S. Cuen-Rochin

The multi-Photomultiplier Tube (mPMT) photosensors will be used in the Water Cherenkov Test Experiment (WCTE) to efficiently detect the photons produced in the whole detector. One of the aims behind the development of WCTE is to test the…

PIONEER is a rapidly developing effort aimed to perform a pristine test of lepton flavour universality (LFU) and of the unitarity of the first row of the CKM matrix by significantly improving the measurements of rare decays of the charged…

Measurements of the response function of the PIENU NaI(T$\ell$) and CsI crystal calorimeter using a monochromatic 70 MeV/c positron beam at various incidence angles are described. The experimental setup and relevant physical processes…

The physics motivation and the conceptual design of the PIONEER experiment, a next-generation rare pion decay experiment testing lepton flavor universality and CKM unitarity, are described. Phase I of the PIONEER experiment, which was…

A next-generation rare pion decay experiment, PIONEER, is strongly motivated by several inconsistencies between Standard Model (SM) predictions and data pointing towards the potential violation of lepton flavor universality. It will probe…

Core-collapse supernovae are among the most magnificent events in the observable universe. They produce many of the chemical elements necessary for life to exist and their remnants -- neutron stars and black holes -- are interesting…

The three body pion decays ${\pi}^+{\rightarrow}l^+{\nu}X~(l=e,{\mu})$, where $X$ is a weakly interacting neutral boson, were searched for using the full data set from the PIENU experiment. An improved limit on…

Hyper-Kamiokande is the next generation underground water Cherenkov detector that builds on the highly successful Super-Kamiokande experiment. The detector which has an 8.4~times larger effective volume than its predecessor will be located…

The rare pion decays ${\pi}^+{\rightarrow}{\mu}^+{\nu}_{\mu}{\nu}\bar{\nu}$ and ${\pi}^+{\rightarrow}e^+{\nu}_{e}{\nu}\bar{\nu}$ are allowed in the Standard Model but highly suppressed. These decays were searched for using data from the…

Charged lepton flavor violating muon decay ${\mu}^+{\rightarrow}e^+X_H$, where $X_H$ is a massive neutral boson, was sought by searching for extra peaks in the muon decay ${\mu}^+{\rightarrow}e^+{\nu}\bar{\nu}$ energy spectrum in the…

Heavy neutrinos were sought in pion decays $\pi^+ \rightarrow \mu^+ \nu$ by examining the observed muon energy spectrum for extra peaks in addition to the expected peak for a massless neutrino. No evidence for heavy neutrinos was observed.…

Two results from the PIENU Experiment are presented reporting a test of lepton universality in pion decay and improved limits on heavy neutrinos coupling to positrons. The status of the full analysis for the $\pi^+ \rightarrow \mbox{e}^+…

A search for massive neutrinos has been made in the decay $\pi\rightarrow e^+ \nu$. No evidence was found for extra peaks in the positron energy spectrum indicative of pion decays involving massive neutrinos ($\pi\rightarrow e^+ \nu_h$).…

The PIENU experiment at TRIUMF aims to measure the pion decay branching ratio $R={\Gamma}({\pi}^+{\rightarrow}e^+{\nu}_e({\gamma}))/{\Gamma}({\pi}^+{\rightarrow}{\mu}^+{\nu}_{\mu}({\gamma}))$ with precision $<0.1$% to provide a sensitive…

A new measurement of the branching ratio, $R_{e/\mu} =\Gamma (\pi^+ \rightarrow \mbox{e}^+ \nu + \pi^+ \rightarrow \mbox{e}^+ \nu \gamma)/ \Gamma (\pi^+ \rightarrow \mu^+ \nu + \pi^+ \rightarrow \mu^+ \nu \gamma)$, resulted in…

The PIENU experiment at TRIUMF is aimed at a measurement of the branching ratio $R^{e/\mu}$ = ${\Gamma\big((\pi^{+} \rightarrow e^{+} \nu_{e}) + (\pi^{+} \rightarrow e^{+} \nu_{e}\gamma)\big)}/{\Gamma\big((\pi^{+} \rightarrow \mu^{+}…