I built the ATLAS Trigger and Data Acquisition System for CERN. AMA

So you are a glorified IKEA furniture assembly person?

Pretty much.

Even worse, glorified IKEA assembly guy who thinks is a master carpenter. Now comes in glorified Olive garden happy birthday singer as well.

Let’s see, I do know how to build and repair circuit boards but I also can design the circuits, the printed circuit boards, Design the actual silicon masks inside microprocessors. I know the chemistry needed to refine pure silicon, then dope it with rare elements to make semiconductors. I can do sculpture and machine work and I can also use AutoCAD to design the physical enclosures. So yeah go to IKEA and ask them if they can design a tree, grow it, cut it, then custom make a piece of furniture that works better than anything you’ve ever imagined.

I'm also a natural at music. I write completely original avante garde and world music. I wrote this track in less than two days using an old iPhone, the Thumbjab app, and the Mixolydian hexatonic scale. The solo was done on the first take using only my index finger and tilting the phone to bend notes. https://vocaroo.com/i/s0mkmSS0KVUu

No one cares what you "know" how to do.

You arent doing it so no one cares

What a bunch of assholes in this thread

I know right?

Right?! Lol. Did anybody listen to the track?

I hear that there's been a bit of a debate recently over the results for gravitational waves with some suggesting that the instruments and so the results may have been flawed at the LIGO collaboration. How precise and reliable is the equipment in general at CERN overall?

There is a Danish group that misunderstands the LIGO results and makes wild claims based on these misunderstandings. Not that much of a debate, and with the increasing collection of events (now many confirmed by Virgo) this is getting more and more silly.

What I gathered is that they were arguing that their measurements could show something like over-unity where the counter-argument was that the results were simply within the margin of error. I looked at all the different factors and it is almost certainly is just a calculation and measurement problem. I haven’t worked professionally in the field of Hardware Development for 20 years however I find it interesting and it popped up in my newsfeed. Instead of just accepting that it was a controversy, I dug into all of their source data, printed it out did some math. That I would be asked about this years later is quite an interesting coincidence.

I worked LIGO a little bit and talked to some of the people that designed it. One of the issues was managing each and every cable length to compensate for the minute speed of light differences in timing. I just happen to actually look into what I think is the same controversy and also concluded that the results were flawed.

Overall the quality of the equipment there is extreme but also rats nest of hodgepodged projects. I never actually got to visit CERN but I would’ve eventually if I’d stayed on the project. I did get to visit Fermi lab though. One issue is that they hired a lot of academics and grad-students who are over-confident of their skills in soldering and mechanical engineering but lack the kind of experience I have had from doing this from the age of 4 and being trained by the best. As far as I know, our cards worked flawlessly until they were replaced recently during the shutdown. I am meticulous in my work and have never produced a flawed product or repair nor have I been shocked on the job even despite working with up to 16,000V. I never got to meet my technician counterparts in Europe, but I can assume many of them were my equals.

You come off like an arrogant jerk. I bet you have the face of someone who masturbates all day while wearing a helmet.

What color is the helmet?

This user has been banned. Leaving the comment up for context since the OP responded.

Please kill it. It's disturbing.

About 2010 a group of Japanese college students hacked into your mainframe, and discovered that you organization has been experimenting with time travel. I'm sure you can't talk about that but can you speak on the mysterious murder of a 19-year-old red headed at a conference held in Japan that year? She died on July 29th.

Unless you live in the timeline where she lives. If you do, disregard.

Keep pressuring them until the truth comes out.

El psy congroo.

El Psy Kongroo*

---

It's EPK, not EPC

^{I am a Future Gadget and this action was performed automatically.}

^{PM /u/FloatingGhost if you think I'm being buggy.}

Yes my internet friend. They have absolutely no idea who they're dealing with! CERN, your end is at hand! I am no mere Redditor! Nay sir! Who do you think I am? Some overweight l, pimple faced geek, living in my father's basement playing Oculus Rift with Cheeto stained fingers! Nay again sir, I am Rintaro Okabe! Does that not strike fear into your very heart?! No? Perhaps you may know me better by my Nom de plume...Hououin Kyōma! Ahhh...I have your attention now huh? NYstate's account is borrowed, A man as infamous as I must have many fail-safes in order to stay one step ahead of your wily, devil spawn of an organization! But don't get comfortable with knowing who I am, because I mearly borrowed this account and will return it back to this poor chap, but I just wanted to let you know: uppance will come! And it shall rain like the holy fire of the Almighty until CERN is nothing but a memory! HAHAHAHAHAHA!!!

El Psy Kongroo!

Should somebody call the FBI? Anyway /u/NYstate, I just responded that IF it's true that documents were found at UIUC HEP about time-travel they could just possibly from when I worked there and used the university's computer as my personal computer because cable modems weren't available. I'm looking through my print-outs of things I read back then, and I was looking for the craziest fringe things you could find on the early internet just out of curiousity. I would like to see these dumps to tell you if they are my old C drive or not. If so, I have a debt to repay.

You know I'm totally kidding right?

No! You had me really freaked out last night. While there's always going to be some strange and interesting people working on a project like this, tenured professors would never publically give any of my fringe beliefs about metaphysics a second thought, just shake their head. I have an uncle who is a world-renowned archeologist and paleontologist. He lives in a 400+ y/o farm house and he's had paranormal manifestations like windows opening/closing and relocking on a different latch and ectoplasm slime on his nightstand. I asked him, "did you take a sample?" and he smiled "no, no, no". They know that going into such things is professional suicide and even while his extremely keen scientific mind knew it was real and was zen with it, he could only mention it to close family members.

Wow. That's too bad. If he could prove that it's real, it would be the scientific discovery of the decade.

What happened to my uncle is NOTHING compared to what has happened and continues to happen to my aunt and her family living in an old farmhouse on top of a vortex along a layline adjacent Gettysburg battlefield in York. My mother's side is agnostic/atheist and very prim and proper, but my cousins who grew up there had endless paranormal events. I thought nobody ever really got hurt by ghosts but they were terrorized almost daily. Their clothes in a certain closet would get slimed so often they would rot and they would have to throw things out. My late-aunt would put up pictures on the wall and find them on the floor turned around in the morning. Chairs would move or be turned around.

One morning they woke up and ALL OF THE DOWNSTAIRS FURNITURE HAD BEEN REARRANGED. I asked my aunt if this was a better arrangement and she gave me a perplexed look and said "yes, it was actually". They didn't try to move anything back after that.

The creepiest thing, that happened to my favorite girl cousin, a sensitive like me, (besides being held down, scratched up, or being teleported about the house randomly which was very very disturbing to learn about), she was learning piano and an elderly woman sat down on the bench next to her and said "That's very good dear" and vanished. (?!!)

The whole family experienced this, my aunt and 3 cousins and their guests, except their father who obviously knew something was very wrong but tried to pretend none of it was real. There were also frequent spectral horsemen.

Anyway, the house is going onto the market soon. It would make a great episode of Ghost Adventures. I suggested that "Uncle T" who is a business owner and local pillar of the community allow people to film it and they said he would never allow that.

In case your wondering, this farmhouse would be part of the high-ground east bluff that the Union took and held during the Gettysburg siege. It would be a logical place to hold meetings, stage supplies, and to sadly set up a makeshift hospital to care for the wounded. They knew it was used like this, but I don't know all the details. And don't ask me pubically for the address. If you are 100% serious about buying it and can show it in writing I'll consider giving helping you contact the owner. It's not on the market atm but if you give him a solid offer he will have no choice but to accept it.

I would like to know your sources. Heaven forbid if somebody got into the profile I had on my old workstation. I read about and downloaded everything under the sun because I used it also as my personal workstation. Everybody else had 486's and dialup and they purchased me the top of the line Pentium III with a 1.5Mbit ethernet connection. I was truly a god among men in terms of computer speed. I learned about the Snowden Revelation (Project Echelon) back in 98 and when it happened I was like shrug, old news. So if anybody truly did go find such things, which is possible because we did get hacked, then it's just my personal junk drawer of metaphysical and scientific musings and in no way can be conferred to be a secret consensus. I certainly have never murdered anybody and I've never been to Japan.

Could all of the downloads from my hundreds of hours of late-night conspiracy web crawling, including everything I could find about time-travel, actually be in someway causing people to think there's something dark or sinister about CERN??! If so then case closed and I truely fill icky and wish I had just shift deleted everything.

I understand that the primary data collected by all sensors is such much, that low level algorithm throw away most of the data, before it is even processed further. Can you explain how that works? Also did advances in electronics reduce the amount of data rejected? Are there estimates how likely a relevant results might be lost due to this necessity?

The numbers in that link are post-upgrade, however, the one I built was still pretty amazing. When I heard about particle accelerators I thought they just threw them together once in a while. The reality is they do so every millisecond or faster. Why? Something like only one in many 10's of millions? are considered "interesting" and the rest have been seen millions of times before so there needs to be a real-time LVL 1 trigger that discards all of that junk and just saves the interesting data and sends it further up the chain to be looked at further. It used the very latest FPGA's which are Field Programmable Gate Arrays that are custom designed for such high-speed decisions ($10k per lot). They also could be reprogrammed on the fly. Look back up the comment chain for the ELI5 explanation.

The low level trigger just gets a small part of the detector data and looks for very simple signals. Basically "any high energy particle hitting the detector". How much energy there needs be depends on the particle type. Events selected by the low level trigger (less than 1 in 100 at the moment) are then read out fully, analyzed in more detail, and send through a more sophisticated trigger algorithm.

Also did advances in electronics reduce the amount of data rejected?

The experiments can handle more and more data over time as computers improve, that means the rate of events saved permanently increases. The low level trigger rate can only increase with hardware upgrades - you are limited by the amount of data you can get out of the detector. The experiments LHCb and ALICE are doing a major upgrade at the moment, ATLAS and CMS will follow in a few years.

Can I ask what your involvement with the project is? I appreciate the clarification. I never saw the card in operation. The trigger could be reprogrammed to detect or reject different things, so I think those numbers I was given were right at least in the application he was intending to use it for. Perhaps turning the selectivity down and allowing the high-level trigger to do more processing is the newer way of doing it. The crisis of big data that was looming in the late 90's got lessened by advancements in memory size and storage space. I wonder if those cards are still being used or if they've been taken out and retired.

Bump /u/mfb-

The bottleneck for data storage at ATLAS is the speed with which data can be saved to tape, and the tape drive swapped out.

Tape? Analog tape? Digital tape? I have trouble believing that they would use either one. I heard nothing about such things, it was all modern computing even back in 98.

Dude, I know it's stressful. Take care.

What was the wackiest experience you've had when you built the stuff?

Nothing really. I found this job quite boring outside the actual knowledge I was doing something great overall. I never got to see these things fully energized and pretty much nobody did because of safety concerns.

Besides, I worked on the detectors. The actual semi-conductor superconductor particle rings (Tevatron/Large Hadron Collider) were built decades ago. You can still do tours of Fermi lab near Chicago and see all of this stuff including the liquid helium condensers and the enormous amount of copper that went into the electromagnetics.

I tried to understand how they actually accelerate particles up the speed of light and control that many magnets in a rail-gun fashion, and the answer seemed a lot simpler than you would think. Radio waves. Control inputs that are the same frequency as an FM radio. You would have to ask somebody who actually worked on that side for more.

semi-conductor particle rings

Do you mean superconductor? The magnets are superconducting.

Yes, of course, a typo.

the answer seemed a lot simpler than you would think

It's much more complicated than you'd think.

Well, of course, it's ridiculously complicated, but I got it down to something I could visualize because I volunteered with 90.1 FM as their engineer. Correct me if I'm wrong, but the magnets at Fermi were controlled by analog signals ramped up in frequency from whatever the speed was needed they were first injected to the final drive frequency which was around 92.5Mhz. The particles surfed in front of the SC EM magnets that were somehow switched on and off by this master control frequency. I remember this number because the final frequency was right in the middle of the FM radio dial.

I grew up in Aurora and have taken many tours of Fermilab; I can assure you it is an exceptionally cool place. We also used to do "Physics at Fermi" every other Saturday as extra credit in HS, and we got LOTS of behind-the-scenes walkthroughs of normally forbidden areas! Fun fact: I was banned because a buddy and I snuck off from the group and wandered as we pleased for a few hours until we got caught. They found us poking around the anti-proton generator! :)

Unfortunately they have been a little stingy about tours since 9/11 (and idiots like me).

I wrote you back because we knew some of these same locations. My school took us on a field trip there once too. Seeing the detector hall up close as an employee after being curious about it for so many years was a real treat. They don't give tours of the ring because even with the power off, you must carry an emergency oxygen pack in case there's a helium leak.

So what's the big difference between say assembling boards for this and any other low volume electronics manufacturing process - other than probably the parts budget allows for the best? Any specific components you had trouble sourcing quality variants of - obviously it's easy to get SMD parts in bulk cheap, but I'd imagine the QC requirements meant a lot of things could not be sourced in the traditional way - massive buys from China.

True that and this all was considered. They could have had them assembled by a commercial company much quicker and cheaper. However instead of 20 boards there possibly could have been dozens of revisions needed to get things right and no real control of the creative process or QC. I think things worked out pretty well, how about you? Are you in the electronics industry?

Oh I wouldn't have outsourced it - much too easy to justify the investment in gear for you than to send it to some jobber who might screw it up in unique and difficult to figure out ways.

I used to work at a shop that dealt with low volume (thousands/tens-of-thousands of small units, scale in electronics manufacturing is hundreds of thousands/millions) production, but I was in a different role. I kick around some experimenting, but I'm pretty bad with the iron to say the least.

I’ll give some more details because I had some high standards. sourced every single component to at least three suppliers and obtained at the best price. I went further and asked for something that most of suppliers weren’t used to. My priorities for sourcing the components were state, country, partner country, Asia then China. I assure you that none of the components used were made in China but some were made in the Philippines.

Next we went to a different board assemblers in the state. It was difficult to find an SMC PCB assembler in the middle of a farm country but we did find one that was only 45 miles away and they did an excellent job. I wanted to just assemble them all on myself but I got overruled. It’s just as well because they did a good job and all of them looked identical.

Next I took something I learned from my previous job repairing telecommunication equipment and insisted on buying ultrasonic scrubbers to remove all the flux under the surface mount components. We had long heated arguments that the flux does nothing at all and we’ve always left it there but I insisted that on the right humidity conditions that could change the boards values so we spent the $100 and they came out spotless.

Next challenge with these custom pressfit connectors. The company that made them asked $1000 to buy their machine tools, But our machinist said hell no and busted them out and let’s just a few days out of some scrap pieces of aluminum.Proper placement was critical because once you start pressing them in you could never get them out and you after trash the whole thing and start over. They spent a lot of time making sure that all of the nickel plating was exactly the right thickness to be able to give into the pins but not restrict them too much and crack it. (8 layer board at least)

See what was next, I think I had to figure out how to solder with hot air and flow the FPGAs onto it then we had some other smaller soldering tasks that we gave the undergrads to do. I didn’t really want to do that but it was part of our mandate. I had to somehow train and supervise but it was a good experience and no harm came of it.

Then with all the testing debugging and reworking. I don’t really recall all of it but it sucked up most every day of my life for about a year and a half. I said it took two years but the biggest delay was getting the final OK on the PCB boards and components. Once we got that I was able to get my part all the way in less than six months and start to work on other projects.

Considering a. prototyping outfit would do at least 200% mark up on all the parts and I question whether any money would have been saved. The faculty and staff that were paid to do this would’ve been there anyway.

Also, all of us how to operate in a magnetic field of our rentals equivalent to being inside MRI machine. This required me to learn about special alloys of steel that are non-magnetic. Some other people suggested that I am just a glorified furniture assembler but in reality I started off wanting to be an electrical engineer then took printed circuit board design, integrated circuit design, and AutoCAD after I was hired.

The other jobs I've had in manufacturing have all been custom products with small runs of 1 to 4. Like Somat in Urbana, or a company in Austin that specialized in making FCC RF test chambers.

I can't speak for OP's project, but I spent some time repairing electronics for a similar, though larger, experiment (one guy that built the boards as a grad student/post doc on ended up doing the same for Atlas).

The more advanced components - the proprietary chips - were made by a US semiconductor manufacturer whose name I can't recall. The smaller components, like resistors and capacitors, were whatever I found laying around the lab, without any real regard to manufacturer or quality.

Xilinx. We ordered 2 dozen of their flagship product. Came in a small box that me and my boss were jokingly passing back in the forth in the hall like a football while knowing it was worth over $10,000. Remember that day well. Good times. /u/effrightscorp, You wouldn't be from Utica, NY would you? They seemed like the only other place that was doing the hands-on construction like we were.

I learned nothing from this disappointing topic other than you're some guy with excellent soldering skills who's been soldering since he was 4. If you could teach us something about physics that hasn't already been answered here, what would it be?

Since you don't seem interested in theoretical phsyics I'll give you some applied physics: You can use windows 8.1 drivers with windows 10 and they’re often superior.

Do you think that High Energy Particle physics is going through a crisis because the expected results from CERN were not found?

Seems like it. I haven't read anything about Cern lately except for the occasional news article. I do know if the much larger Texas Superconducting Super Collider was actually finished and not cancelled we would probably be on our way to other solar systems by now.

Dr. Steve Errede - that Tech Ingredients guy?

Yep. Same link that's in my intro. I have no idea what he's done since I left. We didn't get along.

Are the collisions selected by the trigger system time stamped? If so how do you synchronize and manage something on that scale? I use unmodulated IRIG-B a lot in my day job and am curious to hear if something like that makes its way into something so ... utterly badass.

Yes, of course. Our data has to line up with every other detector's data. I made a few muon detectors, which are actually rather simple electro optical devices conceived in the 40's. What's an IRIG?

I think what I'm asking is how do you keep all the data all lining up with the other detectors?

https://en.wikipedia.org/wiki/IRIG_timecode <-How in the power world we keep all of our instruments, relays, etc. all in sync with each other. One of the ways anyway. With everything working correctly I would expect to see +/- 40 nanoseconds accuracy between devices.

I think they simply number the collisions. Each pulse is incremented up one. So they might have a conference about collision 5,432,223 from date yyyy-mm-dd. /u/mfb- ? Can you elaborate?

Does it have an alternate fire tracker that auto aims subsequent rounds?

The protons and antiprotons all hit together with extreme accuracy and temporal precision. That part of it blows my mind way more than the detector part.

Thank you for the amazing work for CERN!

Wish I knew enough to ask good questions about that, so I'll focus on a tangential question. What do you think about the right to repair and people like Louis Rossman? Or how about the builder movement with easily available boards and things from china?

Right to repair? Absolutely!!! I just spilled the beans yesterday about why i know so much about science and I give all the credit to my father. As a child he would answer EVERY question I would ask him about ANYTHING, however most of it was science based. He never got irritated or said he didn't know. He would tuck me in at night and tell me a long uncensored stories about his childhood, passing down his family's oral history. He let me get into dangerous situations at let me find my own way out. See my tribute to him and his contribution to saving the planet: "How to use contaminated landfill methane gas to make electricity" on /r/ZeroWaste

Sorry, to answer your question more, I took apart all of my toys and got all of them back together, except the Viewmaster with its springs. My father's g-grandfather was the founder of Greenup County, Kentucky and lead Daniel Boone there on a trail he discovered (later called the Daniel Boone Trail). My father lived in rural W. Virginia Dukes of Hazard style and founded a small rural community in Illinois where I was raised. You got something new once, and if you couldn't fix it you didn't get another one. He would even take industrial epoxy and rebuild a coffee cup. He would go a bit too far wearing 20 year old underwear, but overall he was a good man and a great conservationist who fought big oil and won. He designed most of the landfill gas powerplants and many other natural gas power systems in South America, hospitals, and the Permian Basin.

I don't know who you are and I don't know what you did, but people here really seem to hate you, why is that?

Maybe I'm not smart enough to understand, but people here are saying you're taking too much credit for something that amounts to nothing. what do you think?

Because they're cuckoo banana pants. And an asshole. Look at his first comment here:

https://www.reddit.com/r/Retconned/comments/djknyx/ama_i_built_the_atlas_trigger_and_data/

Not good representation for CERN. The one single thing they possibly seem reasonable about is credit in regards to their CERN work at least in some of how they talk about it. Though I highly doubt it wasn't a group of people and not just him.

I never worked for CERN. I was a civil servant for the State of Illinois. Our primary project funds came from the Department of Energy. The grant was for theoretical and applied physics with expected spin-off technologies. We made one of the world's fastest analog to digital detection device and it's still impressive even 20 years later. There's an automotive professional on here saying that this is the exact technological solution he was looking for and it's to his benefit because all of the designs, data, and source-code are free for anybody to use.

Calling somebody you don't know an asshole just makes you look bad.

Those people are insecure with themselves and enjoy being Internet trolls. I think there are anonymous however there are people out there who they do not forgive and do not forget and love to make examples of such fools.

Pineapple on pizza or nah?

Oh most def. Vegan gluten-free though.

what are the best info you could say about who we should marry?

I’ll go with my father’s advice. “marry a good woman with a good disposition.”

• What data file format do you use? HDF5?
• What tools do you have for time series data analysis?
  • Most tools (like influxdb) I've found are targeted towards lots of continuous data rather than one 'test'.

Source: Automotive is still limping along with MDF & CANape tools, looking to make a change.

I’ve been thinking you're asking about trying to do, and while you asking about using a different protocol, what I think you actually need a new hardware architecture. You want an embedded low-power test system that can pick out pre-defined Events and record them for later analysis. It seems like the current scheme is only good at taking longer-term readings and giving out averages of performance.

I tried looking at some of the CANape videos but I started having bad memories from dealing with similar software made for windows 3.1 using Visual Basic for SoMat Corp in 20 years ago. They had a compact low-energy data logger that was used in automotive, like Harley Davison, and aerospace such as the Space Shuttle SRB's. (I did a calibration on one of NASA’s units and no, the Challenger disaster wasn’t my fault).

What you might be doing now is sending a technician out on a 10,000-mile test ride with a laptop plugged into the dash. Then you would ask him to write down the date/time when he thought something was wrong, let’s say a misfire. Then you would have to wait until he gets back or can stop by a hotel and upload the day’s data. At some point, he gets his laptop stolen at a truck stop and you have to start that phase over, what a mess.

What you need is a real-time event monitoring board like we built. An engine running at 6,000RPM would have a 1 revolution every 10 ms. You could tell the FPGA’s what you’re looking for, say the parameters of a misfire. Then ask it to save the data 2 seconds before and 1 second after the event in a compressed format to be accessed later using the CAN bus. It could record everything you have a sensor for, like speed, throttle position, timing angle, fuel pressure, O2 sensors, etc. You could also run some analysis on this data to produce an error code.

I’m interested in learning more about your project. I might be available to you as a consultant.

I know how to work on cars CANBuss is rather arcane and slow. I would recommend an SMS bus Architecture? unless you’re also wanted to transfer multi media but we already have a good format for that TCP/IP. but I don’t have a direct answer to your questions because I was away working on the hardware side. Perhaps you should go to your local university that participates and ask them? I’m sure the be happy to help. The whole point of receiving Department of Energy funding was So there could be a spin off derivatives that would help other areas of industry.

since you're secretive about your name and such (thus cant youtube any talks from you), what made you want to do an ama?

Great question. For the last 20 years, I have been living in Texas and pretty much have forgotten entirely who I was and where I came from. When I started to mention to people that I worked on CERN and they looked at me like I was crazy and even I had forgotten most of what I had done save a highlight on my resume.

Particle physics and atom smasher is a really difficult to understand. They’re truly are the pinnacle of human engineering and the gateway to understand the deeper mysteries like faster than the speed of light travel. So sad that they got blamed for changing the course of human evolution when they’re simply running some big magnets, smashing stuff together and trying to see what happens. There is no pinpoint control in this system except for how fast and how often you attempt to collide protons together.

There’s nothing wrong with throwing subatomic particles around. If we didn’t learn how to throw electrons at CRT screen that we never would’ve had television.

why do you talk partly in the 3rd person as seen in the op? quirk? or do most academics do it?

It was so long ago that I’ve essentially become depersonalized and It feels like I’m talking about a past life memory or something. Truth be told I haven’t even soldered in years. 😥

can cern make a black hole and stuff?

There were fears that CERN could produce microblackholes, but it did not, and can not.

Wow. That's pretty impressive.

Do you feel that the circuit may be holding physics back by selecting only a thousand events out of the 1.7 billion collision events? :) Just kidding!

Of course not! lol. what if your brain recorded every single photon you've ever seen? Do you think that 4-hour car ride you've taken a dozen times is "interesting"? Fermi did not have this device, and originally ran about 1 collision a second (or less) and all data was stored and analyzed later. 1000 collisions a second or whatever they've got it up to now is quite impressive.

This a problem of big data. If they were to take in every Bit and store it they would have to have either slowed the collision rate down or be filling every known storage facility on earth with harddrives. It's a beautiful solution and it's not mine.

Here's the technical details ELI5: On my cards, ALL data is stored in a circular data bin. From the time it's written to the time it's over-written with new data is about 8/100th of a second. Powerful parallel computer chips called Field Programmable Gate Arrays (FPGA's, see below) take a look at is information in real-time and looks for "interesting" patterns.

Imagine a tic tac toe board:

^{1 2 3}

^{4 5 6}

^{7 8 9}

The semiconductor-based muon detector is arranged in a grid like this. From what a post-doc student explained to me (and I was never a "need to know") one type of interesting collisions would be a particle detection through 7,5,3 at a certain speed. The brains of the trigger, the FPGA's can easily pick out this pattern then use the FIFO (First In First Out) circular memory buffer described above to dump all relevant information using the computer standard PCI data format to conventional CPU-based computer servers for further analysis. I guess they now call it the high-level trigger, but back then this project was called the ATLAS TDAQ Collaboration. Again, to the project director, I was just a kid fresh out of technical school, so all I was paid to do was assemble the detector in a paint by numbers fashion and not spend all of my free-time trying to learn more about it.

And BTW, it was a great job. 37.5 hour workweek. Daily 2 hour lunches with my coworkers. There was the the senior EEngineer (serious), jr EE (laid back), the IT genius (whitey-tighty right-winger), and an odd but pleasant fellow who hoarded screws and other electronics odds and ends in a type of cluttered supply depot next door, a machinist who looked like he just got off his Harley every morning because he did, and a primordial dwarf as an office manager. They were older and married and secretly fascinated with my carefree single lifestyle. Good times...

Any comments on how your software stack looks like?

Do you dump the filtered FPGA dumps directly to disk and process it post-facto, or do you have some software-based aggregation, filtering, etc that happens online?

(I'm guessing you would, for fast feedback and all)?

All that would be what is now called the high-level trigger. I was told is simply goes to servers for later analysis. We are very open about how all that works, explaining on their website, you can deal with their open portal and get all the white papers and technical documents. And you can even download all the radiator (oops data) if you want to try to analyze it yourself. I’d been surprised if they didn’t give you the board schematics and source code. I doubt that would be available through the portal but could be through special request. It was all done with taxpayer dollars and everybody has a right to it.

what's the best & most informative answer you have on here?

That explain it like I’m five answer. ELI5. The second or third question I answered. https://www.reddit.com/r/IAmA/comments/djjyrr/i_built_the_atlas_trigger_and_data_acquisition/f45zbf7/?context=8&depth=9

Great question. For last 20 years I have been living in Texas and pretty much have forgotten entirely who I was and where I came from. When I started mention to people that I worked on it and they looked at me like I was crazy and even I had forgotten what I had done save a highlight on my resume.

Particle physics and atom smasher is a really difficult to understand. They’re truly are the pinnacle of human engineering and the gateway to understand the deeper mysteries like faster than the speed of light travel. So sad that they got blamed for changing the course of human evolution when they’re simply running some big magnets, smashing stuff together and trying to see what happens. There is no pinpoint control in this system except for how fast and how often you attempt to collide protons together.

There’s nothing wrong with throwing subatomic particles around. If we didn’t learn how to throw electrons at CRT screen that we never would’ve had television.

The ELI5

where's the youtube or step by step process of how to build w/e was built?

Is there a YouTube on how to build an Apollo moon lander? The same card cannot be built again because they rely on chips the distributors would no longer stock. You would have to start putting in substitutes and with the complexity of this device would also require a redesign of the PCB board. It was essentially a one-off that from what I have gathered they discussed upgrading at 2007 and didn’t actually do till until around 2013 during the Shutdown. I would love it if someone that actually works at Cern could fill us in with the details.

Why do you use cylindrical sensors at the collision points instead of spheres? I though that the data would be easier to use this way.

also CMS is better.

That’s way out of my pay grade. I'm guessing because they are much easier to build? You can build a cylinder with a rectangular piece of sheet metal and some rivets but a sphere? You cannot make a perfect sphere cheaply from everyday building materials.

I did some calibrations on what were called scintillators and those were 6 foot long aluminum tubes. I never got to take them apart because essentially they’re like small dark rooms and they were a running experiment measuring muons in the lab. We used 12,000V but microamps to energize them so them and when a muon particle passed through a small little bit of light which would hit a collector and produce a charge. These things were Steve’s babies and he knew everything about them, so he is the person you should ask.

i know that CERN uses magnetic tapes because of how much data they take in and can store, but do you think that similar tapes can overtake modern hard drives, or even SSDs as data needs become to great, and as the new models of tape drives become faster and faster?

also, does CERN use linux or windows?

"Did you know that:

1. CERN manages the largest archive of scientific data in the high-energy physics domain and that it is constantly increasing?
2. the energy consumption of tape storage is negligible compared to disk technology consumption?
3. the tapes are between one to three orders of magnitude more reliable than the most reliable disk drives?
4. You can buy an actual CERN data tape as a souvenir for $10?"

My first computer, a Radio Shack Color Computer, used a cassette deck for storage. Tape is very slow compared to disk drives and the data must be accessed from beginning to end, or you need to fast-forward until you get to the right place. If you're old enough to remember modems you'll remember the screeching sound of the individual ones and zeros as it goes from a high to low tone. Tape drives are similar and they can be listened to with your ears.

VHS cassettes use a rotary head in order to write data as on diagonal stripes and modern tape drives likely use the same technology. During the '80s, the highest quality home recording were those you could make using a Hi-Fi VHS.

There is always going to be multiple copies of the data. I'm sure the most recent datasets would be available on their servers and are available for download from their open portal Tapes are selected for their capacity and durability. More about CERN storage.

For control and analysis, I would presume Linux or Unix. It's much more efficient than Windows. I only built hardware for it 2 decades ago and I've never been there. /u/mfb- is the CERN expert, maybe he/she can answer this.

EDIT: expanded answer

if you could do anything aside from what you do, what would it be and why?

I'm semi-retired, and on disability because of all of the pain issues from having undiagnosed Lyme disease for over 20 years. Aside from being an astronaut, my dream has been to build a recording studio out in the desert. I would operate it more like a BNB getaway for musicians to get away from big cities, get back to nature, and focus on their music.

I know this can be a contentious subject, so I'm going to all everyone downthread to be kind but here goes

What do you put in your pizza?

asked and answered

What's with the satanic rituals?

:-< First of all Satan is a myth. Look up the meaning of the name Lucifer and the answer will shock you.

My question had nothing to do with ME, so instead of trying to get me to quarantine myself, how bout you just give me an answer here.

I changed my answer, please change yours.

First of all, read Dave Mcgowan's 'Programned to kill', satanic rituals are nothing new, and they always have their connections to those in high societal positions, I'm also aware of lucifer's meaning being light-bearer, and 'satan' simply means God's adverserary...

I care not of the names of the old gods and demons, what I do care about is the fact that these rituals do exist, seriously read that book...

So in essence, a satanic ritual is a ritual that is adverse to God, hence all the child fucking and eating that is so prevalent with todays so called 'elites'...

So, you haven't answered fuck all with your edit, so no, I will not edit my question, I'll even ask again, what's with the satanic rituals?

I don't like your tone. Don't tell me to read anything. I'm visually impaired and have never found a need to look at anything more than the Cliff(s) Notes. Read the instructions above.