So much has happened with the LHC over the past year or so since I started blogging. We’ve recorded splash events, first collisions, stable running and accelerated beams, and now machine operations are going full steam ahead at record breaking energies. Although I’ve enjoyed sharing my thoughts and updates, all good things must come to an end.

Thanks to all my readers who’ve kept up on my posts. I know they’ve been sparse over the past month but I’ve realized that I can’t really do justice to the LHC blog and do the rest of my work. I hope you’ve enjoyed reading what I’ve had to say and best of luck to the rest of the bloggers!

Regina

9:30-ish A.M. – arrive at Brookhaven National Lab. Usually I go to Stony Brook, but today I’m working with one of the post-docs at BNL on how to estimate QCD background.** Upon arriving, we get a quick coffee and get caught up on this weekend’s US Open tennis championships. Discussion of my analysis code ensues.

**ASIDE: QCD (Quantum ChromoDynamics) is the theory of strong interactions. Of the forces we study at the LHC, this is the least exactly understood. It relates to all quark/gluon (color charged) interactions. QCD has two peculiarities: confinement and asymptotic-freedom. In short, confinement means that as you move two quarks away from each other the force between them gets larger (like a rubber band). This explains why you never see single quarks, instead you see showers of quarks (called jets). As they move away from each other, more quarks pop out. Asymptotic-freedom means that high energy quarks and gluons interact less. At a hadron collider, the most prominent thing you get out are jets. They are a significant background that you have to remove to do an analysis. It’s also difficult to simulate just based on the sheer number of jets that come out. My advisor once told me that the least expensive way to simulate all the QCD background needed  is to build a collider and take data. **

10:30 A.M. – After getting some unexpected results in my electron analysis, the anonymous post-doc confirms that there is indeed a bug in my analysis code. This is what I spend the vast majority of my time doing. Writing and debugging code to perform an analysis on data and simulated data. He has written a modified version on my electron selection code, so I work to combine the two.

11:15 A.M. – We get into a discussion about what the electron/photon (called e/gamma) group has defined as an appropriate selection criteria for the electrons I want to include in my analysis. I want to use a standard selection criteria but the standards vary in the early days of data-taking. We decide that the best approach is to use the selection criteria of my greatest background: W bosons produced with jets.

12:15 P.M. – Lunch time. We join the other ATLAS scientists at BNL on the walk over to the cafeteria. The cafeteria contains your standard fare. I usually go for an egg-salad sandwich. The days I go to BNL, I don’t make my own lunch. The discussion flows from the fate of the Tevatron to the post-doc’s baby girl and back to the US Open (I’m a big tennis fan… go figure).

1:00 P.M.: Head back from lunch, and start the discussion of QCD estimation. Unfortunately the bug in my code and discussion of selection criteria for electrons took up the morning, but that leaves the afternoon for some strong force fun. **So how do we do this ** The discussion takes a while, but once it’s done….

**Another Aside!: QCD estimation is done a couple of different ways. It gets pretty detailed, but here is a brief overview. You look at two different regions: an area that you believe to be signal poor and QCD background rich, and the other signal rich and QCD background poor. You can then pick selection variables that are uncorrelated: like a lepton ID variable, and a Missing Energy variable (from neutrinos). You can then plot the values of the events in terms of the two variables and come with four regions: an area that is signal for both variables, an area that passes signal cuts for one variable but not the other (2 of these), and an area that fails the signal cuts for both variables. From these numbers and ratios you can predict the amount of QCD you should get. –I’ll note again, this is simplified, but the general idea is there.**

2:45 P.M.: I now get to write the code that makes these plots And spend the rest of the afternoon doing so.

6:45 P.M.: I get home in time to see the US Open men’s championship get rain delayed, so I pop open my laptop and start coding again. I have a farewell party for a friend who graduated and is moving to Germany tonight, so I can’t work too much longer.

-Regina

To anyone who isn’t a particle physicist an inverse picobarn (pb^-1) is a pretty bizarre unit. I’ll start out with the base unit: the barn (b). It’s a measurement of area, proportional to m^2 or cm^2. The barn unit comes from when nuclear physics was in its infancy and refers to a uranium nucleus which is as big as a barn (1 barn = 10^-24 cm^2). (I still think physicists should hire writers to come up with this stuff… anywho, back to the post).

An inverse barn (or b^-1) in the particle physics world is a measure of collision events in an area of a barn. Throw in a metric prefix (pico which is 10^-12*base unit) and now you’re all caught up to speed. But what does that mean really? Fermilab has over an inverse femtobarn (fb^-1, which means 1000x an inverse picobarn) of data but of course they’ve been running their collider for over a decade. We’ll still need much more data to do searches for things like the Higgs, but very early searches are definitely underway – not to mention all the Standard Model physics and calibration that’s going on too.

So cheers to the first pb-1 of data… I can’t wait to start analyzing.

-Regina

I briefly mentioned that I’ll be doing a search in a previous post. Now I’d like to share a bit what this particle beast is. A leptoquark carries quantum numbers for both quarks and leptons. It would decay by generation such that it mixes families of quarks and leptons. So why do we think it exists? In a word: Symmetry.

Physicists love symmetry (and symmetry breaking ). Symmetry in forces (like electricity and magnetism), symmetry in families and generations of particles, symmetries everywhere. Since the quarks and leptons in the Standard Model have the same family structure it seems like there should be something that ties them together, like leptoquarks.

Granted this is a bit of an oversimplification, theorists have put in lots of work into understanding how these particles work. And now I’m going to be looking for them.

I’ll be giving updates over the next few months explaining more about these particles over the coming weeks.

-Regina

So what is material mapping?… sounds like something cartographers do.
We have lots of computer simulations of the ATLAS detector. To double check to make sure we’ve taken into account every cable we look to see that the particles interact the way we expect them to. Photons, for example, when they to through material convert predictably into an electron/positron pair. When I say predictably, I mean based on the amount of material they go through. We find these electron/positron pairs because they have a displaced vertex (an electron/positron which are close to each other and when you draw a line back from their tracks the origin isn’t the main interaction point). The more material in the way, the faster they convert. So we make sure our Monte Carlo simulations predict where most of the conversions occur to make sure we understand the detector.

I’ll try to provide a link to show a picture of the material map once they have been approved for public viewing.

Until then, Happy July 4th!

Fireworks

Regina

So for those of you that haven’t heard/read… there’s some interesting stuff happening with CP violation at the Tevatron. Here’s some background:
The Tevatron produces copious amounts of particles called B mesons. B mesons (quark-antiquark b – d or s pairs) oscillate between themselves and their antiparticles (Something I’m happy to elaborate on if anyone is interested). This oscillation can violate CP (charge conjugation and parity symmetry) thus preferring one state in the matter/antimatter system vs. the other.  (This also happens in the kaon system, and was one of the first pieces of experimental evidence that CP was violated). According to the standard model, this asymmetry is supposed to be very small (on the order of 10-4) – so small the Tevatron experiments can not measure it accurately. However that’s not what they found…
There is evidence that the asymmetry is about 100x larger than expected or 3.2 sigma (or 3.2 standard deviations). Now that’s not enough away from the predicted value to claim discovery just yet (need 5 sigma to be really sure). But it’s a very interesting result. Here’s a link to the arXiv paper

The New York Times also published a nice article.  You know you’ve hit the big time, when the NYT has an article about it . Although I dislike it when physicists talk about finding faces or toes of god.

-Regina

Sorry it’s been a while since I’ve visited — I may say I enjoy going to meetings in my pjs but you’re always on my mind. I’ve been devoting hours and hours to your service since I’ve been gone. Things are different now, I’ve traveled 4,000 miles to see you, and now I’m back – basking in the glow of your status:

Beam Setup: Injection Probe Beam

I know that last week you were able to reach luminosities higher than ever before, more than doubling our data set size. Those collisions were – for lack of a better phrase – the bees knees.

But I have another request… I’m on shift this week and next week. You’ll see me over at the LAr desk (well maybe not over the monitors… – (it’s sad when I make short jokes on myself)). So far, I’ve been waiting patently – taking calibration run after calibration run, and cosmic run after cosmic run. But I’ve seen that all before, and it just doesn’t do it for me any more.  I would really appreciate it if you were able to squeeze the beam – like I know you’re able to – for me(*). I see the daily plan… so I know you’re thinking about it too.

Sincerely your devoted follower,

Regina

(*) (the proton beam starts fairly broad, the LHC then has magnets to focus it which means higher luminosity (more protons per unit area)- or more collisions and therefore more data)

Sure, they routinely throw up things like the Schrodinger equation and make references to things like quantum mechanics… and whether or not I may laugh periodically… I really dislike The Big Bang Theory (BBT from here on out).

Don’t get me wrong, I know people who love it – my parents for example. When I tell them I went to trivia night, they say things like “Oooh! that’s just like on the BBT”. They ask which of my friends is like Leonard or Sheldon and ask me if the equations they randomly throw up on the screen are actually physics equations. Of course my parents think I’m pretty smart, and they have met some of my physicist friends.

It’s not the science of BBT that I have problems with. It’s how the only physicists in the show are nerdy, socially awkward, and intolerant. Granted Sheldon (the stereotype of stereotypes) is kind of the jerk of the group, but he likens someone who for all intent and purposes is reasonably intelligent to a gorilla… but Penny can’t be smart, she’s pretty and blonde, and likes shoes. >Sigh<

Screen shot from the BBT

“Newton was a smart cookie… ooh is that where Fig Newtons come from?” – Penny

Granted the goal is to be funny, but I hate how the show only has socially incompetent and extraordinarily nerdy guys. And how they make physics completely inaccessible to anyone who doesn’t wear glasses. Sheldon starts teaching Penny physics with a history lesson starting 3000 years ago and chastises her for not taking notes. Instead he could tell her to looking around and see nature. Physics is the study of how nature works. (But that’s not Sheldon’s character… he wants physics to be inaccessible).

I have 20/20 vision, enjoy shoes, hair cuts, showering daily, monkey pants, Glee, and books that don’t have an equation in the text… so do lots of my (physics) friends.  I think lots of people are pushed away from physics at an early age because of shows like this. And it’s self fulfilling: only a certain type is portrayed therefore only that certain type feels welcome… so only a certain type becomes physicists.

Of course, at the end of the day, the BBT is a comedy show. But that doesn’t mean that the writers can’t do something positive for physics… like maybe have a woman physicist on the show who isn’t a sociopath, or a guy who has interests outside of physics.

Granted it’s not just this show in particular. One of my childhood favorites – Saved by the Bell – always has the science teacher as a nerdy, white guy in a lab coat who was really really weird (this was also true of the math teacher… whereas the history/English/art teachers were always women… way to break down barriers Saved by the Bell…). I guess that wasn’t enough of a deterrent for me, but I also had a really cool science teacher in 4th grade. She told me that the world needed little girls like me to go into science. I remember the conversation to this day – I think at the time, I wanted to be an astronaut .

There are lots of programs out there to try to combat this stereotype (as an undergrad, I was involved in Expanding your Horizons and Girl scout Badge day both of which were targeted on getting girls interested in science), but social “norms” are entrenched in everything that we see and do. The only real way to promote change is to talk to normal guys, girls and minorities face to face and tell them that science is for everyone – not just the socially awkward.

And that’s why I dislike the Big Bang Theory

- Regina

Geneva's on top .. notice Reykjavík isn't cancelled

My sympathies are with the people who are stranded, I know I’ve received about 10 emails saying people had to phone into meetings because they couldn’t get back to CERN. I’ll have to keep everyone update on my status… it looks like most airports should be open on Tuesday (my flight leaves Sunday).

Until then, analyses await… and with those analyses come one word: Grid.
The Grid is the mechanism by which we do large scale computing. Instead of running an analysis on a local computer (which has limited capabilities), I send a “job” to a set of computers which copies the conditions of my work area, and breaks the large job into a bunch of smaller ones so it can run over the data set faster. I say this in confidence… I’ve now sent 3000 jobs to the grid. I <3 analyzing I usually send my jobs to BNL (Brookhaven National Lab) and I’ve never had  a problem… but now I’m getting  the following message:

WARNING : Your job might be delayed since BNL is busy. There are 10398 jobs already queued by other users while 292 jobs are running. Please consider replicating the input dataset to a free site or avoiding the –site/–cloud option so that the brokerage will find a free site

I guess lots of people are running over data. Although it’s annoying to have to wait, it makes me happy to think about all the activity that’s been happening.

Here is where our public event displays are located.

7 TeV Collision Event

From the LHC control room. The webcast will start at 8:30 am at CERN (2:30 am Eastern).

From the ATLAS control room.

This one is already live streaming. Be on the look-out for my former roommate Stephanie, she’s run coordinator for the Liquid Argon Calorimeter tonight… and I’m sure she’ll appreciate me mentioning her in the post. I’m so jealous she’s there on the front lines. I know we’re all really nervous and hope everything goes well.

So tune in to watch!!!

It’s always nice to interact with incoming students because it reminds you what it was like to not be caught up in the little details of research. It lets you look at the broad picture and remember the science behind all the compiling code. Plus it’s exciting to talk about all the happenings at the LHC. There were quite a few people interested in particle physics… yay! Nothing like a couple of days of just talking about the physics of particle physics. I think I said “supersymmetry” in the past few days than I have in the past few months. Plus Sunday was so nice, we even went to the beach! — surely that’ll convince people to come here.

But now back to work… the work of particle physics. The vaca was nice while it lasted.

It describes in detail what one everything in one of the ATLAS event displays means. This is something that physicists use and publish, so I suggest that everyone check it out here.

They also have a similar article for CMS. It’s fun to compare the differences

Whenever there is a celebration of one group, I feel like we’re always stuck defending it from questions like: Why do we celebrate Women’s day? When is men’s day?

I wanted to take a moment to address these questions. Days specific to a cause are designed to increase awareness. Today at CERN, we want to show how many women are involved in particle physics. Most people think of an Albert Einstein-y type of character when they hear scientist: older, white man with crazy hair (if you don’t believe me google image search: scientist). There’s nothing wrong with Albert Einstein (obviously) or men in general, but a girl studying science may find it hard to relate to this type of person. This can dissuade her from joining the field or even worse – she may never even consider entering it.

So we have days like today to say, “Hey, ladies: look at all these successful women scientists! You can be one too!”

I just hope next time there’s cake .

Chocolate Cake.... mmmm

-Regina

I apologize to those of you who don’t have free access to Nature (it’s in essence the UK’s version of Science) and can’t read it but I have a bit of a rant.
I’ll briefly summarize:
outgoing Astronomer girl meets painfully awkward English major boy. Girl falls in love, couple get married, girl has children, girl “gave up her life-long dream of joining the SETI Institute to become a full-time mother” and boy “showed an amazing talent for predicting stock-market trends and became a very successful investment manager”.
Later on, boy is on his death-bed and asks girl if she regrets giving up her dreams (really, he asks her now). Girl replies: “Yes, a little, I guess – but having children is a worthy substitute, my love.”
Then boy floats away (you guessed it… he was an alien). Later on girl’s granddaughter has an interest in SETI. Dead-ish alien boy then “returns” to earth to “distract” (i.e. marry and impregnate) the granddaughter so she doesn’t find aliens either.
Huh??
There are so many things wrong with this article. First, the story is beyond poorly written. Between my personal rage and awkward unnatural dialogue I barely got through it. Second, since when do English majors become investment managers and since when is that the definition of success? – I thought Nature would emphasize science, not investment management. It seems if nothing else “girl” would be more adept for her job and the boy could have stayed home with the kids or there could have been a balance of both. But adeptness doesn’t matter, the basic jest of the story is women can not possibly follow their dreams and have a family – and this fact is so obvious that even aliens apparently know this and can use it to prevent being discovered.
I repeat… Huh???

Isn’t that exactly the wrong message we want to send to our young women (myself included)? I know plenty of talented women scientists who have a family/life outside of their work. I would even go so far as to say that having a multifaceted life helps you to be a successful scientist.

Of course, one has to assume that this is the opinion of the author, but it was  published in Nature, a science journal! And that gives Julian Tang (virologist and SETI member) a voice. What does he think of his female colleagues at SETI, especially if they have children? Anyway, this really steamed my clams, it also steamed the clams of one of female faculty in the department and several other grad students (men and women alike) with whom I shared the article – so I’m not the only one. In conclusion:

Dear Nature,
Please stop publishing articles from want-to-be science fiction writers in which potential women scientists must substitute children for a career. It makes the whole field seem like something out of a 1950s sitcom.
Thank you.

-Regina