Coordinates: 49°14′52″N 123°13′50″W / 49.247792°N 123.230596°W / 49.247792; -123.230596TRIUMF is Canada's national particle accelerator centre. It is considered Canada's premier physics laboratory, and consistently regarded as one of the world's leading subatomic physics research centers. Owned and operated by a consortium of universities, it is on the south campus of one of its founding members, the University of British Columbia in Vancouver, British Columbia. It houses the world's largest cyclotron, a source of 520 MeV protons, which was named an IEEE Milestone in 2010. Its accelerator-focused activities involve particle physics, nuclear physics, nuclear medicine, materials science, and detector and accelerator development.Over 500 scientists, engineers, technicians, tradespeople, administrative staff, postdoctoral fellows, and students work at the site. It attracts over 1000 national and international researchers every year, and has generated over $1 billion in economic activity over the last decade.To develop TRIUMF's research priorities, physicists based at the facility and the university follow the Natural Sciences and Engineering Research Council's (NSERC) long-range plan for subatomic physics. TRIUMF also has over 50 international agreements for collaborative research.Asteroid 14959 TRIUMF is named in honour of the laboratory.
We have developed a new array of organic glass scintillator detectors, consisting of up to 20 3cm×3cm×3cm scintillator cubes, each coupled to a photomultiplier tube. The array is sensitive to neutrons with energies ranging from a few hundred keV up to several tens of MeV. It was designed to be coupled with a recoil separator for inverse-kinematics direct measurements of astrophysical (α,n) or (p,n) reactions, where it provides a prompt start signal for identifying recoil-neutron coincidences from the recoil time of flight. In this article, we present the results of both source and in-beam measurements characterizing the properties of a subset of eight detectors used for a measurement of the 22Ne(α,n)25Mg reaction in inverse kinematics. We report specifically on the detectors’ energy and timing resolution and pulse shape discrimination capabilities. From the widths of γ-ray Compton-edge peaks at 311, 341, 477, and 1062 keVee, we find that the energy resolution as a function of energy is well described by FWHM(E)/E=A2/E+B2/E2+C2, with A=0.00(7), B=0.0618(54), and C=0.135(5). From analyzing the time difference spectrum between nearest-neighbor γ-γ coincidence events in the energy range ∼250-600 keVee, produced by a 22Na source, we find an FWHM coincidence timing resolution of 910(40) ps, implying a single-detector time resolution of 640(30) ps. Using mixed neutron-γ-ray fields produced by both the in-beam 22Ne(α,n)25Mg reaction and a 241AmBe source, we find that the pulse shape discrimination provides n-γ separation with a figure of merit >1 down to a threshold of around 100 keVee. Additionally, we demonstrate that the total neutron yield below 100 keVee can be extracted from two-Gaussian fits to energy-gated pulse-shape discrimination spectra. We also discuss the results of Monte Carlo simulations to determine the array’s neutron detection efficiency in its present configuration. Simulating the present 22Ne(α,n)25Mg measurements, we find a neutron singles detection efficiency of 1.56(45)%, with the uncertainty dominated by systematic effects related to the simulation’s input parameters.
The absolute number of negative muons contained in a beam is essential for many experiments at accelerator facilities, but determining it in pulsed beams has been difficult, particularly at high intensities. The method utilizing the yield of the β delayed γ rays from the residual nuclei after the muon nuclear capture reaction has recently been developed to determine the muon number in the pulsed muon beam. In particular, the in-beam activation method employs isotopes with short lifetimes, enabling the beam intensity to be measured over a short period with irradiating muon beams. However, only a limited number of isotopes have reliable measurements of production branching ratios (BRs), which are required to determine the absolute muon number in the pulsed beam. To search for new candidate isotopes that are suitable for in-beam activation method, the production branching ratio after the muon nuclear capture reaction was measured for natural abundance Cu, Zn, and Ag. Considering the strength of the BR, the muon capture probability, the practical detection efficiency of the detector, and rarity of the target material in the surrounding structures, the reaction ^natAg (μ^-, ν_μx) ^107mPd is found to be a useful reference for the muon number calibration.
The star lattice, which can be visualized as a honeycomb network with each vertex replaced by a triangle, provides a rare platform for realizing exotic quantum states such as quantum spin liquids and disorder-driven random-singlet (RS) states. Herein, we investigate the ground-state properties of the three-dimensional (3D) stuffed hyper-star lattice Li2Cu2(MoO4)(3), which exhibits a crossover from short-range spin correlations to a disorder-driven RS-like state below T-& lowast;similar to 15.8 K. Thermodynamic and microscopic measurements capture this crossover through a change in the power-law behavior of various observables, from similar to T- 0.25 for T > T-& lowast; to similar to T-0.50 for T < T-& lowast;. Upon further cooling, a quasifrozen state emerges near T-f = 0.32 K, likely associated with weakly coupled spin chains within the hyper-star spin network. Our results underscore the crucial role of orphan spins and weak residual interactions in stabilizing a disorder-driven quantum-disordered state in three dimensions.
We present advances in plasma control and diagnosis, leading to the production of exceptionally large quantities of neutral antimatter. We measure the time-dependent temperature and density distribution of antiprotons and positrons while slowly combining them to make antihydrogen atoms in a nested Penning-Malmberg trap. The total antihydrogen yield and the number of atoms escaping the trap as a beam are greatest when the positron temperature is lowest and when antiprotons enter the positron plasma at the smallest radius. We control these parameters by changing the rate at which we lower the electrostatic barrier between the antiproton and positron plasmas and by heating the positrons. With the optimal settings, we produce 2.3 & times; 10(6) antihydrogen atoms per 15-min run, surpassing the previous state of the art ( 3.1 & times; 10(4) atoms in 4 min) and the most recent advances in other experiments by factors of 20 and 5, respectively.
Unfolding, in the context of high-energy particle physics, refers to the process of removing detector distortions in experimental data. The resulting unfolded measurements are straightforward to use for direct comparisons between experiments and a wide variety of theoretical predictions. For decades, popular unfolding strategies were designed to operate on data formatted as one or more binned histograms. In recent years, new strategies have emerged that use machine learning to unfold datasets in an unbinned manner, allowing for higher-dimensional analyses and more flexibility for current and future users of the unfolded data. This guide comprises recommendations and practical considerations from researchers across a number of major particle physics experiments who have recently put these techniques into practice on real data.
