| horizontally | is there anything smaller than an electron that we can control? | 00:20 |
|---|---|---|
| horizontally | neutrinos? | 00:20 |
| berndj | how big is an electron anyway | 00:20 |
| horizontally | you can determine its mass if you have an electromagnet and a power supply... and a vacuum pump and an inert gas | 00:22 |
| horizontally | then the electron beam can be visualized however you want with the appropriate applied magnetic field | 00:22 |
| berndj | if you're looking for something with which to expose resist material and electrons *aren't* giving you the resolution you need, maybe you need ions then | 00:22 |
| berndj | more mass == shorter de broglie wavelength at a given energy == better res | 00:23 |
| horizontally | oh right lambda = h/p | 00:29 |
| berndj | so maybe you want a lead ion beam exposure system :) | 00:38 |
| berndj | but even 40eV gives you lambda = 2 angstrom, so unless you want to etch quarks, i think electrons are just fine! | 00:40 |
| cheater | hi | 01:12 |
| cheater | you guys seen those light slow motion captures? | 01:12 |
| cheater | where they show a movie of a single pulse of laser slowly moving through space (and through objects)? | 01:12 |
| cheater | http://web.media.mit.edu/~raskar/trillionfps/ | 01:18 |
| cheater | well.. i was wondeirng if something like this would be doable with electrons | 01:18 |
| cheater | could you photograph electrons travelling in wires just like that? | 01:18 |
| cheater | in resistors, transistors, and inductors? | 01:19 |
| cheater | that would be great to see | 01:19 |
| cheater | but also, if you could "photograph" electric charge in cells like this | 01:19 |
| cheater | and do this kind of experiment with a neuron cell | 01:19 |
| superkuh | No. Not electrons in wires nor charge movement in nerves/neurons. With respect to neurons specifically the spatial repeatability is not there. It will be different every time and the averaging over multiple short pulses will not work. Also, the transverse movement of charge across a 9nm membrane is very fast, while the longitudinal movement of the action potential down the axon itself is much slower at some hundred meters a secon | 01:25 |
| superkuh | d for mylinated axons, or less. | 01:25 |
| horizontally | somehow lambda = h/p doesn't jive with intuition | 01:40 |
| horizontally | isn't something that's more massive going to occupy more space? (i know i know black holes) | 01:40 |
| horizontally | but the ionic or atomic radius size is roughly proportional to the atomic number | 01:40 |
| berndj | if you put it that way it is a little unintuitive | 01:50 |
| berndj | then again, great big blobs of quantum mechanics don't mesh with intuition | 01:51 |
| horizontally | i think a lot of stuff in quantum mechanics does make sense | 02:22 |
| horizontally | you have to understand classical wave motion first | 02:22 |
| horizontally | and there are loads of people who keep reinforcing that stupid mindset that "if you think you know quantum mechanics, you don't" | 02:22 |
| berndj | yeah, talking about QM like it's this mystical thing is also dumb | 03:09 |
| berndj | i always thought of higher-mass -> shorter lambda as semi intuitive; the analogy i was using would be "more momentum = more assertive = 'sharper' needle" | 03:10 |
| berndj | cheater, were you thinking of something like http://en.wikipedia.org/wiki/Electron_Beam_Prober ? | 03:14 |
| berndj | i don't think you could snap individual electrons of course, but maybe you could image wavefronts | 03:14 |
| horizontally | http://engineering.tufts.edu/microfab/index_files/sop/su-8%2520processing.pdf | 06:05 |
| horizontally | they say SU-8 gets all over everything | 06:05 |
| horizontally | and it outgases | 06:06 |
| horizontally | hmm when exposed to UV it solidifies | 06:06 |
| horizontally | one week in H2S04 at room temperature for removing 100um layer | 06:09 |
| bart416 | <azonenberg> Because i've heard of SU8 being exposed by synchotron x-ray emisions <-- synchrotron is off scale compared to medical though :P | 07:03 |
| bart416 | The beam actually ionises everything it touches | 07:04 |
| azonenberg | bart416: lol, true | 10:17 |
| azonenberg | But i wasnt sure if lower energy level might be enough too | 10:17 |
| cheater | berndj: yeah, i was thinking of wavefronts. | 10:20 |
| bart416 | azonenberg, no clue :) | 10:21 |
| bart416 | I'll just leave it at, I'd sit on a reactor before I'd stand within 10m of a synchrotron in operation :) | 10:21 |
| azonenberg | bart416: lol | 10:21 |
| azonenberg | Well, i've stood about two feet from a subcritical research reactor | 10:22 |
| azonenberg | at the US naval academy | 10:22 |
| azonenberg | nice and small, water shielded | 10:22 |
| azonenberg | you can look right down the tubes at the fuel rods | 10:22 |
| azonenberg | through about a foot of water | 10:22 |
| azonenberg | whole thing was about the size of a refrigerator | 10:23 |
| cheater | hey azonenberg you seen those laser snap vids i posted? | 10:25 |
| azonenberg | Nope | 10:25 |
| cheater | i was wondering if something like this can be done with electrons in conductors/semiconductors | 10:25 |
| cheater | 1 sec | 10:25 |
| cheater | http://web.media.mit.edu/~raskar/trillionfps/ | 10:25 |
| cheater | prepare to be amazed | 10:25 |
| cheater | :) | 10:25 |
| cheater | even though the operation is super simple, the outcome is just mind bending | 10:26 |
| azonenberg | lol interesting | 10:27 |
| cheater | check out the bottle | 10:27 |
| cheater | that one's the best | 10:27 |
| cheater | if you scroll ALL the way down they have a video presentation | 10:27 |
| azonenberg | Looking at it | 10:27 |
| cheater | it's after the references funnily enough | 10:28 |
| azonenberg | So they're doing it like an analog (non-storage) oscilloscope | 10:30 |
| azonenberg | replaying the event several times over and over and recording different parts of it | 10:30 |
| bart416 | If you repeat anything long enough you can get as much samples as you need | 10:32 |
| azonenberg | Yeah | 10:32 |
| soul-d | i thought they had array of 500 chips running freely | 10:32 |
| soul-d | triggert | 10:33 |
| bart416 | Only your trigger event has to be exact | 10:33 |
| soul-d | 1/trilions | 10:33 |
| azonenberg | bart416: Yep | 10:33 |
| soul-d | aftehr eachother | 10:33 |
| azonenberg | It looks like what they have is a 1D CCD | 10:33 |
| bart416 | And triggering at that speed isn't that problematic for electronics | 10:33 |
| bart416 | 1 ps is easy | 10:33 |
| azonenberg | bart416: maybe for you :p | 10:33 |
| azonenberg | the stuff i work with has gate delays in the hundreds of ps :p | 10:33 |
| soul-d | the stuff tehy use to | 10:34 |
| bart416 | azonenberg, your gate delay only has to be the same every single time :P | 10:34 |
| azonenberg | lol | 10:35 |
| bart416 | + Transistors are actually coming up to 1 THz | 10:35 |
| bart416 | the record now is 800 GHz or something like that | 10:35 |
| azonenberg | So i heard | 10:35 |
| soul-d | also he say's each pulse looks the same thats not really sientific :) end result is still a aproximation of how 1 cycle could have looked like but doesn't since it's not one cycle | 10:37 |
| bart416 | You know what actually freaks me out, that most of our oscilloscopes and logic analyzers in the lab are actually fast enough to measure the speed of light to a fair precision | 10:38 |
| bart416 | (Over a relatively short distance that is) | 10:38 |
| soul-d | din't some dude do that trick in 1912 ? | 10:38 |
| bart416 | soul-d, hook up a pulsed laser, get a half meter long tube, get it to a near vacuum, put a GaAs photodiode at the other end | 10:39 |
| bart416 | Measure pulse start at laser and pulse start at diode | 10:39 |
| bart416 | You'll have a very nice approximation of the speed of light | 10:40 |
| soul-d | it took a day here :) | 10:40 |
| soul-d | they cut the main fiber lines yesterday of my isp ;) | 10:40 |
| azonenberg | bart416: lol | 10:48 |
| azonenberg | you mean, like having two sensors a foot apart | 10:48 |
| azonenberg | and one gets hit first? | 10:48 |
| bart416 | you could also do that | 10:52 |
| bart416 | Though a foot isn't long enough in most cases | 10:52 |
| azonenberg | it isnt? | 10:52 |
| azonenberg | maybe my mental math was wrong | 10:53 |
| azonenberg | but i recall that having been on the order of 1ns | 10:53 |
| azonenberg | which should be detectable | 10:53 |
| bart416 | It's detectable yes | 10:54 |
| bart416 | Easy in fact | 10:54 |
| bart416 | But your error margin will be fairly large | 10:54 |
| azonenberg | Repeat it a few hundred times and average? | 10:54 |
| azonenberg | You could do that within a millisecond :p | 10:54 |
| bart416 | You'll have to take into account the length of your probe wires :P | 10:54 |
| azonenberg | No different from other high speed logic | 10:54 |
| azonenberg | Treat it as a differential pair | 10:54 |
| azonenberg | you could length match to submillimeter | 10:55 |
| bart416 | You're not taking into account other effects | 10:55 |
| azonenberg | Do tell | 10:55 |
| bart416 | by all means, you're working with transmission lines | 10:56 |
| bart416 | none identical ones at that | 10:56 |
| bart416 | The propagation times will differ | 10:57 |
| bart416 | Quite possibly to well within your measurement interval | 10:57 |
| soul-d | can't you have a beamsplitter and measure at 2 different distances ? | 10:57 |
| bart416 | again, pointless increase of complexity | 10:57 |
| bart416 | Increase the distance | 10:57 |
| azonenberg | But doesnt that increase transmission line effects? | 10:57 |
| bart416 | Then your error becomes less significant | 10:57 |
| azonenberg | or do you mean reflect it back and forth with mirrors | 10:57 |
| azonenberg | using a short test lead? | 10:58 |
| bart416 | no | 10:58 |
| bart416 | What the hell are you guys thinking about? :| | 10:58 |
| bart416 | Your transmission line effects will have less impact over a long distance compared to the time it takes the light to travel | 11:00 |
| bart416 | We've found that anything less than 50cm your error is large | 11:02 |
| bart416 | Ideally you use 1 metre or longer | 11:02 |
| bart416 | Your positional offset of your sensors also becomes less problematic | 11:03 |
| bart416 | If you're off 1mm on 1m it's not as bad as you're off 1mm on 30cm | 11:03 |
| cheater | actually | 11:53 |
| cheater | they don't even need to get the delays right | 11:53 |
| cheater | you can reconstruct the sequence without knowing what order it was in | 11:53 |
| cheater | just as long as the points in the sequence are near enough | 11:54 |
| cheater | reconstructing the order of a sequence f(x_i) for unknown x_i, with the x_i having an unknown linear order, is one of the easier things in inverse problems | 11:57 |
| cheater | i mean if you have an animation and someone scrambles the frame order you can usually come up with the original order | 11:59 |
| cheater | because it's causal | 11:59 |
| bart416 | cheater, depends on the intervals | 12:01 |
| bart416 | :P | 12:01 |
| bart416 | if they're all near identical... | 12:01 |
| cheater | yea | 12:23 |
| cheater | what i'm saying is that jitter in the timebase doesn't matter | 12:23 |
| cheater | as long as it's normal | 12:23 |
| cheater | or another well behaved distribution | 12:24 |
| berndj | <bart416> + Transistors are actually coming up to 1 THz <-- keep those leads short! | 13:55 |
| berndj | do you know if that's crazy lab-style devices or something you can order from digikey level of availability? | 13:56 |
| azonenberg | berndj: that's probably lab scale, but you can easily hit tens to hundreds of GHz in something like a 22nm finfet | 13:57 |
| azonenberg | wire delay is killing modern processors i think | 13:58 |
| azonenberg | performance wise | 13:58 |
| azonenberg | more so than switching delays | 13:58 |
| azonenberg | you have to switch AND drive the capacitive load of the destination wire | 13:58 |
| azonenberg | sure, its probably on the order of femtofarads | 13:58 |
| azonenberg | but thats enouhg | 13:58 |
| azonenberg | when you can only supply nanoamps :p | 13:58 |
| berndj | i'm always amazed at the max pulsed current specs of small transistors | 13:59 |
| smeding | azonenberg: yeah, wiring is a huge part of performance | 13:59 |
| smeding | azonenberg: this is why 3d integration is very promising tech | 13:59 |
| berndj | max 100mA continuous, but keep it <1us and they'll do 10A kind of thing | 13:59 |
| azonenberg | smeding: Yeah | 13:59 |
| azonenberg | TSVs ftw | 14:00 |
| Action: azonenberg wishes he could do DRIE in his home setup | 14:00 | |
| azonenberg | Not happening any time soon :p | 14:00 |
| lekernel | berndj: http://www.teledyne-si.com/schottky_diodes/index.html | 15:18 |
| lekernel | for the transistors, I don't know. let me know if you find something... | 15:18 |
| azonenberg | berndj: also, even some LEDs are like that | 15:37 |
| azonenberg | rated for tens of mA but can take several amps for extremely brief periods | 15:37 |
| azonenberg | Since the limit is normally on the die / bond wires heating up | 15:38 |
| azonenberg | And if your thermal mass is big enough, you can have a high energy pulse that dissipates very little heat comparatively | 15:38 |
| bart416 | azonenberg, actually we can go past 4GHz easily | 16:10 |
| bart416 | It's just that we have no way to remove the heat | 16:11 |
| azonenberg | bart416: with CMOS, yes, but there's still a limit | 16:11 |
| bart416 | GaAs goes pretty high actually azonenberg | 16:11 |
| azonenberg | Amd tjey | 16:11 |
| azonenberg | and they've hit 8 on CMOS experimentally | 16:11 |
| azonenberg | Just not without crazy stuff like liquid helium :p | 16:12 |
| bart416 | highspeed circuits are never with FETs | 16:13 |
| bart416 | at least not with regular ones | 16:13 |
| bart416 | There are a few tricks you can apply | 16:14 |
| bart416 | But most of the time it's bipolar at that point | 16:14 |
| --- Thu Dec 15 2011 | 00:00 | |
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