[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:13.63,Default,,0000,0000,0000,,{\i1}rc3 prerol music{\i0}
Dialogue: 0,0:00:13.63,0:00:19.84,Default,,0000,0000,0000,,Herald: All right, fellow creatures, to be\Nhonest, I never thought that I would be
Dialogue: 0,0:00:19.84,0:00:25.44,Default,,0000,0000,0000,,introducing a talk on measuring\Nradioactivity like ever in my life, but
Dialogue: 0,0:00:25.44,0:00:30.48,Default,,0000,0000,0000,,then again, considering the world stage,\Ncurrent state at large, it might be not
Dialogue: 0,0:00:30.48,0:00:35.60,Default,,0000,0000,0000,,such a bad idea to be prepared for these\Nthings. Right? And gladly, our next
Dialogue: 0,0:00:35.60,0:00:42.00,Default,,0000,0000,0000,,speaker, Oliver Keller, is an expert in\Ndetecting radioactive stuff. Oliver is a
Dialogue: 0,0:00:42.00,0:00:47.04,Default,,0000,0000,0000,,physicist and works at one of the most\Nprominent nerd happy places. The CERN
Dialogue: 0,0:00:47.04,0:00:53.76,Default,,0000,0000,0000,,since 2013 is also doing a PhD project\Nabout novel instruments and experiments on
Dialogue: 0,0:00:53.76,0:01:00.80,Default,,0000,0000,0000,,natural radioactivity at the University of\NGeneva and to even more to add even more
Dialogue: 0,0:01:00.80,0:01:06.48,Default,,0000,0000,0000,,C3 pizzazz. Oliver is active in the open\Nscience community and passionate about
Dialogue: 0,0:01:06.48,0:01:12.96,Default,,0000,0000,0000,,everything open source. All that sounds\Nreally cool to me. So without further ado,
Dialogue: 0,0:01:12.96,0:01:18.40,Default,,0000,0000,0000,,let's give a warm, virtual welcome to\NOliver and let's hear what he has to say
Dialogue: 0,0:01:18.40,0:01:24.80,Default,,0000,0000,0000,,about measuring radioactivity with using\Nlow cost silicon sensors. Oliver, the
Dialogue: 0,0:01:24.80,0:01:28.07,Default,,0000,0000,0000,,stream is yours.
Dialogue: 0,0:01:28.07,0:01:32.56,Default,,0000,0000,0000,,Oliver: Thanks. That was a very nice\Nintroduction. I'm really happy to have the
Dialogue: 0,0:01:32.56,0:01:38.31,Default,,0000,0000,0000,,chance to present here. I'm a member since\Nquite some years and this is my first CCC
Dialogue: 0,0:01:38.31,0:01:44.44,Default,,0000,0000,0000,,talk, so I'm quite excited. Yeah, you can\Nfollow me on Twitter or I'm also on
Dialogue: 0,0:01:44.44,0:01:50.16,Default,,0000,0000,0000,,Mastodon, not so active, and most of my\Nstuff is on GitHub. OK, so what will we
Dialogue: 0,0:01:50.16,0:01:55.70,Default,,0000,0000,0000,,talk about in this talk? I'll give you a\Nshort overview, also about the
Dialogue: 0,0:01:55.70,0:02:02.04,Default,,0000,0000,0000,,radioactivity, because yeah, it's a topic\Nwith many different details and then we
Dialogue: 0,0:02:02.04,0:02:08.18,Default,,0000,0000,0000,,will look at the detector more in detail\Nand how that works in terms of the physics
Dialogue: 0,0:02:08.18,0:02:13.16,Default,,0000,0000,0000,,behind it and the electronics. And then\Nfinally, we look at things that can be
Dialogue: 0,0:02:13.16,0:02:19.16,Default,,0000,0000,0000,,measured, how the measurement actually\Nworks, what are interesting objects to
Dialogue: 0,0:02:19.16,0:02:28.12,Default,,0000,0000,0000,,check and how this relates to silicon\Ndetectors being used at CERN. So the
Dialogue: 0,0:02:28.12,0:02:33.40,Default,,0000,0000,0000,,project is on GitHub called DIY Particle\NDetector. It's an electronic design, which
Dialogue: 0,0:02:33.40,0:02:39.44,Default,,0000,0000,0000,,is open hardware. There's a wiki with lots\Nof further details for building and for
Dialogue: 0,0:02:39.44,0:02:45.36,Default,,0000,0000,0000,,troubleshooting. There is a little web\Nbrowser tool I will show later, briefly,
Dialogue: 0,0:02:45.36,0:02:52.12,Default,,0000,0000,0000,,and there are scripts to record and nicely\Nplot the measurements. Those scripts are
Dialogue: 0,0:02:52.12,0:02:58.06,Default,,0000,0000,0000,,BSD-licensed and written in Python. There\Nare two variants of this detector. One is
Dialogue: 0,0:02:58.06,0:03:03.09,Default,,0000,0000,0000,,called electron detector, the other one\Nalpha spectrometer. They use the same
Dialogue: 0,0:03:03.09,0:03:08.47,Default,,0000,0000,0000,,circuit board, but one is using four\Ndiodes, the other one one photodiode...
Dialogue: 0,0:03:08.47,0:03:14.18,Default,,0000,0000,0000,,There's a small difference between them,\Nbut in general it's pretty similar. But
Dialogue: 0,0:03:14.18,0:03:18.51,Default,,0000,0000,0000,,the electron detector is much easier to\Nbuild and much easier to get started
Dialogue: 0,0:03:18.51,0:03:25.68,Default,,0000,0000,0000,,using. Then you have complete part lists\Nand even a complete kit can be bought on
Dialogue: 0,0:03:25.68,0:03:31.64,Default,,0000,0000,0000,,kitspace.org, which is an open hardware\Ncommunity repository, and I really
Dialogue: 0,0:03:31.64,0:03:36.37,Default,,0000,0000,0000,,recommend you to check it out. It's a\Ngreat community platform and everyone can
Dialogue: 0,0:03:36.37,0:03:44.10,Default,,0000,0000,0000,,register their own GitHub project quite\Neasily. Now, this is a particle detector
Dialogue: 0,0:03:44.10,0:03:51.02,Default,,0000,0000,0000,,in a tin box, so you can use the famous\NAltoids tin box or something for Swiss
Dialogue: 0,0:03:51.02,0:03:57.34,Default,,0000,0000,0000,,chocolate, for example. You can see it's\Nrather small, the board about the size of
Dialogue: 0,0:03:57.34,0:04:03.62,Default,,0000,0000,0000,,a nine volt block battery. And then you\Nneed, in addition, about 20 resistors,
Dialogue: 0,0:04:03.62,0:04:10.36,Default,,0000,0000,0000,,capacitors and these silicon\Ndiodes plus an operational amplifier,
Dialogue: 0,0:04:10.36,0:04:15.12,Default,,0000,0000,0000,,which is this little chip here, this\Nlittle black chip here on the right side,
Dialogue: 0,0:04:15.12,0:04:19.52,Default,,0000,0000,0000,,you can see is all old school large\Ncomponents. This is on purpose, so it's
Dialogue: 0,0:04:19.52,0:04:24.64,Default,,0000,0000,0000,,easy to soldier for complete electronic\Nbeginners. And this by the way, this
Dialogue: 0,0:04:24.64,0:04:30.18,Default,,0000,0000,0000,,picture is already one user of this\Nproject who posted their own build on
Dialogue: 0,0:04:30.18,0:04:38.08,Default,,0000,0000,0000,,Twitter. OK, so natural radioactivity. So\NI would say it's a story of many
Dialogue: 0,0:04:38.08,0:04:44.08,Default,,0000,0000,0000,,misconceptions. Let's imagine we are this\Nlittle stick figure here on the ground.
Dialogue: 0,0:04:44.08,0:04:50.64,Default,,0000,0000,0000,,Below us we have uranium and thorium. We\Nalso have Potassium-40 in the ground and
Dialogue: 0,0:04:50.64,0:04:56.81,Default,,0000,0000,0000,,Potassium-40 is is pretty specific and\Npeculiar. It actually makes all of us a
Dialogue: 0,0:04:56.81,0:05:05.14,Default,,0000,0000,0000,,little bit radioactive. Every human has\Nabout 4000 to 5000 radioactive decays
Dialogue: 0,0:05:05.14,0:05:10.26,Default,,0000,0000,0000,,every second because of the natural\Npotassium and natural potassium comes with
Dialogue: 0,0:05:10.26,0:05:14.98,Default,,0000,0000,0000,,a radioactive isotope, which is just\Neverywhere, it's in bananas. But it's also
Dialogue: 0,0:05:14.98,0:05:20.32,Default,,0000,0000,0000,,in us because we need it for our body\Nchemistry. It's really important and even
Dialogue: 0,0:05:20.32,0:05:26.22,Default,,0000,0000,0000,,some of those decays are even\Nproducing anti-matter. So how cool is
Dialogue: 0,0:05:26.22,0:05:32.43,Default,,0000,0000,0000,,that? OK, so what would we be measuring on\Nthe on ground? Well, there could be some
Dialogue: 0,0:05:32.43,0:05:39.43,Default,,0000,0000,0000,,gamma rays or electrons. Those are from\Nbeta-decays. Or from the Uranium, there is
Dialogue: 0,0:05:39.43,0:05:46.96,Default,,0000,0000,0000,,one radionuclide appearing in the decay\Nchain, which is called Radon, and Radon is
Dialogue: 0,0:05:46.96,0:05:53.32,Default,,0000,0000,0000,,actually a gas. So from the ground the\NRadon can diffuse upwards and travel with
Dialogue: 0,0:05:53.32,0:06:01.14,Default,,0000,0000,0000,,air and spread around. So it's a bit like\Na vehicle for radioactivity from
Dialogue: 0,0:06:01.14,0:06:08.18,Default,,0000,0000,0000,,the ground to spread to other places. And\Nthat Radon would decay with alpha
Dialogue: 0,0:06:08.18,0:06:14.15,Default,,0000,0000,0000,,particles producing electrons and beta-\Ndecays and also gamma radiation further
Dialogue: 0,0:06:14.15,0:06:21.68,Default,,0000,0000,0000,,down in the decay chain. So just to\Nrecapitulate, I've said it already twice,
Dialogue: 0,0:06:21.68,0:06:29.83,Default,,0000,0000,0000,,so alpha particles are actually helium\Nnuclei, so it's just two protons and two
Dialogue: 0,0:06:29.83,0:06:38.15,Default,,0000,0000,0000,,neutrons and the electrons are missing.\NAnd in beta decay basically one neutron is
Dialogue: 0,0:06:38.15,0:06:43.10,Default,,0000,0000,0000,,transformed into a proton and an electron.\NAnd there's also an electron-anti-neutrino
Dialogue: 0,0:06:43.10,0:06:47.69,Default,,0000,0000,0000,,generated. But this is super hard to\Nmeasure. So we're not measuring those.
Dialogue: 0,0:06:47.69,0:06:54.52,Default,,0000,0000,0000,,Mostly we will be measuring electrons from\Nbeta-decays. That's why you see all these
Dialogue: 0,0:06:54.52,0:07:00.33,Default,,0000,0000,0000,,little e's indicating betadecays. Ok, if\Nyou would go to the hospital here on the
Dialogue: 0,0:07:00.33,0:07:08.96,Default,,0000,0000,0000,,left side, we would probably find some x\Nrays from checking our bones or something
Dialogue: 0,0:07:08.96,0:07:16.48,Default,,0000,0000,0000,,like this, or even gamma rays or alpha\Nparticles being used in treatments or very
Dialogue: 0,0:07:16.48,0:07:22.81,Default,,0000,0000,0000,,modern even proton beams are sometimes\Ngenerated for medical applications. Now,
Dialogue: 0,0:07:22.81,0:07:28.18,Default,,0000,0000,0000,,here on the right side, if you go close to\Na nuclear power plant, we probably measure
Dialogue: 0,0:07:28.18,0:07:33.89,Default,,0000,0000,0000,,nothing unless there's a problem in this\Ncase, most likely we would find some gamma
Dialogue: 0,0:07:33.89,0:07:40.64,Default,,0000,0000,0000,,radiation. But only if there is a problem.\NOK, and then actually that's not the whole
Dialogue: 0,0:07:40.64,0:07:46.89,Default,,0000,0000,0000,,story. This is terrestrial radiation. But\Nwe also have radiation coming from
Dialogue: 0,0:07:46.89,0:07:50.86,Default,,0000,0000,0000,,upwards, showering down on us every\Nminute, and there's actually nothing we
Dialogue: 0,0:07:50.86,0:07:56.57,Default,,0000,0000,0000,,can do against it. So protons are\Naccelerated from in the universe.
Dialogue: 0,0:07:56.57,0:08:02.42,Default,,0000,0000,0000,,Basically, the biggest particle\Naccelerator nature has. And once they hit
Dialogue: 0,0:08:02.42,0:08:10.16,Default,,0000,0000,0000,,our atmosphere they break apart into less\Nenergetic particles and it's many of them.
Dialogue: 0,0:08:10.16,0:08:15.85,Default,,0000,0000,0000,,So in the first stage there's lots of pions\Ngenerated and also neutrons. But neutrons
Dialogue: 0,0:08:15.85,0:08:21.62,Default,,0000,0000,0000,,are really hard to measure, so I'll ignore\Nthem for most of the talk. Then those
Dialogue: 0,0:08:21.62,0:08:29.04,Default,,0000,0000,0000,,pions can decay into gamma rays and then\Ntrigger a whole chain of positron electron
Dialogue: 0,0:08:29.04,0:08:34.88,Default,,0000,0000,0000,,decays, which again create gamma rays and\Nso forth. And this goes actually the whole
Dialogue: 0,0:08:34.88,0:08:40.18,Default,,0000,0000,0000,,way down to the earth. We will have a\Nlittle bit of that on the sea level.
Dialogue: 0,0:08:40.18,0:08:46.04,Default,,0000,0000,0000,,And the other more known part of\Natmospheric radiation is actually muons.
Dialogue: 0,0:08:46.04,0:08:52.37,Default,,0000,0000,0000,,So some pions decay into muons, which is\Nkind of a heavy electron and also
Dialogue: 0,0:08:52.37,0:08:57.64,Default,,0000,0000,0000,,neutrinos. But neutrinos are, again, very\Nhard to measure. So I'll ignore them for
Dialogue: 0,0:08:57.64,0:09:03.46,Default,,0000,0000,0000,,most of this talk. And if you look here on\Nthe right side on this altitude scale,
Dialogue: 0,0:09:03.46,0:09:08.42,Default,,0000,0000,0000,,you'll see an airplane would be basically\Ntraveling where most of the atmospheric
Dialogue: 0,0:09:08.42,0:09:13.32,Default,,0000,0000,0000,,radiation is produced. And this is why if\Nyou go on such an airplane, you have
Dialogue: 0,0:09:13.32,0:09:19.88,Default,,0000,0000,0000,,actually several times more radiation\Nin there than here on earth. And, of
Dialogue: 0,0:09:19.88,0:09:24.21,Default,,0000,0000,0000,,course, on the ground, it also depends\Nwhere you are. There are different amounts
Dialogue: 0,0:09:24.21,0:09:30.14,Default,,0000,0000,0000,,of uranium and thorium in the ground and\Nthis is just naturally there. So but it
Dialogue: 0,0:09:30.14,0:09:36.77,Default,,0000,0000,0000,,depends on the geology, of course. OK, so\NI've talked quite a bit about radiation,
Dialogue: 0,0:09:36.77,0:09:43.04,Default,,0000,0000,0000,,and I'm saying I want to use silicon to\Ndetect it. So what radiation exactly?
Dialogue: 0,0:09:43.04,0:09:48.51,Default,,0000,0000,0000,,Maybe. Let's let's take a step back and\Nthink about what we know maybe from
Dialogue: 0,0:09:48.51,0:09:54.84,Default,,0000,0000,0000,,school. So we have this rainbow for\Nvisible light. Right. This is in terms of
Dialogue: 0,0:09:54.84,0:10:03.00,Default,,0000,0000,0000,,wavelength. We have 800 to 400 nanometers\Nspanning from the infrared/red area to all
Dialogue: 0,0:10:03.00,0:10:12.86,Default,,0000,0000,0000,,the green to blue and into the violet. And\Nlower down those wavelengths or let's say
Dialogue: 0,0:10:12.86,0:10:17.74,Default,,0000,0000,0000,,bigger millimeter waves, meter waves and\Neven kilometer, that would be radio waves,
Dialogue: 0,0:10:17.74,0:10:22.37,Default,,0000,0000,0000,,radio frequencies for our digital\Ncommunication systems, wi-fi, mobile
Dialogue: 0,0:10:22.37,0:10:27.72,Default,,0000,0000,0000,,devices and so forth. But I want to look\Nactually more towards the right because
Dialogue: 0,0:10:27.72,0:10:33.44,Default,,0000,0000,0000,,that's what we are measuring with these\Ndetectors. It's shorter wavelength, which
Dialogue: 0,0:10:33.44,0:10:39.80,Default,,0000,0000,0000,,actually means higher energy. So on the\Nright side, we would be having ultraviolet
Dialogue: 0,0:10:39.80,0:10:47.33,Default,,0000,0000,0000,,radiation, which is kind of at the border\Nto what we can measure. And these 800 to
Dialogue: 0,0:10:47.33,0:10:54.08,Default,,0000,0000,0000,,400nm translate into 1.5 to 3 eV, which is\Na unit that particle physicists really
Dialogue: 0,0:10:54.08,0:11:02.93,Default,,0000,0000,0000,,prefer because it basically relates the\Nenergy of an electron after it has been
Dialogue: 0,0:11:02.93,0:11:09.27,Default,,0000,0000,0000,,accelerated by 1 Volt and makes it\Nmuch easier to work with nuclear
Dialogue: 0,0:11:09.27,0:11:15.38,Default,,0000,0000,0000,,particle physics, because everything, all\Nthe energy is always related to an
Dialogue: 0,0:11:15.38,0:11:21.21,Default,,0000,0000,0000,,electron. And this energy, this formula\Nhere is just a reminder that the
Dialogue: 0,0:11:21.21,0:11:25.94,Default,,0000,0000,0000,,wavelengths can be always converted into\Nenergy and it's inversely proportional. So
Dialogue: 0,0:11:25.94,0:11:30.55,Default,,0000,0000,0000,,wavelength increases to the left and the\Nenergy to right. And if you increase
Dialogue: 0,0:11:30.55,0:11:35.96,Default,,0000,0000,0000,,energy more from from the visible range,\Nso let's say thousands of electron volts,
Dialogue: 0,0:11:35.96,0:11:43.40,Default,,0000,0000,0000,,then we arrive here. Millions - mega\Nelectron volts, even GeV. And there is now
Dialogue: 0,0:11:43.40,0:11:51.81,Default,,0000,0000,0000,,a pretty important distinction between\Nthose two areas, and that is the right one
Dialogue: 0,0:11:51.81,0:11:58.02,Default,,0000,0000,0000,,is ionizing radiation and the left one is\Nnon ionizing radiation. UV is a little bit
Dialogue: 0,0:11:58.02,0:12:03.15,Default,,0000,0000,0000,,in the middle of that. So some parts of\Nthe UV spectrum can be ionizing. It also
Dialogue: 0,0:12:03.15,0:12:09.57,Default,,0000,0000,0000,,depends a lot on the material that the\Nradiation is interacting with. For these
Dialogue: 0,0:12:09.57,0:12:13.82,Default,,0000,0000,0000,,detectors I'm talking about today and\Nalpha, beta, gamma radiation, this is all
Dialogue: 0,0:12:13.82,0:12:21.33,Default,,0000,0000,0000,,ionizing, so some examples, lowest energy\Non the lower spectrum would be x rays than
Dialogue: 0,0:12:21.33,0:12:29.44,Default,,0000,0000,0000,,electrons, gamma rays from radioactive\Nnuclides that already talked about in the
Dialogue: 0,0:12:29.44,0:12:34.88,Default,,0000,0000,0000,,previous slide, alpha particles, and that\Nmuons from the atmosphere would be more on
Dialogue: 0,0:12:34.88,0:12:40.30,Default,,0000,0000,0000,,the GeV range and so forth. And for these\Nhigher energies, of course, you need
Dialogue: 0,0:12:40.30,0:12:46.18,Default,,0000,0000,0000,,something like the LHC to accelerate\Nparticles to really high energies. And
Dialogue: 0,0:12:46.18,0:12:56.42,Default,,0000,0000,0000,,then you can even access the TeV regime.\NOK, silicon diodes. What kind of silicon
Dialogue: 0,0:12:56.42,0:13:02.59,Default,,0000,0000,0000,,diodes? I'm using in this project, low\Nlocal silicon pin diodes, one is called
Dialogue: 0,0:13:02.59,0:13:09.03,Default,,0000,0000,0000,,BPW34 it's manufactured from Vishay or\NOsram, costs about 50 cents. So that's what
Dialogue: 0,0:13:09.03,0:13:15.17,Default,,0000,0000,0000,,I mean with low cost. There's another one\Ncalled BPX61 from Osram. It's quite a bit
Dialogue: 0,0:13:15.17,0:13:19.56,Default,,0000,0000,0000,,more expensive. This is the lower one here\Non the right. It has a metal case, which
Dialogue: 0,0:13:19.56,0:13:23.45,Default,,0000,0000,0000,,is the main reason why it's more\Nexpensive. But it's quite interesting
Dialogue: 0,0:13:23.45,0:13:28.52,Default,,0000,0000,0000,,because that one we can use for the alpha\Ndetector. If you look closely, there is a
Dialogue: 0,0:13:28.52,0:13:35.80,Default,,0000,0000,0000,,glass on top, but we can remove that. We\Nhave a sensitive area. So this chip is
Dialogue: 0,0:13:35.80,0:13:43.08,Default,,0000,0000,0000,,roughly 7mm² large and it has a thickness,\Na sensitive thickness of about 50
Dialogue: 0,0:13:43.08,0:13:49.68,Default,,0000,0000,0000,,micrometer, which is not a lot. So it's\Nbasically the half of the width of a human
Dialogue: 0,0:13:49.68,0:13:55.40,Default,,0000,0000,0000,,hair. And in total, it's a really small,\Nsensitive volume. But it's it's enough to
Dialogue: 0,0:13:55.40,0:14:02.20,Default,,0000,0000,0000,,measure something. And just as a reminder,\Nhow much of gamma rays or X-rays we will
Dialogue: 0,0:14:02.20,0:14:09.06,Default,,0000,0000,0000,,detect with this, not a lot because it's\Nhigh, energetic photon radiation kind
Dialogue: 0,0:14:09.06,0:14:15.47,Default,,0000,0000,0000,,doesn't interact very well in any kind of\Nmatter. And because a sensitive area is so
Dialogue: 0,0:14:15.47,0:14:21.40,Default,,0000,0000,0000,,thin, it would basically permeate through\Nit and most of the times not interact and
Dialogue: 0,0:14:21.40,0:14:28.40,Default,,0000,0000,0000,,doesn't make a signal. OK, what's really\Nimportant, since we don't want to measure
Dialogue: 0,0:14:28.40,0:14:35.12,Default,,0000,0000,0000,,light, we have to shield light away. We\Nneed to block all of the light, that means
Dialogue: 0,0:14:35.12,0:14:40.08,Default,,0000,0000,0000,,easiest way to do it is to put it in a\Nmetal case. There is electromagnetically
Dialogue: 0,0:14:40.08,0:14:44.88,Default,,0000,0000,0000,,shielded and completely protected from\Nlight as well. Electromagnetic radiation
Dialogue: 0,0:14:44.88,0:14:49.84,Default,,0000,0000,0000,,or radiowaves can also influence these\Ndetectors because they are super
Dialogue: 0,0:14:49.84,0:14:55.36,Default,,0000,0000,0000,,sensitive. So this sould be a complete\NFaraday cage, complete metal structure
Dialogue: 0,0:14:55.36,0:15:03.12,Default,,0000,0000,0000,,around it. There's a lot of hints and tips\Nhow to achieve that on the wiki on the on
Dialogue: 0,0:15:03.12,0:15:10.08,Default,,0000,0000,0000,,the GitHub of this project. OK, let's\Nthink about one of those PIN diodes,
Dialogue: 0,0:15:10.08,0:15:18.72,Default,,0000,0000,0000,,normally there is one part in the\Nsilicon which is n-doped
Dialogue: 0,0:15:18.72,0:15:23.92,Default,,0000,0000,0000,,negatively doped, and the other part\Nusually, which is positively dropped. And
Dialogue: 0,0:15:23.92,0:15:28.08,Default,,0000,0000,0000,,then you arrive at a simple so called p-n-\Njunction, which is a regular
Dialogue: 0,0:15:28.08,0:15:33.84,Default,,0000,0000,0000,,semiconducting diode. Now, pin diodes add\Nanother layer of so-called intrinsic
Dialogue: 0,0:15:33.84,0:15:41.92,Default,,0000,0000,0000,,layer, here shown with the i. And that\Nactually is the main advantage. Why this
Dialogue: 0,0:15:41.92,0:15:50.80,Default,,0000,0000,0000,,kind of detector works quite well and have\Na relatively large sensitive Sigma's. So
Dialogue: 0,0:15:50.80,0:15:58.32,Default,,0000,0000,0000,,if you think about, let's say, a photon\Nfrom an x ray or gamma-decay or an
Dialogue: 0,0:15:58.32,0:16:03.92,Default,,0000,0000,0000,,electron hitting the sensor. So by the\Nway, this is a cross-section view from the
Dialogue: 0,0:16:03.92,0:16:09.84,Default,,0000,0000,0000,,side, but that doesn't really matter. But\Nlet's say they come here from the top into
Dialogue: 0,0:16:09.84,0:16:16.48,Default,,0000,0000,0000,,the... into the diode and we're looking\Nat the side then we have actually
Dialogue: 0,0:16:16.48,0:16:22.00,Default,,0000,0000,0000,,ionization because this is ionizing\Nradiation, so we get free charges in the
Dialogue: 0,0:16:22.00,0:16:26.96,Default,,0000,0000,0000,,form of electron-hole pairs. So electrons,\Nwhich here the blue ball and the red
Dialogue: 0,0:16:26.96,0:16:34.24,Default,,0000,0000,0000,,circle would be the holes. And depending\Non the radiation kind, how this ionization
Dialogue: 0,0:16:34.24,0:16:39.76,Default,,0000,0000,0000,,takes place is quite different, but the\Nresult is if you get a signal, it means
Dialogue: 0,0:16:39.76,0:16:45.52,Default,,0000,0000,0000,,there was ionization. Now, if just this\Nwould happen, we could not measure
Dialogue: 0,0:16:45.52,0:16:53.12,Default,,0000,0000,0000,,anything. Those charges would quickly\Nrecombine and on the outside of the diode,
Dialogue: 0,0:16:53.12,0:16:58.72,Default,,0000,0000,0000,,it would be a little signal. But what we\Ncan do is we can apply actually a voltage
Dialogue: 0,0:16:58.72,0:17:06.32,Default,,0000,0000,0000,,from the outside. So here we just put a\Nbattery. So we have a positive voltage
Dialogue: 0,0:17:06.32,0:17:12.00,Default,,0000,0000,0000,,here, a couple of volts. And then what\Nhappens is that the electrons would be
Dialogue: 0,0:17:12.00,0:17:18.48,Default,,0000,0000,0000,,attracted by the positive voltage and the\Nholes will travel to the negative
Dialogue: 0,0:17:18.48,0:17:26.72,Default,,0000,0000,0000,,potential. And we end up with a little net\Ncurrent or a small bunch of charges that
Dialogue: 0,0:17:26.72,0:17:35.20,Default,,0000,0000,0000,,can be measured across the diode as a\Ntiny, tiny current. The sensitive volume
Dialogue: 0,0:17:35.20,0:17:41.04,Default,,0000,0000,0000,,is actually proportional to the voltage,\Nso the more voltage we put, the more the
Dialogue: 0,0:17:41.04,0:17:44.88,Default,,0000,0000,0000,,bigger is our volume and the more we can\Nactually measure with certain limits, of
Dialogue: 0,0:17:44.88,0:17:49.52,Default,,0000,0000,0000,,course, because the structure of the pin\Ndiode has a maximum thickness just
Dialogue: 0,0:17:49.52,0:17:56.80,Default,,0000,0000,0000,,according how it is manufactured. And\Nthese properties can be estimated with
Dialogue: 0,0:17:56.80,0:18:02.72,Default,,0000,0000,0000,,C-V-measurements. So here you see an\Nexample of a couple of diodes, a few of
Dialogue: 0,0:18:02.72,0:18:06.24,Default,,0000,0000,0000,,the same type. The two that I've\Nmentioned, they're different versions. One
Dialogue: 0,0:18:06.24,0:18:11.36,Default,,0000,0000,0000,,has a transparent plastic case. One has a\Nblack plastic case. Doesn't really matter.
Dialogue: 0,0:18:11.36,0:18:16.80,Default,,0000,0000,0000,,You see, basically in all the cases, more\Nor less the same curve. And as you
Dialogue: 0,0:18:16.80,0:18:21.76,Default,,0000,0000,0000,,increase the voltage, the capacitance goes\Ndown. So it's great and basically shows us
Dialogue: 0,0:18:21.76,0:18:26.96,Default,,0000,0000,0000,,those silicon chips are very similar, if\Nnot exactly the same chip. Those
Dialogue: 0,0:18:26.96,0:18:34.88,Default,,0000,0000,0000,,differences are easily explained by\Nmanufacturing variances. And then because
Dialogue: 0,0:18:34.88,0:18:39.28,Default,,0000,0000,0000,,this actually, if you think about it, it\Nlooks a bit like a parallel plate
Dialogue: 0,0:18:39.28,0:18:45.12,Default,,0000,0000,0000,,capacitor and actually you can treat it as\None. And if you know the capacitance and
Dialogue: 0,0:18:45.12,0:18:50.24,Default,,0000,0000,0000,,the size, the area, you can actually\Ncalculate the distance of these two plates
Dialogue: 0,0:18:50.24,0:18:58.08,Default,,0000,0000,0000,,or basically width or the thickness of the\Ndiode. And then we arrive at about 50
Dialogue: 0,0:18:58.08,0:19:06.80,Default,,0000,0000,0000,,micrometer, if you put something like 8 or\N10 volts. OK, now we have a tiny charge
Dialogue: 0,0:19:06.80,0:19:11.60,Default,,0000,0000,0000,,current, now we need to amplify it, so we\Nhave a couple of diodes, I'm explaining
Dialogue: 0,0:19:11.60,0:19:16.64,Default,,0000,0000,0000,,now the electron detector, because it's\Neasier. We have four diodes at the input
Dialogue: 0,0:19:16.64,0:19:21.36,Default,,0000,0000,0000,,and this is the symbol for an operational\Namplifier. There are two of those in the
Dialogue: 0,0:19:21.36,0:19:25.84,Default,,0000,0000,0000,,circuit. The first stage is really the\Nspecial one. So if you have a particle
Dialogue: 0,0:19:25.84,0:19:31.20,Default,,0000,0000,0000,,striking the diode, we get a little charge\Ncurrent hitting the amplifier. And then we
Dialogue: 0,0:19:31.20,0:19:34.88,Default,,0000,0000,0000,,have here this important feedback\Ncircuit. So the output is fed back into
Dialogue: 0,0:19:34.88,0:19:40.88,Default,,0000,0000,0000,,the input, which in this case makes a\Nnegative amplification. And the
Dialogue: 0,0:19:40.88,0:19:46.32,Default,,0000,0000,0000,,amplification is defined actually by this\Ncapacitance here. The resistor has a
Dialogue: 0,0:19:46.32,0:19:51.36,Default,,0000,0000,0000,,secondary role with the small capacitance.\NIt is what makes the output voltage here
Dialogue: 0,0:19:51.36,0:19:57.20,Default,,0000,0000,0000,,large. The smaller the capacitance, the\Nlarger the output and it's inverted. Then
Dialogue: 0,0:19:57.20,0:20:02.32,Default,,0000,0000,0000,,in the next amplifier step, we just\Nincrease the voltage again to a level that
Dialogue: 0,0:20:02.32,0:20:08.16,Default,,0000,0000,0000,,is useful for using it later. But all of\Nthe signal quality that has been
Dialogue: 0,0:20:08.16,0:20:13.12,Default,,0000,0000,0000,,achieved in the first stage will stay like\Nthat. So signal to noise is defined by the
Dialogue: 0,0:20:13.12,0:20:18.88,Default,,0000,0000,0000,,first stage. The second one is just to\Nbetter adapt it to the input of the
Dialogue: 0,0:20:18.88,0:20:24.48,Default,,0000,0000,0000,,measurement device that's connected. So\Nhere, this is a classic inverting
Dialogue: 0,0:20:24.48,0:20:29.12,Default,,0000,0000,0000,,amplifier with just these two resistors\Ndefine the amplification factor. It's very
Dialogue: 0,0:20:29.12,0:20:35.36,Default,,0000,0000,0000,,simple. It's just a factor of hundred in\Nthis case. And so if you think again about
Dialogue: 0,0:20:35.36,0:20:39.76,Default,,0000,0000,0000,,the charge pulse and this, the circuit\Nhere is sensitive, starting from about
Dialogue: 0,0:20:39.76,0:20:50.32,Default,,0000,0000,0000,,1000 liberated charges in those diodes as\Na result from ionization. We get something
Dialogue: 0,0:20:50.32,0:20:55.92,Default,,0000,0000,0000,,like 320 micro Volt at this first output,\Nand this is a spike that quickly
Dialogue: 0,0:20:55.92,0:21:01.60,Default,,0000,0000,0000,,decreases. Basically these capacitors are\Ncharged and quickly discharged with this
Dialogue: 0,0:21:01.60,0:21:07.36,Default,,0000,0000,0000,,resistor and this is what we see here. And\Nthen that is amplified again by a factor
Dialogue: 0,0:21:07.36,0:21:14.08,Default,,0000,0000,0000,,of 100. And then we arrive at something\Nlike at least 32 mV, which is conveniently
Dialogue: 0,0:21:14.08,0:21:20.00,Default,,0000,0000,0000,,a voltage that is compatible with most\Nmicrophone or headset inputs of computers
Dialogue: 0,0:21:20.00,0:21:25.60,Default,,0000,0000,0000,,or mobile phones, so that the regular\Nheadset here has these four connectors and
Dialogue: 0,0:21:25.60,0:21:31.52,Default,,0000,0000,0000,,the last ring actually connects the\Nmicrophone. The other is ground and reft.
Dialogue: 0,0:21:31.52,0:21:39.36,Default,,0000,0000,0000,,Left, right for the earbuds. OK, how do we\Nrecord those pulses? This is an example of
Dialogue: 0,0:21:39.36,0:21:46.40,Default,,0000,0000,0000,,1000 pulses overlayed and measured on an\Noscilloscope here. So it's a bit more
Dialogue: 0,0:21:46.40,0:21:52.40,Default,,0000,0000,0000,,accurate. You see the deposits a bit\Nbetter, kind of like the persistence mode
Dialogue: 0,0:21:52.40,0:21:58.16,Default,,0000,0000,0000,,of an oscilloscope. And the size of the\Npulse is proportional to energy that was
Dialogue: 0,0:21:58.16,0:22:03.68,Default,,0000,0000,0000,,absorbed. And the circuit is made in such\Na way that the width of the pulse is big
Dialogue: 0,0:22:03.68,0:22:08.56,Default,,0000,0000,0000,,enough such that regular sampling\Nfrequency of a sound card can actually
Dialogue: 0,0:22:08.56,0:22:14.80,Default,,0000,0000,0000,,catch it and measure it. Yeah, this is\NPotassium Salt. This is cut here. This is
Dialogue: 0,0:22:14.80,0:22:18.72,Default,,0000,0000,0000,,called a low salt in the UK. There is also\Na german variance, you can also just buy
Dialogue: 0,0:22:18.72,0:22:26.32,Default,,0000,0000,0000,,it in the pharmacy or in certain organic\Nfood stores as a replacement salt.
Dialogue: 0,0:22:26.32,0:22:33.12,Default,,0000,0000,0000,,On the right side is an example from this\Nsmall Columbite Stone, which has traces of
Dialogue: 0,0:22:33.12,0:22:38.72,Default,,0000,0000,0000,,uranium on it. And this is measured with\Nthe alpha spectrometer. And you see those
Dialogue: 0,0:22:38.72,0:22:42.64,Default,,0000,0000,0000,,pulses are quite a bit bigger here. We\Nhave 50 microseconds and here we have more
Dialogue: 0,0:22:42.64,0:22:52.88,Default,,0000,0000,0000,,like one milliseconds of pulse width. Now\Nthere's a software on a browser. This is
Dialogue: 0,0:22:52.88,0:23:00.72,Default,,0000,0000,0000,,something I wrote using the Web Audio API\Nand it works on most browsers, best is
Dialogue: 0,0:23:00.72,0:23:06.64,Default,,0000,0000,0000,,Chrome, on iOs, of course, you have to use\NSafari and that records once you plug the
Dialogue: 0,0:23:06.64,0:23:13.12,Default,,0000,0000,0000,,detector, it records from the input at 48\Nor 44.1kHz the pulses. Here's an example
Dialogue: 0,0:23:13.12,0:23:18.56,Default,,0000,0000,0000,,with the alpha spectrometer circuit, you\Nget these nice large pulses. In case of
Dialogue: 0,0:23:18.56,0:23:22.80,Default,,0000,0000,0000,,the electron detector the pulse is much\Nshorter and you see it, you see the noise
Dialogue: 0,0:23:22.80,0:23:28.88,Default,,0000,0000,0000,,much more amplified. This red line is kind\Nof the minimum level that the pulse needs
Dialogue: 0,0:23:28.88,0:23:32.24,Default,,0000,0000,0000,,to trigger. This would be better. And\Nthat's like the trigger level of an
Dialogue: 0,0:23:32.24,0:23:38.16,Default,,0000,0000,0000,,oscilloscope. And you can set that with\Nthose buttons in the browser. You need to
Dialogue: 0,0:23:38.16,0:23:42.96,Default,,0000,0000,0000,,find a good value. Of course, if you\Nchange your input volume settings, for
Dialogue: 0,0:23:42.96,0:23:49.84,Default,,0000,0000,0000,,example, this will change. So you have to\Nremember which, with which settings it
Dialogue: 0,0:23:49.84,0:23:55.60,Default,,0000,0000,0000,,works well. And it is pulsed, for example,\Nis even oscillating here. So for electron
Dialogue: 0,0:23:55.60,0:24:01.44,Default,,0000,0000,0000,,detector, it's basically nice to count\Nparticles. For the alpha detector it's
Dialogue: 0,0:24:01.44,0:24:06.24,Default,,0000,0000,0000,,really the case where the size of the\Npulse can be nicely evaluated and we can
Dialogue: 0,0:24:06.24,0:24:11.12,Default,,0000,0000,0000,,actually do energy measurements. And these\Nenergy measurements can be also called
Dialogue: 0,0:24:11.12,0:24:17.52,Default,,0000,0000,0000,,spectrometry. So if you look closer at\Nthese many pulses that have been recorded
Dialogue: 0,0:24:17.52,0:24:26.56,Default,,0000,0000,0000,,and we find that there is really like much\Nmore intensity, which means many more same
Dialogue: 0,0:24:26.56,0:24:32.16,Default,,0000,0000,0000,,pulses were detected, we can relate it to\Nradium and radon. If we use a reference
Dialogue: 0,0:24:32.16,0:24:35.92,Default,,0000,0000,0000,,alpha source and I have done this, I have\Nmeasured the whole circuit with the reference
Dialogue: 0,0:24:35.92,0:24:41.36,Default,,0000,0000,0000,,sources and provide the calibration on\NGitHub and you can reuse the GitHub
Dialogue: 0,0:24:41.36,0:24:47.28,Default,,0000,0000,0000,,calibration if you use exactly the same\Nsound settings that I have used for
Dialogue: 0,0:24:47.28,0:24:53.60,Default,,0000,0000,0000,,recording. And for example, these two very\Nweak lines here from two very distinctive
Dialogue: 0,0:24:53.60,0:25:02.56,Default,,0000,0000,0000,,polonium isotopes from the uranium decay\Nchain. The top part here which is really
Dialogue: 0,0:25:02.56,0:25:08.24,Default,,0000,0000,0000,,dark, corresponds basically in the\Nhistogram view to this side on the left,
Dialogue: 0,0:25:08.24,0:25:12.16,Default,,0000,0000,0000,,which is electrons. Most of these\Nelectrons will actually enter the chip and
Dialogue: 0,0:25:12.16,0:25:18.80,Default,,0000,0000,0000,,leave it without being completely\Nabsorbed by it, but alpha particles
Dialogue: 0,0:25:18.80,0:25:22.96,Default,,0000,0000,0000,,interact so strongly that they are\Ncompletely absorbed within the 50
Dialogue: 0,0:25:22.96,0:25:29.52,Default,,0000,0000,0000,,micrometers of sensitive volume of these\Ndiodes and OK here is a bit difficult to
Dialogue: 0,0:25:29.52,0:25:35.44,Default,,0000,0000,0000,,see peaks. But the far end of the high\Nenergy spectrum, you see two really clear
Dialogue: 0,0:25:35.44,0:25:40.56,Default,,0000,0000,0000,,peaks and those can only stem from\Npolonium, actually. I mean, we know it's
Dialogue: 0,0:25:40.56,0:25:46.96,Default,,0000,0000,0000,,uranium and that can only be polonium,\Nwhich is that isotope that produces the
Dialogue: 0,0:25:46.96,0:25:56.08,Default,,0000,0000,0000,,most energetic alpha particles and\Nwhich is natural. And I said, if you use
Dialogue: 0,0:25:56.08,0:25:59.84,Default,,0000,0000,0000,,the same setting like me, you can use it.\NSo the best is if you use actually the
Dialogue: 0,0:25:59.84,0:26:04.56,Default,,0000,0000,0000,,same soundcard because they're if you put\Nit to hundred percent input sensitivity,
Dialogue: 0,0:26:04.56,0:26:08.88,Default,,0000,0000,0000,,you will have exactly the same result,\Nlike in my calibration case. And this
Dialogue: 0,0:26:08.88,0:26:13.12,Default,,0000,0000,0000,,soundcard is pretty cheap, but also pretty\Ngood. It costs just two dollars and has a
Dialogue: 0,0:26:13.12,0:26:18.56,Default,,0000,0000,0000,,pretty range and resolves quite well, 16\Nbits and think, oh, you could do that with
Dialogue: 0,0:26:18.56,0:26:24.64,Default,,0000,0000,0000,,Arduino as well, is actually a bit hard to\Ndo. A really well defined 16 bit
Dialogue: 0,0:26:24.64,0:26:31.28,Default,,0000,0000,0000,,measurement, even at 48 kHz. It's not so\Neasy and this keeps it cheap and kind of
Dialogue: 0,0:26:31.28,0:26:34.96,Default,,0000,0000,0000,,straightforward. And you can have just\Nsome Python scripts on the computer to
Dialogue: 0,0:26:34.96,0:26:40.96,Default,,0000,0000,0000,,read it out. And this is as a reminder, in\Norder to measure alpha particles, we have
Dialogue: 0,0:26:40.96,0:26:44.72,Default,,0000,0000,0000,,to remove the glass here on top of the\Ndiode. So I'm doing it just cutting into
Dialogue: 0,0:26:44.72,0:26:50.16,Default,,0000,0000,0000,,the metal frame and then the glass breaks\Naway easily. Is not a problem, there's
Dialogue: 0,0:26:50.16,0:26:56.80,Default,,0000,0000,0000,,more on that on the wiki. Now we\Ncan kind of compare alpha and gamma
Dialogue: 0,0:26:56.80,0:27:03.92,Default,,0000,0000,0000,,spectrometry. Here's an example. This is\Nthe uranium glazed ceramics. The red part
Dialogue: 0,0:27:03.92,0:27:09.84,Default,,0000,0000,0000,,is uranium oxide that was used to create\Nthis nice red color in the 50s, 60s, 70s.
Dialogue: 0,0:27:09.84,0:27:15.04,Default,,0000,0000,0000,,And in the spectrum we have two very\Ndistinctive peaks and nothing in the high
Dialogue: 0,0:27:15.04,0:27:20.80,Default,,0000,0000,0000,,energy regime. Only this low energy range\Nhas a signal. And this corresponds
Dialogue: 0,0:27:20.80,0:27:27.92,Default,,0000,0000,0000,,actually to uranium 238 and 234 because\Nthey use actually purified uranium. So all
Dialogue: 0,0:27:27.92,0:27:33.92,Default,,0000,0000,0000,,of the high energy progeny or daughters of\Nuranium, they're not present here because
Dialogue: 0,0:27:33.92,0:27:38.72,Default,,0000,0000,0000,,it was purified uranium. And this\Nmeasurement doesn't even need vacuum, I
Dialogue: 0,0:27:38.72,0:27:43.28,Default,,0000,0000,0000,,put it just like this in a regular box. Of\Ncourse, if you would have vacuum, you
Dialogue: 0,0:27:43.28,0:27:48.40,Default,,0000,0000,0000,,would improve this peaks by a lot. So this\Nwidening here to the left, basically, that
Dialogue: 0,0:27:48.40,0:27:55.20,Default,,0000,0000,0000,,this peak is almost below the other one.\NThat is due to the natural air at regular
Dialogue: 0,0:27:55.20,0:28:00.96,Default,,0000,0000,0000,,air pressure, which already interacts a\Nlot with the particles and absorbs a lot
Dialogue: 0,0:28:00.96,0:28:06.96,Default,,0000,0000,0000,,of energy before the particles hit the\Nsensor. So in terms of pros and cons, I
Dialogue: 0,0:28:06.96,0:28:12.08,Default,,0000,0000,0000,,would say the small sensor is quite\Ninteresting here in an alpha spectrometry
Dialogue: 0,0:28:12.08,0:28:18.40,Default,,0000,0000,0000,,because it's enough to have a small\Nsensor. So it's cheap and you can measure
Dialogue: 0,0:28:18.40,0:28:25.28,Default,,0000,0000,0000,,very precisely on specific spots. And on\Nthe other hand, of course, the conditions
Dialogue: 0,0:28:25.28,0:28:29.44,Default,,0000,0000,0000,,of the object influence the measurement a\Nlot. So, for example, if there's some
Dialogue: 0,0:28:29.44,0:28:34.56,Default,,0000,0000,0000,,additional paint on top, the alpha\Nparticles might not make it through. But
Dialogue: 0,0:28:34.56,0:28:40.56,Default,,0000,0000,0000,,in most of these kind of samples, alpha\Nradiation actually makes it through the
Dialogue: 0,0:28:40.56,0:28:46.80,Default,,0000,0000,0000,,top, a transparent paint layer. In terms\Nof gamma spectrometry, you would usually
Dialogue: 0,0:28:46.80,0:28:51.76,Default,,0000,0000,0000,,have these huge and really expensive\Nsensors. And then the advantage, of
Dialogue: 0,0:28:51.76,0:28:56.80,Default,,0000,0000,0000,,course, is that you can measure,\Nregardless of your object, you don't
Dialogue: 0,0:28:56.80,0:29:01.04,Default,,0000,0000,0000,,really need to prepare the object a lot.\NYou might want some lead shielding around
Dialogue: 0,0:29:01.04,0:29:06.40,Default,,0000,0000,0000,,it. That's again, expensive, but you can\Ndo it. You can improve the measurement
Dialogue: 0,0:29:06.40,0:29:14.00,Default,,0000,0000,0000,,like that. And it's basically costly\Nbecause the sensor is quite expensive.
Dialogue: 0,0:29:14.00,0:29:19.68,Default,,0000,0000,0000,,Vice versa in the set setup for 15 to 30\Neuro. You have everything you need and
Dialogue: 0,0:29:19.68,0:29:28.16,Default,,0000,0000,0000,,here you're looking at several hundred to\Nseveral thousand euros. OK, now measuring
Dialogue: 0,0:29:28.16,0:29:34.88,Default,,0000,0000,0000,,I have to be a bit quicker now, I noticed.\NSo I talked about the potassium
Dialogue: 0,0:29:34.88,0:29:39.44,Default,,0000,0000,0000,,salt. There's also fertilizer based on\Npotassium baking powder. Uranium glass is
Dialogue: 0,0:29:39.44,0:29:44.80,Default,,0000,0000,0000,,quite nice. You can find that easily on\Nflea markets. Often also old radium
Dialogue: 0,0:29:44.80,0:29:50.08,Default,,0000,0000,0000,,watches. Here's another example of a\Nuranium glaze, the kitchen tile in this
Dialogue: 0,0:29:50.08,0:29:54.40,Default,,0000,0000,0000,,case, this was actually in the kitchen. So\Nthe chances are that you at home find
Dialogue: 0,0:29:54.40,0:29:58.24,Default,,0000,0000,0000,,actually some of those things in the\Ncupboards of your parents or your
Dialogue: 0,0:29:58.24,0:30:01.84,Default,,0000,0000,0000,,grandparents. It is an example of\Nthoriated glass, which has this
Dialogue: 0,0:30:01.84,0:30:08.40,Default,,0000,0000,0000,,distinctive brownish color, which actually\Nis from the radiation. And a nice little
Dialogue: 0,0:30:08.40,0:30:12.72,Default,,0000,0000,0000,,experiment that I can really recommend you\Nto look up is radioactive balloon
Dialogue: 0,0:30:12.72,0:30:17.92,Default,,0000,0000,0000,,experiment. Here, you charge the balloon\Nelectrostaticly and then it would catch
Dialogue: 0,0:30:17.92,0:30:21.84,Default,,0000,0000,0000,,polonium from the air. And it's really\Ngreat. You basically get a radioactive
Dialogue: 0,0:30:21.84,0:30:30.80,Default,,0000,0000,0000,,balloon after it was just left for 15\Nminutes in a normal regular room. OK, now
Dialogue: 0,0:30:30.80,0:30:36.93,Default,,0000,0000,0000,,the last kind of context of all of\Nthis to end this presentation, I want to
Dialogue: 0,0:30:36.93,0:30:43.28,Default,,0000,0000,0000,,quickly remind how important these silicon\Ndetectors are for places like CERN. It's a
Dialogue: 0,0:30:43.28,0:30:48.82,Default,,0000,0000,0000,,cross-section of the ATLAS detector. And\Nhere you have basically the area where the
Dialogue: 0,0:30:48.82,0:30:53.95,Default,,0000,0000,0000,,collisions happen in the ATLAS detector.\NSo this is just a fraction of a meter. And
Dialogue: 0,0:30:53.95,0:31:02.05,Default,,0000,0000,0000,,you have today 50 to 100 head on collisions\Nof two protons happening every 25
Dialogue: 0,0:31:02.05,0:31:08.38,Default,,0000,0000,0000,,nanoseconds. Not right now, but soon\Nagain, machines will be started again next
Dialogue: 0,0:31:08.38,0:31:15.11,Default,,0000,0000,0000,,year. And you also can, by the way, build\Na similar project which has a slightly
Dialogue: 0,0:31:15.11,0:31:19.49,Default,,0000,0000,0000,,different name. It's called Build Your Own\NParticle Detector. This is Atlas and made
Dialogue: 0,0:31:19.49,0:31:25.21,Default,,0000,0000,0000,,out of LEGO. And on this website, you\Nfind a nice plan, how to build or ideas,
Dialogue: 0,0:31:25.21,0:31:32.50,Default,,0000,0000,0000,,how to build it from LEGO to better\Nvisualize the size and interact more with
Dialogue: 0,0:31:32.50,0:31:38.43,Default,,0000,0000,0000,,particle physics. In case of the CMS\Ndetector. This is the second biggest
Dialogue: 0,0:31:38.43,0:31:43.65,Default,,0000,0000,0000,,detector at CERN. Here you see nicely that\Nin the middle, at the core of the
Dialogue: 0,0:31:43.65,0:31:49.36,Default,,0000,0000,0000,,collision, you have many, many pixel and\Nmicrostrip detectors which are made of
Dialogue: 0,0:31:49.36,0:31:59.46,Default,,0000,0000,0000,,silicon. And these are actually 16 m² of\Nsilicon pixel detectors and 200m² of
Dialogue: 0,0:31:59.46,0:32:04.87,Default,,0000,0000,0000,,microstrip detectors also made of silicon.\NSo without basically that silicon
Dialogue: 0,0:32:04.87,0:32:10.65,Default,,0000,0000,0000,,technology modern detectors wouldn't work\Nbecause this fine segmentation is really
Dialogue: 0,0:32:10.65,0:32:16.61,Default,,0000,0000,0000,,required to distinguish all of these newly\Ncreated particles as a result of the
Dialogue: 0,0:32:16.61,0:32:24.61,Default,,0000,0000,0000,,collision. So to summarize the website is\Non GitHub, there is really this big wiki,
Dialogue: 0,0:32:24.61,0:32:29.35,Default,,0000,0000,0000,,which you should have a look at, and\Nthere's a gallery of pictures from users.
Dialogue: 0,0:32:29.35,0:32:34.31,Default,,0000,0000,0000,,There's some simulation software that I\Nused as well. I didn't develop it, but I
Dialogue: 0,0:32:34.31,0:32:38.92,Default,,0000,0000,0000,,wrote how to use it because the spectra\Ncan sometimes be difficult to interpret.
Dialogue: 0,0:32:38.92,0:32:44.44,Default,,0000,0000,0000,,And there's a new discussion forum that I\Nwould really appreciate if some of you had
Dialogue: 0,0:32:44.44,0:32:49.65,Default,,0000,0000,0000,,some discussions there on GitHub. And most\Nof the things I saw today are actually
Dialogue: 0,0:32:49.65,0:32:54.59,Default,,0000,0000,0000,,written in detail in a scientific article,\Nwhich is open access, of course. And I
Dialogue: 0,0:32:54.59,0:33:00.20,Default,,0000,0000,0000,,want to highlight two related citizen\Nscience projects on the one hand, as the
Dialogue: 0,0:33:00.20,0:33:07.38,Default,,0000,0000,0000,,safecast, which is about a large, nice,\Nsensitive Geiger-Müller based detector
Dialogue: 0,0:33:07.38,0:33:12.64,Default,,0000,0000,0000,,that has the GPS and people upload their\Nmeasurements there. This is quite nice.
Dialogue: 0,0:33:12.64,0:33:17.32,Default,,0000,0000,0000,,And also opengeiger is another website,\Nmostly German content, but also some of it
Dialogue: 0,0:33:17.32,0:33:23.41,Default,,0000,0000,0000,,is English, that also uses diode\Ndetectors, showed many nice places. He
Dialogue: 0,0:33:23.41,0:33:29.97,Default,,0000,0000,0000,,calls it Geiger caching, places around the\Nworld where you can measure something,
Dialogue: 0,0:33:29.97,0:33:35.03,Default,,0000,0000,0000,,some old mines, things like this. And if\Nyou want updates, I would propose to
Dialogue: 0,0:33:35.03,0:33:40.16,Default,,0000,0000,0000,,follow me on Twitter. I'm right now\Nwriting up two other articles with more
Dialogue: 0,0:33:40.16,0:33:46.89,Default,,0000,0000,0000,,ideas for measurements and some of the\Nthings you have seen today. Thanks a lot.
Dialogue: 0,0:33:50.95,0:33:57.84,Default,,0000,0000,0000,,Herald: Well, thanks a lot, Oliver. I hope\Neveryone can hear me now again. Yes,
Dialogue: 0,0:33:57.84,0:34:02.88,Default,,0000,0000,0000,,thanks for mentioning the citizen science\Nproject as well. It's really cool I think.
Dialogue: 0,0:34:02.88,0:34:09.84,Default,,0000,0000,0000,,We do have a few minutes for the Q&A and\Nalso a lot of questions coming up in our
Dialogue: 0,0:34:09.84,0:34:18.24,Default,,0000,0000,0000,,instance at the IRC. So the first question\Nwas, can you talk a bit more about the SNR
Dialogue: 0,0:34:18.24,0:34:24.00,Default,,0000,0000,0000,,of the system? Did you pick particular\Nresistor values and or Opamps to optimize
Dialogue: 0,0:34:24.00,0:34:29.28,Default,,0000,0000,0000,,for noise? Was it a problem?\NOliver: Yeah, so noise is the big
Dialogue: 0,0:34:29.28,0:34:36.88,Default,,0000,0000,0000,,issue here. Basically, the amplifier is\None I found that this around four, four
Dialogue: 0,0:34:36.88,0:34:45.04,Default,,0000,0000,0000,,euros, trying to find the slide. Yeah, you\Nhave to look it up on GitHub to the
Dialogue: 0,0:34:45.04,0:34:49.60,Default,,0000,0000,0000,,amplifier type, but this is the most\Nimportant one. And then actually the
Dialogue: 0,0:34:49.60,0:34:54.80,Default,,0000,0000,0000,,resistors, here, the resistance in the\Nfirst stage, sorry, the capacitors is the
Dialogue: 0,0:34:54.80,0:34:59.20,Default,,0000,0000,0000,,second important thing. They should be\Nreally small since I'm limited here with
Dialogue: 0,0:34:59.20,0:35:07.52,Default,,0000,0000,0000,,hand soldarable capacitors. Basically I\Nchoose the one that were just still
Dialogue: 0,0:35:07.52,0:35:11.20,Default,,0000,0000,0000,,available, let's say, and this is\Nbasically what is available is basically a
Dialogue: 0,0:35:11.20,0:35:15.84,Default,,0000,0000,0000,,10 pF capacitor. If you put two of them,\None after another, you half the
Dialogue: 0,0:35:15.84,0:35:20.80,Default,,0000,0000,0000,,capacitance, so you get five. And this, by\Nthe way, is also then the capacitor. So I
Dialogue: 0,0:35:20.80,0:35:29.28,Default,,0000,0000,0000,,kind of tried to keep the same\Nresistor values as much as possible, and
Dialogue: 0,0:35:29.28,0:35:32.72,Default,,0000,0000,0000,,here at the output, for example, this is\Nto adjust the output signal for a
Dialogue: 0,0:35:32.72,0:35:37.68,Default,,0000,0000,0000,,microphone input in the alpha\Nspectrometer, I changed the values quite a
Dialogue: 0,0:35:37.68,0:35:43.44,Default,,0000,0000,0000,,bit to make a large pulse. But, yeah,\Nit's basically playing with the time
Dialogue: 0,0:35:43.44,0:35:47.67,Default,,0000,0000,0000,,constants of this network and this\Nnetwork.
Dialogue: 0,0:35:49.42,0:35:56.00,Default,,0000,0000,0000,,Herald: All right, I hope that answers for\Nthe person. Yeah, but people can get a
Dialogue: 0,0:35:56.00,0:36:02.48,Default,,0000,0000,0000,,contact to you right after the show maybe\Nas well. So there's another question. Have
Dialogue: 0,0:36:02.48,0:36:12.40,Default,,0000,0000,0000,,you considered using an I²S Codec with a\NRaspberry Pi? radiation H80 should be
Dialogue: 0,0:36:12.40,0:36:17.12,Default,,0000,0000,0000,,almost no set up and completely\Nrepeatable. So last ones are for comment.
Dialogue: 0,0:36:19.52,0:36:25.28,Default,,0000,0000,0000,,Oliver: I don't know that component, but,\Nyeah, as I said, using a sound card, it's
Dialogue: 0,0:36:25.28,0:36:31.28,Default,,0000,0000,0000,,actually quite straightforward. But of\Ncourse there's many ways to get fancy.
Dialogue: 0,0:36:31.28,0:36:35.44,Default,,0000,0000,0000,,And this is really this should actually\Nattract teachers and high school students
Dialogue: 0,0:36:35.44,0:36:41.04,Default,,0000,0000,0000,,as well, this project. So this is one of\Nthe main reasons why certain technologies
Dialogue: 0,0:36:41.04,0:36:45.40,Default,,0000,0000,0000,,have been chosen, rather simple than,\Nlet's say, fancy.
Dialogue: 0,0:36:45.40,0:36:51.61,Default,,0000,0000,0000,,Herald: Yeah, so it should work with a lot\Nof people, I guess, and one another
Dialogue: 0,0:36:51.61,0:36:58.17,Default,,0000,0000,0000,,question was how consistent are the sound\Ncards? Did you find the same calibration
Dialogue: 0,0:36:58.17,0:37:04.73,Default,,0000,0000,0000,,worked the same with several of them?\NOliver: So if you want to use my
Dialogue: 0,0:37:04.73,0:37:11.70,Default,,0000,0000,0000,,calibration, you should really buy this\Ntwo dollar card from eBay, CM108. I
Dialogue: 0,0:37:11.70,0:37:20.62,Default,,0000,0000,0000,,haven't seen a big difference from card to\Ncard in this one. But of course, like from
Dialogue: 0,0:37:20.62,0:37:25.79,Default,,0000,0000,0000,,one computer to the mobile phone, it's a\Nhuge difference in input, sensitivity and
Dialogue: 0,0:37:25.79,0:37:30.78,Default,,0000,0000,0000,,noise. And it's very difficult to reuse\Nthe calibration in this case. But you
Dialogue: 0,0:37:30.78,0:37:39.34,Default,,0000,0000,0000,,still can count particles and the electron\Ndetector is anyway, um, mostly it actually
Dialogue: 0,0:37:39.34,0:37:43.12,Default,,0000,0000,0000,,just makes sense for counting because the\Nelectrons are not completely absorbed. So
Dialogue: 0,0:37:43.12,0:37:47.53,Default,,0000,0000,0000,,you get an energy information, but it's\Nnot the complete energy of the electron.
Dialogue: 0,0:37:47.53,0:37:52.97,Default,,0000,0000,0000,,So yeah, you could use it for x rays, but\Nthen you need an x ray machine. So yeah.
Dialogue: 0,0:37:52.97,0:37:58.68,Default,,0000,0000,0000,,Herald: Who doesn't need an x ray machine,\Nright? {\i1}laugs{\i0} So maybe one question I
Dialogue: 0,0:37:58.68,0:38:05.12,Default,,0000,0000,0000,,have, because I'm not very familiar with\Nthe tech stuff, but what actually can be
Dialogue: 0,0:38:05.12,0:38:11.88,Default,,0000,0000,0000,,done with it right in the field. So you\Nmentioned some working with teachers with
Dialogue: 0,0:38:11.88,0:38:17.52,Default,,0000,0000,0000,,these detectors? What have you done with\Nthat in the wild so to say?
Dialogue: 0,0:38:17.52,0:38:23.80,Default,,0000,0000,0000,,Oliver: So what's quite nice is you can\Ncharacterize stones with it, for example.
Dialogue: 0,0:38:23.80,0:38:29.84,Default,,0000,0000,0000,,So since you can connect it to a\Nsmartphone this is completely mobile and
Dialogue: 0,0:38:29.84,0:38:34.38,Default,,0000,0000,0000,,it goes quite well in combination with a\NGeiger counter in this case. So with a
Dialogue: 0,0:38:34.38,0:38:38.44,Default,,0000,0000,0000,,Geiger counter, you just look around,\Nwhere are some hot spots and then you can
Dialogue: 0,0:38:38.44,0:38:44.66,Default,,0000,0000,0000,,go closer with the alpha spectrometer and\Nactually be sure that there is some traces
Dialogue: 0,0:38:44.66,0:38:51.88,Default,,0000,0000,0000,,of thorium or uranium on the stone, for\Nexample. Or in this type of ceramic, these
Dialogue: 0,0:38:51.88,0:38:58.95,Default,,0000,0000,0000,,old ceramics, you can go to the flea\Nmarket and just look for these very bright
Dialogue: 0,0:38:58.95,0:39:04.31,Default,,0000,0000,0000,,red ceramics and measure them on the spot\Nand then decide which one to buy.
Dialogue: 0,0:39:04.31,0:39:12.07,Default,,0000,0000,0000,,Herald: OK, so that's what I'm going to do\Nwith it. Thanks for for highlighting a bit
Dialogue: 0,0:39:12.07,0:39:18.85,Default,,0000,0000,0000,,the practical side, I think it's really\Ncool to educate people about scientific
Dialogue: 0,0:39:18.85,0:39:25.73,Default,,0000,0000,0000,,things as well. Another question from the\NIRC. Didn't you have problems with common
Dialogue: 0,0:39:25.73,0:39:30.100,Default,,0000,0000,0000,,mode rejection by connecting the device\Nthrough the sound card? If yes have you
Dialogue: 0,0:39:30.100,0:39:38.34,Default,,0000,0000,0000,,tried to do a AD conversion digitization\Non the bord itself already? Transfer
Dialogue: 0,0:39:38.34,0:39:42.44,Default,,0000,0000,0000,,transfer wire SP dif?\NOliver: Yeah, so, of course, I mean, this
Dialogue: 0,0:39:42.44,0:39:48.15,Default,,0000,0000,0000,,is the thing to do, if you want to make a\Nlike a super stable, rock solid
Dialogue: 0,0:39:48.15,0:39:54.22,Default,,0000,0000,0000,,measurement device, but it is really\Nexpensive. I mean, we are looking here at
Dialogue: 0,0:39:54.22,0:40:00.84,Default,,0000,0000,0000,,15 euros and yeah, that's the reason to\Nhave this separate soundcard just to
Dialogue: 0,0:40:00.84,0:40:08.21,Default,,0000,0000,0000,,enable with some very low resources to do\Nthis. But I'm looking for these pulses. So
Dialogue: 0,0:40:08.21,0:40:15.66,Default,,0000,0000,0000,,this common mode rejection is a problem.\NAnd also this is kind of Überschwinger -
Dialogue: 0,0:40:15.66,0:40:22.61,Default,,0000,0000,0000,,I'm missing the English term. This is kind\Nof oscillations here. If you design a
Dialogue: 0,0:40:22.61,0:40:27.65,Default,,0000,0000,0000,,specific analog to digital conversion, of\Ncourse, you would take all of that into
Dialogue: 0,0:40:27.65,0:40:32.67,Default,,0000,0000,0000,,account and it wouldn't happen. But here\Nthis happens because the circuit can never
Dialogue: 0,0:40:32.67,0:40:38.10,Default,,0000,0000,0000,,be exactly optimal for certain soundcard\Ninput. It will always be some mismatch of
Dialogue: 0,0:40:38.10,0:40:44.51,Default,,0000,0000,0000,,impedances and.\NHerald: All right, so maybe these special
Dialogue: 0,0:40:44.51,0:40:52.00,Default,,0000,0000,0000,,technical issues and details, this could\Nbe something you could discuss with Oliver
Dialogue: 0,0:40:52.00,0:41:00.11,Default,,0000,0000,0000,,on Twitter of maybe Oliver or want to join\Nthe IRC room for your talk as well. People
Dialogue: 0,0:41:00.11,0:41:07.12,Default,,0000,0000,0000,,were very engaged during your talk. So is\Nthis always a good sign. In that sense I'd
Dialogue: 0,0:41:07.12,0:41:14.68,Default,,0000,0000,0000,,say thank you for being part of this first\Nremote chaos experience. Thanks again for
Dialogue: 0,0:41:14.68,0:41:21.43,Default,,0000,0000,0000,,for your talk and for taking the time and\Nyeah, best for you and enjoy the rest of
Dialogue: 0,0:41:21.43,0:41:28.47,Default,,0000,0000,0000,,the conference of the Congress and a warm\Nround of virtual applause and big thank
Dialogue: 0,0:41:28.47,0:41:33.02,Default,,0000,0000,0000,,you to you, Oliver.\NOliver: Thanks, I will join the chat room
Dialogue: 0,0:41:33.02,0:41:34.55,Default,,0000,0000,0000,,right now.
Dialogue: 0,0:41:34.55,0:41:39.27,Default,,0000,0000,0000,,{\i1}rc3 postrol music{\i0}
Dialogue: 0,0:41:39.27,0:42:14.00,Default,,0000,0000,0000,,Subtitles created by c3subtitles.de\Nin the year 2021. Join, and help us!