The United States nuclear science community adopted a new Long Range Plan (LRP) on 4 October 2023. Every five to eight years the U.S. Nuclear Science Advisory Committee (NSAC) is charged with developing a new LRP by the Department of Energy and the National Science Foundation. NSAC was asked to detail progress since the last LRP and identify and prioritize the most compelling scientific opportunities for the U.S. nuclear physics program to pursue over the next decade. The charge also asked NSAC to “articulate how efforts to promote and sustain a diverse, equitable, and inclusive nuclear science workforce will be fully integrated into every aspect of the vision for the future of U.S. nuclear science.”
The new plan, titled A New Era of Discovery, lays out a compelling vision for the opportunities in our field and makes four recommendations. The full report and the charge are posted at NuclearScienceFuture.org.
The LRP process in the United States started with three town meetings organized by the American Physical Society Division of Nuclear Physics covering (1) hot and cold quantum chromodynamics; (2) nuclear structure, reactions, and astrophysics; and (3) fundamental symmetries, neutrons, and neutrinos. Each town meeting produced a white paper representing the consensus of that community. Collaborations and other working groups also submitted white papers as input to the process. The conveners of the three town meetings were asked to include cross-cutting issues such as workforce development, preservation and accessibility of nuclear data, accelerator and detector science, and computing.
A committee of 62 people, including two international observers, met to discuss the community input and determine four recommendations. The recommendations are summarized below, followed by some observations about the process and the result.
Recommendation 1
The highest priority of the nuclear science community is to capitalize on the extraordinary opportunities for scientific discovery made possible by the substantial and sustained investments of the United States. We must draw on the talents of all in the nation to achieve this goal.
Here we emphasized that this recommendation requires (1) increasing the research budget that advances the science program through support of theoretical and experimental research; (2) continuing effective operations of the national user facilities and completing the Relativistic Heavy Ion Collider science program; (3) raising the compensation of graduate researchers to levels commensurate with their cost of living, without contraction of the workforce; and (4) expanding policy and resources to ensure a safe and respectful environment for everyone.
We emphasized the importance of experimental and theoretical work, as well as the interplay between university research groups, university-based accelerator laboratories, and user facilities to advance our science. The workforce chapter of the LRP elaborates on ways that the nuclear science community can attract talented students to our field, lower barriers to participation, and endeavor to create a welcoming environment for all. We have highlighted the critical role that people play in the scientific enterprise.
The second and third recommendations are of equal priority and are presented in the same order as in the 2015 LRP.
Recommendation 2
As the highest priority for new experiment construction, we recommend that the United States lead an international consortium that will undertake a neutrinoless double beta decay campaign, featuring the expeditious construction of ton-scale experiments, using different isotopes and complementary techniques.
An observation of neutrinoless double beta decay would mean that the neutrino is its own antiparticle and that lepton number is not conserved. It could help explain why the universe has more matter than antimatter and the rate would have implications for the neutrino masses. It is important to note that observing this reaction in different isotopes using different detector technologies will help us understand backgrounds and interpret the signal. There are three experiments that are ready to proceed now: CUPID, LEGEND, and nEXO. Each requires a strong international collaboration.
Recommendation 3
We recommend the expeditious completion of the EIC as the highest priority for facility construction.
The Electron-Ion Collider (EIC) will be capable of colliding high-energy beams of polarized electrons with heavy ions, polarized protons, and polarized light ions. It will enable us to study how low Bjorken-x gluons and sea-quarks contribute to the mass and spin of the nucleon. Further, we will investigate the extremely dense gluonic, nuclear environment. The EIC facility builds on significant advances in accelerator and detector design. Significant international support and collaboration is crucial to realize the Electron-Proton/Ion Collider (ePIC) detector at the EIC.
Recommendation 4
We recommend capitalizing on the unique ways in which nuclear physics can advance discovery science and applications for society by investing in additional projects and new strategic opportunities.
The LRP discusses many opportunities for further investment, including accelerator and detector upgrades, detector and accelerator research and development, emerging technologies in computing and sensing, multidisciplinary centers, and nuclear data.
Producing the LRP required an incredible amount of work by a great many in our community. The town meetings and other meetings and workshops were extremely valuable in helping the community to come together and consider the future. Robust participation in these meetings included graduate students and postdocs as well as junior and senior nuclear scientists. The produced white papers are an important resource now and for the future. I am especially grateful to the LRP writing committee for their hard work and collegial approach to difficult decisions.
As we discuss the report with funding agencies, Congress, and other decision makers I am struck by how receptive they are to our message and their gratitude that our community takes the time to consider and prioritize opportunities for the future. We have emphasized that nuclear science offers compelling discovery science, a trained workforce with skills that are critical to many professions, and numerous applications that benefit society. Our community has an exciting future, one that promises A New Era of Discovery.
NSAC Chair and Old Dominion University
Disclosure Statement
No potential conflict of interest was reported by the author(s).