Particle Physicists` New Extreme Teams

NEWSFOCUS
Particle Physicists’
New Extreme Teams
LHC will soon be the world’s sole great atom
smasher, leaving ATLAS and CMS with only
each other for competition.
With fewer rival teams and many more
teammates, researchers working on ATLAS
and CMS face as much competition from
within the collaboration as from without. Particle physics relies on an extreme division of
Life at the world’s biggest atom smasher is an odd combination of selfless labor, but scientists now face the reality that,
cooperation and intense competition
even as they work on their specialized tasks,
others within the same team are doing the
MEYRIN, SWITZERLAND—Eighteen years ron Collider (LHC). Aiming to create new same thing. In the past, one collaboration worago, as an undergraduate student at Eind- particles and maybe even open new dimen- ried mostly about getting scooped by another;
hoven University of Technology in the Neth- sions, the circular accelerator blasts protons now members of a collaboration seem to
erlands, Martijn Mulders worked on an exper- together within four huge particle detectors worry as much about getting scooped by their
iment seemingly ideal for a physicist in train- spaced around its 27-kilometer circumfer- own teammates.
ing. Using lasers, he would study fluctuations ence. The two largest detectors, known as
“In the old experiments, when we had 300
in a glowing plasma, work directly relevant to ATLAS and CMS, vie for those discoveries, or 400 people, really it was an easier job,” says
the manufacturing of microchips. The small- while one called LHCb studies cerGeorge Mikenberg, an ATLAS
scale “tabletop” experiment gave Mulders tain familiar particles in great premember from the Weizmann Insticontrol over every aspect of the work.
cision and another called ALICE
tute of Science in Rehovot, Israel,
Yet he found the experience wanting. studies a form of nuclear matter sciencemag.org
who has worked at CERN since
Podcast interview
“With a tabletop experiment, it’s just you and produced when the LHC smashes
1982. “You can remember 300
with author
the tabletop,” Mulders says. “You are kind lead ions. Some 3000 researchers Adrian Cho.
faces.” Still, he and other physiof isolated.” So, as a graduate student at the work on ATLAS, and 3600 work
cists say they’re happy in the colUniversity of Amsterdam, he switched fields, on CMS, including Mulders. “The whole laborations of thousands. “This works,”
moved here to the European particle physics world of particle physics is here,” he says. “So Mikenberg says, “so what the hell?”
laboratory, CERN, just west of Geneva, and I don’t look at it as a big collaboration but as a
did his thesis research as one of 550 mem- small world. … It’s perfect being here.”
Among the worker bees
bers working with a particle detector called
It’s something of a brave new world for CERN’s building 40, which houses the
DELPHI. “What I really like about life in a particle physicists. Since their field was born ATLAS and CMS collaborations, feels like a
big collaboration is that there’s always plenty in the 1930s, they have worked on ever-bigger gigantic beehive. Within the eight-story cylinof challenging things to do,” Mulders says. machines in ever-bigger teams. For decades, drical structure, balconies of cubicles ring a
“What you do gets appreciated.”
collaborations of hundreds of research- vast atrium. On the ground floor, a café serves
Mulders, 39, now works in perhaps the big- ers have been the norm. But by pushing into physicists who gather in twos and threes, their
gest scientific collaboration ever assembled. the thousands, the two large LHC collabora- conversations melding into a multilingual
Three years ago, CERN turned on the world’s tions confront physicists with new issues and thrum. Puckishly, researchers with CMS have
highest-energy atom smasher, the Large Had- pressures. That’s especially true because the plastered a life-sized photo of the detector
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Online
NEWSFOCUS
Accelerator Laboratory (Fermilab) in Batavia,
Illinois, the Tevatron collider smashes protons
and antiprotons at one-third the LHC’s energy
on their side of the atrium. The ATLAS team
and feeds detectors called CDF and D0 that
can’t respond in kind because a full-scale
support teams of 500, down from 700 a few
image of 25-meter-tall ATLAS won’t fit.
years ago. (The 25-year-old Tevatron will shut
A particle physics collaboration works a
down later this month.)
bit like a Woodstock-era commune. MemThe sheer scale of the ATLAS and CMS
bers cooperate in running and maintaining
collaborations, however, brings new factors
their detector, collecting the raw data, and
into play. “The increase in size from CDF and
converting them into a readily analyzed forD0 to the LHC collaborations was a factor of
mat. Later, like so many commune members
6,” says Shahram Rahatlou of Sapienza Unigathering for dinner, they go through the data,
versity of Rome, who heads a CMS working
breaking into smaller groups to search for
group searching for exotic new particles. “The
particular particles or phenomena—
number of physics topics you can study
just as some commune members
has not increased by a factor of 6. It’s
might opt for the nut loaf while others
maybe a factor of 2.” So what do you do
prefer the tempeh. Once the collaborawith six times as many people?
tion has approved a result for publicaThe answer: Compete with your
tion, essentially all members put their
neighbor. Some of CMS’s 10 physicsnames on the author list.
analysis working groups are now as big
Also like a commune, most partias the current CDF and D0 collaboracle physics collaborations are run as
tions, Rahatlou says. And within those
vaguely defined democracies. Both
working groups, every interesting
ATLAS and CMS have a few elected
analysis will be pursued independently
officers, a hierarchy of boards and
by at least two teams, sometimes sevcommittees, a slate of working groups
eral more. The same holds true in the
to help manage the work—and little
ATLAS working groups.
means to force anybody to do anySuch competition produces invaluthing. “The political system is quite
able crosschecks, physicists say. “It’s
close to anarchy—not in the pejoraabsolutely essential for topics as
tive sense, but in the sense that there
important as the Higgs and SUSY that
is very little formal authority,” says
you have multiple teams working in
David Coté, a postdoc at CERN who
parallel,” says John Ellis, a theorist at
works on ATLAS.
CERN, who is not a member of either
In more detail, each detector is a
collaboration.
high-tech canister surrounding a point
Still, researchers can have too much
at which the LHC’s countercirculating “I don’t look at it as a big collaboration, but of a good thing. When the LHC started
beams collide. Those collisions can
taking data in March 2010, scientists
blast into existence massive new sub- as a small world. … It’s perfect being here.”
set out to remeasure the properties of
atomic particles that quickly decay
—MARTIJN MULDERS, CERN known particles, such as the massive top
into telltale combinations of familiar
quark, which had been discovered at the
ones. The detector’s myriad subsystems aim from the outside, physicists say. Coté is search- Tevatron in 1995. In both collaborations, four
to characterize that debris. So for “service ing for new particles predicted by a concept or five teams measured basic parameters such
work,” a physicist might help calibrate the called supersymmetry, or SUSY. So are the as the top quark’s mass. And in each collabosubsystem that detects particles called muons 500 other physicists in ATLAS’s SUSY work- ration, leaders of the top quark working group
or tune the “trigger” software that identifies ing group, he says. But only a fraction of them had to choose one analysis for publication.
promising collisions and makes the detector work in the subgroup that covers the SUSY “You couldn’t even use one as a crosscheck of
record its data.
signature Coté is working on with a couple another because they were practically identiA similar division of labor holds sway in dozen colleagues. And on a daily basis he cal,” says Christophe Delaere, a CMS memthe sexier arena of data analysis. For exam- works with a few colleagues at CERN. “We ber from the Catholic University of Louvain
ple, ATLAS and CMS physicists are in hot are a little core group of four people who are in Belgium.
pursuit of the long-sought Higgs boson, the interacting every day,” Coté says.
Physicists say that experience has spurred
key to their theory of how all the other parthem to be more creative in devising analyses
ticles get their mass. To find it, they look for A crowded table
to avoid overlap. All agree that if people are
combinations of particles that theory says the The huge LHC collaborations continue a willing to do what’s needed, there’s plenty of
Higgs could decay into: a pair of photons; decades-long trend toward bigger teams in work to go around. “If you ask any physics
two massive particles called W bosons; or a particle physics. From 1989 to 2000, CERN analysis group in ATLAS, they will tell you
particle called a bottom quark and its anti- ran the Large Electron-Positron collider, they need more people, even with 3000 of us,”
matter partner, among many other possibili- which fed four detectors, each with a team Strandberg says.
ties. So a Higgs hunter might join a group of hundreds of physicists. At Fermi National
Still, on hot topics, toe-to-toe competition
In your face! A life-sized photo of CMS hangs
CREDIT: BENOIT JEANNET AND MAXIMILIEN BRICE/CERN
across from the ATLAS team’s offices.
that is focusing on just one decay mode and
work on some detail of that analysis.
Coaxing researchers to do their share of
service work is a perpetual challenge, physicists in both collaborations say. “I think it’s a
constant struggle in all experiments, not only
ATLAS, that you have this tension between
the low-level work and analysis,” says Sara
Strandberg of Stockholm University, who
heads ATLAS’s “combined performance
group” to check the quality of the data coming
out of the detector.
Even with thousands of teammates, life in
the collaborations is homier than it appears
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when he read the memo. “They didn’t even let
me know they were working on it,” he says.
Wu denies that she was trying to get the
drop on the collaboration. Her team had presented a preliminary search with much less
data to a subgroup of the ATLAS Higgs working group in November 2010, she says. When
she saw the signal in April, the subgroup was
not scheduled to meet for another week or
so, so her team wrote the internal memo, she
says. The memo was an attempt to follow the
rules, Wu says: “If there had not been a leak,
this would not have been an issue.” Wu insists
group. After all, the main competition is still
the other collaboration. “If somebody comes
and has a very good analysis that’s almost
complete, you can’t just ignore it,” Paus says.
Murray says that the April incident has
raised the only allegations of such tactics he’s
aware of. Still, physicists can estimate when
certain analyses should pay off. For example, within a year, researchers should have
enough data to either spot the Higgs boson or
rule it out. As fruition nears, somebody else
could well be tempted to parachute to glory.
Two cultures
Look out below!
In the L-shaped control room
Even amid extreme competifor the CMS detector, banks
tion, researchers say, most colof computer monitors cluslaboration members play by
ter in three islands. Overhead,
the rules and work with workmore monitors show graphs that
ing groups. But with Nobelkeep tabs on the detector and its
caliber quarry like the Higgs
100 million data channels, the
boson and SUSY particles
trigger that makes it record
finally within range, physievents, the hardware that does
cists worry that some may opt
the recording, and many other
for rougher tactics. “There is
facets of the machine. Occathe good-citizen approach,
sionally, a snatch of a song—a
and then there is the approach
bit of funk or a measure of U2’s
‘I am better than you, and
“In a Little While”—pierces the
I’m going to kill you,’ ” says
chatter of a dozen researchers
Maurizio Pierini, a postdoc at
taking “shift” to alert them to
CERN and a member of CMS.
one condition or another.
Physicists particularly
The room has a thrownworry that a few rogue re- “If you ask any physics analysis group in ATLAS, they will together look. The shift
searchers might follow along
leader—Delaere of the Cathoon a hot topic and then swoop tell you they need more people, even with 3000 of us.”
lic University of Louvain—
—SARA STRANDBERG, STOCKHOLM UNIVERSITY explains that CMS researchers
in at the last moment with their
own version of the work, prehad planned to put computers in
senting the collaboration or working group her team did not leak the signal—which this room and the control room in a larger
with a fait accompli to claim discovery. proved spurious—and says somebody else one above it, complete with a broad window
“There was a rule even before we started tak- may have done so to discredit her.
through which observers could look. But
ing data that this kind of parachuting is not
In the wake of the incident, both col- then physicists decided they needed more
allowed,” says Maria Spiropulu of the Cali- laborations moved to force people to work computers, so the machines wound up in the
fornia Institute of Technology in Pasadena, within the working groups, researchers say. bigger, brighter room and the people in the
who works on CMS. But all collaboration And most physicists say rogue researchers smaller, danker one.
members have access to the data, so there’s have little hope of besting an analysis that has
The story hints at the cultural differences
little to prevent someone from trying.
received ongoing attention from the working between CMS and ATLAS. “ATLAS someIn fact, some physicists say such a ploy group. That’s especially true because to make how I think of as being very Swiss,” says
has already been attempted. In April, blogs it to submission for publication, an analy- CERN theorist Ellis. “My impression is that
and other news sources buzzed with reports sis must first win the approval of the work- it’s a very democratic collaboration that has
that an ATLAS team led by Sau Lan Wu of ing group. The details differ between ATLAS a very well-framed constitution and rules—
the University of Wisconsin, Madison, had and CMS, but after that step an analysis sort of what you’d expect from the Swiss.”
spotted the Higgs boson decaying into two must be presented to the full collaboration CMS, Ellis says, is “more of a seat-of-thegamma rays. Outraged researchers sensed an both in a talk and in a preprint. Researchers pants operation.”
attempt to scoop the collaboration and scram- must respond to all comments before leaders
Others say that ATLAS management
bled to find the source of the leak. According release the paper. (After such vetting, journal strives more for consensus whereas CMS
to blog accounts, somebody left an internal peer review is often quick.)
management is more “top down.” “CMS peoATLAS memo describing the analysis on
Nevertheless, it might not be so easy ple complain that decisions are taken at a high
a printer, and somehow it found its way to to turn a blind eye to a rogue analysis, says level and that it affects the work you’re doing
the public. Murray, the senior convener of Christoph Paus of the Massachusetts Insti- at a lower level,” says CMS member Pierini.
the ATLAS Higgs working group, says he tute of Technology (MIT) in Cambridge, who “ATLAS people complain that there aren’t
became aware of the group’s analysis only is co-convener of the CMS Higgs working any decisions at a high level and that this leads
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seems inevitable. In July, both ATLAS and
CMS reported at a conference possible hints
of the Higgs boson, especially as it decays into
two W bosons (Science, 29 July, p. 507). Six
different groups within ATLAS now want to
improve the Higgs-to-WW analysis, says Bill
Murray of Rutherford Appleton Laboratory
near Didcot, United Kingdom, senior convener of the ATLAS Higgs working group.
“We can’t publish all six different analyses,”
Murray says. “We have to pick the best one.”
The others will be written up in internal documents, he says.
NEWSFOCUS
to confusion on the lower level.”
That difference has practical consequences, physicists say. When data-taking
began at the LHC in March 2010, Pierini and
colleagues missed a deadline to install a trigger setting they needed for their SUSY search.
Unable to persuade CMS-run management to
extend the deadline, they missed out on the
first month of data-taking. “A little flexibility
would have let us put the trigger in a day later,”
Pierini says.
ATLAS’s populist approach also has its
drawbacks. For example, ATLAS has two
software systems from two different groups
for tracking muons. That’s because the
collaboration had no way of telling one group
to yield to the other or of making the groups
work together. “ATLAS is definitely willing
to duplicate effort,” says Joshua Cogan, a
graduate student from Stanford University
in Palo Alto, California. “And ATLAS is definitely willing to let you pursue something
even if they know [the collaboration] will veto
it” in the end.
The view from the bottom
Within the gleaming ATLAS control room—
which, with its slick, curving consoles and
gigantic computer displays, looks like the set
of a network newscast—an alarm pings. It
alerts the ATLAS shift leader that, with datataking paused, a physicist in the United States
wants to test one of the detector’s many subsystems. With a click of a mouse, the shift
leader transfers control of the “hadron calorimeter,” demonstrating how ATLAS and
CMS can be controlled from around the globe.
“There is the
good-citizen
approach, and
then there is the
approach ‘I am
better than you
and I’m going to
kill you.’”
—MAURIZIO PIERINI,
CERN
Yet for all the power of decentralized control, the collaborations seem to be driven by
humbler bits of technology: coffeemakers.
They are everywhere at CERN, many of them
the fancy jobs that grind their own beans and
make an espresso good enough to satisfy Italian researchers. Each one is emblematic of the
importance of being here.
Meeting for coffee “is superimportant,”
says Thilo Pauly, a postdoc at CERN who
coordinates the daily operations of ATLAS.
“In order to make decisions, you have to go
by the normal procedure and go to the right
meetings,” he says. “But of course, it helps
if you start to make alliances, … and the
preparation is typically done in coffee meetings.” Stephanie Majewski, a postdoc at
Brookhaven National Laboratory in Upton,
New York, says she didn’t drink coffee until
she came to CERN. “You meet with eight different people and have eight cups of coffee,
U.S. Physicists, a Long Way From Home
CREDIT: BENOIT JEANNET AND MAXIMILIEN BRICE/CERN
MEYRIN, SWITZERLAND—It’s not hard to find an American here at the European parti-
cle physics laboratory, CERN. Among physicists working on the particle detectors fed by the
world’s biggest atom smasher, the Large Hadron Collider (LHC), researchers from the United
States outnumber those from any other nation. Of the 3600 researchers working on the massive CMS detector, 900 hail from the United States, as do 700 of the 3000 researchers working
on the ATLAS detector.
Still, working at CERN isn’t like working at home, says Aaron Dominguez, a CMS member
from the University of Nebraska, Lincoln. The United States is not one of CERN’s 20 member
nations, so U.S. researchers have little say in how the lab is run. “You learn how the lab works,
and you deal with it,” Dominguez says. “It’s the role of a guest.”
The United States has gone to great lengths to keep its scientists integrated in the far-away
experiments—for example, by establishing a remote center for CMS at Fermi National Accelerator Laboratory in Batavia, Illinois. Nevertheless, many make personal sacrifices to be here. Vivek
Sharma of the University of California, San Diego, is co-leader of the working group within the
CMS team that’s searching for the Higgs boson. He spends 8 weeks at CERN for every week at
home with his wife and their 7-year-old daughter.
“It’s more of a sacrifice for them,” Sharma says. On weekends, he says, he and his family
rely on Internet video links to “be” together: “When they wake up, we just put on the cameras.
They go about their things and I go about mine, and we have conversations.”
–A.C.
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and by the end of the day you’re shaking,”
she says. Like all the other young physicists
interviewed by Science, she says that a stint at
CERN is essential for getting ahead.
Those at the bottoms of the ATLAS and
CMS heaps, the postdocs and graduate students, say the competitive pressures can be
intense. “Very quickly it can become very
demotivating to think that there are 150 other
people working on the same thing you are,”
says Maiken Pedersen, a graduate student
from the University of Oslo who is working
on a SUSY search on ATLAS. “It’s difficult
to be fast enough” to compete with others.
And there are many others: ATLAS and CMS
employ about 1000 graduate students and
hundreds of postdocs each.
So how does a young physicist stand out
in the crowd? “Shameless self-promotion,”
ATLAS’s Majewski says with a laugh.
“When writing up [a job] application,
you really just have to brag about yourself,
which some physicists are pretty good at.”
Majewski worries that in the huge collaborations, people with better social skills may
rise faster and further than those with the
better scientific skills.
Others say that collaboration members
know who has done what and that talent wins
out. “In the end, the right people are getting the
jobs,” says MIT’s Paus, the co-convener of the
CMS Higgs working group. “Not everybody
can stay in the field.”
Be that as it may, young physicists say
they feel fortunate to participate in such a
grand adventure. “We may be able to make
discoveries that will alter the future of physics,” says Benjamin Hooberman, a postdoc
from Fermilab who works on CMS. “And I
want to be a part of that.” That spirit keeps
3000 physicists working and playing (fairly)
well with one another in an environment in
which self-interest and team interest seem to
collide about as often as the protons whizzing around at light speed. –ADRIAN CHO
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