Draft V1 Prepared by the Subatomic Physics LRP Committee Contents

2022-26

Draft v1 Prepared by the Subatomic Physics LRP Committee Contents

1 Executive Summary1 2 Science Drivers and Canadian Impact2 2.1 Higgs, physics at the electroweak scale and beyond...... 3 2.2 Fundamental symmetries and observed asymmetries...... 7 2.3 Neutrino properties...... 9 2.4 Dark Matter and potential dark sectors...... 11 2.5 New physical principles and structures...... 13 2.6 Hadron properties and phases...... 15 2.7 Nuclear structure...... 16 2.8 Cosmic formation of nuclei...... 18 2.9 Impact and Synergies with other fields...... 19 3 Canadian Subatomic Physics Research Plan 21 3.1 Science opportunities for Canada...... 21 3.2 Infrastructure and Enabling technologies...... 25 3.3 Research Portfolio...... 28 3.4 Science Recommendations...... 29 4 Realizing the Research Plan 34 4.1 Canadian Subatomic Physics Community...... 34 4.2 Funding...... 39 4.3 Infrastructure and Technical Support...... 43 4.4 Research Policy...... 46 5 Subatomic Physics and Society 48 5.1 Subatomic Physics Training for the Knowledge Economy...... 48 5.2 Technological applications of SAP research...... 50 5.3 Commercial opportunities...... 50 5.4 Cultural benefits...... 51 Appendices 52 A Case Studies 53 B Glossary 54 C Terms of Reference 55 C.1 Context...... 55 C.2 Committee...... 55 C.3 Mandate...... 56 C.4 Process and timeline...... 56 C.5 Deliverables...... 57 C.6 Conflicts of interest and confidentiality...... 57

i Contents ii

D Long Range Plan Committee Membership 58 D.1 Committee Members...... 58 D.2 Ex-officio Members & Observers...... 58 E Long Range Planning process 59 E.1 Timeline...... 59 E.2 Confidentiality and Conflicts of Interest...... 60 1 1

2 Executive Summary

3 [The Executive Summary will be included in v2 of the Report.]

1 4 2

5 Science Drivers and Canadian Impact

6 The overarching goal of subatomic physics is to push the knowledge frontier of what the Universe 7 is made of at the very smallest distance scales. In doing so, subatomic physics has been able to 8 distill and translate observations of natural phenomena into universal laws expressed by a few 9 mathematical equations. The existence of this expansive theoretical scaffolding is the very reason 10 specific questions about the Universe can be formulated and we can advance systematically in 11 the exploration of the unknown. 12 The field of subatomic physics research has progressed significantly over the past couple of 13 decades, driven by technological advances, computing power, and theoretical developments. As 14 a prime example, the discovery of the Higgs boson in 2012 at the LHC provided the capstone for 15 the Standard Model of particle physics, but many questions remain as ‘science drivers’ for the 16 field and indeed the Higgs has now become a tool to push forward our understanding. 17 The LRP Committee identified eight science drivers for the field of subatomic physics research 18 in 2022, that encapsulate a number of underlying questions:

19 • Higgs Physics, the Electroweak Scale and Beyond

20 – What is the precise nature of the Higgs sector and the ﬂavour sector of the Standard 21 Model? What is the physics of electroweak symmetry breaking? What lies beyond the 22 electroweak scale?

23 • Fundamental Symmetries and observed Asymmetries

24 – What are the fundamental symmetries in nature, and how do we explain observed 25 imbalances, e.g. the matter-antimatter symmetry in the universe?

26 • Neutrino Properties

27 – What is the nature of neutrino mass and of neutrino interactions?

28 • Dark Matter & potential Dark Sectors

29 – What is the nature of dark matter in the universe, and its interactions? Is dark matter 30 part of a more extended dark sector?

31 • New Physical Principles & Structures

2 2.1. Higgs, physics at the electroweak scale and beyond 3

32 – What principles and formal theoretical structures underly the forces/matter in the 33 universe? How is gravity to be understood at the quantum level?

34 • Hadron Properties and Phases

35 – How do quarks and gluons give rise to the properties of nucleons and other hadrons, 36 and to the hadronic phases of matter in extreme conditions?

37 • Nuclear Structure

38 – How does nuclear structure emerge from nuclear forces and ultimately from quarks 39 and gluons?

40 • Cosmic Formation of Nuclei

41 – How do the properties of nuclei explain the formation of the elements in the late 42 universe?

43 These science drivers are deeply inter-connected and in combination deﬁne three broad 44 science directions in subatomic physics, as illustrated in Fig. 2.1. To address the breadth of these 45 science drivers requires a diversiﬁed research program of bold projects with complementary 46 objectives, exploiting a variety of different techniques. In the rest of this chapter, these science 47 drivers are described in more detail, focussing on recent progress and Canadian activities and 48 achievements. Indeed, Canadian subatomic physics has an enviable global reputation, with 49 impact on many of the major projects that have pushed our understanding forward in recent 50 decades. The Council of Canadian Academies’ 2018 report "Competing in a Global Innovation 51 Economy: The Current State of R&D in Canada" highlights the global impact of Canadian 52 subatomic physics research, as measured by average relative citations which grew from 1.79 53 to 2.05 compared to the Canadian average of 1.43. Given its global impact, but relatively small 54 community size, physics and astronomy was highlighted in the report as a research opportunity 55 for Canada, and future opportunities and plans will be described in Chapter 3.

56 2.1. Higgs, physics at the electroweak scale and beyond 57 The discovery of the Higgs boson in 2012 identified one of the main agents for the breaking at low 58 energies of the fundamental electroweak symmetry in nature. Yet, the electroweak sector remains 59 one of the most puzzling aspects of the Standard Model. The Higgs boson is a type of matter that 60 has never been seen before with properties yet to be fully studied. Its mass, for example, is not 61 constrained by any symmetry in the Standard Model, and unlike the mathematical structure of the 62 other forces of nature that are fully specified based on symmetry properties, the addition of Higgs 63 interactions leads to a large number of undetermined parameters in the Standard Model. This 64 makes our current understanding of the role the Higgs boson plays in the Universe particularly 65 ad-hoc and incomplete, and in stark contrast with the structural simplicity of other aspects of the 66 Standard Model. In particular, this raises the fundamental question of what underlying principles 67 determine the properties of the Higgs boson. This question motivates the possible existence of 68 new physics phenomena beyond those described by the Standard Model, but also identifies the 69 Higgs boson as a unique probe to explore physics processes at and beyond the electroweak 70 energy scale. 71 Exploration of physics phenomena at and beyond the electroweak scale is taking place in 72 proton-proton collisions at the LHC and will continue in the coming years at the High-Luminosity 2.1. Higgs, physics at the electroweak scale and beyond 4

Figure 2.1: (Placeholder) Schematic representation of the eight Science drivers and their inter-connections. 2.1. Higgs, physics at the electroweak scale and beyond 5

73 LHC, through both the measurement of known electroweak processes and searches for signatures 74 of new phenomena. Looking forward, a future electron-positron collider, such as the proposed ILC 75 in Japan or FCC-ee in Europe, would operate as a Higgs factory, producing an enormous number 76 of Higgs bosons, thereby making it possible to measure Higgs properties to an unprecedented 77 level of precision, and possibly uncovering hints of physics phenomena beyond those predicted in 78 the Standard Model. 79 Precision measurements of physics processes at lower energies also provide a complementary 80 window into new physics at or beyond the electroweak scale. Indeed, the degree of precision of 81 both measurements and Standard Model predictions is an aspect of subatomic physics research, 82 that is unique among all the sciences, and can be used to reveal small discrepancies arising 83 due to new physics. This sensitivity can be achieved through the study of rare or forbidden 84 processes in the Standard Model; for example, in the decays of tau leptons, kaons, bottom and 85 charm hadrons, or the study of theoretically well-understood processes such as electron-electron 86 scattering.

87 2.1.1. Canadian contributions and achievements 88 Canadian researchers have been and continue to be at the forefront of experimental investigations 89 of physics at the electroweak scale and beyond. They hold leadership roles in several different 90 complementary international projects at the energy and precision frontiers located at unique 91 off-shore facilities. Speciﬁc achievements of Canadians in the past ﬁve years include the following:

92 • The ATLAS experiment is one of two large multi-purpose detectors recording the results 93 of proton-proton collisions produced by the LHC at the highest energy ever achieved in a 94 laboratory. It is developed, maintained and operated by an international collaboration of 95 more than 3000 physicists from 41 countries, among which Canadian physicists have and 96 continue to play a key role in all aspects of the program. Sample achievements in the past 97 ﬁve years include:

98 – Canadians have directly contributed to the analysis of ATLAS data resulting in the pub- 99 lications of 120 refereed papers on a wide range of topics including the measurement 100 of Higgs boson properties, studies of the electroweak sector, and searches for hints of 101 new physics phenomena.

102 103 – Concurrently, the ATLAS-Canada Team has also undertaken the development and 104 construction of novel detector elements with significantly improved performance in 105 order to upgrade the ATLAS detector and pave the way to the future physics program 106 at the HL-LHC. 107 * The ATLAS-Canada Team has built and delivered to CERN one quarter of all 108 required muon detector elements, and is now completing their integration into 109 ATLAS. These new muon detecting elements will provide the ATLAS experiment 110 with the capability to identify in real-time proton collisions of interest that should 111 be recorded for future detailed offline data analysis. 112 * The ATLAS-Canada Team has taken on responsibilities for the construction of a 113 new state-of-the-art particle tracking system that will make it possible to precisely 114 reconstruct the trajectory of thousands of charged particles simultaneously created 115 in proton-proton collisions at the HL-LHC. 116 * The ATLAS-Canada Team is also developing a new electronics readout for the 117 ATLAS calorimeter system that will significantly improve the ability to precisely 2.1. Higgs, physics at the electroweak scale and beyond 6

118 measure the energy of particles, under the harshest experimental conditions 119 foreseen at the HL-LHC.

120 • The Belle-2 experiment at the KEK laboratory in Japan searches for evidence of new physics 121 in a wide range of final states where the Standard Model predictions are well understood. 122 Its physics program is based on the study of a record-breaking quantity of electron-positron 123 collisions at a specific energy enhancing the production of B-hadrons, and is complementary 124 to the LHC physics program. Canadians have been leading the development of key aspects 125 of the Belle-2 experiment, and now contributing to its operation. Sample achievements 126 during the past five years include:

127 – The Canadian Team provided beam background shields for the endcap calorimeters 128 which protect the apparatus against the high level of radiation generated from the 129 intense accelerated particle beams. These shields additionally contain monitors used 130 to characterize backgrounds during beam injection to assist in collider operations. 131 – Canadians developed the reconstruction code for the Belle-2 calorimeter successfully 132 exploiting the full waveform information to produce signiﬁcantly better energy resolution 133 in the presence of backgrounds and uniquely providing new hadron identiﬁcation 134 capability. This contribution positively impacts the entire Belle-2 program, increasing 135 the overall sensitivity of physics studies. 136 – The interpretation of collision data requires detailed simulation of known physics 137 processes, for example, to estimate backgrounds. The Canadian Team wrote and now 138 maintains the virtual model of the Belle-2 detector necessary for enabling the entire 139 Belle-2 physics program. 140 – Canadians have already started exploiting the new and growing Belle-2 data set and 141 published timely results in the search for new particles belonging to a possible ‘dark 142 sector’ in the Universe. 143 – Canadians have been leading the development of the international Chiral-Belle project, + − 144 a proposal to upgrade the SuperKEKB e e collider with polarized electron beams. 145 The main goal of Chiral-Belle is to precisely measure the weak mixing angle, a 146 fundamental parameter of the Standard Model, at energy scales complementary to 147 other measurements, to search for evidence of new physics beyond the Standard 148 Model. The Canadian Team is leading the study of the accelerated particle beam 149 dynamics around key components of this future accelerator infrastructure; the Spin 150 rotators used to align the polarized electrons at the collision point, and the Compton 151 polarimeter used to continuously monitor the polarisation of the electron beam with 152 high precision.

153 • The NA62 experiment at CERN is designed to study rare kaon decays and measure 154 decay branching fractions with high precision. Canadian involvement in NA62 includes 155 contributions to the calorimetry and tracking. The experiment took data during 2016-2018 156 and a future data taking period is planned for 2022-2025. In the past ﬁve years, the 157 Canadian Team has focused on the primary objective of the experiment, the measurement + + 158 of the ultra-rare kaon decay mode K → π νν¯. The decay process is highly suppressed in −10 159 the Standard Model, yet its probability of occurence is precisely calculated at the 10 level. 160 The measurement of this ultra rare decay process provides a unique opportunity to probe 161 for new physics at very high mass scales in a complementary way to searches conducted 162 at the LHC. A highlight of this ongoing analysis work is the development of a novel particle 2.2. Fundamental symmetries and observed asymmetries 7

163 identiﬁcation approach based on machine learning resulting in a signiﬁcant improvement 164 over prior approaches, thereby increasing the sensitivity of this search for new physics.

165 • The goal of the MOLLER experiment is to make the world’s most precise off-resonance 166 measurement of the weak mixing angle, using polarized electron-electron scattering at the 167 Jefferson Laboratory (JLab) in the USA, as a sensitive test for physics beyond the Standard 168 Model. The experiment is under development and scheduled to begin data taking in 2027. 169 Since the last LRP, the Canadian team has made signiﬁcant progress in leading the design 170 of the magnetic spectrometer and the integrating detectors and associated electronics. The 171 Canadian team has also established leadership roles in simulation and analysis software.

172 • The MoEDAL experiment at the LHC is a dedicated detector array designed to detect 173 magnetic monopoles and other highly ionizing massive particles hypothesized in a number 174 of physics scenarios beyond the Standard Model. During the past five years, Canadians 175 have participated in the experiment’s data taking and contributed to the publications of the 176 collaboration’s first physics results providing some of the most stringent constraints to-date 177 on the existence of monopoles. Canadians have also led the development, construction 178 and, now current installation of a new detector system to significantly expand the physics 179 program of the experiment during the future LHC Run-3 data-taking campaign.

180 • The MATHUSLA experiment proposal has been developed during the last LRP period. The 181 proposed experiment is a dedicated large volume detector to be located on the surface 182 above one of the interaction regions at the LHC. The goal of the experiment is to search for 183 neutral long-lived particles hypothesized to exist in various new physics scenarios beyond 184 the Standard Model. Canadians have been instrumental in developing the physics case for 185 this experimental proposal through various sensitivity studies. Canadians have also recently 186 begun to participate in the construction and commissioning of a demonstrator unit and will 187 contribute to the analysis of preliminary data recorded with this demonstrator.

188 • The development of a future Higgs factory is identiﬁed by the international community as 189 a top priority. The ILC is the most advanced and mature proposal on the world-stage, 190 that, if approved, would be located in Japan. There are also complementary proposals for 191 electron-positron machines, such as the post HL-LHC Future Circular Collider (FCC-ee) that 192 could eventually be transformed into the next energy frontier hadron machine. In the past 5 193 years, Canadians have continued to contribute to R&D work for the design of a tracking and 194 calorimeter systems for a future ILC detector. More recently, Canadians have also joined 195 international efforts for the development of semi-conductor sensor devices that can sustain 196 very high radiation levels and be used in the design of tracking systems at future colliders. 197 This R&D program will build on existing Canadian infrastructure and enable Canadians to 198 take one a central role in a future international collider project.

199 • The Canadian particle theory community has been active in proposing ways to test whether 200 the Higgs boson discovered in 2012 is the same as the one predicted by the SM using data 201 from the LHC and beyond, and in exploring novel new physics signatures that motivate 202 analyses at colliders.

203 2.2. Fundamental symmetries and observed asymmetries 204 Principles of symmetry play a fundamental role in dictating the form of the laws of nature; yet, 205 the full realization of our universe also relies on subtle mechanisms via which symmetry is 206 broken or hidden. As such, precision experimental tests of both observed symmetries and known 207 symmetry violations provide a powerful and complementary approach to the search of new 2.2. Fundamental symmetries and observed asymmetries 8

208 physics phenomena beyond the Standard Model. More specifically, tests of invariance under 209 the discrete transformations of charge conjugation (C), parity (P), and time reversal (T) provide 210 important probes for new physics. Experimental observations have established that the symmetry 211 associated with the individual P and combined CP transformations is violated in nature, and 212 these effects are incorporated in the Standard Model, although their fundamental origin remains 213 unknown. Moreover, the observed magnitude of CP violation in nature is insufficient to explain 214 the predominance of matter over antimatter observed in the universe. Sources of CP (or T) 215 violation due to new physics phenomena can be searched for through a number of different 216 experimental approaches; e.g. precision measurements of CP violation in Kaon and B-meson 217 decays, searches for CP violation in neutrino oscillation observed in long-baseline experiments 218 and searches for the existence of electric dipole moments violating time-reversal symmetry in 219 neutrons, atoms and molecules. Interestingly, the violation of parity symmetry provides for an 220 extremely sensitive means to study the neutral current weak interaction, which is otherwise 221 generally masked by the dominating electromagnetic processes. As a result, precision tests of the 222 weak interaction can be achieved using parity violating measurements made in electron-electron 223 scattering, electron-proton scattering, atomic systems, and using cold neutrons. Other important 224 tests of symmetry properties of the Standard Model include lepton flavour universality and lepton 225 number conservation, that can be explored in various particle decays and experiments studying 226 the nature of neutrinos. Finally, the combined CPT symmetry, believed to be an exact symmetry of 227 nature, can be tested in spectroscopy experiments using anti-hydrogen atoms, and any observed 228 deviation would imply a breakdown of relativistic quantum field theory.

229 2.2.1. Canadian contributions and achievements 230 The following describe some of the Canadian contributions and achievements in the past 5 years 231 related to the exploration of fundamental symmetries.

232 • ALPHA is an experiment at CERN that aims to test CPT symmetry and the universality of 233 gravitational interactions between matter and antimatter using anti-hydrogen spectroscopy. 234 With strong leadership from Canadians, the ALPHA collaboration has produced a series of 235 noteworthy achievements such as a test of anti-hydrogen charge neutrality, the measure- 236 ment of the anti-hydrogen 1s2s transition frequency and a demonstration of anti-hydrogen 237 laser cooling.

238 • TUCAN is an experiment that aims to measure the neutron electric dipole moment with un- 239 precedented precision using ultra-cold neutrons produced at TRIUMF. Canadians achieved 240 important milestones in the establishment of this physics program: a new fast kicker mag- 241 net was built feeding a new proton beamline with a high-power spallation target, and the 242 ﬁrst ultra-cold neutrons were successfully produced at TRIUMF and their interactions with 243 superﬂuid helium characterized.

244 • Canadians have continued to develop at TRIUMF two complementary experimental pro- 245 grams to search for an electric dipole moment of the electron in atomic and molecular 246 systems. The goal of the FrEDM project is to competitively search for a permanent electric 247 dipole moment of the electron using a laser-cooled francium atom fountain. The high-Z 248 francium atoms feature a high sensitivity to an electric dipole moment. Canadians have 249 been contributing to the development of the apparatus at Lawrence Berkeley National Labo- 250 ratory and its use with Cesium atoms to learn to control the various sources of systematic 251 uncertainty affecting this challenging measurement. This program will pave the way to 252 a proposed future program of searches for electronic dipole moments using molecular 2.3. Neutrino properties 9

253 states, where the experimental sensitivity to parity and time-reversal violating effects can be 254 signiﬁcantly enhanced compared to atomic systems.

255 • Canadians have used the TRINAT facility at TRIUMF to study the decays of short-lived 256 isotopes produced at ISAC in the search for new physics. The recently added capacity 257 to efﬁciently optically pump trapped atoms has enabled Canadians to achieve the most 37 258 precise measurement of the beta decay asymmetry to date using K.

259 • Using cold neutrons produced at the Oak Ridge National Laboratory, Canadians have con- 3 260 tributed to the ﬁrst measurement of parity violation in the neutron-proton and neutron- He 261 systems, providing the most stringent constraints to date on the weak nucleon-nucleon 262 coupling constants. Following in the footstep of these efforts, Canadians have also partici- 263 pated in the development of the future Nab experiment that will test for physics beyond the 264 Standard Model through the study of cold neutron beta decay. Speciﬁcally, Canadians have 265 developed a 30 keV proton accelerator at the University of Manitoba that will be used to 266 characterize the large area silicon detectors used in the Nab experiment.

267 • Canadians have also made signiﬁcant progress in the development of experiments capable 268 of testing, and measuring, fundamental symmetries as part of a variety of other research 269 programs such as ATLAS, Belle-2, Chira Belle, MOLLER, NA62, T2K, Hyper-K, DUNE, 270 SNO+, nEXO and LEGEND, and experimental programs at radioactive beams facilities. 271 The speciﬁc Canadian achievements on each of these projects are presented as part of the 272 descriptions of other science drivers.

273 • A primary motivation for exploring new sources of CP violation and lepton number violation 274 is their connection to the matter antimatter asymmetry in the universe. Canadian theorists 275 have been actively analyzing these new physics signatures, the associated cosmological 276 implications, and new opportunities for experimental tests.

277 2.3. Neutrino properties 278 In recent decades, studies of neutrinos have revealed many of the properties of these elusive 279 particles, from the paradigm-changing discovery that neutrinos have non-zero mass to the 280 measurement of the surprisingly large mixing angles between the different neutrino species. Still, 281 there is much to learn. We do not yet know the absolute scale of the neutrino mass which has an 282 important bearing on the impact neutrinos have on the evolution of the Universe, which of the 283 neutrino species is the lightest, or even whether neutrinos and antineutrinos are distinct particles. 284 We also don’t yet know whether neutrinos violate CP symmetry in a way that could help explain 285 the excess of matter over antimatter in the Universe. 286 The most promising experimental approach to determining whether neutrinos are their own 287 antiparticles or not is through the search for neutrinoless double beta decay (0νββ). Observation 288 of this lepton number violating process would be clear evidence for physics beyond the Standard 289 Model, and clearly demonstrate that neutrinos are Majorana-type particles and hence potentially 290 obtain their masses in a manner completely independent of the much celebrated Higgs Mecha- 291 nism. The observed rate of 0νββ would also constrain the absolute neutrino mass. A number of 292 experiments around the world are searching for 0νββ using different technologies and different 293 candidate isotopes. Canada has an opportunity to play a leading role in this effort as SNOLAB 294 provides an exceptional low background site. 295 Precision measurements of neutrino oscillations provide the potential for further fundamental 296 breakthroughs. Neutrino oscillation experiments, such as those based on high luminosity neutrino 297 beams, reactor anti-neutrinos, and atmospheric neutrinos, will attempt to determine the neutrino 2.3. Neutrino properties 10

298 mass hierarchy and CP-violating phase. They will also search for signs of new physics such as 299 the existence of sterile neutrinos and non-standard neutrino-matter interactions. 300 Neutrinos can also act as ‘messengers,’ providing to us otherwise inaccessible information 301 about such things as supernova explosions, the composition of the interior of the Earth, the solar 302 core, and high energy particle acceleration processes in the cosmos. Such natural neutrinos also 303 provide an opportunity to study the properties of neutrinos and search for beyond-the-standard 304 model physics.

305 2.3.1. Canadian contributions and achievements 306 Canadian researchers are at the forefront of experimental investigations into the properties of 307 neutrinos. Speciﬁc achievements of Canadians in the past ﬁve years include the following:

130 308 • The Canadian-led SNO+ experiment at SNOLAB will search for 0νββ in Te. It will also 309 contribute to neutrino oscillation studies through measurements of reactor anti-neutrinos 310 and low energy solar neutrinos. Significant milestones in the development of this research 311 program have been achieved. The SNO+ experiment began operation in 2017 with a 312 Water-fill Phase. In 2019, purification of liquid scintillator and filling with liquid scintillator 313 began until the COVID-19 pandemic necessitated the suspension of operations in April 314 2020, restarting in October 2020.

315 • The goal of the EXO-200 and proposed future nEXO experiments is to search for 0νββ in 316 xenon. The EXO-200 experiment concluded its operation in 2018 at the Waste Isolation 317 Pilot Plant (WIPP) in New Mexico. Canadians have played a leadership role in both the 318 operation of the detector and subsequent data analysis, achieving sensitivity similar to 319 the most sensitive searches and ﬁnding no statistically signiﬁcant evidence for 0νββ. In 320 parallel, Canadians have contributed to the development of the next generation nEXO 321 experiment, to possibly be sited at SNOLAB, and have taken responsibility for the delivery 322 of key components of the detector such as the outer detector muon veto, water circulation 323 and assay systems and photon sensor testing. 76 324 • LEGEND is a program of 0νββ experiments based on Ge. There is the potential that the 325 proposed future LEGEND-1000 experiment could be located at SNOLAB. A small effort on 326 this research program has recently been established in Canada with contributions initially 327 focused on the development and characterization of specialized germanium sensors.

328 • The T2K experiment is an ongoing long-baseline neutrino experiment in Japan. Canadians 329 have played an active role in this experiment at all stages, contributing to multiple aspects of 330 construction and analysis, with their work culminating in the publication of the ﬁrst signiﬁcant 331 constraint on the neutrino CP-violating phase, a result which is having a profound impact on 332 the community at large and the planning for the next generation of oscillation experiments.

333 • The future Hyper-K project in Japan builds on the successes of the T2K experiment with 334 construction of an eight times larger far detector and upgrades to the JPARC beam intensity 335 to build a world-leading neutrino experiment. The Hyper-K project was approved and 336 construction of the detector began in 2020. Canada has taken a leading role in Hyper- 337 K since its conception. The Canadian team’s recent activities have focused on various 338 initiatives aimed at suppressing sources of systematic uncertainties that may ultimately limit 339 the precision of Hyper-K measurements. For example, Canadians have led the proposal 340 for a new hadron production experiment to gather hadron interaction data in phase space 341 regions relevant to Hyper-K measurements. Canadians developed the concept of moving 2.4. Dark Matter and potential dark sectors 11

342 the near detector to different off-axis positions to sample different neutrino energy spectra. 343 Canadians have also been leading a proposed test experiment at CERN to establish 344 the detector technologies, calibration methods and detector models of the intermediate 345 water Cherenkov detector necessary for percent level neutrino differential cross-section 346 measurements.

347 • The future DUNE experiment, at the Sanford Underground Research Facility (SURF) in 348 South Dakota, will study neutrino oscillations using an artiﬁcial neutrino beam, as well as 349 atmospheric, solar and supernova neutrinos. A new Canadian involvement in DUNE has 350 recently been established with contributions around the following key areas of the physics 351 program: near detector commissioning, development of the data acquisition, trigger and 352 calibration systems, and development of the DUNE computing model.

353 • IceCube is a high energy neutrino telescope sited at the South Pole. In addition to studies 354 of ultra-high energy neutrinos, IceCube also makes signiﬁcant contributions to the precision 355 measurement of mixing parameters at high energy. Canadians have established leadership 356 in key data analyses such as atmospheric neutrino ﬂuxes and oscillations, supernova 357 neutrinos, indirect dark matter searches and tests of Lorentz invariance. Additionally, 358 Canadians have been playing an active role in the development and use of new optical 359 modules that will be deployed as an extension to IceCube to enhance the angular resolution 360 of high-energy neutrino events. This IceCube upgrade work pursued by Canadians will have 361 an extensive synergy with the work required to develop similar trigger and reconstruction 362 algorithms for the proposed P-ONE detector, which will use almost identical optical modules 363 used in the IceCube Upgrade, indeed, Canada has been preparing to take on a major role 364 with the proposed P-ONE project off the coast of Vancouver Island, BC, a project that would 365 expand the global capabilities and sky coverage of neutrino telescopes.

366 • HALO is a Canadian-led supernova neutrino experiment operating at SNOLAB. The Cana- 367 dian team has extended its leadership to the development of the proposed HALO-1kT 368 experiment that would be sited at the Laboratorio Nazionale del Gran Sasso (LNGS) in Italy. 369 HALO-1kT is a detector of opportunity being pursued because of the availability of 1000 370 tonnes of lead from the decommissioning of the OPERA experiment.

371 • The BeEST experiment aims to perform the highest-sensitivity search for keV-scale sterile 7 372 neutrinos to date using the electron capture decay of Be implanted into superconducting 373 quantum sensors. Canadians have contributed to the publication of the ﬁrst limits with this 374 technique. These new constraints improve upon previous decay measurements by up to an 375 order of magnitude.

376 • Canadians are involved in a number of experiments studying, or planning to study, coherent 377 elastic neutrino-nucleus scattering using different types of target nucleus. These include 378 COHERENT, Scintillating Bubble Chamber (SBC), NEWS-G, and MINER. The coherent 379 elastic neutrino-nucleus scattering process provides a clean environment to search for new 380 physics and is also astrophysically important, playing a role in supernova processes and 381 their detection.

382 2.4. Dark Matter and potential dark sectors 383 Compelling data from galactic rotation curves, the dynamics of galaxy clusters, the large scale 384 structure of the universe, and the cosmic microwave radiation point to ∼ 85% of the matter in the 385 universe today consisting of non baryonic or dark matter. Furthermore, neutrino measurements 386 and large-scale structure indicate that only a small fraction of dark matter can be in the form of 2.4. Dark Matter and potential dark sectors 12

387 neutrinos. A global experimental and theoretical effort is testing many hypotheses concerning 388 the nature of dark matter, including thermal relics from the universe, a category which includes 389 weakly interacting massive particles (WIMPs), and a range of theoretically motivated lighter 390 mass scenarios such as axions, sterile neutrinos, dark photons and other dark sector degrees of 391 freedom including the mediators of new forces through which dark matter may interact. 392 Experiments can search for dark matter in at least three ways: through direct detection 393 of ambient dark matter in the galactic halo, production and detection in accelerator-based 394 experiments, and through observation of dark matter annihilation signatures. 395 Direct searches for dark matter candidate are carried out in large ultra-clean underground 396 observatories or through their possible interactions with strong magnetic field. The most sensitive 397 searches for high-mass WIMPs use noble liquids as a target while direct searches for low-mass 398 WIMPs use a variety of techniques and materials including searches for scattering off electrons. 399 Searches for WIMPs interacting with nucleon spin use targets such as fluorine. The direct 400 searches for axions, on the other hand, typically rely on the possible axion-to-photon conversion 401 that could take place in a strong magnetic field such as that present in a resonant cavity or in the 402 vicinity of a nucleus in a target material. 403 Dark matter particles and particles related to a possible dark sector could be produced in 404 accelerator-based experiments in high-luminosity particle collisions or beam dump experiments. 405 The strategy with this experimental approach is to search for visible or invisible decays of a dark 406 mediator particle that would couple to both dark matter and known Standard Model particles. 407 Indirect searches for dark matter are also carried out by astronomical observatories looking 408 for signatures of dark matter annihilation, including cosmic rays and neutrinos.

409 2.4.1. Canadian contributions and achievements 410 The presence of SNOLAB gives Canada a prime position from which to take a leading role in the 411 direct search for dark matter. Canadians have been particularly productive in the past ﬁve years 412 and the following highlights some of their recent achievements.

413 • The Canadian-led DEAP-3600 experiment uses a large liquid-argon detector at SNOLAB 414 to search for high-mass WIMPs. It has been in operation since 2017 and successfully 415 demonstrated the very low background levels achievable in liquid-argon, based in part on 416 the use of advanced pulse-shape discrimination techniques. The DEAP-3600 collaboration 417 has published the best dark matter limits in liquid argon that are complementary to limits 418 obtained with other target materials. Canadians have also contributed to the interpretation 419 of these limits in the context of effective ﬁeld theories and the velocity distribution of dark 420 matter given uncertainties in galactic dynamics.

421 • The Canadian-led PICO bubble-chamber program at SNOLAB employs superheated ﬂu- 422 orinated targets to search for spin-dependent WIMP-nucleus interactions. The PICO-40 423 detector is in operation and the PICO-500 detector, in construction. The PICO collabo- 424 ration has published the most stringent direct-detection constraint on the WIMP-proton 425 spin-dependent cross-section.

426 • The SuperCDMS experiment, under construction at SNOLAB, uses germanium and silicon 427 detectors to search for low-mass WIMPs. Canadians have signiﬁcantly contributed to the 428 analysis of the data taken during deployment at Soudan Mine, USA and follow-up publication 429 of the results of detectors operating with a high-voltage bias, exploiting the Luke-Neganov 430 effect.This work forms the basis of the depolyment of SuperCDMS-SNOLAB. In addition, 431 the Canadian Cryogenic Underground Test Experiment (CUTE) at SNOLAB has been built 2.5. New physical principles and structures 13

432 and commissioned which will allow for thorough pre-testing of crystals before deployment in 433 SuperCDMS-SNOLAB and for early dark-matter results.

434 • Canadians researchers have contributed to the publication of a joint analysis with the 435 IceCube and Antares neutrino observatories searching for dark-matter annihilation in the 436 center of the Milky Way galaxy.While no excess over the expected background is observed, 437 these limits present an improvement of up to a factor of two in the relevant dark matter mass 438 range with respect to the individual limits published by both collaborations.

439 • The Canadian-led NEWS-G experiment at SNOLAB searches for low-mass WIMPs using 440 spherical proportional counters filled with light atomic mass gases, such as neon, methane, 441 and helium, and thus features particular sensitivity to low mass WIMPs. Canadians have con- 442 tributed to the publication of the first dark matter search results with a spherical proportional 443 counter at the Laboratoire Souterrain de Modane in France. At the time of publication, the 444 results set new constraints on the spin-independent WIMP-nucleon scattering cross-section 445 for WIMP masses under 0.6 GeV. Canadians have also been significantly contributing to 446 the installation and commissioning of the experiment at SNOLAB that will operate shortly.

447 • Canadians have initiated and developed the new SBC international collaboration for the 448 development of a scintillating bubble chamber that will combine the scintillation of noble 449 liquids with the rejection of electromagnetic backgrounds found in bubble chambers, to 450 search for low mass WIMPs. Canadians have been involved in the development of all 451 aspects of the experiment.

452 • Canadian theorists have been actively involved in developing models for dark matter over 453 the full mass range, studying a range of astrophysical and terrestrial constraints, and have 454 proposed many novel ideas for direct and indirect detection.

455 2.5. New physical principles and structures 456 The development of the Standard Model, built upon the foundations of relativistic quantum field 457 theory, gauge invariance and a variety of symmetry principles, has proved to be a remarkable 458 scientific achievement. It allows quantitative predictions, often to very high precision, to be made 459 about subatomic physics. While much theoretical work builds upon this structure to analyze 460 collective phenomena, such as hadronic and nuclear physics, or seeks to understand how it could 461 be expanded to unify symmetries or resolve empirical questions such as the nature of dark matter 462 and neutrino mass, theorists are also driven to explore a number of underlying questions about 463 the structure of the Standard Model itself. 464 Quantum field theory is the foundation on which the SM is built, and while a high degree of 465 quantitative control has been achieved in a number of regimes, a full understanding of the theory 466 has yet to be achieved and there are mysteries to be understood. Examination has revealed 467 surprising connections, e.g. dualities, between seemingly unrelated theories leading to new 468 techniques to calculate at both weak and strong coupling. Important recent progress in the study 469 of strongly-coupled field theory has involved the so-called conformal bootstrap approach, where 470 analyticity and unitarity constraints are used to extract information about quantum field theories 471 even in the absence of a traditional perturbative expansion. Lattice gauge theory is a more direct 472 approach to understanding strong dynamics in gauge theories and QCD in particular, and is 473 also the subject of considerable theoretical development, e.g. to understand chiral fermions, and 474 indeed as a potential application for quantum computing. Another focus of recent research has 475 been the study of scattering amplitudes, yielding new insights into underlying geometric structures 476 and possibly even the nature of spacetime as well as practical methods for doing calculations in 2.5. New physical principles and structures 14

477 QCD and gravity. Notably, many of these approaches rely on deep and growing links between the 478 formal and the phenomenological approaches to particle theory. 479 Developing a consistent and complete understanding of gravity at the quantum level remains 480 one of the grand challenges in physics. String theory provides a theoretical framework which 481 accommodates both classical general relativity and quantum mechanics, but is a rich mathe- 482 matical structure, and its concrete application to subatomic physics remains less clear. Most 483 recently exploration of string theory has been productive in elucidating many nontrivial aspects of 484 and connections between quantum field theory, QCD, condensed matter physics, black holes, 485 spacetime, quantum information, and formal mathematics. Perhaps the most far-reaching and 486 nontrivial structure to emerge in this way is the AdS/CFT correspondence or holography, which 487 ties together theories of gravity with quantum field theories in lower dimensions. This discovery 488 nearly 25 years ago continues to stimulate a vast body of theoretical work touching on strong 489 dynamics in quantum field theories relevant to particle and condensed matter physics, thermal 490 dynamics, hydrodynamics and the quark-gluon plasma, and of course black holes. In recent years, 491 this approach to thinking about the (quantum) physics of black holes has led to new connections 492 to quantum information theory and quantum computing, and new insights about Hawking radiation 493 and a possible resolution of the information loss paradox. Some of these new ideas can be 494 formulated in the traditional language of gravitational path integrals, pointing once again to the 495 power of this dual perspective to provide a novel and productive viewpoint on deep puzzles in 496 conventional physics. 497 The synergy between particle physics and early cosmology also provides fertile ground for 498 formal theoretical research that seeks to understand the very early universe. Current cosmological 499 data requires an early epoch of inflation or an alternative description that produces the large 500 scale features observed today and the origins of structure. A full theoretical understanding of 501 early cosmology, and its initial conditions, remains an active research area and one of the few 502 areas where very high scale subatomic physics may leave observable imprints. Various early 503 universe scenarios also lead to predictions, such as the formation of primordial black holes, 504 phase transitions, or topological defects, that are now topical as potentially observable sources of 505 gravitational waves. Finally, understanding the nature of dark energy, and/or the small size of the 506 cosmological constant, remains another grand challenge under study that lies at the intersection 507 of quantum field theory and gravity, and may be a window to understand other deep aspects of 508 fundamental physics.

509 2.5.1. Canadian contributions and achievements 510 The Canadian formal theory community has actively contributed to, and indeed provided leader- 511 ship for, many of the topical directions of research progress outlined above. Speciﬁc examples of 512 developments since the last LRP include the following:

513 • New insights into the structure of scattering amplitudes in quantum field theory and gravity, 514 and associated foundational components of field theory and conformal field theory.

515 • Developments in the basic understanding of thermal systems, the relativistic hydrodynamic 516 regime, and its applications e.g. to the quark gluoon plasma.

517 • New understanding of the phase structure and dynamics of strongly-coupled gauge theories.

518 • Developments in understanding holography, and the connections of black holes and space- 519 time structure to quantum information theory.

520 • New insight into the quantum features of black holes, entropy, and low dimensional models 521 of quantum gravity. 2.6. Hadron properties and phases 15

522 • Varied developments in understanding quantum ﬁeld theory in the very early universe, in de 523 Sitter space times, and the implications for gravitational wave signatures.

524 Canada has high-proﬁle theory centers, including the Perimeter Institute, but the formal theory 525 community is diverse, and widely distributed across Canada. Researchers actively collaborate in 526 small teams that are often international with members in multiple countries.

527 2.6. Hadron properties and phases 528 The nature of the fundamental constituents of hadrons, quarks and gluons, is one of the major 529 unsolved problems of modern physics. Strong interactions between quarks and gluons at very 530 high energies (short distance scales) are described within the Standard Model by the theory of 531 Quantum Chromodynamics (QCD), but a full understanding of the strong force at long distances, 532 where quark confinement dominates, is one of the major unsolved problems of subatomic physics. 533 To gain insight into the strongly interacting, non-perturbative regime of QCD, where quark 534 (colour) confinement dominates, a number of different approaches are being followed. One 535 strategy is to measure hadron properties such as mass, spin and polarizability, in electron 536 scattering and photoproduction experiments. Another is to search for hybrid mesons predicted to 537 exist by lattice QCD calculations as a means to understand how the quark and gluonic degrees 538 of freedom that are present in the fundamental QCD Lagrangian manifest themselves in the 539 spectrum of hadrons. Evidence for new types of hadrons, including tetraquark and pentaquark 540 state, are exciting discoveries which strongly motivate further study. Measurements of the 541 electromagnetic form factors of mesons, such as the charged pion and kaon, will elucidate the 542 role of confinement and chiral symmetry breaking in fixing the hadron’s size and mass as well as 543 the transition from the perturbative-QCD to strongly-coupled domains (short to long distances). 544 Exotic matter can also be created by colliding nuclei at relativistic energies, creating conditions 545 similar to those that existed shortly after the Big Bang, which informs the construction of the 546 phase diagram of nuclear matter.

547 2.6.1. Canadian contributions and achievements 548 Canadians are at the forefront of the quest to understand the properties of hadrons, on both the 549 experimental and theoretical fronts. Canadian achievements in the past ﬁve years include the 550 following.

551 • The Canadian theoretical community leverages a range of calculational approaches, includ- 552 ing Lattice QCD, Light Front Holographic QCD and Chiral Pertubation Theory to advance the 553 ﬁeld and to support the Canadian experimental efforts. For example, recent achievements 554 include the ﬁrst direct lattice QCD calculation predicting the existence of tetraquarks with 555 valence content ud¯b¯b, and calculations of the Standard Model predictions for the differential + − 556 branching ratio of the rare decay Bs → φµ µ .

557 • The Gluex project currently taking place at Jefferson Lab aims to measure the proper- 558 ties of hybrid mesons produced through photo-production. Canadians have maintained 559 responsibility for the gain calibrations of the silicon PMTs for the Barrel calorimeter which 560 was designed and built in Canada. The Canadian team also led the measurement of the 0 561 photon-beam asymmetry for η and η mesons, concluding that this photoproduction process 562 is dominated by natural parity exchange with little dependence on momentum transfer.

563 • The pion form factor program at Jefferson Lab has been led by Canadians, garnering over 564 1000 citations for their work collecting and analyzing the data from various experiments. 2.7. Nuclear structure 16

565 • Canadians have conducted a program of measurements to extract the spin polarizabilities 566 of the proton at the Mainz Mictrotrom (MAMI) in Germany. Such polarizabilities are fun- 567 damental observables of hadron structure, and are amenable to calculation with various 568 QCD-inspired models and effective theories. Several measurements have been published 569 and shown to be in agreement with several different types of predictions obtained using 570 different theoretical approaches.

571 • Canadians continue to play a pivotal role in the investigation of ultra-relativistic heavy ion 572 collisions in general, and the properties of the quark-gluon plasma in particular, through 573 the calculations of relevant experimental observables using hydrodynamics techniques and 574 the development of this formalism. Canadian involvement in these efforts has spurred the 575 development of the requisite detector concepts at past and future heavy ion colliders, as 576 well as advancing our knowledge of hadron structure.

577 2.7. Nuclear structure 578 Atomic nuclei, the core of all visible matter, constitute unique many body systems of strongly 579 interacting fermions. Their properties and structure are of paramount importance to many 580 aspects of physics. Many of the phenomena encountered in nuclei share common basic physics 581 ingredients with other mesoscopic systems, thus making nuclear structure research relevant to 582 other areas of contemporary science, for example in condensed matter and atomic physics. 583 More broadly, science and society rely on our understanding of the atomic nucleus. Its −15 584 relevance spans distances from 10 m (the proton radius) to 12 km (neutron star radius) and 585 the evolutionary history of the universe from fractions of a second after the Big Bang to today; 586 13.8 billion years later. 587 The universe has a wide variety of nuclei, only a handful of which, that are stable or long- 588 lived, exist on earth whose properties led to the traditional nuclear models. The rare isotopes, 589 nuclei towards the limit of nuclear binding, are however unfolding a new view as their observed 590 properties are showing unexpected deviations from conventional knowledge, thereby challenging 591 the fundamental understanding of nature’s principles in building these many-body quantum 592 systems. 593 Low-Energy nuclear physics research addresses the existence of atomic nuclei, their limits, 594 and their underlying nature. It also aims to describe interactions between nuclei and dynamical 595 processes such as ﬁssion. The ultimate goal is to develop a predictive understanding of nuclei 596 and their interactions grounded in fundamental QCD and electroweak theory. There is broad 597 international consensus on the intellectual challenges of nuclear structure, which are captured 598 well in the following overarching questions:

599 • How does the structure of nuclei emerge from nuclear forces?

600 • What new features and phenomena emerge with large neutron-proton asymmetry in rare 601 isotopes?

602 • What is the role of rare isotopes in shaping the visible matter in the universe?

603 Answers to these questions require a broad and deeper understanding of atomic nuclei, both 604 experimentally and theoretically. The last decades saw progress in our understanding of the 605 strong nuclear force. However, studies of exotic nuclei, enabled by the developments of rare 606 isotopes beams are changing our conventional knowledge of how protons and neutrons are 607 organized especially with large neutron-proton asymmetry and at the limits of nuclear binding. 608 For example, new forms of nuclei, nuclear halos and neutron skin appear and the well-established 2.7. Nuclear structure 17

609 shell gaps near stability are being eroded by the spin-isospin effects of the 2N and 3N forces 610 and new magic numbers appear far from stability. 611 Exploration of rare isotopes towards the extreme limits of N and Z binding will provide the 612 insights needed for a comprehensive understanding of nuclei. This exploration is revealing novel 613 quantum many-body features and leading us toward the true global understanding of complex 614 quantum systems and of the mechanisms responsible for the emergent features found in atomic 615 nuclei. Furthermore, it will open new avenues to cross-discipline contributions in basic sciences 616 and societal applications.

617

618 2.7.1. Canadian contributions and achievements 619 Canada is a world-leader in the theoretical descriptions of atomic nuclei from ﬁrst principles. The 620 ultimate goal of these efforts is to develop a predictive ab-initio theory of nuclear structure and 621 nuclear reactions, to understand nuclei studied at rare isotope facilities. A strong collaboration 622 between Canadian experimentalists and theorists exists and has led to feedback on the quality of 623 inter-nucleon interactions used as input to these calculations, improving the knowledge of the 2N 624 and 3N forces. The following list highlights recent Canadian achievements in the past ﬁve years.

625 • Canadians have helped reveal the imprints of the nuclear force from a study of proton 10 626 elastic scattering on C. The Canadian led experiment, carried out with the IRIS facility 627 at the TRIUMF-ISAC laboratory, measured the shape and magnitude of the differential 628 cross section. Ab-initio nuclear reaction calculations performed by a collaboration led by the 629 TRIUMF theory group, showed that those observables are strongly sensitive to the nuclear 2 630 force prescription. Comparison with the data suggests that the N LOsat chiral effective 631 interaction does a better job, compared to the other forces, but is still not an adequate 632 description of the nuclear force.

633 • The observed β-decay rates in nuclei, found to be systematically smaller than for free 634 neutrons, implies apparent quenching of the fundamental coupling constant. An international 635 theory collaboration, with key contributors from the TRIUMF group, has recently solved 636 this 50-year-old puzzle from ﬁrst-principles. Their work showed that this quenching arises 637 to a large extent from the coupling of the weak force to two nucleons as well as from 638 strong correlations in the nucleus. Combining effective ﬁeld theories of the strong and 639 weak forces with powerful quantum many-body techniques, the group carried out ab-initio 100 640 calculations of β-decays from light- and medium-mass nuclei up to Sn that are consistent 641 with experimental data. These results also have implications for heavy element synthesis in 642 neutron star mergers and predictions for the neutrino-less double-β-decay.

643 • Canadians have also made important contributions to the measurement and understanding 644 of Halo nuclei. For example, recent studies with Canadian leadership at the Radioactive Ion 29 645 Beam Factory (RIBF) in Japan have unveiled a two-neutron halo in F. It is the heaviest 646 and the ﬁrst Borromean halo observed in the proton sd-shell to date. While the results are 647 explained by state-of-the-art shell model calculations with effective interactions, ab-initio 29 648 predictions are challenged in explaining the halo in F, pointing once more to our limited 649 knowledge of the nuclear force from ﬁrst principles. 50˘55 650 • Canadians contributed to high-precision mass measurements of Sc isotopes at LEBIT 651 and the TITAN facilities at TRIUMF. This work added important information to the under- 652 standing of emerging closed-shell phenomena at N=32 and N=34 above the Z=20 magic 2.8. Cosmic formation of nuclei 18

653 number. Speciﬁcally, the new data enabled a complete and precise characterization of 654 the trends in ground state binding energies along the N=32 isotone, conﬁrming that the 52 655 empirical neutron shell gap energies peak at the doubly magic Ca. Furthermore, the 656 results suggest that closed-shell behavior only appears in the mass surface for Z ≤ 20. 80 657 • Canadians led the recent study of the structure of Ge using the GRIFFIN spectrometer 658 at TRIUMF-ISAC. The new experimental evidence combined with shell model predictions 80 659 clearly indicated that low-energy shape coexistence is not present in Ge, in contrast to 660 previously reported results.

661 2.8. Cosmic formation of nuclei 662 Humanity has long sought to understand the origin of visible matter and the abundance of 663 the known atoms. While it has been firmly established that the synthesis of elements in the 664 universe occurs through a variety of nuclear processes, from quiescent stellar burning to dynamic 665 conditions involving the remnants of stellar explosions and compact object mergers, only half of 666 the total number of nuclei that are expected to exist between the neutron- and proton-dripline have 667 been discovered, about 3450 nuclei. Much work remains to precisely understand the different 668 nucleosynthesis processes at play. 669 Understanding nucleosynthesis is accomplished by a combination of astrophysical observa- 670 tions and simulations, nuclear physics data, and the input of nuclear theory predictions. Specifi- 671 cally, from a nuclear physics point of view, the study of astrophysical reactions of interest and 672 knowledge of properties of the nuclei involved requires stopped and accelerated radioactive ion 673 beams such as those produced by the ISAC and ARIEL facility at TRIUMF. Nuclear physics 674 measurements can also help elucidate the physics of neutron stars, the smallest and densest 675 objects in the universe, and supernovae explosions, in particular through precise measurements 676 of the neutron skin thickness in neutron-rich nuclei that help constrain the equation of state of 677 neutron-rich nuclear matter. 678 This field is also highly synergistic with multi-messenger astronomy, with the recent remarkable 679 developments with simultaneous observations at multiple electromagnetic wavelengths and in 680 gravitational waves, as first carried out for the binary merger GW170817.

681 2.8.1. Canadian contributions and achievements 682 Research efforts in the Canadian nuclear physics community cover all the processes of nucleosyn- 683 thesis and associated astrophysical phenomena. The ISAC and ARIEL facilities at TRIUMF in 684 Canada bring immense scope for such studies where Canadians are leading projects. Canadians 685 are also involved in selected projects at offshore facilities with complementary technology. Some 686 research highlights since the last LRP are summarized below:

687 • Direct measurement of the proton capture reactions at astrophysical energies are possible 688 using the recoil spectrometers DRAGON and EMMA at TRIUMF. Using this infrastructure, 38 39 689 Canadians have recently achieved the measurement of the K(p,γ) Ca reaction, greatly 690 reducing the uncertainties in the knowledge of the mechanism involved in the Ar, K and Ca 691 synthesis. Canadians have also exploited the joint capabilities of the EMMA and TIGRESS 83 84 692 detectors at TRIUMF to make the ﬁrst measurement of the Rb(p,γ) Sr reaction, an 693 important measurement in the p-process for constraining the reverse reaction.

694 • Canadians have contributed to several leading studies of nuclear properties relevant to the 695 understanding of nucleosynthesis processes. For example, Canadians performed mass 2.9. Impact and Synergies with other ﬁelds 19

696 measurements of Ga and In isotopes using the TITAN Penning trap at TRIUMF, adding 697 precise inputs for r-process simulations. Canadians also contributed to the precise measure- 130 698 ment of the half-life of Cd, resolving the discrepancies between previous measurements 699 for this crucial r-process nucleus. Canadians have also been involved in the BRIKEN project 700 campaign at RIKEN in Japan measuring beta delayed neutron probabilities for a wide region 701 of neutron-rich nuclei.

702 • Canadian researchers have been developing programs to measure the rate of neutron 703 capture in the synthesis of heavy elements using the infrastructure at TRIUMF, Michigan 704 State University and Argonne National Lab.

705 • Canadian researchers have been leading ongoing efforts to measure the neutron skin 48 706 thickness in Ca via parity violating electron scattering using the CREX experiment.

707 • Canadians have continued to maintain a world-leading position in predicting nuclear struc- 708 ture properties that are necessary for nuclear astrophysics. For example, Canadians have 8 9 709 achieved impressive level of precision in calculating direct capture rates of the Li(n,γ) Li 710 reaction using ab initio reaction theory. Canadians have also been pursuing astrophysical 711 simulations of binary mergers.

712 2.9. Impact and Synergies with other fields 713 The overarching goal of subatomic physics, to push the frontier of our knowledge of what the 714 Universe is made of, and the associated development of specialized research tools, naturally 715 leads to strong links with many other research fields. 716 Unique opportunities and synergies exist at the boundary between subatomic physics research 717 and other fields, along the following two fronts, scientific and technological. From the scientific 718 point of view, findings in the fields of astrophysics and cosmology provide complementary 719 information in addressing several of the subatomic physics science drivers, and in turn the 720 advancement of knowledge in subatomic physics has a direct impact on models of cosmology 721 and astrophysics phenomena. For example, the rapidly developing multi-messenger approach to 722 study astrophysical objects lies squarely at the boundary between the fields of subatomic physics 723 and astrophysics. From a technological standpoint, techniques and instruments developed for 724 subatomic physics research have and continue to be adapted for use in a wide range of other fields, 725 paving the way to innovative and ground-breaking work. These fields include biology, data science, 726 electrical engineering, material science, medical imaging and public health. Specific examples 727 of these synergies include particle detection techniques used in medical imaging, accelerator 728 mass spectrometry employed in biomedical research and in archaeology for radiocarbon dating, 729 applied nuclear imaging of plants and soil and muon tomography used in several areas such as 730 geology and security and environmental protection. In turn, developments in quantum sensing 731 and techniques in atomic, molecular and optical physics offer novel, and possibly groundbreaking, 732 opportunities to address science drivers in subatomic physics. 733 In summary, there exists valuable scientific opportunities in cross-disciplinary collaboration at 734 the boundaries between different fields of research, and subatomic physics research is uniquely 735 positioned to contribute to and benefit from initiatives in regions of overlap with other fields (see 736 Fig. 2.2) 2.9. Impact and Synergies with other fields 20

Figure 2.2: (Placeholder) Schematic representation of the science drivers and synergies with other research ﬁelds. 737 3

738 Canadian Subatomic Physics Research

739 Plan

740 With an established track record, ongoing and newly developing international partnerships, 741 valuable local research facilities such as TRIUMF, SNOLAB and the Perimeter Institute, and 742 significant recent support for the development of experimental infrastructure, the Canadian 743 community is poised to capitalize on a number of science opportunities over the coming five 744 years, and the decade beyond. This chapter outlines the emerging science opportunities and 745 the enabling technologies that will support progress. The research program is then presented 746 in the form of a multi-dimensional portfolio of projects, that will help the Canadian community 747 maximize its scientific impact, training opportunities, and benefits to society. The existing portfolio, 748 and emerging opportunities lead to a series of Science Recommendations.

749 3.1. Science opportunities for Canada 750 Unique features of the Canadian subatomic physics research ecosystem position the community 751 well to seize emerging scientific opportunities, with the goal of maximizing scientific impact, 752 training opportunities and benefits to society. In particular, Canada has significant research 753 infrastructure in TRIUMF, SNOLAB, and the Perimeter Institute. In addition, there are active 754 community organizations and flexible funding structures to support new scientific initiatives. 755 Canada also has an excellent standing as a trusted international partner, and the community has 756 the capacity train additional highly qualified personnel (HQP). 757 Several scientific opportunities exist in the coming years, and these are highlighted for each 758 of the science drivers in the sections below.

759 Higgs, physics and the electroweak scale and beyond 760 In the coming decade, there will be unique opportunities to thoroughly explore the Higgs sector, 761 study the physics of electroweak symmetry breaking, as well as search for new physics at the 762 energy frontier, with signiﬁcant prospects for a wide range of exciting new results. Dedicated 763 searches for unconventional physics signatures will also offer signiﬁcant discovery potential. 764 There will be several opportunities to indirectly explore new regions of multi-TeV physics through 765 measurements of known and rare physics processes at an unprecedented level of precision, 766 providing complementary possibilities for observing hints of new physics. It is also likely that by

21 3.1. Science opportunities for Canada 22

767 the end of the decade, the situation with respect to persisting anomalies in the B-physics sector 768 pointing to possible lepton flavour violation will be clarified. 769 Building on its expertise and past investments, Canada is well-positioned to seize all of these 770 scientific opportunities through its participation and leadership, for example, in the broad physics 771 programs of ATLAS and Belle-2, dedicated searches for new physics at MATHUSLA and MoEDAL, 772 and precision programs such as those of MOLLER and NA62. Finally, there is the opportunity to 773 advance detector and accelerator R&D synergistically with the development of Chiral Belle, the 774 International Linear Collider and the Future Circular Collider projects.

775 Fundamental symmetries and observed asymmetries 776 Exploration of the fundamental symmetries in subatomic physics and their violation will continue 777 to be at the forefront of searches for new physics phenomena and principles, providing powerful 778 and complementary sensitivities. Opportunities exist for probing symmetries to a new level of 779 precision by exploiting a variety of different techniques. 780 Within the landscape of possibilities, the combined Canadian expertise in atomic, nuclear, 781 particle physics and accelerator research offers unique opportunities for Canada to play a 782 scientifically leading role world-wide. TRIUMF can become a global centre for tests of CP and 783 T violation via EDM searches, with the start of operations for the Canadian-led TUCAN project, 784 the FrEDM experiment, and the development of the RAMS facility using radium monofluoride 785 molecules. New tests of parity violation can be achieved with FrPNC, studies of beta decays with 786 ISAC and TRINAT at TRIUMF, and the launch of Nab operations at ORNL. Canadian are also 787 well-positioned to play a significant role in future tests of the electroweak symmetry structure and 2 788 the running of sin θW with the development of MOLLER, along with Belle-2 and the possible 789 Chiral Belle upgrade. Spectroscopic tests of anti-hydrogen with significantly improved precision 790 will be feasible with ALPHA-3 and ALPHA-g, and the deployment of Canadian-led HAICU. Tests 791 of lepton flavour universality will continue with NA62 at CERN, and the potential development of 792 PIENUXe. Tests of neutrino properties and CP violation will continue with long-baseline neutrino 793 experiments such as T2K and will move to the next generation of precision with HyperK and 794 DUNE operations. Tests of lepton number violation via neutrinoless double beta decay can be 795 further explored with next generation experiments such as nEXO, LEGEND or other detectors 796 complementing the existing SNO+ program at SNOLAB.

797 Neutrino properties 798 The coming decade should be another exciting one for neutrino physics. At its conclusion, it is 799 likely that the mass hierarchy will be determined, and the search for CP violation will be well 800 underway, potentially yielding conclusive results. At the same time, searches for 0νββ will have 801 continued to push forward, and will likely have achieved sensitivity to span the inverted hierarchy 802 parameter space. Measurements of astrophysical neutrinos will have continued to inform us 803 about the highest energy processes in the cosmos, and neutrinos will have further illuminated 804 our understanding of the workings of the Sun and the interior of the Earth. Research in neutrino 805 physics continues to move forward with vigour, and new breakthrough discoveries are a distinct 806 possibility. 807 Canada is well-positioned to play a leading role in all of these scientiﬁc achievements, with 808 the development of HyperK and DUNE, the evolution of IceCube and potential development of 809 POne, and the primacy of SNOLAB as the preferred location for tonne-scale 0νββ experiments 810 such as nEXO. 3.1. Science opportunities for Canada 23

811 Dark Matter and potential dark sectors 812 Significant breakthroughs in our understanding of the nature of dark matter are possibly within 813 reach in the next decade. Experiments designed to directly detect the presence of dark matter in 814 our galactic halo are likely to achieve significant increases in sensitivity through the continuing 815 development of experimental techniques. As experimental sensitivity approaches the important 816 background from solar and atmospheric neutrinos (the so-called "neutrino floor"), possible 817 new directions include the development of experiments capable of exploring diverse mass 818 scales, dark matter electron scattering, and directional capability in the reconstruction of dark 819 matter interactions. In the coming decade, several accelerator-based projects aiming to produce 820 dark matter particles and particles related to a possible dark sector should also have acquired 821 significant data allowing further direct tests of this paradigm. The search for dark matter through 822 observation of its annihilation signatures will be pursued using a variety of observatories of 823 increasing sensitivity. 824 Canada has a bright future in the search for dark matter and is in an excellent position to 825 seize these scientific opportunities. By the end of the decade, the SuperCDMS experiment 826 at SNOLAB, will have explored a large swath of parameter space for low mass WIMPs and 827 approach sensitivity to the solar and atmospheric neutrino background. In the meantime, CUTE 828 (the Cryogenic Underground Test Experiment) at SNOLAB will enable early exploitation of the 829 SuperCDMS crystals for physics results. The DEAP collaboration has joined the Global Argon 830 Dark Matter Collaboration with the goal of running DarkSide-20k at LNGS in Italy and then 831 a multi-hundred tonne detector ARGO with SNOLAB being the preferred location. The PICO 832 experiment is expected to continue to improve its leading sensitivity in the spin-dependent WIMP 833 sector, while the new SBC experiment will adapt this exciting new scintillating bubble-chamber 834 technology to the search for low mass WIMPs. The NEWS-G experiment is also poised to make 835 interesting contributions to the low mass regime and will explore directional sensitivity using 836 a novel composite central anode in its detector. High-precision accelerator-based dark sector 837 searches will be carried out at ATLAS, Belle-2, NA62, MoEDAL and MOLLER. The DarkLight 838 experiment is also preparing a technical design report for use of the intense ARIEL electron 839 beam on a thin target at TRIUMF to explore dark sectors. Canadians will also take part in 840 the commissioning and operation of a demonstrator for the future MATHUSLA project. Indirect 841 searches for dark matter annihilation will continue at IceCube.

842 New physical principles and structures 843 The Canadian theory community has developed strength across a number of research sub-ﬁelds, 844 and is well-positioned to play an active role in deciphering and interpreting signatures of new 845 particle and astroparticle physics. There are also emerging opportunities for growth in hadronic 846 and nuclear theory, that would enable the community to play a larger synergistic role with the 847 experimental program. In turn, these developments continue to spur efforts to identify underlying 848 structures that can systematize and extend our understanding. 849 The Canadian formal theory community has contributed to and is well-positioned to further 850 develop several areas, including the underlying structure of scattering amplitudes, and the recent 851 developments in understanding the black hole information paradox and Hawking radiation.

852 Hadron Properties 853 In the coming decade, new experimental capabilities and advances on a range of theoretical 854 fronts will help to shed light on nucleon structure and hadron properties. 3.1. Science opportunities for Canada 24

855 Upgraded detectors for GlueX at JLab and at MAMI will extend the reach in precision and 856 available nuclear targets. The proposed JLab Eta Factory (JEF) involves a significant upgrade 857 to the GlueX base instrumentation, enhancing the energy and position resolution, and allowing 858 for unprecedented precision in exotic hybrid meson searches. The Solenoidal Large Intensity 859 Detector (SoLID) at JLab will study Generalized Parton Distributions, which can provide a 860 tomographic 3D picture of the nucleon. Neutron spin polarizability measurements will be possible 3 4 861 with a combination of measurements on He and He at MAMI, with the development of an active, 862 high-pressure helium target. 863 Looking ahead, the future Electron-Ion Collider (EIC) is the only North American collider to be 864 constructed for the foreseeable future and it is on Canada’s doorstep. The new opportunities at 865 the EIC will make it possible to achieve a transformational understanding of the dynamical system 866 of quarks and gluons. There is significant synergy between the EIC and 12 GeV JLab program, 867 with a rich and diverse set of experiments capable of precisely studying QCD, from the nature of 868 the finite temperature many-body problem, to mapping the transition from hadronic to partonic 869 degrees of freedom. Canadian researchers are involved in all these projects worldwide, along 870 with forefront theoretical developments, and are poised to make significant discoveries about 871 hadron structure.

872 Nuclear Structure 873 Developing a predictive understanding of nuclei and their interactions requires a wide variety 874 of complementary experiments and theoretical tools. The coming decade will see the start 875 of operations of new-generation infrastructure that will enable a systematic study of nuclear 876 properties and patterns, potentially opening up a window to new and unexpected phenomena. 877 In Canada, the ARIEL and CANREB facilities at TRIUMF will come online signiﬁcantly 878 extending the physics capability and reach for nuclear structure research. Canadian scientists 879 will also continue to play a decisive role globally by contributing to the development of unique 880 instruments and leading physics programs at RIBF(Japan), FAIR (Germany) and FRIB (USA). 881 The development of new ab initio theory, for both nuclear structure and interactions, is also 882 Integral to this program. The synergy between experiment and theory, in terms of designing 883 the most sensitive experiments and the feedback on the theoretical framework, will be crucial to 884 shape a path towards the overarching goal of the ﬁeld: a predictive standard model of nuclei.

885 Cosmic formation of nuclei 886 The next decade will offer new scientific opportunities in studying heavy element synthesis due 887 to the significant increase in the infrastructure for radioactive beams worldwide, combined with 888 multi-messenger observations of neutron star mergers. For example, it should be possible to 889 directly study key reactions and key nuclei necessary to understand the nuclear pathway during 890 an explosive astrophysical event. 891 Canada is uniquely positioned to assume a leading role in these investigations with the start 892 of operations for the ARIEL and CANREB facilities at TRIUMF. To fully exploit TRIUMF’s future 893 beam capacity, various extensions to and upgrades of existing experimental capabilities are 894 planned. For examples, a LaBr3 array is being planned that aims to achieve a ten fold increase 895 in gamma tagging sensitivity of DRAGON. To enable new directions in reaction cross section 3,4 896 measurements, especially with He, an active target time projection chamber (EXACT-TPC) is 897 also being planned. 898 Offshore infrastructure will also offer unique scientific opportunities. Decay studies of highly 3.2. Infrastructure and Enabling technologies 25

899 charged ions and beta delayed neutron emission will be possible at GSI/FAIR. Neutron skin 900 thickness measurements of neutron-rich nuclei for exploring the equation of state of asymmetric 901 nuclear matter is planned at GSI/FAIR and at FRIB. 902 Future developments in ab initio theory promise to extend the reach to high-mass nuclei 903 utilizing exascale computing power and the development of quantum computing and algorithmic 904 capabilities. In the modeling of compact object mergers a variety of new developments are 905 planned including molecular dynamics simulations. 906 In the longer term, the installation at TRIUMF of a low-energy storage ring with a neutron 907 generator is being explored. This large scale infrastructure project could provide a unique capacity 908 for directly measuring the neutron capture cross sections of rare isotopes.

909 Opportunities arising from synergies with other ﬁelds 910 In the coming decade, knowledge acquired in other research ﬁelds may also help to advance our 911 understanding of the subatomic physics science drivers. Examples include:

912 • Future developments in astronomy and astrophysics; e.g. potential gravitational wave 913 signatures of early particle cosmology, potential signatures of dark matter in a number of 914 future ground-based and satellite observatories, developments in the simulation of galaxy 915 structure and formation, and multi-messenger observations of compact object mergers that 916 could provide insight into the equation of state of high density matter.

917 • Next generation experiments measuring the cosmic microwave background will achieve a 918 signiﬁcant increase in precision in constraining the nature of neutrinos, dark matter, and 919 dark sectors.

920 • Developments in the technology of quantum sensing and computing, and theoretical as- 921 pects of quantum condensed matter are occurring rapidly and are likely to open further 922 opportunities in exploring the subatomic physics science drivers; some examples will be 923 outlined below.

924 Likewise, there are opportunities for future subatomic physics research outcomes to have an 925 impact on other related research ﬁelds:

926 • An experimental measurement of the absolute neutrino mass scale could have direct 927 implications in cosmology.

928 • Precise measurements of new nuclear properties and rates will enable better understanding 929 and modeling of processes in stellar astrophysics.

930 • Developments in accelerator and detector technology are likely to open further opportunities 931 for research into new medical physics diagnostics and treatment.

932 3.2. Infrastructure and Enabling technologies 933 Progress for each of the science drivers depends on many factors, but a variety of infrastructure 934 and enabling technologies are critical for both experimental and theoretical developments. These 935 are described below along with their application to each of the science drivers.

936 3.2.1. Specialized Infrastructure 937 Subatomic physics research is enabled by and critically relies on the development and availability 938 of unique infrastructure, as shown in Fig. 3.1. 3.2. Infrastructure and Enabling technologies 26

Figure 3.1: (Placeholder) Science drivers and enabling infrastructure. 3.2. Infrastructure and Enabling technologies 27

939 Particle Accelerators 940 Particle accelerator infrastructure continues to be a driving force in the development of experi- 941 mental particle and nuclear physics, and is an enabling infrastructure for almost all the science 942 drivers. The ﬁeld of accelerator physics is in turn synergistic with subatomic physics itself, driven 943 by many of the science goals, but with many broader applications. Accelerator infrastructure 944 with signiﬁcant Canadian access and involvement includes: TRIUMF in Canada, LHC at CERN, 945 JPARC and KEK in Japan, Fermilab, JLab, RHIC and the future EIC in the US, and MAMI in 946 Germany. Developments in this type of infrastructure include:

947 • Accelerator R&D, focused on the Superconducting Radiofrequency (SCRF) technology.

948 • Development of high-luminosity beams (neutrinos, electrons, neutrons, kaons, pions, ions, 949 or antimatter), for precision measurements, e.g. at Fermilab and JPARC.

950 • Development of polarized beams of different species.

951 Rare Isotopes 952 Studies of nuclear structure, including those relevant for astrophysical processes that formed 953 the heavy elements, are enabled by rare isotope beams. TRIUMF is a world-class facility that 954 provides unique isotope beams at low energy and near Coulomb barrier energies, a capacity that 955 will grow with completion of ARIEL, with a comprehensive set of detectors for analysis. 956 Complementary capabilities exist at the following offshore rare isotopes facilities with relativistic 957 beams: Facility for Rare Isotope Beams (FRIB) in the USA, Facility for Antiproton and Ion Research 958 (FAIR) in Germany, and the RI Beam Factory (RIBF) at RIKEN in Japan 959 Some of the important areas of development in this type of infrastructure are in beam targetry, 960 beam transport and detector capabilities.

961 Low backgrounds 962 Measurements of rare processes and those requiring high precision depend critically on low 963 background facilities. This enabling infrastructure is critical for experimental progress in searches 964 for dark matter and neutrino properties, and for high-precision tests of fundamental symmetries. 965 Facilities with signiﬁcant Canadian access and involvement include: SNOLAB and TRIUMF 966 in Canada, Gran Sasso in Italy, and WIPP in the US. Speciﬁc developments in this type of 967 infrastructure include:

968 • Ultra-pure materials for 0νββ experiments.

969 • Development of improved material assay techniques.

970 • Production of ultra-clean materials including underground electro-forming of copper and 971 underground pulling of crystals is under investigation and can be developed.

972 • precisely controlled electromagnetic ﬁelds, precisely controlled and monitored beam proper- 973 ties and beam dynamics, high and precisely measured beam polarization, and specialized 974 precision detectors.

975 3.2.2. Enabling tools and emerging technologies 976 Developments in the area of instrumentation, data analysis, theory and computing enable tool- 977 driven revolutions that can open the door to future discoveries. It is therefore important to maintain 978 and further strengthen a research and development environment that stimulates and supports 979 innovation in these areas. 3.3. Research Portfolio 28

980 Detector R&D 981 Detector R&D is key to enabling future discoveries. As such, it is important that the community 982 maintains a diversified portfolio of both generic R&D and R&D activities with a focus on solving 983 the known technological challenges of the next generation of experiments. Instrumentation 984 development for particle physics is both a driver for, and a beneficiary of, progress made in other 985 areas of subatomic physics and other fields of science and industry, and technology innovation 986 often emerges from these synergies. Examples of detector developments include:

987 • radiation-hard semi-conductor devices for tracking detectors in future collider experiments.

988 • high-performance and novel photodetectors (also operating at cryogenic temperature and 989 low dark current).

990 • Low threshold nuclear and electron recoil detection technologies, including quantum sen- 991 sors.

992 • Combined features such as the development of 4D tracking and 5D imaging.

993 Analysis, Theory and Computing 994 Tools for the analysis of ever-more complex data sets, and the development of the theoretical 995 framework to understand the basic laws of subatomic physics need to evolve in concert with 996 experimental techniques. Subatomic physics has driven the development of many analysis 997 technologies, including Monte Carlo simulation for modelling signal and backgrounds, and the 998 machine learning algorithms for data analysis. Meanwhile, developments in phenomenologi- 999 cal modelling, computational technologies and in our theoretical understanding, point to new 1000 connections and synergies. Speciﬁc developments include:

1001 • Machine Learning methodologies in triggering, simulation and data analysis.

1002 • Computing and networking technologies, including cloud and distributed computing to 1003 manage large data sets.

1004 • Quantum Computing and quantum algorithms for reconstructing, simulating, and analysing 1005 data from large particle physics experiments.

1006 • New amplitude calculation techniques, that have allowed higher-order analysis of Standard 1007 Model backgrounds at colliders.

1008 • New theoretical connections and synergies with other ﬁelds, e.g. the use of quantum 1009 information tools in analyzing the physics of black holes.

1010 3.3. Research Portfolio 1011 In order to maximize Canada’s scientiﬁc and societal impact, accounting for all the opportunities 1012 outlined above, the following overarching objectives for the subatomic physics research plan have 1013 been identiﬁed:

1014 • Focus effort on the most relevant research problems.

1015 • Fully exploit Canada’s unique facilities, competitive advantages, and past investments.

1016 • Partner in leading international research projects and deliver on commitments.

1017 • Maintain capacity and ﬂexibility, through R&D support, to explore and develop new scientiﬁc 1018 opportunities.

1019 • Fully engage HQP in all aspects of scientiﬁc research to maximize training outcomes. 3.4. Science Recommendations 29

1020 The LRP Committee sees value for the community in formulating the research plan at any 1021 point in time as a portfolio of research projects, where an optimum balance among various 1022 dimensions would maximize the likelihood of scientiﬁc impact according to the objectives above 1023 while minimizing risk. The axes (or dimensions) of the portfolio include the following:

1024 • Canadian scientiﬁc specialization vs breadth.

1025 • Experimental project lifecycle (R&D and new construction vs operation/science output).

1026 • Guaranteed scientiﬁc output vs high-risk/high-reward.

1027 • Project timeline.

1028 • Theory vs experiment.

1029 With an optimal balance across these dimensions, the portfolio provides a community-led 1030 vision of the future subatomic physics science priorities and the most efﬁcient means to tackle 1031 them. It also conveys both new science opportunities, transversal inter-connections between 1032 research sub-ﬁelds, and the need for additional resources on the longer timelines that are now 1033 common for large-scale subatomic physics projects. 1034 A schematic representation of the current subatomic physics research portfolio, in relation to 1035 the science drivers, is shown in Fig.3.2.

1036 3.4. Science Recommendations 1037 The LRP Committee has developed a number of Science recommendations that build upon the 1038 ongoing research activities, as exhibited in the portfolio, and the emerging research opportunities 1039 outlined above. These recommendations are described below. 1040 Canada is fortunate to have several world-class subatomic physics research labs and facilities. 1041 These include the experimental infrastructure for nuclear and radioactive beam physics at TRI- 1042 UMF, and one of the deepest underground low-background facilities for neutrino and dark matter 1043 physics at SNOLAB. In addition, the Perimeter Institute is one of the premier centres in the world 1044 for various aspects of theoretical physics. These centres conduct research, and also act as focal 1045 points to stimulate collaboration with the global community. Signiﬁcant investments have been 1046 made over the past decade at TRIUMF, including the development of ARIEL, and at SNOLAB in 1047 fully expanding its user footprint. It is a high priority that these investments be fully capitalized 1048 upon to pursue the new science opportunities that they enable.

1049 Science Recommendation: High priority Canadian Infrastructure

We recommend fully capitalizing upon the unique science opportunities provided by the SNOLAB and TRIUMF infrastructure, and by the Perimeter Institute, in the pursuit of the science drivers. 1050

1051 Subatomic physics relies critically on both theoretical and experimental developments, as 1052 it seeks to understand the basic physical laws. It is vital for the health of the community that 1053 theoretical work is pursued along two paths, one that is fully collaborative with nuclear and particle 1054 experiment to interpret and understand data and point to new opportunities, and the other to 1055 explore new theoretical structures and seek to understand aspects of nature that fall outside the 1056 Standard Model, such as the quantum nature of gravity, black holes, and early cosmology. The 3.4. Science Recommendations 30

Proposed Projects R&D Phase Construction Operation Continued Exploitation NuclearCosmic StructureHadron NucleiDark Properties Matter/SectorsNeutrinoEW Properties & SymmetriesBeyondNew Physical Principles

Theory Theory

Rare isotopes TRIUMF: ISAC experiments facilities TRIUMF: ARIEL photo-fission TRIUMF: CANREB TRIUMF: 2nd proton beamline RIBF FAIR Phase-0 FAIR FRIB

Accelerator-based CREX GLUEX SoLID JEF

From quarks and gluons to nuclei Electron-ion collider EIC

Direct dark matter SNOLAB: DEAP SNOLAB: SuperCDMS SNOLAB: PICO-500 SNOLAB: NEWS-G SNOLAB: SBC DS20k ARGO

Accelerator-based TRIUMF: DarkLight TRIUMF/LLNL: BeEST

Neutrinoless SNOLAB: SNO+ double-beta decay nEXO LEGEND

Neutrino IceCube observatories SNOLAB: HALO HALO-1kT P-ONE

Matter in the weakly coupled universe Long-baseline T2K neutrino HK DUNE

pp collider ATLAS ATLAS (HL-LHC)

e+e- collider Belle-2 Chiral Belle ILC FCC-ee

Accelerator-based NA62 MoEDAL MOLLER MATHUSLA PIENUXe

Rare isotopes TRIUMF: Francium experiments facilities TRIUMF: RAMS

Neutron source TRIUMF: TUCAN Nab

Anti-matter source ALPHA-3/g Beyond the electroweak scale HAICU

2020 2025 2030 2035 Year

Figure 3.2: (Placeholder) A schematic representation of the Canadian subatomic physics research portfolio, with current and approved projects shown in solid colours, and potential future projects with concrete timelines at the time of writing shown in hatched colours. 3.4. Science Recommendations 31

1057 Canadian theory community has traditionally had signiﬁcant success in both these directions, and 1058 requires support to enable continuing global impact.

1059 Science Recommendation: Theory

Critical mass and research breadth are vital for the theory community in Canada, to maximize the future impact of subatomic physics research.

We recommend maintaining strong support to ensure the vibrancy of the theory community over the next decade, both to explore new directions and to support the synergistic interaction between subatomic theory and experiment. 1060

1061 The Canadian subatomic physics community has achieved considerable global impact by 1062 carefully identifying experimental projects which address the leading scientiﬁc questions. The 1063 opportunities for the ongoing and future program were outlined above, and the current suite of 1064 projects ﬁlls out the portfolio represented schematically in Fig. 3.2. These considerations lead to 1065 the following recommendations for the experimental program.

1066 3.4. Science Recommendations 32

Science Recommendation: High priority experimental programs

We recommend pursuit of the following scientiﬁc program, which is identiﬁed as essential to address the science drivers.

• From quarks and gluons to nuclei: – Explore the structure of hadrons and nuclei using rare isotope and accelerator- based facilities. • Matter in the weakly coupled universe: – Search for the existence of dark matter using complementary direct and indirect experimental techniques. – Explore the properties of neutrinos through long-baseline experiments, neutrino observatories, and searches for neutrinoless double beta decay. • Beyond the electroweak scale: – Study matter and its interactions at the highest energy possible both directly and indirectly.

This scientific program is currently implemented through Canadian leadership in a set of flagship projects identified based on their potential scientific payoff, Canadian core expertise, the level of community engagement, opportunities for the scientific and technological training of the next generation, and Canadian investments to date:

• Flagship projects with broad physics outcomes – From quarks and gluons to nuclei: TRIUMF ARIEL-ISAC experiments, EIC. – Matter in the weakly coupled universe: T2K/HK, IceCube, SNO+. – Beyond the electroweak scale: ATLAS/ATLAS@HL-LHC, Belle II. • Flagship projects with strategic physics outcomes – From quarks and gluons to nuclei: JLab 12 GeV, Offshore RIB experiments. – Matter in the weakly coupled universe: DEAP, PICO-500, SuperCDMS. – Beyond the electroweak scale: ALPHA/HAICU, MOLLER, TUCAN.

To maximize Canada’s future scientiﬁc impact, we recommend the support of projects and initiatives within the scientiﬁc program (above) that are under development or may be developed in the future, with the potential for high impact.

• From quarks and gluons to nuclei: – The future program should include the full exploitation of TRIUMF and offshore RIB facilities, as well as JLab programs. • Matter in the weakly coupled universe: – The future program should include the search for dark matter, including via multi-ton scale direct detection. – The future program should include the further exploration of neutrino properties via next generation neutrinoless double-beta decay experiments, long baseline experiments and neutrino observatories. • Beyond the electroweak scale: – The future program should include the exploitation of a future Higgs factory, and energy frontier collider, along with high-precision indirect probes.

Potential future projects with ongoing development activities at the time of writing and their timelines are listed in the portfolio presented in Fig.3.2. 1067 3.4. Science Recommendations 33

1068 With the longer term outlook through to 2036 in mind, it is important to emphasize that the 1069 development of future projects depends critically on the ability of the community to explore, 1070 develop and assess the utility of new technologies in a manner that is not tied too closely to their 1071 ﬁnal project application. Canada’s involvement in new domestic and international projects relies 1072 on the capacity to develop and utilize new technologies. However, such generic R&D is not fully 1073 supported within the current project-based funding ecosystem, and we highlight the need for 1074 additional support for this critical aspect that supports the long-term development and progress of 1075 subatomic physics. Science Recommendation: Enabling R&D

We recommend the support of enabling R&D activities for the future development of accelerators and detector technology, and the development and use of emerging technologies including novel computational and analysis tools. 1076 1077 4

1078 Realizing the Research Plan

1079 Bringing the ambitious plans of the Canadian subatomic physics community to fruition will require 1080 support from multiple sources: the major onshore research facilities, TRIUMF, SNOLAB, and the 1081 Perimeter Institute; the universities that support the majority of subatomic physics researchers 1082 including students and postdocs; supporting infrastructure such as high-performance computing 1083 and networking; and the federal funding agencies NSERC and CFI. In addition, the community 1084 will need to be cohesive and inclusive to efﬁciently tackle the science drivers and optimize trainee 1085 success.

1086 4.1. Canadian Subatomic Physics Community 1087 The pursuit of the research plan depends first and foremost on the Canadian community of 1088 subatomic physics researchers. This community has been successful on the global stage through 1089 its organization and a cohesive collaborative approach. It is also truly national, with Fig. 4.1 and 1090 Table 4.1 showing the geographical distribution of grant-eligible investigators in subatomic physics 1091 and its evolution over a time scale of 10 years. The subatomic physics community continues to 1092 be vibrant with strength across all regions in Canada, with significant recent growth in Ontario. 1093 The renewal of senior investigators in the community, at just over 2% per year, is consistent with 1094 the expected retirement rate, but there has recently been additional growth driven in part by the 1095 injection of CFREF funding through the McDonald Institute and the consequent hiring of 12 new 1096 faculty. Further renewal over the coming decade will be needed. In this regard, the TRIUMF 1097 faculty bridge program is effective and such links between universities and national Canadian 1098 facilities could be expanded to further support community renewal. 1099 The research profile of the Canadian community has evolved over the past two decades, 1100 to reflect progress in the field and evolving science priorities. Fig. 4.2 shows the changing 1101 research trends within the community over the past 20 years, for example the increased focus on 1102 neutrino properties and searches for dark matter, consistent with global trends and the presence 1103 of SNOLAB in Canada. Looking forward, given Canada’s primary position hosting TRIUMF and 1104 the start of operation of several new international facilities over the next decade (e.g. FRIB and 1105 FAIR), there are opportunities for growth in the area of nuclear structure. 1106 Subatomic physics is a research field that relies critically on the interplay between theory and 1107 experiment for progress. The Canadian theory sub-community has traditionally comprised roughly 1108 30% of the community as a whole, but the fraction of NSERC-funded theory investigators has

34 4.1. Canadian Subatomic Physics Community 35

British Columbia UBC UFV Newfoundland UNBC MemorialU SFU TRIUMF UVic

Alberta Nova Scotia UAlberta AcadiaU UCalgary StMary’sU ULethbridge Saskatchewan New Brunswick URegina Manitoba Quebec MtAllisonU USaskatchewan BrandonU Ontario ConcordiaU UManitoba CarletonU SNOLAB ULaval UWinnipeg GuelphU UToronto McGillU LaurentianU UWaterloo UMontreal McMasterU WesternU UQAM Perimeter YorkU Queen’sU

Figure 4.1: (Placeholder) The Canadian institutions participating in subatomic physics research in 2021. 4.1. Canadian Subatomic Physics Community 36

Region 2011 2015 2021 BC 86 88 88 Prairies 38 38 40 Ontario 60 66 81 Quebec 35 31 32 Atlantic 6 8 8 Total 225 231 251

Table 4.1: The number of subatomic physics NSERC-funded investigators in 2011, 2015 and 2021, broken down by geographical region.

1109 dropped slightly over the past decade to 24%, while the total number of investigators has grown. 1110 The institutions where theorists work are now more closely aligned with those of experimentalists, 1111 reflecting a convergence to form larger subatomic physics groups. This may reflect the focus 1112 of the global community on ever more complex problems that require greater collaboration. 1113 However, there are emerging opportunities for growth in areas of theoretical physics that are 1114 currently under-represented in Canada, such as nuclear theory, and it is also vital that the two 1115 primary themes of theoretical research - formal development of new principles and structures, and 1116 synergistic phenomenology with experiment - be vigorously pursued. All aspects of theoretical 1117 research benefit from effective channels for communication and collaboration. Building on the 1118 work of existing centres such as the Perimeter Institute, the McDonald Institute, BIRS, TRIUMF 1119 and SNOLAB, there are opportunities to further support the theory community with thematic 1120 workshop programs that have been successful elsewhere around the world, e.g. at institutions 1121 like KITP and the INP in the US, CERN in Switzerland, MITP in Germany, and ECT* in Italy. 1122 The subatomic physics community is also developing cross-disciplinary collaborations with 1123 adjacent research fields, as highlighted in Section 2.9. This is highly valuable, as such col- 1124 laborations have traditionally provided fertile ground for both new theoretical ideas and new 1125 technological applications. There are important overlaps in science goals with areas of astronomy 1126 and cosmology, atomic molecular and optical physics and materials science more generally. 1127 Cross-disciplinary collaborations are also driven by overlapping technological tools, and by the 1128 development of emerging technologies such as quantum sensing. 1129 Beyond the scientific profile of the subatomic physics community, there is also a need to 1130 address broader issues of equity, diversity and inclusion. Canadian society is diverse, and the 1131 celebration of this diversity is an important aspect of our national identity. Moreover, equality of 1132 opportunity and equitable representation are important drivers for the economy and for scien- 1133 tific progress. A national physics-wide community survey by the CAP EDI committee in 2020, 1134 confirmed that diversity within the field did not match the broader society. Indeed, the fraction of 1135 NSERC grant holders in the subatomic physics community who are women has evolved from 12% 1136 in 2016 to 15% in 2021, but remains well below the level of a number of other STEM fields. The 1137 CAP EDI survey indicated that within the wider physics community, these gender disparities are 1138 similar at all levels from undergraduate students to faculty, while the disparities for other equity 1139 groups were more significant for those in later career stages. While the final results of the survey 1140 were not available at the time of writing, the LRP Committee partnered with the CAP EDI survey 1141 team to add questions that would allow data to be dis-aggregated for the subatomic physics 1142 sub-community. Thus, while the initial survey in 2020 provides a baseline, in coming years the 1143 longitudinal data from annual surveys will provide valuable input for the community to assess 4.1. Canadian Subatomic Physics Community 37

100 LRP 2022 2020 90 Preliminary 80 2000 70 60 50 40 Number of Investigators 30 20 10 0 Nuclear AstrophysicsNuclear StructureHadron PropertiesSymmetriesEW and beyondNeutrinosDark Matter/SectorNew Principles

Primary Science Drivers

Figure 4.2: The number of subatomic physics investigators, categorized by the primary science driver of their research, is shown for 2000 and 2020.

1144 progress toward diversity goals, and the inclusivity of the community overall. In this regard, the 1145 efforts led by funding agencies such as NSERC and CFI to ensure that review committees are 1146 diverse, and requiring grant applicants to address EDI initiatives explicitly is welcome.

1147 Community Recommendation: Equity Diversity and Inclusion

The Canadian subatomic physics community lacks diversity, as do some other science and technology ﬁelds. This lack of representation has many causes, and spans the full career range from graduate students to senior faculty. It is widely recognized that diversity is valuable for the research enterprise, and that a lack of diversity in itself creates a barrier to entry into the ﬁeld.

• We recommend the pursuit of further sustained actions aligned with the Tri-Council Dimensions Charter, including regular data-gathering and analysis, targeted initiatives to enhance EDI within community activities, and community use of formal EDI committees through the Institutes to support these efforts and/or coordinate with partners. • We recommend that the subatomic physics community promote balanced representation in high visibility leadership roles, as individuals in these positions are important role models, while recognizing that achieving adequate representation can increase the workload for members from under-represented groups. • We recommend that the subatomic physics community promote inclusion through acknowledgement of the legacy of colonization in Canada, e.g. with the use of land acknowledgements at events held in Canada, consistent with the spirit of the Calls to Action of the Truth and Reconciliation Commission of Canada and of the United Nations Declaration on the Rights of Indigenous Peoples. 1148 4.1. Canadian Subatomic Physics Community 38

Year Grad Students Supervised (Ave/FTE) Grad Student Capacity (Ave/FTE) 2015 2.1 3.7 2020 2.6 3.7

Table 4.2: The average number of MSc and PhD students supervised per FTE, compared with the corresponding capacity for supervision. In 2020, roughly 60% of current graduate students were international.

1149 The Canadian subatomic physics community includes many undergraduate and graduate 1150 students, postdoctoral fellows and research associates, who provide the engine that drives 1151 significant research progress and who receive broad training in a technical and international 1152 research field. This training is an integral component of the subatomic physics research program. 1153 As discussed in more detail in Ch.5, one special feature of training within subatomic physics is the 1154 highly collaborative and international nature of its activities. In this regard, the LRP community 1155 survey highlighted a significant latent capacity for additional graduate student training (see 1156 Table 4.2). This capacity represents a valuable opportunity to maximize both the scientific output 1157 from existing investment, and the training of highly-skilled members of the Canadian workforce. 1158 Career development for new faculty and research scientists within Canada is also critical for 1159 renewal of the research field. Another outcome of the community survey was that Early Career 1160 Researchers (along with all faculty and researchers to a lesser extent) highlighted the ability 1161 to recruit talented trainees as the primary barrier to increased research productivity. There are 1162 opportunities for the collaborative nature of the field to again provide support, through efficiently 1163 sharing of information. It is also recognized that supplemental research funding and time for 1164 research can be highly valuable during the early years of a career. The newly rebranded NSERC 1165 Arthur B. McDonald Early career Research Fellowship program provides such support; an ex- 1166 pansion to match the scale of similar early-career programs in other countries would be valuable 1167 within subatomic physics and in other Canadian research fields to kickstart the careers of new 1168 faculty and research scientists.

1169 Community Recommendation: Training and Career Development

• To enable HQP to receive training that makes use of the national collaborative structure of SAP research, we recommend the coordination and sharing of training opportunities across Canadian centers, institutes, and universities. • To support early career development, we recommend that Early Career Researchers be supported to quickly gain knowledge of the Canadian subatomic physics research support and funding ecosystem, and be given opportunities to interact broadly with the community. 1170

1171 The Canadian subatomic physics community has used self-organization effectively to increase 1172 its global impact, and supported the community Institutes which can provide advocacy to govern- 1173 ment and funding agencies. The LRP processes operating every 5 years are an important part of 1174 community organization, but the LRP Committee also sees value in formalizing some existing and 1175 successful, but less formal, advocacy activities carried out on a more frequent basis, for example 1176 by the community Institutes CINP and IPP.

1177 4.2. Funding 39

Figure 4.3: Subatomic physics average annual funding in different categories over ﬁve year windows, as a function of time. The CFI projects and matching contribution amounts do not include the major CFI awards in support of TRIUMF ARIEL infrastructure, the SNOLAB facility and the Perimeter Institute. The MacDonald Institute (MI) funding portion only corresponds to the funds allocated in direct support for research.

Community Recommendation: Communication and Engagement with Stakeholders

We recommend the formalization (e.g. by CINP and IPP) of a subatomic physics community consultation committee for engagement and advocacy to funding agencies and government. 1178

1179 4.2. Funding 1180 Funding for both Capital and operations is critical to support the subatomic physics research plan. 1181 We characterize the necessary support in the recommendations below.

1182 4.2.1. Capital funding 1183 The subatomic physics community has been successful in securing signiﬁcant support for capital 1184 investment from CFI programs over the past 15-20 years, and the recent moves to allow for more 1185 ﬂexible matching conditions and importantly to regularize the timing of competitions are welcome 1186 in facilitating longer-term planning. CFI capital funding for subatomic physics projects has totalled 1187 $372M since 2002, 52% of which was in direct support of the major Canadian subatomic physics 1188 facilities (TRIUMF, SNOLAB, Perimeter Institute). For 2019-20, the SAP community received 1 1189 $13.5M, or 3.8% of CFI award funding. This level of support going forward will enable substantial 1190 development of new projects in the coming years, as envisaged within the Research Portfolio.

1https://www.innovation.ca/propos/gouvernance/annual-corporate-reports 4.2. Funding 40

300 MI-funded Investigators LRP 2022 NSERC-funded Investigators Preliminary 250

200

150 Number of Investigators 100

0 2011 2021 2006 2007 2008 2009 2010 2012 2013 2014 2015 2016 2017 2018 2019 2020 Year

Figure 4.4: The number of funded subatomic physics investigators over the past 15 years.

Funding Recommendation: CFI Programs

Support for the development of capital infrastructure through CFI has been highly beneﬁcial for the development of subatomic physics research in Canada.

We recommend continuation of this investment at current annualized levels, as this will be critical for the success of the research plan including many of the proposed future initiatives. 1191

1192 4.2.2. Operations funding 1193 The success of Canadian subatomic physics research programs depends critically on both access 1194 to new capital funding to develop and build new experiments, and the operational support to run 1195 the experiments, uncover new science, and train HQP. 1196 The dedicated NSERC SAP Evaluation Section, with its envelope funding model and Project, 1197 Individual, MRS and RTI grant programs, has proven to be beneﬁcial to subatomic physics 1198 research, which can involve large multi-national teams, and longer timelines. With an appropriate 1199 level of coordination and funding, the CFI and NSERC SAP envelope funding structures can 1200 successfully support the subatomic physics community in maximizing its research and training 1201 impact. The community also appreciates that NSERC acted quickly and decisively to minimize 1202 the impact of COVID-19 on Canadian research, implementing valuable extensions and providing 1203 recovery funds in 2020 to mitigate the problems associated with lockdowns and disruptions to 1204 international activities. This has helped the community weather the global pandemic and continue 1205 many of its ongoing research projects. 1206 As noted above, the community has been particularly successful in securing capital support 4.2. Funding 41

40 RTI LRP 2022 MRS Preliminary 35 DG Project DG Individual 30 Inflation curve relative to 2006 dollars Funding (M$) 25

20 15

0 2011 2021 2006 2007 2008 2009 2010 2012 2013 2014 2015 2016 2017 2018 2019 2020 Year

Figure 4.5: NSERC funding allocated to different programs within the subatomic physics envelope within the past 15 years. Support for recurring operations costs (within the Discovery Grant programs, labeled as DG Individual, DG Project/Team, and the MRS program) has grown in recent years. However, over 15 years, this growth has now just caught up to inﬂation. Meanwhile, the portion of funds allocated to capital funding through the Research Tools and Instruments (RTI) program has decreased to a minor fraction of the envelope. CFI has become the primary source of capital funding. Note that the increase to the envelope in 2007 corresponds to a one-time out-of-envelope contribution to SNOLAB operating funds. 4.2. Funding 42

1207 from CFI. However, operations funding has been limited over the past decade. As illustrated 1208 in Figure 4.3, operations funding has not kept pace with capital investments in recent years, 1209 resulting in a significant change to the ratio of capital to operations funding. 1210 In 2019/20, the NSERC SAP envelope of $26M amounted to 0.8% of all Tri-Council funding, 2 1211 and less than 2% of NSERC funding. This is well below the 3.8% of CFI funding awarded to 1212 SAP projects during this period, and points to limitations on the full exploitation of this capital 1213 investment to maximize scientific and training output. Indeed, the SAP envelope has been 1214 essentially flat between 2005 and 2015, which significantly eroded operational support after 1215 accounting for inflation. Since 2015, the envelope has increased by 23% ($5.5M), helping to 1216 alleviate what had become a critical deficit of operational project support. While this increase is 1217 welcome and will help to maximize the science impact of prior capital investments, after adjusting 1218 for 1.5% inflation, it amounts to approximately flat funding in real terms since 2005. 1219 The success and evolution of the Canadian community, and the development of subatomic 1220 physics globally over the past 5 years, justifies further increases in the SAP envelope, as outlined 1221 below:

1222 1. Accommodating the transition of twelve CFREF-supported MI faculty into the SAP envelope 1223 (requiring $1.2M assuming current per FTE funding). These faculty are all embedded within 1224 the subatomic physics community and working on projects with timelines that extend beyond 1225 the CFREF program.

1226 2. Operational funding needs:

1227 (a) Capitalizing on campital investment: The Subatomic physics community has continued 1228 to be highly successful in securing CFI funding for new experimental infrastructure at 1229 both onshore and offshore facilities. To capitalize on these investments, and allow the 1230 Canadian community to be internationally competitive, further operational funding is 1231 required. 1232 (b) Maximizing training opportunities: recent investments in infrastructure at TRIUMF (in 1233 particular ARIEL) and SNOLAB (providing full usage of science user space) creates 1234 the opportunity to grow the global stature of these facilities, and build broad training 1235 opportunities for HQP. This requires sufficient operational support to maximize the 1236 science impact of the facilities. Investments in infrastructure at offshore facilities 1237 such as CERN and JLab also require full operational support to maximize training 1238 opportunities for Canadian HQP. 1239 (c) Developing future flagship projects: as indicated in the portfolio, the next decade will 1240 see the first operation of several new international nuclear facilities (FRIB, FAIR, EIC), 1241 and a new generation of neutrino and dark matter detection experiments. The ability 1242 of the Canadian community to take on effective roles in these transformative projects 1243 will depend on both NSERC SAP envelope funding for operations and CFI and RTI 1244 funds for capital contributions. Full engagement in these projects will require further 1245 increases in the envelope into the second half of the decade.

1246 =⇒ Full pursuit of the proposed research plan, including (a-c) above require a growth 1247 in research capacity and HQP over the next 5 years. Indeed, there is recognition 1248 that the community has the capacity to train 40% more graduate students. With the 1249 current number of investigators, and with average student stipends, this requires

2https://www.nserc-crsng.gc.ca/NSERC-CRSNG/Reports-Rapports/plans-plans_eng.asp 4.3. Infrastructure and Technical Support 43

1250 a $4M increase to the envelope, which would enable a number of the critical 1251 developments outlined above.

1252 3. New opportunities funding (e.g to support the RTI program) continues to very limited, and 1253 restoring this fraction of envelope to a baseline of 5% requires additional funding ($1M)

1254 In total, these arguments support growth of the SAP envelope by $6.2M (in current dollars) 1255 through 2026. This requested growth target would need to scale in proportion to further growth of 1256 the Canadian SAP investigator community. 1257 Operational funding needs associated with 1, 2(a,b), and 3 reﬂect core components of the 1258 research program, and are critical to efﬁciently maximize the return on investment in ongoing 1259 projects, and the infrastructure developed at TRIUMF and SNOLAB and at offshore facilities. 1260 Further timely investment will allow for a more robust engagement with new international facilities, 1261 e.g. as outlined in 2(c), and other emerging opportunities. 1262 The arguments outlined above, in combination with the science recommendations presented 1263 in Chapter 2, lead to the following recommendations for NSERC SAP envelope funding.

1264 Funding Recommendation: NSERC SAP Envelope

To maximize the impact of current and future investments, and to take advantage of future science opportunities, growth of the NSERC SAP envelope is required for operational support.

• The existence of the NSERC subatomic physics envelope structure, and its programs, is highly beneficial for the operational funding of SAP research. We recommend its retention to efficiently support the implementation of the research plan. • Growth of the envelope is required to ensure that the Canadian programs remain globally competitive, maximize the full community capacity for effective HQP training and the return on capital investment, and to ensure sufficient availability of funds for small infrastructure projects and to enable future development. As described above, these arguments lead to a recommendation for growth of the envelope by $6.2M in 2021 dollars over the next 5 years. • We recommend continued support for all the programs available within the NSERC envelope; this includes the MRS program for experimental projects, which critically supports the efficient collaborative use of unique technical resources in the development and construction of new instruments, and the RTI program which provides important support for detector and accelerator development. • We recommend the monitoring and protection of the envelope fraction allocated to fund theory investigators. In addition, the minimum award threshold should not be below the level of funding required for sufficient HQP support, analogous to the minimum funded level in other Physics Evaluation Sections. 1265

1266 4.3. Infrastructure and Technical Support 1267 In addition to capital and operations funding, support for key infrastructure is required to implement 1268 the research plan. 4.3. Infrastructure and Technical Support 44

1269 The major Canadian subatomic physics research laboratories and institutes provide critical 1270 value for the community, and are a core component of Canada’s infrastructure. The national labo- 1271 ratories, TRIUMF for nuclear and particle physics and accelerator-based science, and SNOLAB, 1272 for deep underground astroparticle science, along with the Perimeter Institute for Theoretical 1273 Physics, have global stature and play an important role in positioning Canada in the global 1274 subatomic physics community. These physical facilities are supported by virtual institutes, the 1275 Canadian Institute for Nuclear Physics (CINP) and the Institute of Particle Physics (IPP), with a 1276 membership that collectively encompasses the Canadian subatomic physics investigator commu- 1277 nity. Most recently, an injection of funds from the CFREF program facilitated the establishment 1278 of the McDonald Institute (MI), which supports the sub-community involved in underground 1279 astroparticle science. 1280 Starting with the major experimental laboratories, TRIUMF and SNOLAB, recent investments 1281 (discussed in Chapter 3) will enable growth in their scientific output, and this will require sustained 1282 operational funding to fully exploit those prior investments. TRIUMF has recently transitioned 1283 from a joint venture to a not-for-profit corporation, and continues to rely on 5-yearly federal 1284 funding allocations to support the majority of its operations and programs. SNOLAB continues to 1285 develop, and has been well supported through the CFI MSI program with provincial matching in 1286 Ontario. The flexibility in the MSI program is valuable. However, to fully develop as a global re- 1287 search laboratory, further flexibility to support research-focussed technical staff would be valuable.

1288 Funding Recommendation: Support for Canada’s world-leading Centers

Canada’s large-scale centers for subatomic physics research have global stature, and provide competitive advantages in pursuing high-priority scientiﬁc programs.

We recommend maintaining strong support for Canadian centers (TRIUMF, SNOLAB, Perimeter Institute) so that they remain at the forefront of research worldwide. 1289

1290 The efﬁcient sharing of resources within the subatomic physics community has been impor- 1291 tant for its success. In part, this includes the community-led research supports such as MRS 1292 technical support labs across the country, and the IPP Research Scientist program. The latter 1293 program, which funds eight senior experimental research scientists who are able to lead Canada’s 1294 participation in major international projects, has been critical in enabling Canada to take on 1295 leadership roles in these projects. This value is highlighted clearly in the IPP Brief to the LRP, 1296 which emphasizes that the Canadian particle physics community considers the IPP Research 1297 Scientist program to be its highest funding priority.

1298 Funding Recommendation: IPP Research Scientist Program

The IPP Research Scientist program has had a major impact on Canada’s leadership and contributions to international projects.

We recommend maintaining full support for the IPP Research Scientist program. 1299

1300 The McDonald Institute, currently supported by the CFREF program, has been a signiﬁcant 4.3. Infrastructure and Technical Support 45

1301 addition to the Canadian subatomic physics community since the last LRP. It has supported the 1302 growth of the sub-community focussed on underground and sub-surface observatories seeking 1303 to study neutrinos and dark matter. In particular, this funding has enabled the development of 1304 signiﬁcant technical support programs at partner institutions, and it would be valuable to maintain 1305 this support once the CFREF funding comes to an end.

1306 Funding Recommendation: Arthur B. McDonald Institute

The existence of the Arthur B. McDonald Institute and its research support and outreach programs has added considerable value to the community; its CFREF funding is coming to an end.

We recommend that in addition to growth of the SAP envelope to support operational costs, new mechanisms should be identiﬁed to fund and maintain continuity of the research and technical support programs provided by the Institute. 1307

1308 Subatomic physics has for many years been one one of the leaders in the development of 1309 research computing and networking, with the world wide web famously developed at CERN, and 1310 machine learning tools used for many years in simulation and data analysis. The ongoing and 1311 future computing needs are hard to overstate, with increasing data rates and the need for high 1312 precision modelling and simulation. The subatomic physics community has been a major user of 1313 Compute Canada services, and relies on Canarie for networking infrastructure, along with dedi- 1314 cated support services such as the MRS-funded HEPNET program. With the Canadian research 1315 computing infrastructure undergoing a period of restructuring, with the New Digital Research 1316 Infrastructure Organization (NDRIO), members of the community have been fully engaged. It is 1317 important that the new structures that emerge have the appropriate organization and sufﬁcient 1318 resources to address the speciﬁc needs of the subatomic physics community over the coming 1319 decade.

1320 Funding Recommendation: Canada’s Digital Research Infrastructure

All components of digital research infrastructure (e.g., Compute Canada, Canarie) are critical to the success of subatomic physics research.

We recommend long-term support for the evolving Canadian research computing backbone (including NDRIO) at a level appropriate to address the needs of the subatomic physics research community. 1321

1322 The longer-term 15-year outlook for this LRP brings into focus the importance of enabling 1323 research and development that will facilitate Canada’s participation in new domestic and interna- 1324 tional project opportunities that may emerge in coming years. The development and application of 1325 emerging technologies is critical to assess their utility in enabling progress in subatomic physics. 1326 Efforts that are not directly tied to a speciﬁc project are valuable, but difﬁcult to fund within the 1327 current ecosystem.

1328 4.4. Research Policy 46

Funding Recommendation: Funding for Enabling R&D

New research opportunities are enabled by the development of novel instruments and technologies. This development relies upon the ability to explore technological frontiers in a non-project speciﬁc way.

We recommend that appropriate mechanisms be identified to efficiently fund modest and timely investments in non project-specific R&D activities, that have the potential to address the scientific goals of subatomic physics research. 1329

1330 4.4. Research Policy 1331 Canada’s subatomic physics research program makes use of major onshore facilities such as 1332 SNOLAB and TRIUMF, but also utilizes the best facilities worldwide to conduct research. These 1333 facilities include CERN in Switzerland which hosts the LHC, JPARC and KEK in Japan which host 1334 the T2K and Belle II experiments respectively, JLab in the US, which is one of the major nuclear 1335 user facilities globally, along with smaller engagements in a number of other labs worldwide. 1336 The participation of the community in large-scale global projects is a feature of subatomic 1337 physics research, but also highlights some structural concerns with the Canadian research 1338 ecosystem. In particular, while NSERC and CFI provide valuable support for the development of 1339 projects and project components up to a threshold of $10-20M, there is less structure in place to 1340 facilitate Canada’s involvement in larger-scale projects, or the associated in-kind contributions 1341 that may be needed for participation in international laboratories. Within Canada, examples 1342 of potential large-scale initiatives over the coming decade include an expansion of the science 1343 cavern space at SNOLAB, and the development of a storage ring at TRIUMF. It is also highly 1344 valuable for those labs to continue enabling the participation of Canadians at international offshore 1345 labs, for example by providing in-kind contributions such as those for the LHC accelerator complex 1346 that supports Canada’s participation at CERN and involvement in the ATLAS experiment. This 1347 role is enhanced by the continuing development of world-leading infrastructure and expertise at 1348 these labs. However, it is notable that support by the labs for offshore engagements has often 1349 required an ad hoc negotiation process. 1350 The above concerns highlight the fact that establishing a national structure to oversee the full 1351 life-cycle development and management of large-scale projects with total costs of over $100M, 1352 and a single point of contact to help develop and manage international agreements, would greatly 1353 assist the community in engaging fully in emerging large-scale science opportunities over the 1354 coming decade.

1355 Policy Recommendation: Support for Large-scale Science Endeavours

Coordination of capital costs and operational funding over the life-cycle of large-scale ($100M) science endeavours and infrastructure projects is difﬁcult within the current ecosystem, and we recommend the formation of a new administrative structure to provide this coordination (as articulated, for example in Recommendation 4.7 of the Naylor Report3). 1356

3Canada’s Fundamental Science Review 2017, Investing in Canada’s Future, http://www.sciencereview.ca/ 4.4. Research Policy 47

Policy Recommendation: Canadian Ofﬁce to Engage Internationally

Subatomic physics research is intrinsically global, and increasingly requires complex multinational agreements. We recommend the identiﬁcation of an ofﬁce in Canadian government responsible for engaging with the international community, with the goal to advance major new science initiatives. 1357

eic/site/059.nsf/eng/home. 1358 5

1359 Subatomic Physics and Society

1360 The impact of Canadian subatomic physics research and development activities goes beyond indi- 1361 vidual scientiﬁc endeavours, with many far-reaching contributions to Canadian society. Progress 1362 in subatomic physics inspires and enriches our culture while simultaneously pushing the bound- 1363 aries of technology. Indeed, subatomic physics improves our fundamental understanding of 1364 the physical world while developing enabling technologies like particle accelerators, advanced 1365 electronics, communication and data analysis techniques and trains technically skilled people that 1366 allow Canada to lead the world in discovery and innovation. Subatomic physics also connects 1367 people across cultures and across national and societal boundaries as they ask and seek to 1368 answer fundamental questions while fostering the development of an innovative knowledge-based 1369 economy. Progress in subatomic physics also leads to new commercial opportunities that exploit 1370 subatomic physics technology or discoveries. 1371 The different levels of impact for subatomic physics research can be visualized with an onion- 1372 layer model, with the core subatomic physics community at the centre and the layers representing 1373 increasingly broader sectors of society:

1374 • Collaborating scientiﬁc ﬁelds

1375 • Training for the knowledge economy

1376 • Technological applications

1377 • Commercial opportunities

1378 • Cultural beneﬁts

1379 The ﬁrst of these impact layers, relating to cross-boundary science, was discussed in Section 1380 2.9. We consider the broader areas of impact and the return on investment in subatomic physics 1381 research for Canada in this chapter.

1382 5.1. Subatomic Physics Training for the Knowledge Economy 1383 An important aspect of the subatomic physics program is the training of highly qualified personnel 1384 (HQP). The scope of HQP training within the field is rich and diverse, spanning the gamut from 1385 theoretical constructs, data acquisition and analysis, hardware design and fabrication, testing and 1386 refinement, reporting and promotion, and project management. Training of HQP in subatomic 1387 physics is realized through hierarchical learning utilizing both undergraduate and graduate

48 5.1. Subatomic Physics Training for the Knowledge Economy 49

Figure 5.1: Career plans of current subatomic physics graduate students, from the LRP community survey with a sample size of 106. Similar outcomes for past graduate students were observed from a survey conducted in developing the IPP Brief to the LRP.

1388 students and postdoctoral fellows within university or institute settings. The students participate 1389 in both group and independent activities based on the common themes of a particular research 1390 group. This learning process is augmented with participation in conferences or workshops or 1391 other training opportunities. For example, programs like the TRIUMF Summer Institute or the 1392 Canadian Tri-institute Summer School on Elementary Particle Physics offer unique opportunities 1393 for students to learn and network. 1394 Subatomic physics research has many unique and distinctive features that provide exceptional 1395 opportunities for training and preparation for speciﬁc ﬁelds in the knowledge economy:

1396 • The scope, size and international nature of collaborative networks through which research 1397 is performed. (It is important that in an era of growing security concerns, this openly 1398 collaborative aspect be maintained.)

1399 • The efﬁcient sharing of global research resources and funding.

1400 • The breadth and required interplay between different skills and technologies.

1401 • The breadth of technical and non-technical skills and expertise acquired (e.g., from the- 1402 ory, complex data analysis, to instrumentation and software development, and system 1403 integration).

1404 Graduate students in subatomic physics indeed move on to a range of technical careers, as 1405 summarized in Fig. 5.1. 5.2. Technological applications of SAP research 50

1406 5.2. Technological applications of SAP research 1407 From the development of quantum mechanics to the birth of the internet, subatomic physics has 1408 had an impact on society in many ways. These include the direct impact of technology developed 1409 for research applications. Spinoffs from subatomic physics research have revolutionized medical 1410 treatment, medical imaging, security, wireless networking and fueled economic growth. The 1411 connections include, but are not limited to, the diagnosis and treatment of disease through isotope 1412 production, radiation therapies, nuclear power, nuclear waste management, material science, 1413 and detector development applicable to dosimetry in medical and space applications. Medical 1414 physics infrastructure supported by nuclear physics is a key ingredient in the development of 1415 radio pharmaceuticals. Also, subatomic physics has developed pivotal diagnostics techniques 1416 able to inform effective, safe, radio-therapy. 1417 These developments are spurred by the high level of technological innovation demanded for 1418 progress in subatomic physics research. The community is often required to develop its own 1419 unique instrumentation to make progress in tackling the science drivers, which can lead to broader 1420 applications.

1421 5.3. Commercial opportunities 1422 Over the past five years Canadian researchers have advanced techniques that can save lives 1423 while fueling an economy of tomorrow. In response to the global pandemic, the Mechanical 1424 Ventilator Milano (MVM) Collaboration, an international collaboration of national nuclear and 1425 particle physics laboratories from Italy, Canada, the United States, and other countries, has 1426 leveraged its collective expertise in the design of gas handling and electronic control systems to 1427 develop an economical ventilator for both mandatory and assisted ventilation. The simplicity of 1428 the design, which is made possible by the MVM’s sophisticated control system, allows for ease of 1429 availability of parts, and rapid manufacturing. Guided by medical experts and in cooperation with 1430 industrial partners Vexos and JMP Solutions in Canada, the MVM Collaboration has succeeded in 1431 record time to design, develop, build and certify a safe ventilator in response to the COVID global 1432 crisis. In Canada the effort was led by Nobel Laureate Art McDonald, involving team members 1433 from TRIUMF, CNL Chalk River, SNOLAB and the McDonald Institute. The MVM development 1434 is a prime example of how the expertise of subatomic physicists who are trying to unravel the 1435 mysteries of the Universe can be effectively be utilized to the benefit of society in tackling its other 1436 grand challenges. 1437 The subatomic physics community has a history of mutually beneficial collaboration in a variety 1438 of industry sectors. The exacting production requirements and emphasis on newly emerging 1439 technology can open the door to new development opportunities and commercialization. As 1440 is apparent from the MVM example above, there is also considerable value (and uniqueness) 1441 in the globally connected subatomic physics laboratory and collaboration infrastructure, which 1442 provides the expertise and capacity to pivot and rapidly address new priorities from genesis to 1443 commercialization. 1444 Several other novel collaborations are developing technologies for societal benefit, particularly 1445 in the medical sphere. A few examples are listed below:

1446 • Researchers at TRIUMF and SFU are investigating the use of thorium target material for 1447 medical isotope production.

1448 • Researchers at TRIUMF and Guelph U are teaming up to improve range veriﬁcation in 1449 proton/hadron cancer therapy via gamma-ray spectroscopy techniques. 5.4. Cultural beneﬁts 51

1450 • Researchers at McGill U and U Sherbrooke are collaborating to study the possibility of 1451 using the light emission properties in liquid Xe developed for rare event searches (nEXO) 1452 for medical imaging in PET.

1453 Beyond health research, investigations in the environmental sector are also being pursued. 1454 Examples include the following:

1455 • Researchers at TRIUMF and Calgary are studying water & atmospheric ﬂow/tracking 1456 through radioactive isotope tracing.

1457 • MOLLER collaboration members are working with researchers in the biosciences to investi- 1458 gate the growth behavior of fungi and other plants under extreme environmental conditions 1459 by working on the customization of MOLLER electronics design to produce a small DAQ 1460 system that can be deployed in a remote area, to monitor environmental data.

1461 • SNOLAB and Laurentian U are part of a R&D effort led by the CNSC to improve tech- 1462 nologies for the veriﬁcation of nuclear non-proliferation treaties - spherical proportional 1463 counters (SPCs) developed by NEWS-G could lead the way to a compact and non-intrusive 1464 technology to monitor nuclear reactors and international nuclear safeguarding.

1465 While cutting edge R&D is the life-blood of subatomic physics, opportunities for societal or 1466 commercial benefit need incubation for broader impact. Such incubation can occur through 1467 university technology transfer offices, and in technical transfer centres like TRIUMF Innovations, 1468 the commercialization arm of TRIUMF, dedicated to linking cutting-edge science and technology 1469 to tangible business opportunities. TRIUMF Innovations acts as a connector to the business world 1470 by providing market opportunities for applied physics-based technologies that emerge from the 1471 TRIUMF network—by streamlining access to TRIUMF’s world-class expertise and infrastructure, 1472 and by connecting TRIUMF researchers and technologies to the world via industry partnerships, 1473 licensing, and business development. As one example, through TRIUMF Innovations, IDEON is 1474 moving forward, offering muon detectors for better diagnosis of mining deposits. 1475 Commercialization opportunities are often apparent, driven by the development of new tech- 1476 nology and applications within subatomic physics. However, there are a number of challenges. 1477 Timescales for research are often significantly longer than those that are tolerable for return on 1478 investment within industry. There is also limited time for university faculty and research staff to 1479 develop contacts and nurture relationships with industry. The exacting performance requirements 1480 for cutting edge subatomic physics research may also go beyond what is most viable commercially. 1481 However, in some cases these requirements push the boundaries of manufacturing, and lead to 1482 new and more efficient processes. The current ATLAS silicon tracker upgrade is an example.

1483 5.4. Cultural benefits 1484 Subatomic physics research has a long-lasting impact on society, through the inspiration provided 1485 by gaining a greater collective understanding of the basic laws of nature, and through its highly 1486 collaborative global structure. The excitement generated by new discoveries in the field can serve 1487 to inspire Canadians and be leveraged to attract Canadian youth towards dynamic careers in 1488 science and technology. 1489 Canada has been fortunate to have had several recent winners of the Nobel Prize in Physics; 1490 from Art McDonald in 2015 for the discovery of neutrino oscillations and his leadership role with 1491 the SNO experiment in Sudbury, Ontario, to Donna Strickland’s award in 2018 for high-intensity 1492 laser physics, and Jim Peebles’ award in 2019 for multiple contributions to theoretical cosmology. 5.4. Cultural benefits 52

1493 Beyond these significant peer accolades that reinforce the stature of Canadian subatomic 1494 physics endeavours and enhance public interest and excitement, public outreach is at the core 1495 of subatomic physics activities to support public education and interaction with the community. 1496 Outreach is also critical to EDI, in reaching out to under-represented groups, and seeking to 1497 engage the Canadian public and future students in subatomic physics. The major institutes, 1498 TRIUMF, SNOLAB, the Perimeter Institute, the McDonald Institute and universities have outreach 1499 programs that are an essential core service to help foster impact at all levels - the general public, 1500 elementary and high school students and undergraduate students. It is important to recognize 1501 that outreach efforts take time and effort. There are opportunities for the community to efficiently 1502 support further outreach by partnering with the major centers (TRIUMF, SNOLAB, PI, MI) and 1503 other community organizations. 1504 As we conclude this report, it is important to recognize that the global nature of subatomic 1505 physics research, a field that relies critically on international cooperation and transparency (in this 1506 era of growing security constraints), also has non-negligible environmental impacts in this era of 1507 heightened concerns around climate change. Subatomic physics research facilities are significant 1508 users of power, and this applies broadly to researchers through the wide use of computing 1509 resources. Some facilities also generate radioactive materials, requiring careful decommissioning. 1510 Widespread air travel was also a feature of the research field prior to 2020. With the global 1511 COVID-19 pandemic of 2020 and 2021, the value of online collaboration and communication tools 1512 was fully realized. A silver lining is that this should allow a reduction in the climate impacts of 1513 research-related travel in the future, without significantly affecting the globally connected nature 1514 of subatomic physics research. 1515 A

1516 Case Studies

1517 [Case studies, high resolution images, and quotes are being collected, and will be distributed 1518 throughout the ﬁnal report using call-out boxes to provide concrete examples of impact.]

53 1519 B

1520 Glossary

1521 [Glossary of acronyms used in the report.]

54 1522 C

1523 Terms of Reference

1524 C.1. Context 1525 The Canadian subatomic physics community establishes its scientiﬁc, and thus funding, priorities 1526 through ﬁve-year Long-Range Plans (LRP). These plans advise the Canadian subatomic physics 1527 research community and relevant stakeholders on priorities for both current and future endeavours. 1528 The most recent Long-Range Plan covered the period 2017-2021, in addition to providing an 1529 assumption-based forecast for into 2026. A new LRP exercise is to be conducted. The new plan 1530 will be in effect from 2022 through 2026, with its scope extending through 2036. A renewal of this 1531 2022-2026 plan will occur before 2026. The Canadian Subatomic Physics Long-Range 2022-2026 1532 is jointly supported by the Institute of Particle Physics (IPP), the Canadian Institute of Nuclear 1533 Physics (CINP) and the Natural Sciences and Engineering Research Council (NSERC). The 1534 additional stakeholders, TRIUMF, SNOLAB, the Perimeter Institute and the Canadian Foundation 1535 for Innovation (CFI), are supportive of this process.

1536 C.2. Committee 1537 The LRP process will be driven by the Canadian subatomic physics community. A Committee 1538 will be asked to review this community’s input and to formulate the Long-Range Plan. The 1539 LRP Committee will be composed of an appropriate number of experts who will cover the main 1540 sub-disciplines of subatomic physics in Canada, including both experimental and theoretical 1541 aspects: nuclear physics, nuclear astrophysics, physics of elementary particles and ﬁelds, and 1542 particle astrophysics. The Committee will be co-chaired by senior members of the research 1543 community with an extensive knowledge of the Canadian and international subatomic physics 1544 research environments. The membership may have some overlap with that of the previous LRP 1545 Committee to ensure continuity. 1546 The following representatives from the LRP commissioning bodies will be non-voting members 1547 on the LRP Committee.

1548 • Director of the Institute of Particle Physics

1549 • Executive Director of the Canadian Institute of Nuclear Physics

1550 • NSERC Team Leader working with subatomic physics

1551 • Co-Chairs of the NSERC Subatomic Physics Evaluation Section for 2020-2021

55 C.3. Mandate 56

1552 In addition, the LRP Committee will invite ex ofﬁcio members who will be non-voting observers 1553 and resources for the other members:

1554 • TRIUMF Director

1555 • SNOLAB Director

1556 • Perimeter Institute representative

1557 • CFI Director of Programs working with subatomic physics

1558 The LRP Committee may choose to hold certain closed sessions without the presence of ex 1559 ofﬁcio members.

1560 C.3. Mandate 1561 Taking into account (i) the ever increasing internationalization of projects and collaborations in 1562 addressing the fundamental questions of subatomic physics, (ii) the concurrent requirement to 1563 maintain and further develop world-class domestic research programs and infrastructure, (iii) the 1564 established expertise and strengths of the Canadian community and (iv) the recognition of the fact 1565 that the Canadian subatomic physics community cannot be involved in all research endeavours, 1566 the Committee is asked to identify subatomic physics scientific ventures and priorities that should 1567 be pursued by the community on a five to fifteenyear horizon and that would ensure continuous 1568 Canadian global scientific leadership. Budgetary estimates, both for new capital investments 1569 as well as for operations, must be provided as well, including funding ranges for prioritized 1570 endeavours. These ranges should include funding levels that would allow for a restrained, yet 1571 efficient, contribution to the ventures, as well as levels that would enable a more extensive 1572 contribution. 1573 The Committee’s assessment will be based on a broad consultation with the Canadian 1574 subatomic physics community. The Committee will have to assess the feasibility, technical 1575 readiness and risks associated with particular endeavours. It is crucial that such an assessment 1576 be made through a fair and rigorous process. 1577 The Committee is also asked to consider and discuss factors that affect the subatomic physics 1578 community and to make recommendations on how to possibly lessen any negative impacts they 1579 may have, or enhance any positive ones. Examples of such factors include, but are not limited to, 1580 various funding opportunities, the relationship between funding agencies and other organizations, 1581 the activities of national research organizations, and the international context. 1582 The report should address Equity, Diversity and Inclusion as well as supporting early career 1583 researchers within the context of the subatomic physics research community.

1584 C.4. Process and timeline 1585 The LRP Committee membership recruitment will be completed by Spring 2020, and a kickoff 1586 meeting will be held immediately after. NSERC staff will coordinate membership recruitment in 1587 consultation with the Committee Co-Chairs as well as CINP and IPP. 1588 CINP and IPP will be tasked to prepare briefs for the LRP Committee. These briefs must 1589 summarize the scientiﬁc vision and priorities put forward by the sub-communities they represent 1590 and serve, including both experimental and theoretical facets. Overall recommendations may 1591 also be included in the briefs. It is expected that each institute will broadly consult with the 1592 sub-communities through various formats and ensure a fair and rigorous process. The briefs 1593 are to be submitted to the LRP Committee and to NSERC no later than December 1, 2020. C.5. Deliverables 57

1594 The Institutes must ensure that the briefs are available to the entire community through their 1595 public Web sites. Eventual responses to the briefs by individuals or organizations would be 1596 accepted. Throughout the process, the LRP Committee may also solicit additional input from 1597 various sources, as it sees ﬁt. 1598 The LRP Committee will hold public consultations (town hall meetings) in early 2021, after 1599 receiving the briefs. Face-to-face or phone meetings of the Committee will then be held up to the 1600 Summer of 2021.

1601 C.5. Deliverables 1602 The LRP Committee will submit its ﬁnal report to NSERC, CINP and IPP no later than September 1603 30th, 2021. The report will be publicly released, thereafter, in both ofﬁcial languages.

1604 C.6. Conflicts of interest and confidentiality 1605 All members must strictly comply with the Code of Ethics and Business Conduct for Members of 1606 NSERC Standing and Advisory Committees. Moreover, for the purpose of this exercise, a member 1607 will be considered to be in a situation of conflict of interest during a discussion on prioritization of 1608 a specific endeavour that would directly benefit the member or the member’s organization. 1609 D

1610 Long Range Plan Committee

1611 Membership

1612 D.1. Committee Members Eckhard Elsen CERN, Switzerland Chris Jillings SNOLAB, Canada Rituparna Kanungo St. Mary’s University, Canada Bob Laxdal TRIUMF, Canada Augusto Macchiavelli LBNL, USA Juliette Mammei University of Manitoba, Canada 1613 Jeff Martin University of Winnipeg, Canada Adam Ritz (co-chair) University of Victoria, Canada Niki Saoulidou University of Athens, Greece Kate Scholberg Duke University, USA Brigitte Vachon (co-chair) McGill University, Canada Alex Wright Queen’s University, Canada

1614 D.2. Ex-ofﬁcio Members & Observers Cliff Burgess Faculty, Perimeter Institute (PI) Emily Diepenveen (until Jan 1, 2021) Team Leader, NSERC Jens Dilling Assoc Lab Director, Physical Sciences, TRIUMF Olivier Gagnon Manager, John R. Evans Leaders Fund, CFI Thomas Gregoire NSERC SAPES (co-chair) Jeter Hall (from April 8, 2021) Research Director, SNOLAB 1615 Garth Huber Executive Director, CINP Kevin Lapointe (from Jan 1, 2021) Team Leader, NSERC Alison Lister NSERC SAPES (co-chair) Tony Noble Scientiﬁc Director, McDonald Institute (MI) J. Micheal Roney Director, IPP Nigel Smith (until April 8, 2021) Executive Director, SNOLAB 1616

58 1617 E

1618 Long Range Planning process

1619 E.1. Timeline 1620 The planning process conducted by the SAP LRPC is outlined in this section. It is important to 1621 highlight that all stages of the process in 2020 and 2021 were conducted during the COVID-19 1622 pandemic, which required that all meetings of the LRPC and all public townhall consultations 1623 were virtual and conducted via videoconference. The use of virtual meetings, which were broadly 1624 accessible to members of the community including students, allowed the LRPC to hold a number 1625 of topical townhall meetings, to expand the consultation phase of the planning process. 1626 The LRP Committee met every 2-3 weeks through the planning process via videoconference, 1627 and the main stages in the planning process are summarized below:

1628 Launch of the SAP LRP process 1629 • June 11, 2020 - CAP CINP-IPP joint session

1630 • June 22-23, 2020 - CINP townhall

1631 • July 15,16,21, 2020 - IPP townhall

1632 Environmental Scan 1633 • Sep/Oct 2020

1634 – Analysis of historical funding data from NSERC and CFI 1635 – Analysis of national long-range plans:

1636 * Canadian SAP LRPs from 2006, 2011 and 2017 1637 * Canadian Astronomical Society LRP 2020 1638 * US P5 Report 2014, and the ongoing SNOWMASS process for 2020 1639 * US Nuclear Science LRP 2015 1640 * European NuPECC LRP 2017 1641 * European Particle Physics Strategy Update 2020.

1642 • Nov 2020 - SAP LRP Community survey

1643 – 370 grant-holder and HQP respondents to survey questions on research activities, EDI 1644 and outreach

1645 • December 1, 2020

59 E.2. Conﬁdentiality and Conﬂicts of Interest 60

1646 – CINP and IPP Position papers 1647 * Position papers submitted to the LRP by the Canadian Institute of Nuclear Physics 1648 (CINP) and the Institute of Particle Physics (IPP). These documents summarize the 1649 existing research activities and future plans and priorities of those communities.

1650 Community Consultation

1651 • Topical Townhall 1: Subatomic Physics Community

1652 – Feb 16, 2021 - Education, Training and Careers 1653 * moderated Q&A session 1654 – Feb 17, 2021 - Equity, Diversity, Inclusion, Early Career researchers, Community 1655 organization 1656 * moderated Q&A session

1657 • Topical Townhall 2: Subatomic Physics Science Opportunities

1658 – Mar 8, 2021 - Science Planning and Opportunities 1659 * international panel discussion and moderated Q&A session 1660 – Mar 10, 2021 - Subatomic Physics Connections: Interfacing to other ﬁelds and society 1661 * panel discussion and moderated Q&A session

1662 • Emerging themes consultation document (released April 16, 2021)

1663 • LRP Community Townhall

1664 – April 20, 2021 - Canadian subatomic physics in 2021 1665 * summary of funding data and community survey 1666 – April 21, 2021 - Feedback on emerging themes 1667 * moderated Q&A discussion of emerging themes document

1668 Report Preparation

1669 • June 11, 2021 - LRP draft recommendations presented for feedback (CAP Congress)

1670 • August 3, 2021 - draft report v1 released for community feedback

1671 • September 10 (TBC), 2021 - draft report v2 released for community feedback

1672 • September 30, 2021- LRP report text ﬁnalized

1673 • December 2021 (TBC) - formatted bilingual report completed.

1674 E.2. Confidentiality and Conflicts of Interest 1675 As described in section C6 of the Terms of Reference, all LRPC members were required to comply 1676 with the Code of Ethics and Business Conduct for Members of NSERC Standing and Advisory 1677 Committees. Moreover, for the purpose of this planning exercise, members were considered to 1678 be in a situation of conflict of interest during a discussion on prioritization of a specific endeavour 1679 that would directly benefit the member or the member’s organization. 1680 To manage conflicts of interest, all members declared their interests in writing when joining 1681 the committee, or when those interests changed. These declared interests were circulated 1682 confidentially to all LRPC members for transparency. Members were requested to remain silent 1683 during specific discussions for which they had a declared conflict of interest.