Preface

Abstract

These are the proceedings of the “New Scientific Opportunities at the TRIUMF ARIEL e-linac” workshop, which took place at TRIUMF laboratory, in Vancouver, Canada, May 25-27, 2022. The workshop was a hybrid of in-person and online attendance via Zoom, gathering together theorists and experimentalists with shared interests in MeV-scale physics at the intensity frontier, in order to stimulate ideas and collaboration for novel applications of new, high-intensity, modest-energy accelerators like the ARIEL e-Linac.While the LHC and its large detector collaborations continue to seek BSM physics at the energy frontier, and increasingly large subterranean detectors probe neutrino and dark matter signals with greater and greater sensitivities, the increasing scale of these experiments represents a substantial undertaking, in terms of cost and timeline. These have yielded important results, confirming the existence of the Higgs and furthering our understanding of neutrino dynamics, but they have not yet provided a clear view of what lies beyond the Standard Model. The prevailing expectations of the previous decades—minimal supersymmetry, WIMP-based dark matter—have not yet been observed.A complementary experimental thrust in the quest for new physics is to probe lower energy scales at the intensity and precision frontiers. Such experiments can be mounted more nimbly, and in parallel, to focus on different reported anomalies as lampposts, to improve precision in places where new physics may lurk, and to test new classes of BSM physics that may arise at those energies. With no definitive guidance on the form an underlying theory must take, this is an increasingly appealing approach to the search.Modern accelerator designs can provide higher and higher beam currents, achieving high luminosities without the need for thick targets, unlocking new experimental avenues. Energy Recovery Linacs (ERLs) at the sub-GeV scale are a particularly exciting emerging platform, with a series of machines at various levels of development, including the planned upgrade for ARIEL, the MESA accelerator complex currently under construction, and the planned PERLE facility.The articles in these proceedings showcase the experimental avenues now being explored, or which could be undertaken at ARIEL and similar-scale accelerators, as well as theoretical studies in these regimes, and the status of accelerators that will enable these and future experiments that aim to address current anomalies and outstanding questions in particle and nuclear physics.The workshop was funded by the Gordon and Betty Moore Foundation, to which the organizing committee give their sincere thanks.Jan Bernauer (CFNS, Stony Brook University and RIKEN BNL Research Center)Ross Corliss (CFNS, Stony Brook University)Michael Hasinoff (University of British Columbia)Rituparna Kanungo (Saint Mary’s University)Jeffery Martin (University of Winnipeg)Richard Milner (Massachusetts Institute of Technology)Katherine Pachal (TRIUMF)Stanley Yen (TRIUMF)