The advisory panel on high energy physics presented its long range planning report to the federal government on January 28th at a conference in Washington, DC The report urged that the US should host the next-generation electron- positron linear collider that many in the particle physics community view as the linchpin to the next 20 years of high energy physics research. The two leading particle physics groups within the APS echoed this sentiment in a statement released on the day of the conference.
The High Energy Physics Advisory Panel (HEPAP) presented to the US Department of Energy (DOE) and the National Science Foundation (NSF) the plans for a variety of large and small scale projects in the area of high energy physics research envisioned over the next 20 years. Written by the HEPAP Subpanel on Long Range Planning for US High Energy Physics, the report is designed to serve as a roadmap that prioritizes what the panel feels are the most important projects for the international high energy physics community.
Fred Gilman, chair of HEPAP and a physicist at Carnegie Mellon, said that high energy physics research is at the brink of an "extraordinary" period of discovery that will answer some of the most fundamental and profound questions about the nature and origins of the Universe. These range from the existence of unseen dimensions and the nature of dark matter and dark energy - which are believed to comprise fully 96% of the mass of the universe and hold the key to its ultimate fate - to the existence of the Higgs particle, which is believed to give particles their mass.
The APS Divisions of Particles and Fields (DPF) and of the Physics of Beams (DPB) both issued statements supporting and praising the HEPAP report. The DPF statement also urged that the US host the linear collider. The report estimates building the linear collider in the US would cost between $5 billion and $7 billion, with one third of the financing coming from international contributions and between $1 billion and $2 billion coming from the existing US particle physics program.
"We support the construction of a high energy, high luminosity, electron positron linear collider as the next major international particle physics initiative," said DPF spokesman Chris Quigg. "Although an international linear collider laboratory will be an essential component of the US research program wherever it is built, we feel that the US should offer to host it. It would complement the Large Hadron Collider (LHC) being constructed in Europe to exploit the scientific opportunities ahead of us."
DPB Executive Committee member Ron Davidson applauded the strong endorsement by the Subpanel of a vigorous long-term accelerator R&D program. "If the panel's vision comes to fruition, it will result in the most advanced accelerator facility ever built," he said. "We remain strongly committed to the tradition of active partnership in the development of major accelerator based initiatives."
Among the highlights of the report is for the creation of a new planning mechanism for establishing research priorities in particle physics in the form of a panel. The Particle Physics Project Prioritization Panel - dubbed the "P5" - would assess and prioritize proposed experiments and other research initiatives to ensure the highest scientific return on public funding for particle physics. At present, public funding in the form of US Government grants totals between $750 million and $780 million per year with the lion's share - about $700 million - coming from the DOE and the remainder coming from the NSF.
Under the timetable envisioned by the report, the electron positron linear collider would become operational around 2012, about six years after the LHC, (a proton proton circular collider now under construction at CERN in Switzerland), is scheduled to go on line. The LHC will have energies on the order of 14 Tera electron volts, seven times more powerful than the Fermilab Tevatron, currently the world's highest energy accelerator.
One change between the original draft report released last October and the final report released on January 28th involves a small project called BTeV, which is designed to probe for new quark physics at the electro weak scale by studying "flavor changing processes" and probing for CP violations. With a total price tag of $250 million and delayed funding, the draft said "we regret that we cannot recommend funding BTeV as a line item at this time." The final report instead states that the BTeV project, whose total cost estimate was cut to $165 million, "cannot be funded with the scope and timetable originally envisioned." It said revised plans "should be brought to P5 for evaluation this year."
Joel Butler of Fermilab, one of the lead scientists on the BTeV project, welcomed the new language and praised the new P5 process for evaluating "mid size" projects during a time that will, he said, be dominated by huge projects. "It is expected that P5 will observe and monitor the progress of each proposal as it moves through the laboratory and agency reviews (and) will provide advice on how to fit the best mid size projects into the constraints of the overall program," he said. "P5 is expected to be a mechanism for helping mid size projects, which are so important to the diversity, vitality, and progress of high energy physics, find a way to proceed in an era dominated by the construction of very large new facilities, such as the LHC."
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