\section{International facilities} \label{sec:IntFac}

\subsection{Thomas Jefferson National Accelerator Facility} \label{sec:IntFac:jlab}

\href{https://www.jlab.org/}{Jefferson Lab (JLab)} is the world's
largest nuclear physics user facility, numbering nearly 1700 users, which is an increase
of nearly 50\% since 2013.
%GH: numbers from JLab Director presentation in July 2020.
Canadians are the third largest international group at JLab, behind France and
Italy. 
The JLab 12-GeV Upgrade, enabling a doubling of the available electron beam
energy and the construction of a suite of new detectors, was completed in
2017, opening up many
new physics opportunities that have been rated very high merit by a wide
variety of scientific reviews.  Canadians have leading roles in several high profile experiments that are either currently acquiring data, or scheduled to acquire data in the near future, including the GlueX experiment in Hall D, and the pion form factor experiment in Hall C.

Over the course of this long range plan, Canadian efforts at JLab will revolve around several new initiatives, in which they take leading roles:
\begin{enumerate}
\item
 JEF - JLab Eta Factory involves a significant upgrade of the GlueX base instrumentation by replacing the inner section of the GlueX forward calorimeter (FCAL) with a higher-granularity detector (FCAL-II), and is planned to come online in 2024.  See Sec.~\ref{sec:qcd_jef}.
     \item
     The MOLLER experiment aims to make the world's most precise off-resonance measurement of the \emph{weak mixing angle}, using polarized electron-electron scattering.  The ``early finish'' for the construction project is July 2025, but the DOE schedule provides float until 2027. This will be followed by roughly 3 years of data taking and probably two additional years of analysis effort. The Canadian group is responsible for the development of the integrating detector array, for which a proposal was submitted to the 2020 CFI competition, as well as other important aspects of the project.  See Sec.~\ref{sec:funsym:moller}.
     \item
     The Solenoidal Large Intensity Detector (SoLID) will use the latest detector and
readout technology to enable an increase in luminosity by a factor of 10
compared to existing detectors.  SoLID is in an advanced stage of project
planning, with Canadians contributing to Cherenkov detector R\&D and
construction.  SoLID will see continuing scientific activity through 2036.  See Sec.~\ref{sec:qcd_solid}.
\end{enumerate}

In order
to capitalize on this leadership and the noteworthy scientific opportunities,
these Canadian efforts should be supported with high priority.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{CERN (Antiproton Decelerator and ELENA)}  \label{sec:IntFac:cern}

The Antiproton Decelerator (AD) at CERN is the world’s only facility which provides
low energy antiproton beams.
The ALPHA--Canada collaboration at the  \href{https://home.cern/science/accelerators/antiproton-decelerator}{Antiproton Decelerator at CERN} draws upon Canadian expertise in atom, laser,
microwave and trap techniques that are common to other CINP projects, such as
the TITAN, CPT, TRINAT, FrPNC, and UCN experiments.  ALPHA--Canada is the single
largest group in ALPHA, consisting of about 1/3 of the international
collaboration.  The Canadian contributions to the ALPHA program are very
significant, and they have leading scientific and technical impact within the
collaboration.

%GH: text from ALPHA_Canada_brief.tex
Construction of a second generation apparatus – ALPHA-2 – was enabled by significant Canadian contributions. It provides optical access to trapped antihydrogen for laser spectroscopy, which was not previously possible. During the current LPR period---using ALPHA-2---we have realized dramatic increases in trapping rates and exciting physics results, including 10$^{-12}$ level laser spectroscopy, 10$^{-5}$ level microwave spectroscopy, and a first-ever demonstration of H laser cooling. ALPHA-3 upgrades ALPHA-2 with state-of-the-art laser and frequency metrology.
In parallel, a new apparatus, ALPHA-g, has been constructed to directly measure the effect of gravitational force on antimatter---for the first time. ALPHA-Canada is a leading player in this project, with more than 80\% of the construction funds coming from Canadian sources.

ELENA — Extra Low ENergy Antiproton — is a major upgrade to the AD,
and will further slow antiprotons from the AD (5.3 MeV) to the 100 keV regime, while
serving the beams simultaneously to up to four experiments. After several years of
development, ELENA is expected to deliver its first beams for ALPHA in 2021. The
advent of ELENA will ensure antiproton physics opportunities at CERN for the next 10+
years.
HAICU is a proposed R\&D initiative by ALPHA-Canada, and its initial goal is to
develop quantum sensing techniques in Canada, using atomic hydrogen and other cold
atoms as a proxy for antihydrogen. Such techniques, once demonstrated, will be
developed at CERN for experimentation with antihydrogen atoms at unprecedented
precisions.

The combined capabilities of the ALPHA-3 and ALPHA-g infrastructures at CERN, and the R\&D platform HAICU at home in Canada, will offer tremendous opportunities for fundamental science and advanced HQP training. These initiatives will enable Canadian scientists and their HQP trainees to capitalize on very significant investments, from Canadian and international sources, in ALPHA’s research infrastructure. They will directly result in precision tests of fundamental symmetries, and of some of the most basic assumptions in physics.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Canadian involvement in the Electron-Ion Collider (EIC)} \label{sec:eic4}

%GH: text from EIC_Canada_Brief.tex

The \href{https://www.bnl.gov/eic/}{Electron-Ion Collider (EIC)} is a major new collider facility to be built at Brookhaven National Laboratory on Long Island, New York, by the US Department of Energy in the current decade. At the EIC, polarized electrons will collide with polarized protons, polarized light ions, and heavy nuclei at luminosities far beyond what is currently available. The facility will answer several fundamental questions central to completing an understanding of atoms and integral to the agenda of nuclear physics today.

The EIC project achieved two milestones in 2019-2020, with the first critical decision (CD-0) establishing mission need, and with the site selection of Brookhaven National Lab. The project aims to complete the next three critical decisions by the end of 2023, and to start operations by 2030. The EIC Users Group is coordinating the international efforts to instrument the two interaction regions of the collider, with Expressions of Interest invited by November 2020.

Canadian subatomic physicists have participated intensively in the planning of this new facility and have chartered a multi-institutional EIC-Canada Collaboration to coordinate participation. 
Expanding on programs in experimental and theoretical nuclear physics, hadronic physics, heavy ion physics, and electroweak physics, Canadian participation in the Electron-Ion Collider will focus on detector design and physics program development (2022--2026), detector construction (2026--2030), and operations (2030 and beyond).

The Electron-Ion Collider (EIC) will consist of a polarized electron ring with a variable beam energy from 10 to 20~GeV, and an ion ring with a variable beam energy from 50 to 250~GeV, allowing for beams of polarized protons, deuterons and $^3$He, as well as unpolarized nuclei up to lead and uranium. This range of energies will allow for center of mass energies $\sqrt{s}$ from 20 to 100~GeV (upgradeable to 140~GeV) with a collision luminosity $\mathcal{L}$ of 10$^{33-34}$~cm$^{-2}$ s$^{-1}$ (optimal luminosity of 10$^{34}$~cm$^{-2}$ s$^{-1}$ at $\sqrt{s} \approx 105$~GeV, about 1000 times larger than at HERA, the only previous electron--proton collider). Despite the high luminosity, the interaction rate and multiplicity/occupancy rate are manageable compared to the proton--proton collisions at the Large Hadron Collider (LHC). Event rates up to $10^5$~Hz per unit solid angle are expected.

The EIC will be built at the Brookhaven National Laboratory in Upton, New York, where the Relativistic Heavy Ion Collider (RHIC) has collided two beams of polarized protons or of unpolarized heavy ions with each other for the past two decades in the STAR and PHENIX experiments. The EIC project will require the addition of a new rapid-cycling polarized electron synchrotron, and the upgrade of one of the existing hadron ring with electron cooling and new spin transport elements (see Figure~\ref{fig:facil_eic_schematic}).

\begin{figure}[htbp]
\begin{center}
%\vspace{-0.5cm}
\includegraphics[width=3.5in]{Figs/EIC-Schematic_WhiteBG.png}
\vspace{-0.2cm}
\caption{\label{fig:facil_eic_schematic}
The Electron Ion Collider adds a polarized electron beam to the existing Relativistic Heavy Ion Collider (RHIC) accelerator complex with its two hadron rings, substantially avoiding the need for civil construction. Two interaction regions will allow for dedicated collider detectors.}
\end{center}
\end{figure}

The high luminosity means that the electron beam must be injected from the polarized source with its final polarization of 85\% and in flexible spin patterns, building on the operational experience of the Jefferson Lab program. The RHIC facility has operated successfully with polarized proton beams of 80\%, and has demonstrated a polarized $^3$He source at 85\%.

Two interaction regions will each allow for a collider detector. Due to the asymmetric nature of the collision (in contrast to, \textit{e.g.} Belle-II or the LHC), the detectors are highly asymmetric.
Three classes of events are of interest and determine the detector requirements.
\begin{itemize}
    \item \emph{Inclusive measurements} ($ep/eA \to e'X$), in which either the scattered electron or the full scattered hadronic debris is detected with high precision, require good electron identification and excellent electron energy/momentum and angular resolution.
    \item \emph{Semi-inclusive measurements}, in which the scattered electron is detected in coincidence with at least one hadron, require hadron identification ($\pi^\pm$, K$^\pm$, p$^\pm$) over a wide kinematic range, and good vertex resolution for charm and bottom separation.
    \item \emph{Exclusive measurements}, in which all scattered particles are detected, require high rapidity coverage, including a zero degree calorimeter for neutrons/photons.
\end{itemize}
Based on these requirements, detectors will be developed by several international consortia. The first phase of this process is currently underway through a Yellow Report process, and Expressions of Interest (EoIs) by countries or geographical regions interested in potential EIC equipment cooperation are due by November 2020. An EoI from the EIC-Canada Collaboration will be among them.

The EIC-Canada Collaboration anticipates that the next 5 years will be a period of growth. Opportunities exist for subatomic physics groups with detector technology expertise to join the EIC-Canada Collaboration. The current members are in leadership positions in the detector development and physics working groups, as well as the software working groups.
The start of the first North American collider of this century will be associated with significant scientific interest. In the first years of the 2030s, significant new results will be published by the two detector collider collaborations.  It is anticipated that the Canadian participation in the first new North American collider in this century will become similar in scope as, \textit{e.g.}, the Canadian participation in the Belle-II experiment.

There is significant synergy in the physics programs of the Electron-Ion Collider and the Jefferson Lab 12 GeV facility. As the Electron Ion Collider program is ramping up, the Jefferson Lab 12 GeV program continues to take advantage of the energy upgrade completed in 2017. As of summer 2020, there are another 11 years of physics experiments approved for running at Jefferson Lab, with additional experiment proposals evaluated annually. The Jefferson Lab leadership is currently engaging in a 1-year idea gathering effort to define how their mission will be reshaped or expanded in the 2030s. However, this is unlikely to include a hardware project of similar scope as the Jefferson Lab 12 GeV upgrade or the Electron-Ion Collider construction. With the completion of the upgraded detector construction and commissioning (including the GlueX experiment that is in its third year of data taking), this bandwidth has become available to Electron-Ion Collider detector design and construction efforts. While EIC-Canada anticipates an increasing focus on the Electron Ion Collider program, this will not come at a cost to the Jefferson Lab 12 GeV program. Canadian participants remain committed to the success of the Jefferson Lab parity program, a unique program world-wide.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\subsection{Leveraging opportunities at other facilities world-wide} \label{sec:IntFac:others}

The Canadian contributions at the facilities listed below (in alphabetical order) are smaller but they nonetheless have significant impact within their respective collaborations.
Each are worthy of funding on their own merits.  In some cases, the
investigators have indicated that their efforts are expected to wind down over
the next years, whereas the efforts at new major radioactive beam facilities that are presently under contruction, like FRIB and FAIR, will increase over the next decade.

%%%%%%%%%%%%%%%%%%%%%%
\subsubsection{Argonne National Laboratory (ATLAS), USA}\label{sec:IntFac:others:ANL}

%need also to mention 
Canadian physicists use beams from the in-flight reactions or the CARIBU (Californium Rare Isotope Breeder Upgrade) fission fragment source at the \href{https://www.phy.anl.gov/atlas/}{ATLAS facility} for nuclear structure and astrophysics studies. The Canadian Penning Trap (CPT) mass spectrometer (see Sec.~\ref{sec:NA:CPT}), originally constructed for use at the TASCC facility of the AECL Chalk River Laboratories, has been
operational at Argonne National Laboratory since 2001. Its mass measurement program is complementary to that carried out with the TITAN facility at ISAC (Sec.~\ref{sec:nucstruc:titan}). 
%Iris: Can I say something like this???
However, the future involvement of Canadian groups in the CPT program reaches an a natural end due to faculty retirements.

A temporary setup at Argonne is the \href{https://groups.nscl.msu.edu/SuN/SuN_info.php}{SuN (Summing NaI(Tl))} total absorption spectrometer from Michigan State University. In collaboration with the University of Guelph neutron capture cross sections will be constrained via the ``$\beta$-Oslo method" (see Sec.~\ref{sec:NA:SuN}). 

%%%%%%%%%%%%%%%%%%%%%%
\subsubsection{Duke University Free-Electron Laser Laboratory (DFELL), USA and Mainz Microtron (MAMI), Germany}

At the Duke University Free-Electron Laser Laboratory in North Carolina has been a considerable investment of Canadian infrastructure from the
former Saskatchewan Accelerator Laboratory to the High Intensity Gamma Source
(HI$\gamma$S).  

The MAMI accelerator complexin Mainz is planned to wind down operations over the next 5--7 years.  Canadian plans are to transition efforts to JLab, the Duke facility, and the new EIC.

%%%%%%%%%%%%%%%%%%%%%%
\subsubsection{Facility for Antiproton and Ion Research (FAIR), Germany} \label{sec:intfac:fair}

\href{https://fair-center.eu/}{FAIR} at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt/Germany is the largest of the next generation of radioactive beam facilities that are presently under construction. First beams are expected within the next 5 years. As for the other two in-flight fragmentation facilities, RIBF and FRIB (Sec.~\ref{sec:intfac:ribf} and \ref{sec:intfac:frib}), the research program is largely complementary to the nuclear structure and astrophysics program carried out at TRIUMF-ISAC. 

Canadian scientists are involved in various independent research programs under the NUSTAR umbrella . Examples are reactions with relativistic beams in the SUPER-FRS collaboration (see Sec.~\ref{sec:nucstruc:relatavistic}) and $\beta$-delayed neutron experiments within the DESPEC collaboration (see e.g. Sec.~\ref{sec:NA:briken}). In addition, Canadian scientists are heavily involved in the design and construction of detectors for the ILIMA research program at the existing Experimental Storage Ring (ESR) and the future Collector Ring (CR) (see Sec.~\ref{sec:nucastro:esr}). This collaboration is crucial as seed for the future plans of a heavy-ion storage ring coupled to the TRIUMF-ISAC facility (see Secs.~\ref{sec:NA:beyond} and \ref{sec:isacupgrade} ).

%%%%%%%%%%%%%%%%%%%%%%
\subsubsection{Facility for Rare Ion Beams (FRIB), USA} \label{sec:intfac:frib}

\href{https://frib.msu.edu/}{FRIB} at Michigan State University/USA is one of the next generation of radioactive beam facilities that are presently under construction. First beams for commissioning of setups are expected by late 2021/ early 2022. As for the other two in-flight fragmentation facilities, RIBF and FAIR (Sec.~\ref{sec:intfac:ribf} and \ref{sec:intfac:fair}) , the research program is complementary to the nuclear structure and astrophysics program carried out at TRIUMF-ISAC. Canadian nuclear physicists were involved in experiments at the former NSCL and will continue to contribute to the exciting science program that FRIB will enable.

%%%%
%GH: text from Gwen, Nov 6

\subsubsection{Grand Accelerateur National d'Ions Lourds (GANIL)}

%%%ID 29/11/2020 shortened version version
\href{https://www.ganil-spiral2.eu/}{GANIL} is France's national heavy-ion facility and is one of the premiere research centers that specializes in the production of a wide variety of intense stable and rare-isotope beams for nuclear physics research and applied nuclear science.  The facility can produce fast rare isotope beams by in-flight projectile fragmentation at the LISE facility or with the Isotope Separation Online (ISOL) at the SPIRAL facility.

In 2020, the facility commissioned the SPIRAL2 superconducting linear accelerator that will be used to accelerate light ion beams (protons, deuterons, and helium) to 40~MeV with very high intensities of up to 5~mA.  Canadian physicists collaborate with GANIL staff on nuclear instrumentation and detector development projects as well as conduct research at the GANIL facility on the structure of nuclear matter (Sec.~\ref{sec:nucstruc}), nuclear astrophysics (Sec.~\ref{sec:nucastro}), and low-energy precision tests of fundamental symmetries (Sec.~\ref{sec:funsym}).

%%%ID 29/11/2020 Original long version
%\href{https://www.ganil-spiral2.eu/}{GANIL} is France's national heavy-ion facility and is one of the premiere research centers that specializes in the production of a wide variety of intense stable and rare-isotope beams for nuclear physics research and applied nuclear science.  After accelerating stable primary beams ranging from C to U to high energies ($<$100~MeV/u) in the coupled cyclotron facility, fast rare isotope beams are produced by in-flight projectile fragmentation at the LISE facility.  These high-energy primary beams can also be sent to the SPIRAL facility where they are stopped in a thick graphite target to produce radioactive beams at low energies (60~keV) using the Isotope Separation Online (ISOL) method.  These low-energy SPIRAL beams can be used directly for experiment or they can be injected into a third cyclotron for post acceleration to intermediate energies ($<$25~MeV/u).  In 2020, the facility commissioned the SPIRAL2 superconducting linear accelerator that will be used to accelerate light ion beams (protons, deuterons, and helium) to 40~MeV with very high intensities of up to 5~mA.  Canadian physicists collaborate with GANIL staff on nuclear instrumentation and detector development projects as well as conduct research at the GANIL facility on the structure of nuclear matter (Sec.~\ref{sec:nucstruc}), nuclear astrophysics (Sec.~\ref{sec:nucastro}), and low-energy precision tests of fundamental symmetries (Sec.~\ref{sec:funsym}).


%%%%%%%%%%%%%%%%%%%%%%

\subsubsection{Mainz Energy-Recovering Superconducting Accelerator
(MESA), Mainz, Germany}

\href{https://www.mesa.uni-mainz.de/eng/}{MESA} is a high current electron accelerator that is under construction in Mainz, Germany. The Canadian MOLLER group is pursuing a synergistic opportunity to contribute to the P2 parity violation experiment there, as it will use the same detector electronics being developed by this group for the MOLLER experiment at JLab.  Beam operation is foreseen to start in 2023.
%%%%%

\subsubsection{Oak Ridge National Laboratory (SNS) and National Institute of Standards and Technology (NIST), USA}
%GH: info from cold_neutron_Nab_brief.tex

As discussed in Sec.~\ref{sec:funsym:neutron}, Canadians have been
involved in fundamental neutron studies using the \href{https://neutrons.ornl.gov/sns}{Spallation Neutron Source
(SNS)} at Oak Ridge.  
The Nab experiment will begin collecting data in 2021 and continue until 2024. after which spin polarized cold neutrons will be used with the same apparatus to measure the neutron beta decay correlation coefficients  ``big A'' and ``big B''. 

The BL3 experiment, at the \href{https://www.nist.gov/ncnr}{NIST Center for Neutron Research}, in Gaithersburg, Maryland, will achieve an improvement on the precision of the neutron lifetime using the ``beam'' method that will resolve the long-standing discrepancy between the ``beam'' and ``bottle'' methods.  
The project infrastructure proposal is currently under review by the US National Science Foundation under the Mid-Scale Infrastructure program (\$3M).  The experiment intends to run by 2025.

In the long term (beyond 2029), Canadian work at both facilities are expected to gradually ramp down, as efforts are diverted to the MOLLER experiment at JLab and the EIC.

%%%%%%%%%%%%%%%%%%%%%%
\subsubsection{RIKEN Nishina Center (RNC), Japan}\label{sec:intfac:ribf}

The \href{https://www.riken.jp/en/research/labs/rnc/}{RIKEN Nishina Center} in Wako/ Japan operates the Radioactive Ion Beam Factory (RIBF), which can produce the presently most intense exotic radioactive beams by in-flight fragmentation. The research program carried out at RIBF is complementary to the nuclear structure and astrophysics program carried out at TRIUMF-ISAC. The experimental program of Canadian scientists comprises reactions with relativistic beams (see Sec.~\ref{sec:nucstruc:relatavistic}), as well as the measurement of $\beta$-delayed neutron emitters with the BRIKEN setup which will conclude in 2021 (see Sec.~\ref{sec:NA:briken}).

%%
%GH: text supplied by Greg Christian
\subsubsection{Texas A\&M University Cyclotron Institute}\label{sec:intfac:texas}
The \href{https://cyclotron.tamu.edu/}{Cyclotron Institute at Texas A\&M University} delivers heavy-ion beams in a wide range of energies using its K150 and K500 cyclotrons. In-flight rare-isotope beams created with the MARS separator are also available. Canadian scientists making use of this facility focus on indirect measurements of astrophysical capture reactions, e.g. through measurements of transfer cross sections or decay branching ratios. A particular emphasis placed on experiments that directly complement work being done at TRIUMF.
