Last year, the Senate Energy and Water Development Appropriations Subcommittee included language in its FY 2006 report requesting the Department of Energy to submit a report regarding the Rare Isotope Accelerator. House and Senate conferees reiterated this requirement, stating, "The conferees support the Rare Isotope Accelerator (RIA) but are concerned that the Department does not seem to be making tangible progress toward realization of RIA." DOE had 120 days to submit a report "to define a specific path forward on RIA." The report, less the "Introduction and Charge" which excerpted the Senate report language (and which can be read under "Nuclear Physics" at http://www.aip.org/fyi/2005/098.html) is below:
"Response to Questions in Senate Report 109-84 Regarding the Rare Isotope Accelerator (RIA)
[One-page "Introduction and Charge" with the Senate Energy and Water Development Appropriations Subcommittee report language was excerpted at this point.]
"This report, prepared by the Office of Science for Nuclear Physics, is in response to this request.
"Plans Regarding Moving Forward with RIA
"Even with the planned doubling of funding for basic research in the physical sciences over the next ten years announced by the President in his State of the Union address, the Department is compelled to balance commitments to specific programs in the context of its broader research portfolio and the Department's and the Nation's priorities.
"The RIA as originally envisioned would be a facility with unprecedented capabilities world-wide, but with an estimated cost of $1.1 billion, it would represent a major investment by the Federal Government. Consistent with advisory committee guidance, the highest priority for Nuclear Physics facilities is the effective use of its existing world-class facilities—the Relativistic Heavy Ion Collider and the Continuous Electron Beam Accelerator Facility—to foster the discoveries and advancements in scientific understanding for which they were built. The FY 2007 Budget Request and the subsequent five-year budget plan fully support this top facility-related priority as well as the critical need to maintain a strong ongoing university and the national lab research program. Given these priorities, the Department has concluded that it is not prudent to proceed with RIA at this time. The Department continues to believe that research in rare isotopes is an important element in the Nation's portfolio of scientific capabilities. The Department believes that the United States can maintain leadership in this area of nuclear physics via the alternate path described below.
"The Department is exploring the possibility of starting design and construction of an alternate exotic beam facility around the end of this decade. Near-term funding would be provided to develop research capabilities at both domestic and international facilities so that the U.S. research community is fully engaged at the forefront of nuclear structure and astrophysics studies and prepared to fully utilize the U.S. exotic beam facility when it would come into operation. In keeping with this strategy for an alternative future facility, the FY 2007 Budget supports generic exotic beam research activities but not RIA-related conceptual design work.
"The FY 2007 OSTP/OMB R&D Budget Priorities Memorandum stated that ‘Within discovery-oriented physical science investments, priority will be given to those projects and programs that are demonstrably well-coordinated with related programs in other agencies and countries.' Our near-term plans are consistent with this guidance, and we will actively pursue partnerships with other countries and other agencies, including the National Science Foundation (NSF), for this alternate exotic beam facility. The NSF supports the National Superconducting Cyclotron Laboratory at Michigan State University, which is considered to be the leading rare isotope facility in the United States and serving over 600 scientists from the U.S. and abroad. With expertise in exotic beam research crossing agency boundaries, it is natural to ensure that efforts are coordinated across agencies to support an optimal nuclear physics program for the Nation. The Department is proposing a path forward that will address the Nation's needs in this scientific area while ensuring the overall scientific productivity of the Office of Science's programs.
"The Department will seek outside expert guidance from the scientific community and advisory bodies such as the National Academies and the DOE/NSF Nuclear Science Advisory Committee (NSAC) in defining this alternate facility. A scientific assessment of the role and importance of rare isotope science in a national and international context is underway at this time by the National Academies, with a report expected this fall. The Academy's findings as well as guidance from NSAC will be important input to the Department's decision on how to proceed with the implementation of national capabilities for exotic beam studies.
"Answers to Specific Questions
"Q. The status and progress of the conceptual research and development supporting the development of RIA over the past 6 years
"A. Research and development activities directed towards the RIA were begun in 2000 based on guidance provided in 1999 by a NSAC study. In August 2003, a RIA research and development (R&D) workshop was held at which experts in the field identified areas for prioritized efforts for R&D required prior to the construction of RIA. Since then, R&D has been based on these priorities, which address performance enhancement and cost and schedule risk. On an annual basis, the priorities have been revisited and found to remain appropriate. All R&D activities since FY 2006 have been directed to generic studies related to a next generation rare isotope beam capability; no efforts directed towards a project-specific Conceptual Design Report for RIA have been funded.
Major Areas of R&D:
The gas cell, where unstable nuclei can be brought to rest and then rapidly extracted to produce reaccelerated beams, is an innovative device that greatly extends the capability to study the most unstable nuclei. R&D efforts have demonstrated that ions can be extracted from a gas cell in tens of milliseconds with nearly 50% efficiency.
A prototype high performance electron-cyclotron resonance ion source for the driver accelerator has been built, and tests have demonstrated extraction of bismuth ions; testing to meet the specifications for uranium is ongoing.
Prototype superconducting accelerator cavities for the low and medium velocity segments of a heavy-ion driver linear accelerator have been developed.
Development of targets that produce radioactive elements reliably while having the capability to dissipate high power levels is being pursued. The so-called ‘two stage' target, where a neutron production stage is separated from the radioactive element production stage, has been tested.
The efficient acceleration of heavy ions requires one or two stages of stripping to increase the ion charge state. A project is underway to investigate a concept utilizing flowing liquid lithium films to withstand the high power beams without failure.
Laboratory tests using high power electron beams to simulate uranium beams show that lithium films can withstand high power beams without degradation.
Diagnostics concepts for low intensity beams have been developed and devices built and tested, and are already in use in several accelerator facilities.
Fragment separators collect the shower of nuclear species produced in a fragmentation reaction and separate the species of interest from the rest. Several designs, each adapted for a different use in an exotic beam facility, are being investigated. Studies are underway to investigate the suitability of superconducting materials in the high radiation environment of these separators.
Advanced computer software for beam dynamics calculations has been developed, and is being used to study beam halo effects, a significant source of unwanted equipment activation.
"Q. The priority research areas the Department will complete prior to site selection for RIA
"A. Given the Department's position on RIA as stated above, there are no RIA-specific priority research areas that are currently targeted. In FY 2007 and the outyears, generic R&D continues for an exotic beam facility aimed at topics that optimize performance and reduce cost and schedule risks.
"Q. The process by which the Department selects recipients for its research and development funding
"A. R&D funds are awarded on an annual basis according to merit-based peer review. Each year proposals are solicited separately from universities and laboratories. A panel of experts is convened to assess the scientific and technical merit of the proposals, the validity and feasibility of their approach, the competence of the proposer(s), and the appropriateness of their budget and schedule.
"The criteria for assessing scientific and technical merit of R&D proposals includes the degree to which the acquired knowledge could enhance the performance, reduce the construction and/or operating costs, and reduce the engineering and scheduling risks associated with a rare isotope beam facility.
"Q. How the results of current and future research and development may affect the design of RIA or the path forward
"A. The results of current and future research and development will be used to optimize the scientific and performance capabilities of a rare isotope facility and to reduce the cost, schedule and risk of its construction.
"Q. What technical hurdles remain before RIA site selection can resume?
"A. The Department is not aware of any ‘show-stopping' technical hurdles relevant to site selection for a future exotic beam facility. R&D, as discussed above, will continue to be supported to optimize performance and reduce costs and technical risk. This R&D will address issues that will need to be resolved before the final design and start of construction (e.g., to verify the best method to stop and collect rare isotopes for reacceleration and that targets can withstand high intensity beams).
"Q. What funding will be required to clear those hurdles and what is the expected length of time for completion of these activities.
"A. Annual funding at roughly the level proposed in the FY 2007 Budget Request ($4 million) will be required until final decisions are made on the technical design and construction begins. Of course, several National Laboratories may well continue to augment these efforts by supporting relevant R&D activities via their indirectly-funded Laboratory Directed Research and Development (LDRD) programs."