The high-energy physics community in the United States gathered at intervals from 1982 through 2001 to collaborate and plan out a common future in Snowmass Village, Colorado – hence their name, the Snowmass group. This year, Snowmass on the Mississippi is taking place July 29 through August 6 in Minneapolis, Minnesota. Organized by the American Physical Society’s Division of Particles and Fields, the goal of Snowmass 2013 is to continue the community’s long-term physics aspirations.
Dr. Meenakshi Narain recently gave us a personal glimpse into the future of her field and the roles of the Open Science Grid (OSG) and the Snowmass group. Professor Narain is co-principal investigator of Brown University’s experimental particle physics group, which played a prominent role in the Higgs boson discovery. She is also one of the conveners of the Snowmass New Particles group. Currently, Narain serves as coordinator of the Fermilab LHC Physics Center (LPC) and as lead for the OSG Snowmass group (which she founded).
Narain is involved with the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) at CERN in Switzerland and with the DØ experiment at Fermilab in Batavia, Illinois. The CMS detector, a five story digital camera recording hundreds of images per second of particle collision debris, is one of the large experiments at the LHC. In addition to trying to understand the properties of the Higgs boson, they are looking for new particles that might reveal what is beyond the Standard Model and the current understanding of particle physics. The OSG is the primary computing infrastructure for the LHC in the United States.
Researchers are facing a two-year shutdown of the LHC, so it can be reconfigured. When the LHC comes back online in 2015, the increase in collision energy from 8 trillion electron volts (TeV) to 13 TeV will generate a lot more data. Narain says the upgrade will enable them to study more properties of the Higgs boson and discover more heavy particles if they are present. Under the umbrella of Snowmass, researchers intend to define their vision for the long-term future, which includes accelerators at higher energies (14 TeV, 33 TeV and 100 TeV) and nearly 150 times larger datasets at higher collision rates. These upgrades provide a challenging environment for detectors – and for analyses seeking small signals for new particles, which is similar to searching for needles in a haystack.
During the shutdown, the OSG will be indispensable. To understand the potential for detecting new particles, researchers have to be able to predict their properties ahead of time. This means studies need to be simulated on the OSG at the new energy settings. Researchers will use these simulations to determine how much data will be needed to discover these new particles. Everyone in the Snowmass “New Particles” group is contributing to these studies, which all take an enormous amount of computing power. The analysts rely on efficient computing models, storage, computing power, and software to match the computing problem. Instrumentation is also critical.
The OSG is also creating easier ways for various teams to collaborate and share simulated data. “The OSG brings the community together in a seamless way and helps us forge collaborations,” notes Narain. Instead of duplicating each other’s work, researchers can compare data and models and share common tools. These collaborative efforts will help influence the design of the future detectors at hadron colliders.
The CMS and ATLAS teams (ATLAS – A Toroidal LHC Apparatus – is one of the particle detector experiments) are able to make simulated data available to each other and work across the entire particle physics community. They also share information with the theoretical community, which has expertise in building models for possible new physics signatures at higher energy scales. Ultimately, experimentalists and theorists work together to develop the tools that enable them to use the OSG for simulations. Narain recognized this need for extensive computing and common tools – and, in her dual role as the NP group convener and LPC co-coordinator, took the initiative this January to assemble a team with researchers from CMS/LPC and ATLAS. The Snowmass Virtual Organization within the OSG has been very instrumental in these collaborations.
Narain has also been busy recommending the OSG to Brown University colleagues who have large computing needs. Thinking across disciplines is emphasized at Brown, so Narain proposed that university researchers call upon particle physicists to find commonalities in processing large data sets (an example is public health, which gathers a lot of data). “We in particle physics have vast experience in large scale computing, trying to extract small signals from a large background or noise,” she said. “Others can look at commonality of how we do statistical analyses, how we process large data sets.”
Narain points out that the benefits of research in areas such as particle physics are not always readily apparent to the general public. Physics is asking basic questions about the undiscovered principles of nature. “We don’t start knowing what we are looking for,” she says. “Basic research gives us discoveries we didn’t expect. Then our expertise can cross-pollinate to other fields in ways we couldn’t have predicted.”
Narain described Snowmass as a way for the field to coordinate research for the next ten years or so. The different high energy physics sub-fields can ask each other tough questions and discuss how to evolve to the next stage – essentially sharing information across many thousands of scientists.
“We try to ask what the big questions are and how we will try to answer them,” she said. “We have confirmed the Higgs boson and made progress over the last year understanding its properties. The question now is what does that imply for the future or for the existence of yet undiscovered new particles? Is it the missing piece that completes the puzzle or is it a connecting piece to a whole new part of the puzzle?” For example, the Higgs boson might help resolve the question of dark matter. She continued, “What different types of experiments do we need to do over the next few years and decades? We will try to make the case for different accelerators and different experiments and build a strong argument for important and exciting physics for the funding agencies.”