Ultracold neutrons (UCNs) are a powerful tool for probing the Standard Model at high precision. The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration is building a new UCN source to provide ...unprecedented densities of UCNs for experiments. This source will use a tantalum-clad tungsten spallation target, receiving up to 40 µA of 480-MeV protons from TRIUMF’s main cyclotron. The beamline and target were constructed from 2014 to 2016 and operated at beam currents up to 10 µA from 2017 to 2019 as part of a prototype UCN source. We describe the design choices for the target and target-handling system, as well as our benchmarking of the target performance using UCN production measurements.
The TRIUMF Ultra-Cold Advanced Neutron (TUCAN) collaboration aims at a precision neutron electric dipole moment (nEDM) measurement with an uncertainty of \(10^{-27}\,e\cdot\mathrm{cm}\), which is an ...order-of-magnitude better than the current nEDM upper limit and enables us to test Supersymmetry. To achieve this precision, we are developing a new high-intensity ultracold neutron (UCN) source using super-thermal UCN production in superfluid helium (He-II) and a nEDM spectrometer. The current development status of them is reported in this article.
The study of pion production from nuclei is important for understanding pion interactions, as well as interactions between nucleons, inside the nucleus. These studies are sensitive to high-momentum ...components of the nuclear wave function and to short-range correlations between nucleons in nuclei. Studies of the (p,$\pi\sp-$) reaction on a variety of target nuclei have demonstrated the dominance in these reactions of the two-nucleon processes NN $\to$ NN$\pi$. These investigations have now been extended to compare the (p,$\pi\sp+$) and (p,$\pi\sp-$) reactions, and to study the extent to which pion production in nuclei reflects the behavior of the various underlying free NN $\to$ NN$\pi$ channels. Part of the dissertation includes the techniques and results of two experimental studies. The first is a comparative study of the reactions $\sp{13}$C(p,$\pi\sp+$) and $\sp{13}$C(p,$\pi\sp-$), exploring (p,$\pi\sp{\pm}$) transitions to discrete final states and to the continuum regions in the mirror nuclei $\sp{14}$C and $\sp{14}$O. This study has provided rich spectra, spectroscopic applications, and a number of systematic features associated with the relevance of free NN $\to$ NN$\pi$ results to pion production inside the nucleus. The results of this study are supported by comparison to (p,$\pi\sp+$) theoretical calculations and to results from other nuclear reaction studies. The second experiment is a subsequent study of the reaction $\sp{12}$C(p,$\pi\sp+$), with special focus on one anomalous transition to a final highly excited $\sp{13}$C state, to be compared to a similar $\sp{13}$C(p,$\pi\sp+$) transition to a final $\sp{14}$C state. The experimental features exhibited by the above anomalous transitions in $\sp{13}$C(p,$\pi\sp+$) and $\sp{12}$C(p,$\pi\sp+$) do not fit in easily with the generally applicable picture of a quasifree two-nucleon production mechanism. The techniques and results of two other experiments carried out to test alternative explanations to these anomalous states are also part of the dissertation. The first is a study of the transfer reactions $\sp{11}$B($\alpha$,p)$\sp{14}$C and $\sp{11}$B($\alpha$,d)$\sp{13}$C. The second is a $\sp{12}$C(p,$\pi\sp+$n) coincidence experiment exploring the neutron decay modes of the $\sp{13}$C state. In addition to their spectroscopic value, these studies are also relevant for understanding the pion production mechanism inside the nucleus.
