Particle physics creates the right path to frontiers

June 6, 2008 | 7:13 am

The final day of the Fermilab Users’ Meeting set a course to discovery with an eye to the energy, intensity, and cosmic frontiers of particle physics at Fermilab.

But the course presents budget and outreach hurdles.

“It is very important not to be discouraged by the past,” said Joseph Dehmer, director of the division of physics of National Science Foundation. “I think we’ll have good coming years. The opportunity for discovery is greater than it has ever been at any time in history.”

Hundreds of users attended talks about Tevatron advances and analysis, proposed neutrino experiments, the US participation in CMS at the LHC, dark energy and dark matter searches, and research on a high-intensity proton beam.

US Congressman Bill Foster, a 22-year-veteran of Fermilab, urged users to attend the third Workshop on Physics to plan experiments that would meet short-and mid-term research goals.

“Don’t be afraid to try something new,” he said.

A culture that supports only short-term projects has hurt particle physics, Foster said, but the recent Senate approval of a supplemental funding bill and public interest in keeping the country competitive offer hope.

“Across the political spectrum there is recognition of the need for basic research,” he added. “The problem is keeping the politicians focused.”

Washington policy makers repeatedly stressed that particle physicists must make the case for the benefits of particle physics to the nation’s health, security, and economic well being.

“Advances in technology are not steady, but when it happens, it can change civilization,” Dehmer said. “Particle physicists are the most fearlessly creative group of people I know. They push the frontiers of technology and social organization.”

See all reports from the Fermilab Users’ Meeting 2008 here.

Tona Kunz

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Fermilab hears views from Washington, DC

June 5, 2008 | 7:06 pm

The particle physics community is moving in the right direction to keep the field vital, but needs to increase the momentum amidst difficult budget times.

A series of talks Wednesday by Washington policy makers at the annual Users’ Meeting focused on how Congress and funding agencies view particle physics and what those groups want to hear from the field in the future.

Michael Holland, examiner for the Office of Science projects for the Office of Management and Budget.

The particle physics community has made great strides in presenting scientific opportunities on the energy, intensity, and cosmic frontiers and focusing on the excitement of discoveries on the horizon, said Michael Holland, examiner for the Office of Science projects for the Office of Management and Budget.

He called for the community to continue to engage further the public imagination in its research projects while also producing statistics for policy makers that show the broader benefits to the nation. Holland asked for more data on particle physics as a net exporter of talent and a pathway to national innovation.

The High Energy Physics Advisory Panel has undertaken a study of how many of those receiving degrees in particle physics go on to work in government and private industry, including the fields of computing, medicine, and finance.

“That will be essential for keeping you in the game,” Holland said. “People may be your most important product.”

Dr. Dennis Kovar, acting associate director for High Energy Physics at DOE’s Office of Science.

The work of the particle physics community to develop a “realistic, robust” P5 roadmap recently approved by HEPAP also strengthens the case for particle physics funding, said Dr. Dennis Kovar, acting associate director for High Energy Physics at DOE’s Office of Science.

The report sets the stage for the United States to become a world leader at the intensity frontier, building on Fermilab infrastructure, and to make exciting discoveries at the energy and cosmic frontiers, “There really is an exciting future,” he added. “The question is how do you get from here to there in terms of resources and making a case.”

The large number of particle physics connections with universities in dozens of states creates a great political asset for the field, said Adam Rosenberg, a Congressional staffer for the House Committee on Science and Technology. He stressed strengthening ties with other scientific fields as well.

The FY2009 budget scenario will require combined efforts because it is shaping up to be “eerily similar” to the FY2008 budget and could lead to a holding pattern in funding until the arrival of a new administration.

A continuing resolution likely would prolong the severe budget challenges for particle physics, Kovar said.

“We will do our best to ensure a world-class, strong program with the resources available,” he added.

See all reports from the Fermilab Users’ Meeting 2008 here.

Tona Kunz

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CMS physicists prepare for LHC dress rehearsal

June 5, 2008 | 12:45 pm

Scientists across the world are eagerly awaiting the startup of the Large Hadron Collider, under construction in Switzerland. This also is the case at Fermi National Accelerator Laboratory in Batavia, Illinois, where scientists gathered today for the second day of their annual Users’ meeting. The day started out with presentations on the status of the LHC and the CMS experiment, one of the two general collider detectors that are being built along the 27-km ring of what will be the world’s most powerful proton smasher.

Jos Engelen, chief scientific officer at CERN, provided an update on the LHC schedule. The cooldown of the last LHC sector of superconducting magnets started at the end of May and the entire machine should be at its operating temperature of 1.9 K in July. This temperature is necessary for the magnets to become superconducting and to achieve strong magnetic fields. The magnets steer beams of proton around the LHC ring and make them collide at the centers of large particle detectors such as CMS. Four of the eight sectors have already been cooled to 1.9 K. Here is a chart of the current temperatures of all LHC sectors.

The CMS collaboration plans to carry out its final test of its detector at the end of July using cosmic rays, showers of particles that rain on Earth. Even 100 meters underground, the CMS detector will see a decent rate of muons creating signals in various detector subcomponents.

“This will be a full dress rehearsal,” said Joel Butler, US CMS project manager.

Scientists from US institutions represent about a third of the 2848 scientists of the CMS collaboration. “There are currently 203 graduate students in US CMS, and the number is growing,” said Butler.

The LHC experiments will shed light on how elementary particles obtain mass, look for dark matter particles, and search for extra dimensions, just some of the many research goals for its experiments. And, of course, scientists hope for the unexpected.

“The LHC is a discovery machine. There could be something new and exciting that shows up early,” said Butler. “We believe we are ready for the event samples that we will get.”

Here is Butler’s talk (PDF).

See all reports from the Fermilab Users’ Meeting 2008 here.

Kurt Riesselmann

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What will be the FY09 budget?

June 5, 2008 | 12:42 pm

That’s the billion dollar question. Well, not quite. In fiscal year 2008, high-energy physics received $689 million, a reduction of 8.4 percent compared to FY07. The cuts led to staff reductions at several Department of Energy national laboratories, including Fermi National Accelerator Laboratory in Illinois and Stanford Linear Accelerator Center in California.

On June 4, Dennis Kovar, acting director for High Energy Physics at the DOE Office of Science, spoke at the Fermilab Users’ meeting. His office is working with the national laboratories and universities to mitigate the effects of the funding cuts.

“High-energy physics is at a productive and exciting period today, but the circumstances are challenging,” he said. “As you know the funding has had a significant impact.”

Speaking in front of approximately 300 scientists, Kovar said that the high-energy physics community must be prepared for a continuing resolution that could last six months, beginning October 1.

“The ‘09 appropriation is pivotal,” said Kovar. “If, in fact, [the budget for 2008] becomes the basis, it will significantly affect what [research] can be done.”

Kovar went on to talk about the recommendations released by the High-Energy Physics Advisory Panel to the US Department of Energy and the National Science Foundation on May 28 in a report entitled A Strategic Plan for the next 10 years (PDF). Whether these recommendations will be implemented depends on how much federal funding high-energy physics research will receive in the upcoming years and the decisions made by DOE and NSF.

“Today, the US is one of the leaders [in high-energy physics] for sure. The opportunities for the future have been laid out in various reports. There was a need for a realistic strategic plan,” said Kovar. He added, “This plan appears to be realistic and robust, with the flexibility to adapt to new information and circumstances.”

Here is a link to the PowerPoint file of Kovar’s talk.

See all reports from the Fermilab Users’ Meeting 2008 here.

Kurt Riesselmann

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Understanding the universe is all about volume

June 4, 2008 | 6:02 pm

This afternoon cosmologist Scott Dodelson, Fermilab, gave a fun talk at the Fermilab Users’ meeting. Dodelson, who is the acting head of the Fermilab Center for Particle Astrophysics, spoke about the evolution of the universe and how mapping the universe will provide the answers to many questions that scientists have.

To make the case, he compared maps of celestial objects in the universe to maps of the population of the United States. He first showed a map of the US population as of 1790 (see image right). At that time, immigrants from Europe had only settled in areas along the east coast and lived in small villages. But a map of the US population today shows that the population has spread across the entire continent, with clusters of large cities and traces of the “primordial” population areas.

“I claim that the story of the evolution from the early map to today’s map is the history of the United States,” said Dodelson. To reconstruct the entire history, researchers would have to obtain maps of the population distribution between 1790 and today, and examine them in finer and finer details. Examining them as a function of time, these maps would reveal the impact of civil wars and many other events, down to the social structure of society. “If we look at this evolution, we can understand the evolution of the people and the sociological, economic, and political forces,” he said.

Similarly, maps of the distribution of celestial objects will reveal the fundamental forces behind the evolution of the universe and its constituents. Dodelson looked around the auditorium and pointed out that the universe started out smooth, but now “the density of the universe in the room is 30 orders of magnitude larger than the average density of the universe.” The universe started smooth and evolved to be clumpy because of gravitational instability, he said.

Dodelson went on to talk about the Sloan Digital Sky Survey, which has recorded two- and three-dimensional maps of the universe. (The online database, managed by Fermilab, receives a million queries a month.) Together with other observations and future maps, the SDSS results will help to solve the mysteries of the universe such as dark energy. But more work is needed.

“The SDSS covers only 10-to-the-minus-4 of the available cosmic volume,” Dodelson said. “With regard to [the map of the] United States, this corresponds to Birmingham, Alabama.”

A new project, the Dark Energy Survey, will provide better maps of the universe. The DES collaboration plans to build its digital camera by the end of 2010 and mount it on the 4-meter Blanco telescope in northern Chile. Data taking would begin in September 2011. The DES camera would map a volume ten times larger than SDSS. The data could reveal information on dark energy, neutrino mass, and even test gravity.

“It’s all about volume,” said Dodelson. “These maps will help us to fill in the details of the cosmic evolution… Going way beyond Birmingham will help us do extraordinary science.”

A PowerPoint file of Dodelson’s talk is available online (PPT).

See all reports from the Fermilab Users’ Meeting 2008 here.

Kurt Riesselmann

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Fermilab still in race for Higgs boson

June 4, 2008 | 11:41 am

Today is the first day of the Users’ meeting at Fermi National Accelerator Laboratory, the largest US national laboratory for particle physics. Several hundred of the 2300 physicists who are using Fermilab’s infrastructure and accelerator complex to conduct experiments have gathered here at the laboratory to hear about the latest news in particle physics and to discuss plans for the future of the field. Fermilab provides a live video stream of this meeting.

“We have a packed agenda for the next two days,” said Kevin Pitts, chairman of the Fermilab Users Executive Committee, at the beginning of the meeting. The day started out with talks about the Fermilab accelerator complex, which provides the beams for collider experiments as well as neutrino experiments.

Ron Moore, Fermilab Accelerator Division, reported (PDF) that the performance of the Tevatron proton-antiproton collider reached new heights, increasing the opportunity for experimenters to make discoveries. The month of May provided more collisions than ever before, yielding 0.2 inverse femtobarns (the scientific unit used to count the number of collisions). The total number of collisions delivered to the two collider experiments, CDF and DZero, now exceeds 4 inverse femtobarns.

“We are steadily climbing. Things are going very well,” said Moore.

Just yesterday, Moore said, the Fermilab antiproton source set a new record for the number of antiprotons produced in one hour, delivering more than 27×10¹⁰ in that hour. Last year, the average was around 20×10¹⁰ per hr. This year, it is about 25×10¹⁰ per hr. This bodes well for the future of the Tevatron program. The more collisions the Tevatron produces, the greater the chance that a significant number of collisions will produce the sought-after Higgs particle.

“We will have a one-week shutdown for maintenance some time this year. Otherwise it is just run, run, run,” said Moore.

The 4 inverse femtobarns delivered to each collider experiment, CDF and DZero, so far is about half the projected total by the end of September 2009.

Oscar Gonzalez, of the Spanish research institute CIEMAT, reported (PDF) on some of the most important results obtained by the CDF and DZero experiments in the last year. Of interest for Higgs hunters is the world’s most precise, single measurement of the mass of the W boson. Reducing the uncertainty in the size of the W mass reduces the range for the predicted mass of the Higgs boson, the elusive particle that is the key to understanding the origin of the mass of elementary particles. “We [physicists] have a lot of confidence that the Higgs will be there,” said Gonzalez. Particle physics measurements made by many experiments indirectly point to the existence of the Higgs boson, confirming the Standard Model of particles and interactions. Measuring the W boson mass with great precision is another test of the Standard Model.

The W boson weighs, in subatomic units, 80,413 MeV/c², with an uncertainty of 48 MeV/c², said Gonzalez. To appreciate this achievement, imagine this particle is a person and has a weight of close to 80 kilograms. Then scientists are able to tell you the mass of the particle plus/minus 48 grams. I don’t know my weight with that precision!

The CDF and DZero experiments have used only a fraction of the data collected to obtain this result. “Preliminary studies suggest that [a total error of] 25 MeV/c² is achievable with the current data sample we have,” said Gonzalez.

Because physicists know the value of the W boson and the top quark so well, the indirect upper limit for the mass of the Higgs boson is now at 160 GeV/c² at a 95 percent confidence level. But finding the Higgs is not easy.

Said Gonzalez, “The strategy of the search for the Higgs at the Tevatron has to deal with the small cross section,” or probability that a proton-antiproton collision at the Tevatron will produce the Higgs. The search for proton-antiproton collisions that produce a pair of W bosons, with one W boson decaying into a Higgs boson, is currently the best chance to find a Higgs boson. The Tevatron collider experiments are approaching the level of sensitivity needed to exclude a Higgs boson with a mass of 160 GeV/c². “We expect to have news very soon,” said Gonzalez, pointing at the upcoming ICHEP 2008 conference this summer in Philadelphia.

(Because of the way that the Higgs boson interacts with other particles, it is easier for Tevatron experimenters to exclude a Higgs particle with 160 GeV/c² than, say, a Higgs boson with 120 or 140 GeV/c².)

In the next couple of years, the CDF and DZero experiments will improve their reach and begin to exclude other mass values as well-or see the first hints of the Higgs particle. Because of searches at the European laboratory CERN (using the LEP collider) scientists know that the Higgs must be heavier than 114 GeV/c².

According to Gonzalez, the success of the search for the Higgs boson at Fermilab does not depend just on collecting more collision data. He pointed out that the exclusion limit is improving much faster because of improvements in data analyses and new search strategies. “We expect another factor of two in two years,” he said.

The numerous physics results churned out by the CDF and DZero collaborations are available on the Web (CDF here, DZero here). Links to many of the talks presented at the Fermilab Users’ meeting are online as well.

See all reports from the Fermilab Users’ Meeting 2008 here.

Kurt Riesselmann

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