Well, there are many types of radiation, but I would say, basically, you have two general ones. One is basically electromagnetic waves, basically is like light. Light is a kind of radiation; just light doesn’t have … Normal light, visible light, doesn’t have enough energy to damage you, right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
But as you start to increase the frequency … So for example, red is low frequency light we can see, right?

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
As you start to increase, you go up to the blue and then violet and then our eyes cannot see anymore, right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
It’s the same … Then, of course, you can still increasing these frequencies, this energy. That’s what we call them, for example, ultraviolet, right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
At some point it becomes what’s called ionizing radiation, that then it can start to damage matter by removing electrons from the shell. So that’s one kind of radiation, right? So this goes from radio waves to light to X-rays, right-

Dr. Bill Cardoso:
Correct.

Dr. Marcos Turqueti:
… to Gamma-rays. The other kind of radiation is basically atoms or their piece or parts of the atoms. So it’s what’s called a baryonic matter. So baryonic matter with high energy, that means that they are accelerate there at fast speeds, right? So they can be electrons, it can be protons, it can be subatomic particles, but they are, basically, parts of atoms or atoms themselves. Okay?

Dr. Bill Cardoso:
Because one of the things as we work with X-rays and we have samples being imaged, from cell phones to medical devices, can you explain to us how that radiation interacts with the matter and what’s the process, like the photoelectric process and all that, how do we create an image, right? Why is some radiation stopped by parts of the matter and some parts of radiation not stopped where they can go through?

Dr. Marcos Turqueti:
Absolutely. Yeah, yeah. So let’s talk about more general principles because, then again, depends a lot of what kind of object and what kind of radiation, right? So let’s talk, for example, an interesting thing. For example, things that can shoot you from some kind of radiation can be useless for [inaudible 00:08:38], right? For example, you have these neutrons, right? For example, that was found out early with atomic bomb, right? For example, neutrons you can use quite successful like water and light elements to shield it because of one thing that’s called cross-section, right? So let’s say the neutron is like depend of energy has a cross-section, and you need this small molecules of water, that they are very close together, right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
Then it increase the probability of interacting with neutrons. Now, lead is not that good for some kind of neutrons, and you would think, oh, lead’s good for shielding, right? Lead is good for shielding against electromagnetic radiation, right?

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
So that’s interesting. So let’s talk a little bit more about electromagnetic radiation.

Dr. Bill Cardoso:
But it’s all about the cross-section and the water just because of loose shape of those molecules, in the way they get together. It can stop neutrons more efficiently.

Dr. Marcos Turqueti:
They get much closer because the lead, for example, is a lattice, right?

Dr. Bill Cardoso:
Yeah, exactly.

Dr. Marcos Turqueti:
They’re big. They’re big atoms, but they are far apart, right?

Dr. Bill Cardoso:
Right. Mm-hmm .

Dr. Marcos Turqueti:
So that’s why then the neutrons go in-between the empty space between this big atoms, let’s say, and the water molecules are much smaller, but they are not so far apart. So let’s say the probability of interacting with these neutrons is large.

Dr. Bill Cardoso:
Much larger.

Dr. Marcos Turqueti:
So about imaging formation, so to form an image with being, in general, using what’s called, let’s say, shadow projection, you actually need what you’re trying to image to absorb some radiation, right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
If what you’re trying to image, it will not absorb the radiation, you’ll not see anything. It’s like you’re trying to image a window, right-

Dr. Bill Cardoso:
Mm-hmm , right.

Dr. Marcos Turqueti:
… with the visible light. It will just pass through because you are trying to project a shade, right? If the light, for example, just go through, you’ll not project anything. So you do need to have some absorption of the material, absorbing some of this radiation, right? And then, just like a shadow, you have a candle and let’s say your hand and you see the shading behind. So it’s kind of the same principle.

Dr. Bill Cardoso:
So you talk about radiation and irradiation in environment. Is radiation bad for us given that it’s all around?

Dr. Marcos Turqueti:
Yes. So that’s a very good question, and there’s a big debate on that, and the principle depend … Well, we live with it, right?

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
Certainly we live with it. So it is impossible for you to not being exposed to radiation all the time. There’s people that … There’s two, let’s say, trains of thought, one that says that you need actually a minimal exposure to radiation starts to be harmful for you. Okay? I think that what most of the scientists think nowadays, and there’s another train of thought that say any level is bad, okay? That’s the old thing. The thing is that our body is built to live with the radiation, right? So, for example, if we didn’t have a mechanism to repair ourselves when we are hit by radiation, we wouldn’t live even like six months because we are come … So our body has already mechanisms to repair DNA, and that’s basically required for our complex life. Otherwise, you can’t exist because, then again, it’s impossible … Even this mountain, right-

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
… in that we are still not able to shield completely. We still get radiation for the environment. Okay? So you’ll see we’re under a mountain with a lead shield and we still have a problem that radiation still coming through, right? So even if you live under a mountain, you still would get some level radiation.

Dr. Bill Cardoso:
Now, you mentioned this mechanism we have to repair against or repair for radiation impact. Is there a moment where this mechanism breaks and radiation becomes very harmful?

Dr. Marcos Turqueti:
Yes. There’s two situations that I would say. One is if you have many, many events, okay? So if you are exposed to a very high field that it overwhelms your body capability to repair itself, right? So that’s one situation. The other situation is you can be … Also, then again, it is also is everything that relates to probability, and if you have more hits, you are exposed to a larger probability.

Dr. Bill Cardoso:
Sure.

Dr. Marcos Turqueti:
You can also have a higher energy … So higher energy is a very interesting thing. For example, both for electromagnetic waves and for baryonic radiation, let’s say, very, very high energy photons or neutrons, they have a very, very low probability of interacting with you. Okay? They will normally go through your body, and you will never know. But when they interact, they cause a lot of damage because they have a lot of energy, right? So they deposit all their energy. So that’s it is like the … is these two things. So how many hits you are taking and then what energy is this hit? Right? And then you need to know that through that, as energy goes higher, the probability of interaction also reduce to a certain point.

Dr. Bill Cardoso:
Yeah. So let’s about something that’s your specialty, which is interaction of this radioactive particles or photons with electronics, right? That’s something we get asked a lot, is an X-ray image of a component going to damage the component? I know that’s something you would study quite a bit because you design electronics to go in sometimes high-radiation environments, right?

Dr. Marcos Turqueti:
Mm-hmm .

Dr. Bill Cardoso:
So how … I know there’s no “yes” or “no” answer to this question, but give us how you think about this process of radiation potentially damaging or not damaging electronic components.

Dr. Marcos Turqueti:
Yeah, I’ll just say that is interesting because it’s just like our body, is the same principles, right? It depends for, let’s say, how long you are exposed so how much of radiation is going through your body, right? Of course, different from us. Not exactly true, but internal components, they don’t have … depending on the damage, they don’t have a mechanism to heal themselves, right? However, the principles are the same. If you have a lot of radiation for a long time, for example, you … It depends also the energy of the radiation.

Dr. Bill Cardoso:
Correct.

Dr. Marcos Turqueti:
But for example, X-rays usually … They will not do damage to the bulk. For example, the bulk, if you’re using silicon or [inaudible 00:17:23], they don’t have … Usually, these kind of X-rays we’re talking about, they don’t have energy to, let’s say, damage the atoms, the lattice itself, right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
They, however, have energy to ionize the atoms. That means take electrons away. Okay?

Dr. Bill Cardoso:
Correct.

Dr. Marcos Turqueti:
And that’s the way the X-rays can damage electronics. And then again, you need a lot; usually is a question of probability, how much photons of X-rays you are blasting to it because when the X-ray, lets say, interact with the shell of an electron, let’s say, it happens to kick one electron out. This electron can be recaptured and nothing will happen. Right?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
But it is electrons can stay on the material, what you call, it’s like a charge trap. Okay?

Dr. Bill Cardoso:
Right.

Dr. Marcos Turqueti:
And that usually, if you have a lot of these accumulating, you can start degrade your electronics. It’s interesting also to know that there is studies that is charged traps, they can be reversed by processes called annealing and reverse annealing, right? If you heat up the component and then cool it down, there’s some probability that you can reduce this, but that would say that’s the way, the only … yeah, is the way that more likely that the X-ray could damage semiconductors, okay, semiconductors. And then again is a question of time of exposure, right? If you leave the thing whole day there, well, and you’ll have enough energy to ionize the atoms, you are increasing the probability of damage.

Dr. Marcos Turqueti:
Now, if you can manage to do something really fast, the probability will be very, very small. Okay?

Dr. Bill Cardoso:
Right.

Dr. Marcos Turqueti:
Is that everything about probabilities.

Dr. Bill Cardoso:
Yeah, because it has to be with the amount of power, right? Even the kV, the energy of the photon, how many photons per second, how long you leave it there. Talk to us about these two different mechanisms, right? The single-event upset, which is a dynamic damage that can happen. It can be fixed by, for example, flipping a flop or flopping a flip, that changed by an energy deposition, and then you have you what you describing, it’s bulk damage, where you really have a gate rupture or you can just destroy a transistor because enough energy is deposited that you can, basically, burn it. So how does single-event upsets work?

Dr. Marcos Turqueti:
Yeah, single-event upsets, I would say, is very different, and so single-event upset, it will something that will not damage permanently your device, is basically … and they happen usually when you are operating the device. Okay?

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
So let’s say you have, let’s say, a transistor storing a bit and saying that bit is zero, then you have, let’s say, X-ray that hits the transistors and now deposit some energy there, and they start to change to one. Okay?

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
And then again, this can happen even without an X-ray. Okay? The X-ray just increase the probability it’ll happen, but you have this environmental radiation that can cause this, too. Okay? But then again, this is something that you, then, you can just reset and so this will not damage your device, right?

Dr. Bill Cardoso:
Yeah. So this becomes an issue if you are sending, for example, large memory bank to space, right? There was a lot of radiation.

Dr. Marcos Turqueti:
Yeah, yeah.

Dr. Bill Cardoso:
A bit might be flipped accidentally, and that can cause … or the memory of an FPGA that might change the how the FPGA operates, right.

Dr. Marcos Turqueti:
Exactly.

Dr. Bill Cardoso:

Dr. Marcos Turqueti:
Exactly. Exactly. Then again, if it is a concern, there are usually techniques to avoid, like you’ll have a triple redundance and things like that, and so this is a big issue for huge supercomputers because then, again, environmental radiation. Although the probability is low, you have so many, so many transistors in these supercomputers that you are bound to have these single-event upsets, especially in this huge memory banks. So they do have ways to mitigate that to make sure that will not cause a big problem.

Dr. Bill Cardoso:
Yeah, and you can’t find enough mountains to put the supercomputers.

Dr. Marcos Turqueti:
Yeah, yeah. That’s right.

Dr. Bill Cardoso:
Now, one of the things we get asked as well is, okay, so I’m worried that my components going to be potentially damaged by an X-ray inspection machine, but at the same time, how is that same component impacted by radiated … by the TSA at the airport or the shipping company or … I mean, or when it flies, there’s so much radiation around us that the components that we received via Amazon, right-

Dr. Marcos Turqueti:
Mm-hmm .

Dr. Bill Cardoso:
… the carrier, they’re likely to have been imaged already, right?

Dr. Marcos Turqueti:
Yeah. Well, this is radiation, all the same, right? It’s the same kind. Then, again, it is a question of probability. You can have, if you’re very unlucky, a component that will be damaged. But as you can notice, you don’t see this happening, right?

Dr. Bill Cardoso:
No, it doesn’t. Exactly, yeah, yeah.

Dr. Marcos Turqueti:
See, so you have millions of Amazon shippings transatlantic, right? They go in airplanes, and you notice that your laptops still works, right? So that’s because the probability of this happens is really small. So maybe someone very unlucky will get the computer and say, “Oh, it’s not working.” Maybe it has something to do with this but could be many other things. So it’s hard to say, but that just shows that the probability of happening is really, really small.

Dr. Bill Cardoso:
Exactly. Now, do you have a … What do you have to share with us about how radiation damages plastics and rubbers and other, especially medical devices, and things that might maybe part of a more complex system? It has electronics, there’s a battery, it maybe has a catheter or something that’s rubberized or plastic. I mean, I don’t remember seeing … Do you have an experience with that on how radiation might damage those things?

Dr. Marcos Turqueti:
A little bit, and plastics, they are more susceptible to neutrons because they absorb better and gamma radiation that is like electromagnetic radiation, high energy, right? However, there is a mechanism that you can see on plastics. For example, there’s some kind of plastics that, for example, you leave outside, right?

Dr. Bill Cardoso:
Yeah.

Dr. Marcos Turqueti:
You notice that the plastic change the color and becomes more brittle, right?

Dr. Bill Cardoso:
Exactly.

Dr. Marcos Turqueti:
That is actually a radiation damage, usually is because the UV radiation-

Dr. Bill Cardoso:
UV light.

Dr. Marcos Turqueti:
Yeah. Okay, so that I think is called photolysis. Okay?

Dr. Bill Cardoso:
Exactly. Mm-hmm .

Dr. Marcos Turqueti:
And that’s is basically because, then again, the radiation interacting with the molecules, the bonds. So is then is not damaged on the atoms themselves so is on the bonds between atoms, right? So you’re creating chemical reactions there.

Dr. Marcos Turqueti:
So this photolysis does affect plastics, and so you can cause this with UV radiation, but you can also cause it with X-rays, but then again, notice how long it takes for the plastics to start degrading, and there’s some plastics much more susceptible than others. Okay? There are some kinds of plastics that are really very radiation hard, so it depends on the plastic, right? And then again, depends on the time of exposure is very important, time and intensity, basically the number of events, right?

Dr. Bill Cardoso:
Yeah. I just noticed that because I still have some boxes from the last time I moved, I think, 20 years ago, before this last move, or 12 years ago, and the plastic on the box, the tape, is brittle. So over time, it just deteriorates and this photology is just … makes it brittle and fragile.

Dr. Marcos Turqueti:
Exactly.

Dr. Bill Cardoso:
So Megan, how we do in time?

Dr. Bill Cardoso:
Last question for Marcos. So share with us what’s next for you. You working with those two experiments; what’s exciting happening at LBL and in your career?

Dr. Marcos Turqueti:
Well, here at the lab, there’s a lot of variety, right? So there are a lot of things. And again, radiation is a very useful tool here. We have an ELS … is being upgraded right now. It was actually used on COVID research to image the COVID virus, right?

Dr. Bill Cardoso:
Oh, wow.

Dr. Marcos Turqueti:
Because exactly it produce a very pure X-ray beam, right-

Dr. Bill Cardoso:
Mm-hmm .

Dr. Marcos Turqueti:
… that is used to image the virus. So there are many, many things, so you’ll never know what will be your next challenge. But then again, with these tools, for like radiation, you have almost no limits, right? You have other whole medical fields in the human body. So lots of things to do.

Dr. Bill Cardoso:
Yeah, we’re going to put a link to LBL on the YouTube link because it’s a fascinating lab with a fascinating history, from founder to the kind of work you guys do today, and more people have to learn about it.

Dr. Bill Cardoso:
So that’s it. Thanks so much for your time, Marcos.

Dr. Marcos Turqueti:
You’re very welcome.

Megan Bergsma:
Thanks, Marcos.

Dr. Marcos Turqueti:
Was a pleasure.

Dr. Bill Cardoso:
My pleasure, man. Thanks so much. I’ll talk you soon. Bye-bye.

Dr. Marcos Turqueti:
Bye-bye.

Megan Bergsma:
Bye.

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