Finding the Key to the Universe
DATELINE: Geneva, Switzerland, July 4, 2012: The news from CERN was hotter than the fourth of July.
Perhaps one day in the future, people will ask each other, “Where were you when the Higgs boson was found?”
It is a given that Ohio State physicists will know.
Some of them were right there at the CERN press conference in Geneva on July 4, 2012 when the stunning news was announced.
The Higgs boson, sometimes called “the God particle,” had been found. Wherever they were, many of them were watching and were practically beside themselves to have played major roles in this awe-inspiring discovery.
Imagine being involved in a massive scientific search for the most important thing in the universe—a subatomic particle thought to be so fundamental that nothing or no one could exist without it, yet which has never been seen.
“I’ve been working for 19 years looking forward to this day,” said Stan Durkin, an experimental high-energy physicist, who works on the Large Hadron Collider's CMS detector. “I can’t express how excited I am.”
“It is very satisfying to finally have evidence of what is most probably the Higgs particle,” physicist Richard Kass, who works on the ATLAS detector, said. “Both Harris (Kagan) and I have been involved with Higgs searches, for a long time--since about 1984.”
Both CMS and Atlas found the Higgs. The Higgs signature from the two experiments is nearly identical.
James J. Beatty, professor and chair of the Department of Physics, could not be prouder of his faculty and their graduate students and postdoctoral researchers. "The discovery of the long-sought Higgs opens a new era of exploration at the LHC. We are eager to learn of this particle's detailed properties and what they may tell us about new physics. We are proud of the achievements of the OSU faculty who worked many years to build the two experiments that made this discovery."
The news from CERN on July 4 was based on “extremely strong evidence for a new particle at a mass of approximately 126 GeV/c2 observed both by ATLAS and the Compact Muon Solenoid (CMS) experiment. The natural interpretation is that this observed state is the Higgs boson based on the measurements released today of its decay modes. The Higgs boson gives rise to the mass of the fundamental particles: quarks, electrons, muons.”
For anyone not currently living on the planet, CERN is the European Organization for Nuclear Research and the home of the Large Hadron Collider (LHC), called by many “the Ultimate Discovery Machine,” buried deep underground in Geneva, Switzerland and hunting the “God particle” has been its main mission.
BACKSTORY: Called a collider because it creates collisions between protons —not just any collisions, but ones traveling at nearly the speed of light—yes, picture “Big Bang” collisions, and the hope was the LHC would lead to the first real look at how the universe formed and how it functions—on every level.
It would allow for really big science and the culmination of an unprecedented collaborative effort on the part of physicists worldwide, who worked for eighteen years to build this ultimate Discovery Machine.
The massive experiments conducted in the 17-mile long LHC tunnel were predicted to change not only the way we do physics, but the way we think about and what we know about the universe itself.
So, it was no wonder that all eyes were on CERN when the LHC was “turned on” and hurrahs went up as the first beam successfully steered its way around its course in the early hours of September 10, 2008.
But researchers, like Ohio State’s Stan Durkin, quickly pointed out that this was just the first step in a long quest.
Durkin knew about long quests. Back then, he and his Ohio State colleagues, T.Y. Ling, Brian Winer, Richard Kass, and Harris Kagan, along with a lot of other physicists worldwide were looking for the Higgs boson, something no one had yet seen, but believed is what gives subatomic particles their mass.
The Large Hadron Collider consists of four accelerators. Ohio State was then and is still the only university in the country to collaborate on three of the four LHC detectors: ALICE, ATLAS, and CMS. Nine of our faculty and 15 of their graduate students and postdocs initially helped build these detectors.
Physicists at Ohio State have spent the last 19 years designing and building hardware for Large Hadronic Collider experiments at CERN as well as analyzing the data once actual data taking began. Ohio State joined the CMS collaboration in 1994 along with the first wave of U.S. universities.
BACK TO THE FUTURE: ATLAS, the largest detector, is larger than a five-story building.
K.K. Gan, Richard Kass, and Harris Kagan, who have spent 16 years on the ATLAS experiment, built the “camera,” capable of capturing the subatomic particles created by the collisions. They had hoped this would let them find exotic particles.
It led them to the most exotic and elusive of them all.
Also currently on the ATLAS team are postdoc Josh Moss and graduate students Matthew Fisher, Hayes Merrit, and Advait Nagarkar, all of whom Kass credits with playing important roles in ATLAS data taking and data analysis.
Kass explained how his team’s technical contributions to the ATLAS experiment aided in the Higgs search,” the pixel detector measures the trajectory of charged particles, including the ones that come from the decay of the Higgs.
“The pixel detector is like a digital camera on steroids. Imagine one with about 100 million pixels that can take about a million pictures per second.
“Also, the Beam Loss Monitor and Beam Condition Monitor protect the ATLAS detector from damage should something go wrong with the LHC beams,” Kass said.
“These devices sense if the LHC's proton beams are not being steered correctly. If even a small fraction of the protons that are in the LHC actually hit the ATLAS detector enormous damage could result. The BLM and BCM send signals to accelerator control and if certain conditions occur the beams will be turned off as a result.
“The BCM and BLM use artificial diamond (made by a chemical vapor deposition process) to detect the beam particles.
“In addition these devices help measure exactly how much data ATLAS has taken. Knowing how much data we have taken is very important when comparing our data with theoretical predictions.”
Durkin is the head of the CMS Endcap Muon detector electronics--a key detector element in the Higgs search. He and his colleagues had been relying on the CMS to prove its existence.
The Ohio State CMS group presently consists of faculty members L. S. Durkin, Christopher Hill, Richard Hughes, and Brian Winer; engineer Benjamin Bylsma; along with three postdocs: Wells Wulsin, Carl Vuosalo, and Khristian Kotov; and three graduate students, Marissa Rodenburg, Jessica Brinson, and Andrew Hart.
Hill, who joined the Ohio State physics department in 2011, has been on the experiment for seven years. He is CMS assistant physics coordinator responsible for all of the physics analyses going on at the CMS detector and is presently at CERN helping with analysis and publicity related to this announcement.
Durkin, Ling (now retired), and Bylsma played a leading role in the design and construction of Cathode Strip Chamber (CSC) electronics for the CMS Endcap Muon detector.
“We initiated the architecture of the CSC electronics system, developed key front-end ASICs (Application Specific Integrated Circuits), designed and tested five different types of circuit boards and implemented all of the data acquisition firmware in the system,” Durkin said.
“The scope of our contributions includes 220,000 channels of cathode front-end electronics and the entire chain of data acquisition electronics that reads out digitized data from all the cathode and anode channels in the system.
“Overall, Ohio State physicists designed and built over 3200 electronics boards of five different types for this project. “
WHAT NEXT? Finding what appears to be the Higgs boson is only the beginning. There will be no time for resting on any laurels.
As Durkin put it, “Observing a signal well above background is not an endpoint though. To finish the job we need to measure the boson's properties.
“There are strong theoretical arguments that a Standard Model Higgs is not enough to complete our understanding of particle physics. Most of us are secretly hoping that this is not a run-of -the-mill type Higgs boson and that while making detailed measurements of the particle's decays we are led to a new understanding of nature.
“The next few years at the LHC will be extremely exciting. I can't wait to see what we will uncover. The successful discovery of a Higgs-like boson in a real sense will complete the Standard Model. Having spent more than 18 years of hard work reaching this goal, I am ecstatic.”
As further evidence of this intent, Durkin’s CMS group is presently designing improved electronics for the Endcap Muon chambers. The electronics will be manufactured and installed on the detector next spring.
“From a physics point of view it was (is) crucial to find evidence of the Higgs,” Kass said.
“However, it will be even more exciting to find evidence of a second (or third) Higgs particle as many of the successors to the standard model of particle physics predict that many different Higgs particles should exist.
“The goal of the LHC (and its experiments ATLAS and CMS) is to map out the physics beyond the standard model and finding additional Higgs particles will be a tremendous help in doing so.”
K. K. Gan added, "It is fortuitous that the Department of Physics has invested so heavily in the LHC physics program. This exciting program will continue to produce many interestng results in the next twenty years, enabling new generations of undergraduate and graduate students to do world-class science."