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Regina Caputo | USLHC | USA

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Standby for 7 TeV Collisions

Monday, March 29th, 2010

We’ve been getting word that 7 TeV collisions are supposed to start happening tonight as early as 7 am at CERN (1 am Eastern standard time). As I’m writing the sign on the LHC Ops page is Beam Status: Ramp (the current energy is 480  GeV… no wait 500 GeV and rising 🙂 ). I’ll be watching the ATLAS control room live tonight (got the coffee pot going already)… but for those of you who want to watch too here’s a couple of links:

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!!!

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Visiting Student Weekend at Stony Brook

Wednesday, March 24th, 2010

Phew… the past 3 days were our perspective student weekend. We put on our best foot forward to show accepted graduate students what life at SB is like. The current graduate students host the visitors – we show them around campus, take them to places in the area, to breakfast – the professors tell them about opportunities in the grad program… all-in-all a good time. Plus… lots of free food, my little office fridge is bursting with leftovers. (bagels and pizza… breakfast of champions).

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.

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Decoding the ATLAS event display

Thursday, March 18th, 2010

I was reading my favorite particle physics magazine this morning, Symmetry Breaking, and found a very exciting article that I wanted to share with those of you who don’t get it.

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 🙂

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International Women’s Day

Monday, March 8th, 2010

To all my female scientist friends and colleagues, present and future: Happy International Women’s Day. ATLAS is inviting women to go on shift today in the control room (not that they’re not invited normally, but especially today). Check it out! And Symmetry Breaking did an article on women at the energy frontier!

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

Chocolate Cake.... mmmm

-Regina

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The Futures Section of Nature

Saturday, March 6th, 2010

Yesterday, I was reading in the Futures section of Nature (vol. 463, 25 Feb 2010),  a short story called Distraction: A fine romance by Julian Tang.

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

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It’s not easy being green

Wednesday, March 3rd, 2010

As you’ve seen from other posts the sleeping giant that is ATLAS is awaking from its winter rest. The first events from 2010 were recorded.
This morning, I look at the LAr detector status: green.

Being Green

Being Green

Green for all systems go. 🙂
It took a lot to get here, and soon we’ll be ramping up… more to come then.

-Regina

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In preparation for data

Tuesday, February 23rd, 2010

With the winter shutdown rapidly coming to a close, the ATLAS team has been preparing for the eventual flood of data. I’m sure you remember all those posts the bloggers have made about having lots of meetings, well the number of meetings is exponentially dependent on the expectation of data. Despite my love of meetings, here’s lots to do, so meetings are inevitable. I’ve been trying to get all my early analyses in order because things will happen very quickly. Of course things never go as smoothly as one would hope. The past few weeks I’ve been madly searching for converted photons (in simulated data, of course). Photons, either created during the primary interaction or during other processes, convert in the detector as they pass through material into electron/positron pairs. These are useful in mapping the material in the detector because more conversions occur near more material. They are also useful in calibrating the detector because we can measure how much energy they deposit.
Thankfully I found the little buggers, (I needed to do a photon recovery – which I hadn’t needed to do previously) so the analysis marches on. I’m specifically looking at doing a calibration study – E/p of the converted photons. This is a measurement of the energy deposition (E) in the calorimeter and compare it to the momentum measurement ( p ) from the tracking system. The ratio (for a massless particle of course) should be 1. (Electrons are pretty light compared to the momentum that they have so we can approximate it as zero for now). But this ratio also depends on how well we can determine the momentum of the charged particle in the tracker and how well we measure the energy deposition in the calorimeter.
Charged particles enter the tracking detectors and are bent in the magnetic field. The curvature of the bend is proportional to how fast the particle is going (its momentum) – slow particles have their trajectory affected more than faster particles. Then given the curvature we can calculate the momentum. These particles then enter the calorimeter where they deposit their energy. How quickly they do this depends on the radiation length of the material of the detector and – again – the energy of the entering particle. We can then compare the two values to see how closely the detectors are calibrated to each other.
We have lots of particles that we use to do this kind of calibration. I’m using photons is because we should see a lot of them at the beginning (high cross section). For other particles we’ll have wait a bit. Also we’ll want to be able to calibrate at all different energies to see how the calorimeter and tracking responds. Photons just so happen to get to really high energies (higher than Zs and Ws) and that’s where the exciting physics is going to be.

-Regina

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APS “April” meeting or Bust!

Monday, February 15th, 2010

This weekend/week is the APS “April” meeting in Washington, DC. Every year the APS has a series of meetings for each of the physics disciplines. The April meeting is reserved for Nuclear/Particle/Astrophysics. This year I submitted an abstract and gave a talk about the work I did on the uniformity study of the calorimeter (See my previous post). You can check out my abstract here.

You can actually check out all the abstracts, but I’m just giving you a link for mine :). At the meeting we get the opportunity to meet other physicists to see what other experiments are working on. There’s lots of interesting science and a great opportunity to network. I joined lots of my colleagues from the Phenix collaboration. But… April meeting in February, you ask? This year it was a joint meeting with the American Association of Physics Teachers. It was a great opportunity for physicists and physics teachers to get together and discuss how to get more students interested in physics. These talks are particularly interesting because there’s always an emphasis on getting more girls into physics – something I’m obviously very interested in.

Also as I learned this week, it’s actually possible for anyone to give a talk at the APS meeting (provided they are a member – which means they pay membership feel), so every year there are people from the non-scientific community who come and present their theories. Most of these talks end up in the same session or two, so they’re easy and kind of fun to go to. Most of these are crazy and logically inconsistent or just plain wrong. If they are particularly crazy they fall into the realm of “crackpot”. I was shown a list of criteria for determining who is the biggest crackpot. See the them listed.

See if you can read the abstracts and find the ones that fall in this realm.

-Regina

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Sorry, Higgs, I’m just not that in to you.

Tuesday, January 19th, 2010

It’s an exciting time for your humble LHC blogger. She may just have a thesis topic… So what does that mean? (I often times wonder that myself).

With the recent success and in anticipation of high energy collisions (and therefore data), it’s time to figure out what can be found and what can’t given the projected amount of data. (We’re going to be running at ~7 TeV for the first part of the year, then ~10 TeV the latter half). Now lots of people are doing cross sections measurements – which is a different beast than searches (see below).  Cross section measurements take a particle that we know – Zs and Ws for example – and check to see if we measure what we predict. This is very important to do and I’m over simplifying but that’s the basic idea. Despite it’s importance, I personally feel like if I’m working on the highest energy accelerator in the world, I’d at least like to try to do a particle search.

The Cross Section Beast

The Cross Section Beast

This isn’t a completely trivial question because ever since the Tevatron turned on, theorists have been making predictions as to what was out of reach to our current experiments.  So what makes for a good early search? Lots of things, I’ll list some here:

  • Of interest…

Maybe this goes without saying, but I’m going to go ahead and say it anyway. A search has to be well defined and predicted. One doesn’t just look for the Higgs, or SUSY or Z’, they look for specific decay products that could come from the predicted particle and can not be explained by sometime else. Although we’re going to be 3.5x and 5x higher energy than the Tevatron, there has been years of data collected at the Fermilab experiments. Now there are some particles that are simply outside of their reach. For example just due to conservation of energy, nothing can be created >2TeV, but due to statistics (need that high fluctuation over the background again…) some limits are in the 100-200 GeV range. Increasing the energy will allow us, even with less data to raise limits.

  • High Signal:Background ratio

Since there is going to be a smaller data set (only 1 year of running), we simply won’t have enough statistics to say with confidence that we discovered certain particles. We need to say that the signal is an actual signal – not just a fluctuation of the background. I elaborate this in my Higgs post. This also means that there would be a distinct signature for example: something that would decay to 2 very high energy electrons and 2 very high energy jets. It could be di-boson production or W/Z+jets, but the electrons would come from a W/Z which was very far off mass shell – which is not impossible, but maybe not as probable.

  • Missing Energy (MET to be more specific)

This is a bit contentious, and maybe more a personal taste than anything. We won’t have a completely calibrated detector initially. The detector is calibrated by taking standard particles (Ws and Zs for example) and reconstructing them. We then convert the electrical signal out of the machine to energy and momentum. To do this, the more Z and W events the better – which like everything takes time. So the energy of the signal can be off. This isn’t a bad thing, but the way we calculate missing energy (say in the form of neutrinos) is by balancing the energy in the detector. For example if there is 40 GeV deposited in 1 part of the xy plane, then there has to be another 40 GeV in another part of the xy plane to balance it out. If we don’t really know if it’s 40 GeV or 45 GeV, then it’s hard to calculate missing energy. (I should also point out, it’s transverse energy, not just energy – which I can elaborate on if anyone is interested).

So these requirements gives us a whole range of particles to search for. I’m involved in a physics group called exotics. Exotics are a generic term for anything beyond the standard model and isn’t the Higgs or SUSY. This isn’t to say that Higgs/SUSY searches aren’t beyond the standard model… I guess they get their own groups since so many people are interested in them. It makes the exotics working group more intimate :-). My interests (and potential thesis) are in particles that would unite quarks and leptons (like how a W unites the family of quarks and the family of leptons). These generically are called leptoquarks.

So what’s wrong with the Higgs? It like the captain of the high school football team and head cheerleader all rolled into one particle to the high energy physics community. I don’t know… I’m just not that into it.

-Regina

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With Great Energy per unit Time, Comes Great Responsibility

Tuesday, January 12th, 2010

Happy new year LHC Blog enthusiasts! I hope everyone had a happy and safe holiday season.  I was lucky enough to get to go back home to Colorado this year, but unlucky enough to not have enough snow/nice weather to go skiing. Oh well, we all know the best time to ski is late winter/early spring. It’s been a while since I’ve contributed anything, so it seems only fitting to give a recap of what’s been happening in terms of the LHC, particle physics, and life as a graduate student in general.

I’m sure most people who read this blog are up-to-date as far as the LHC status. We had a very successful end of 2009 run and were able to get collisions at a record breaking energies. (Sorry for the cheesy title… It’s hard to get back into work after a break, anywho…). We’re all excited for things to start back up in February. (And by excited I mean frantically trying to write code so when the data starts rolling in, we’ll have a way to analyze it).

In other exciting particle physics news, CDMS (Cryogenic Dark Matter Search) in mid-December reported two candidate WIMP (Weakly Interacting Massive Particles) events. This experiment is near and dear to my heart because as an undergraduate, I worked as a Summer Intern for CDMS at Fermilab. It’s important to say that not all particle physics is done at large colliders with gigantic collaborations. It’s a really exciting experiment and I encourage anyone interested to check it out or ask questions!

On the subject of graduate student life… The holidays are always a difficult time. Despite grad school being “free”, (It’s not really free, the grants or the graduate school pays our tuition, and usually not our school fees), our stipend isn’t that much especially when you compare it to others who went into the private sector. (I went to an engineering undergrad so all my friends – with the same degree as I have – now making 70,000+/year). Even my younger sister who works as an office manager of a business makes almost double – a fact she loves to bring up over the holidays… At least I get 2 weeks off  ;-). This means that my family usually gets macaroni necklaces and hand drawn cards as presents.  But even worse is the dreaded question that everyone seems to ask:  When are you going to graduate?

For those of you reading who went to graduate school – you know – you might as well ask my age, weight, and why there are holes in my shirt. And I don’t just get it from parents… it comes from friends, in-laws, former teachers, Marge Simpson, etc… It’s getting to the point where I’m afraid to go back to my home town because I’m now in 20th grade. Not that this is atypical. I can expect another 1.5+ years if I hope to hit the average. But it’s not about fulfilling a class requirement any more. I’m done with classes. It’s about doing a unique (or somewhat unique) bit of research and writing it up and that takes time – or so I’m told.  >sigh<

So if you’re one of those people who asks their grad student friends/colleagues/children when they’re going to graduate. Please stop and just smile when they give you a present that they made all by themselves – remember it comes from the heart.

Happy New Year!

-Regina

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