Particle Physics Panel Assesses US Influence on Global Stage

A new report from the High Energy Physics Advisory Panel (HEPAP) stresses the importance of international collaboration in particle physics research and argues that the U.S. should prioritize being a “partner of choice” for other nations. However, it finds that the U.S. is not always viewed as a reliable partner, largely due to unpredictable budgets and inadequate communication, and that shortcomings in domestic HEP programs are jeopardizing U.S. leadership.

Accordingly, the report offers recommendations aimed at improving project governance, increasing international participation in U.S.-based experiments, and encouraging the leadership of U.S. scientists in projects abroad. It also suggests expanding the portfolio of small- and mid-size projects based in the U.S. and strengthening domestic capabilities in areas where the U.S. is beginning to lag globally, such as in certain types of accelerator technology development.

The report is the latest in a series of “international benchmarking” studies commissioned by the Department of Energy’s Office of Science. Since 2021, the office’s advisory committees have evaluated DOE’s research programs in Basic Energy Sciences, Fusion Energy Sciences, Biological and Environmental Research, and Advanced Scientific Computing Research in their international contexts.

The particle physics report was produced by a HEPAP subcommittee chaired by Fermilab scientists Patricia McBride and Bonnie Fleming. HEPAP has simultaneously been working to finalize the next Particle Physics Project Prioritization Panel (P5) report, which will present a consensus strategy for U.S. high energy physics over the next decade and is likely to incorporate findings from the benchmarking study. The panel is set to vote on a draft of the P5 report on Dec. 8.

Project governance reforms suggested

For decades, particle physics research has relied on international collaborations to build facilities and carry out experiments beyond the reach of a single nation. For example, CERN, the European research center that hosts the Large Hadron Collider, has 23 member states and attracts over 10,000 users from around the globe each year. The report notes that particle physics collaborations can include just a few scientists or several thousand.

“The U.S. particle physics program is part of a global research ecosystem,” it stresses.

The report argues that traditional benchmarks of competitiveness, such as research citations, do not adequately reflect leadership within the field. Instead, it emphasizes the ability of the U.S. to play a leading role in international collaborations as a primary metric of success.

The report identifies several impediments the U.S. faces in attracting international collaboration, including the uncertainty of the U.S. appropriations process, inadequate communication, and inefficiencies in project management and oversight. Particle physics projects often operate on multi-year or multi-decade timescales, but funding levels for larger projects are determined annually by Congress on a line-item basis, limiting the ability of DOE and the National Science Foundation to adhere to planned project funding profiles. Funding delays can have “cascading effects” that disrupt partner nations’ project schedules, and budget uncertainty can lead to inefficiencies even without abrupt funding cuts, the report states.

It also offers examples of disruptive project terminations, citing the cancellation of the construction of the Superconducting Super Collider in 1993 as an exceptionally jarring episode that harmed the reputation of U.S. particle physics. More recently, funding cuts to DOE in 2008 led to the premature termination of the B-factory program at SLAC, disrupting an international partnership.

Furthermore, the report argues that U.S. decision-makers have not always communicated adequately with international partners, who have been caught off guard by sudden project cancellations. In addition to the SSC and B-factory incidents, the report points to examples such as the cancellation of projects at Fermilab’s Tevatron in 2003 and 2005, as well as the termination of the BABAR experiment in 2008 and the end of Tevatron CDF and D0 experiments in 2011.

The report recommends that DOE and NSF involve partners earlier in decision-making processes and work to mitigate the impact of unilateral decisions. It also urges physicists to ensure political leaders “understand the negative consequences — both immediate and long term — of abrupt reductions in funding, including the negative impact on international partners.”

DOE and NSF project management processes are also a barrier to international collaboration, the report finds. It highlights the example of LBNF/DUNE, the flagship neutrino project hosted by Fermilab, which includes contributions from 36 partner nations and CERN. The Office of Science’s contribution to LBNF/DUNE is expected to exceed $3 billion, and the project faces governance challenges.

The report draws a distinction between the CERN model of project governance and the “host-led” model. Under the CERN model, no one country or institution leads a collaboration. Instead, governance is determined through multilateral agreements that lay out each partner’s responsibilities. Under the host-led model, partners provide well-defined contributions, such as a piece of experimental equipment, but do not hold responsibility for the project overall.

The report states that both models have been effective, but the CERN model is found to work well when the project’s degree of financial sharing is high, as is the case with DUNE. However, it finds that existing DOE project management policies are best suited to the host-model of governance and do not readily accommodate substantial deliverables from outside the U.S. This has posed challenges for the project, which has struggled to integrate and coordinate contributions from international partners.

The report recommends that DOE and NSF convene a task force to identify project management and oversight procedures that are suited to large-scale international projects. It stresses that the strongest partnerships involve collaboration starting from the earliest stages of conceptual development and require organizational structures that enable shared decision-making, shared responsibility, and shared credit. In addition to DUNE, the report highlights future cosmic surveys as an area that could particularly benefit from new approaches for international partnerships.

The report suggests that the U.S. could better facilitate the participation of U.S. scientists in international projects by expanding the use of mechanisms such as sabbaticals and teaching buyouts that allow them to work for extended periods at facilities abroad. It also encourages institutions to cultivate welcoming atmospheres for international scientists and provide support for acquiring visas, noting that such scientists have faced increased difficulties participating in U.S.-hosted projects due to visa delays and national lab access restrictions.

Erosion of ‘core’ research flagged as key concern

To cultivate leadership and remain an attractive partner, the U.S. must also maintain a robust portfolio of domestic research projects at all scales, the report argues. In particular, it says the U.S. must “reinvigorate” its core research program, increase its support for small projects, and lay the groundwork for future domestic flagship facilities.

While funding for large-scale construction projects has increased in recent years, funding for core research activities has dropped from about $361 million in 2014 to about $326 million in 2023, and inflation has caused an additional 30% reduction in spending power, the report estimates. It argues that this decline has “threatened U.S. leadership in the field by limiting the resources available to cultivate new ideas and to develop the next generation of facilities.” It adds that the core research program is the main source of support for students and that adequate funding is necessary to maintain the particle physics workforce.

In addition, the report highlights the importance of demonstration experiments and small projects with budgets under $100 million, which help maintain the diversity of the field, develop U.S. technical capabilities, and provide training opportunities for young scientists. However, the report finds obtaining funding for small projects in the U.S. can be difficult and that other nations are often “more nimble in moving from concept to data-taking experiments.”

Several U.S. programs support projects at this scale, such as NSF’s Major Research Instrumentation and Mid-scale Research Infrastructure programs and DOE’s Dark Matter New Initiatives funding opportunity. However, the report states that restrictions on funding and a lack of coordination between agencies have hindered projects.

The report recommends establishing a new funding mechanism that would allow small projects to be initiated and executed more rapidly. “Dedicated funding lines and greater partnership between DOE and NSF in funding small projects would benefit individual experiments as well as the portfolio as a whole,” it states.

At the other end of the spectrum, the report endorses the construction of a next-generation international flagship particle physics facility based in the U.S. and says that planning efforts should not wait until after LBNF/DUNE is completed. Such a facility would “attract a whole new generation of scientists while boosting opportunities to train students and sustain a leading scientific workforce.”

The report notes that Europe has become increasingly competitive in certain key areas of accelerator science and technology, including collider beam technology and operation, accelerator component fabrication, and plasma wakefield acceleration R&D. Accordingly, it recommends the U.S. establish a “national accelerator R&D program on future colliders to coordinate the participation of U.S. accelerator scientists and engineers in global energy frontier collider design studies as well as maturation of technology.”