Quantum Diaries

When I came here two years ago I brought my Volkswagen from the states. It was cheaper to bring my German made (one of the last ones) car here than buy a new one. I like my car, it had low miles, was paid for, and was familiar to me, which made adapting to French and Swiss driving habits easier. I also knew I could get it repaired here without any trouble.

When I lived several years ago in Hamburg, Germany, I didn’t need a car. And I wish I could have done the same thing here. There I could get around by public transport or bicycle and not have to worry about insurance, maintenance and repairs. It is a lot cheaper, and if I was in a hurry, I could always take a taxi.

I can’t do that here. I work on 3 different sites at CERN. The experiment is at the red CMS dot on the picture below. Meetings are most often at the main site (next to the red ATLAS dot). CMS is the furthest away from the main CERN site. The other site I visit, Prevessin, is somewhere in between. The LHC ring is 27 km in circumference. In the course of a day, I often have to switch sites. This is a minimum of 8.5 km (I will measure this the next time I do it with my car’s trip computer!). And I take a short cut through the countryside…not the longer truck or bus route! Not that there is a bus.

So some days, when things are not well planned, or something crops up, I make 4 trips. Each one takes about 25 minutes (if I am lucky I make it in 20), unless I get stuck behind a farmer on his or her tractor, or I have to wait for the cows to be moved to the next pasture. Some days, I feel like all I am doing is driving. Those days I have to remind myself what a nice countryside it is, since I am spending about 1.5 hours driving in it, almost always on the same roads, staring at the same cows.

But being the nature loving type, I occasionally get rewarded with a glimpse of something special. Regularly I see grey herons and large birds-of-prey in the fields, an odd fox, and tremendous views of the Alps as I just leave CMS on my way to CERN. Then I am glad I made the drive that day.

A la prochain…

In about four days I am off to the States for Christmas. I am looking forward to seeing my family, getting some sun (it is most often gray during the day here in Geneva during the winter – and I am spending too much time underground), not wondering how much that pair of sneakers is in dollars this week, and just not thinking too much about work. Its good to have a break, and I still like to fly, I don’t know why…

But about work, I have thought of some “resolutions” for the next year:

1. I will not scribble my to-do lists everywhere and then have to sort though a pile of notes to figure out what I noted. I will write them down on the same piece of paper in legible handwriting. I will actually write the critical things in my notebook again. Scraps of paper get lost.
2. I will actually take at least a half hour for lunch and go away from my computer or electronics to give my eyes a break. Even if I just stare at the wall while I eat. Eating in front of your computer risks sticky/crumby keys and orange juice on the screen.
3. I will not send e-mails without checking the TO: field carefully since Mac Mail auto-completes the name, and it isn’t always the right person. So-and-so doesn’t need to hear about the missing cables.
4. I will write documentation with details for my colleagues.
5. I will label things – spare parts, cables, etc. so my colleagues can find them too.
6. I will find time to read about physics and not browse the electronic parts and tools at Farnell.
7. I will work on my French conversation so that I don’t get hung up on because I am taking too long to formulate my sentence on the phone. Not everyone here speaks English!
8. I will try to keep the lab and the cabinet underground neat. I will not dump things on the lab bench.
9. I will remember to turn off the soldering iron/microscope lamp.
10. And lastly, I will not procrastinate the jobs I don’t like. Better to get them done and over with then fret over doing them! The scratches from the cable ties and the banged knuckles heal.

Happy New Year et Bonne Année

Pam

This week was our last “Global Run” for the year. We called it GREN (Global Run End of November) since it was only supposed to be a week, but was extended until the end of this first week of December.

During the GREN we include parts of the CMS detector that are located underground in the data taking stream. This includes the trigger electronics, the system that decides if an interesting event has taken place, and the system that I am most involved with. For the first time since we started these Global Runs (GREJ,GREA, GRES, etc.) my beloved (perhaps that is a bit too personal) Regional Calorimeter Trigger has joined in. And not only one or two crates, as is often the case when we test “slices” from the calorimeters (see previous posts), but the whole thing. Eighteen crates of our electronics receiving bits of data representing energy from the Hadron Calorimeter (HCAL) electronics (which gets its data from the central part of the HCAL) then processing it, and sending out the results to the Global Calorimeter Trigger, which sorts it and forwards the highest energies (including location in the HCAL) to the Global Trigger (GT), who finally combines it to find coincident signals in the top and bottom of the HCAL. (Phew!) If it then it passes the requirements set at the GT, i.e. energy greater than some value and the coincidence, the GT sends out a Level-1 Accept (L1A) to the systems that just sent it. This L1A tells the electronics that that was a good event (it is saved in a memory until told otherwise) and the data is retrieved and sent on to the High-Level Trigger, a computer farm, for processing. There we can refine the tracks in the muon chambers and tracker, the energy deposit in the calorimeters…for later analysis.

Our source of events is cosmic-ray muons (basically heavy electrons) caused by protons and nuclei from space interacting in the atmosphere. The higher energy muons can get through a lot of material relatively unscathed (to our detector underground), and we can use the light they leave in the calorimeter as the pass through as a way of detecting them. It’s exciting to see my system in its final form, working!

Of course, we are not ready yet. Though all the electronics are there, it is still somewhat rough. I still have to get another system into the mix, the electromagnetic calorimeter, who are busy commissioning right now. They have to be timed in with the HCAL. And we are using only one of the two spigots out of the RCT – one still lacks the connections out, and will need intense testing, very soon.

I am pretty happy about it. I will post a picture of one of our triggered events here soon!

One of my colleagues remarked that we were not “On the Critical Path”, which was an opinion I was glad to hear. This was the “little thing” that made my day. However, there is no time to sit back and relax yet!

A la prochain…

I started this on a friday, about 17:00 (5pm) when we’d been working all day underground again. We had endured one water cooling failure, network problems, and various configuration problems all day. It was a frustrating day so far, and it was hard to keep oneself motivated. Fortunately we have colleagues willing to set us up with a supply of coffee to help keep us going. We just contribute 50 Euro cents per cup (honor system) to pay for this supply.

To make it, one just takes the little aluminum coffee capsule (no advertising here for the brand), puts it in the coffee maker, fills the back with water if it is empty, puts a cute little plastic Euro-sized cup under the nozzle, presses one of two cup-size buttons, and in a few seconds…voila! you have coffee, hot and strong, with minimal mess.

Normally I object to these capsules because of the waste, but we don’t have a way to keep the coffee maker by a sink or anything, so these little capsules are the way to go. Its hard to keep the area clean anyways.

This keeps us going through our day. Now, not everyone drinks coffee, and some don’t even like the smell, so it is probably tough to sit downstairs near the maker. But I used to sneak sips from my mom’s cup at an early age, and we’d make a sort of cafe au lait after dinner with our leftover milk, so I guess it is natural that I am still drinking it.

The funny thing is, I don’t use it to stay up late like some folks. If I have a difficult project and I am falling behind, I usually get up early (have some coffee, of course) and get started with a fresh outlook.  I’m terrible at staying up late.

And soon, speaking of staying up late, I will probably do a shift. We are starting a two-week period taking data using cosmic-rays (mostly muons – a heavy electron, basically) to integrate and test our detector (all but three endcap disks have been lowered – its getting cozy in the cavern) and the various bits of software and hardware that we use to collect the data. The days will be managed by experts on the system, and the non-experts will take shifts…going from 17:00-1:00 (swing) and from 1:00-9:00 (graveyard). I volunteered early, with the hope that I could “reserve” swing shift. I won’t function properly for days if I do graveyard, its like jet-lag. Either way, I am glad I only have 2 km to drive home after shift to lovely downtown Versonnex.

Maybe it will be easy, and I can catch up on my blogging….I can only dream.

A la prochain…

Or if you are from the Madison, Wisconsin area, “The White Stuff”, of which there was plenty there. But this morning, in Versonnex, France, we woke up to a soggy couple of inches. While it is soggy down here, it means the mountains could have high quality white stuff – which they do – several Swiss resorts open this weekend.  Time to wax the skis…

I spent the weekend getting away from it all up in Zurich. It was a fun trip, even though there was rain, and a very cold Monday. This is not a cheap city, and with the recent fluctuations in the exchange rates, so I am glad we had advance purchase tickets. The highlight of the trip was a solo acoustic concert by John Hiatt on our last night there. For those of you not familiar with him, you might remember a song done by Bonnie Raitt:  “Thing Called Love”, he wrote that and performed it on his break though album “Bring the Family”, but she got the hit.  His music probably is not to everyones’ taste, but I have enjoyed it since my uncle introduced me to “Slow Turning” in 1989.

As for work, we have really had a struggle lately with our infrastructure.  It has been frustrating, we plan some tests, and are thwarted.  This is supposed to be all over by friday.  So, in the meantime, I am looking at ways to test the 108 cables I installed recently.  It requires me to think a little differently than I have done, with each of  our crates receiving information from 5 other crates.  I’ve set them up to send “fake” data from one to crate the other to test the cards themselves, but all 18 share information (you should see the rat’s nest of cables).  Some of the tools are already in place – I want to make things more random to test lots of bits.   I’m making progress, even though nothing has been written yet,  sometimes its just a though exercise worked out while walking to lunch.

A la prochain…

I spent the last couple of weeks trying to arrange a cable tray under our RCT racks. It goes for a few meters – maybe 8 – and we are going to lay excess cable in it. I thought this would be easier, but there is a bit of overhead in the whole operation. First I had to get the approval of one of the people who is in charge of the fibers that sit below it. I didn’t want to be in their way. Which is important, since they belong to the Hadronic Calorimeter, which supplies the RCT with slightly over half of its signals. Then I had to ask the technical people who are in charge of installing these things if it was all right. They said sure, we can do this, no problem. However, then it sat for a bit, so I pestered and finally got referred to someone who could do “small jobs” like this to do it. So now it is in. I am happy. Small things like this just make life easier, and now I can install 108 cables on monday, which is a good time to do it.

There is a lot of other equipment around, so I really don’t want to just go ahead and install the cable tray, and then have to rip it out again.  I already had some of the cables in, only to have to pull them out again.   We had wanted the cables to go another way, but there just isn’t space for  it.

The rest of my week I learned how to send a message from one program to another.  This was kind of fun – I like to learn new computing tricks.  I did however run into a bug with another program that stalled me for a bit, but there turned out to be a work around.  What it did is save us from ourselves – forgetting to click a button on one web browser while we ran another program.  Now the test program is all self contained – much better.

On the other side of life – it got quite cool the last week. It probably could have snowed in the mountains, but we aren’t getting much rain at all.  Its a little worrisome.  We really want to ski this winter!

A la prochain…

Tomorrow I have another full day underground, probably friday as well. We are in the process of testing and installing cables. The cables were tested for continuity at the vendor that produced them but after we install them we test them again to make sure the data comes over the cable from the calorimeters’ boards to our RCT’s boards.
A lot can go wrong. At our end, the RCT, we use VGA connectors to make the connections to our boards. I don’t know if you have ever taken a look at how your monitor connects to your PC, but if you have a VGA or even a newer version of a monitor connection, they often have pins. These can get bent if you put the connector in badly. Or, as we found out, it is possible to put the connector in the wrong way entirely. We only use a few of the VGA connectors pins, so we can reverse the connector (the shell bends easily) without much effort. So we are working on figuring out if: 1o26 data cables are plugged in correctly and the boards at both ends work. We are doing this bit by bit to start, with an eventual goal of automating it. But first it is cable by cable, and it goes slow.

When we are down there, there are no visual clues as to what time of day it is, so I just go on two things, my computer – which has a display of the time, and my stomach, which seems to tell me I am hungry with astounding regularity.

To be able to work underground, we are required to watch a DVD about safety, take a test about safety on the web, and wear the appropriate attire. This includes two special pieces of equipment: a hard hat

and a pair of very flattering steel-toed safety shoes.

The hard hat is a nice one, with a quick-adjust so that I can put it on and
off without tweaking my ponytail that I keep my long hair in (the environment is not long-hair friendly – fans keep the air moving in the racks and hair gets tangled in things). It also has a headlamp, which is supposed to help if we have a power outage (imagine total blackness) and I find it useful for dark corners underground. The shoes, well, the less said the better. No special clothing, but it is better to have a warm fleece and wear (dark-colored) washables, as the floor is pretty dirty, and nothing that is too new. I have found grease on my clothes from goodness-knows-what. It is definitely a “dress-down” type of environment.

It is noisy, cool (all the water cooling and fans in there), and kind of cramped, but we get all done that we need to, and I will be glad to have finished it. But there is always more to be done.

I re-read my last post today, and found it was quite uninspired. I enjoyed my week off, but in my haste to get something posted, it turned out a bit dry.

Well, I just haven’t done much of this sort of writing.

In the 5th grade, we were required to write a page a day in a journal that the teacher or student teacher read (we had only 17 students in the class). We spent about 15 to 30 minutes in the morning on it. Some days I was inspired, but I was a typical 5th grader and usually stared at the blank page for awhile – it wasn’t even a big page, but because of that, it was certainly more than 75% rubbish. I hope to do better than that here.

Now, I can write an e-mail and blather on to my friends for quite awhile. If I were to do the same thing for this, you would probably only hear about my cats (one shown below – just because I can), my apartment, whether or not the skiing will be any good this year, and grumbling about the price of peanut butter.

I do write, fairly regularly, but it is scientific writing, which can be a bit tricky sometimes. I just recently spent about two weeks (not full time) working on a 5 page paper for a workshop’s proceedings. It isn’t hard to fill up the 5 page limit anymore, and I find that I have way more that I would like to say than I can put down. It also requires careful planning to say what is needed in the minimum of space. First and foremost, since this is a going to a more general audience, I must define my terms – including all the Three Letter Acronyms (TLAs) that I use to save space. I also have to describe my system in a way that makes sense. Mine has a natural flow – since it processes data in parallel, so it isn’t hard. The hard part comes when I need to describe other things that I didn’t have a part in, that I only use to get the system to work with all the other parts or that provide the data for my system. While I think (I may be kidding myself) that I understand these other systems decently enough, it is hard to put that down on paper, as I never feel expert enough for that. After I have written it all down, you pick at it for a bit and then send it to my colleagues, who may or may not respond. After including their comments (if any) I pick a bit more, and then finally, usually because of a deadline, I submit my paper…once in awhile, sometime later, I get a comment or a question on it from someone who has actually read it.

I think I prefer this blogging to the above.

A la prochain…