arXiv subjects

T. J. Stocki

Publications and source records attributed to T. J. Stocki.

6 recordsLinked to original sources

arXiv2005

Ortho-para transition rate in $μ$-molecular hydrogen and the proton's induced pseudoscalar coupling $g_p$

We report a measurement of the ortho-para transition rate in the p$μ$p molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate $Λ_{op} = (11.1 \pm 1.7 \pm^{0.9}_{0.6}) \times 10^4$ s$^{-1}$ that is substantially larger than the earlier result of Bardin {\it et al.} We discuss the striking implications for the proton's induced pseudoscalar coupling $g_p$.

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arXiv2005

Scalar interaction limits from the beta-neutrino correlation of trapped radioactive atoms

We have set limits on contributions of scalar interactions to nuclear beta decay. A magneto-optical trap (MOT) provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and be detected in coincidence with the beta. This allows reconstruction of the neutrino momentum, and the measurement of the beta-neutrino correlation, in a more direct fashion than previously possible. The beta-neutrino correlation parameter of the 0+ to 0+ pure Fermi decay of 38mK is $\tilde{a}$=0.9981+-0.0030+-0.0037, consistent with the standard model prediction a=1.

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arXiv2004

Recoil alignment in muon capture on nitrogen-14

We report a measurement of the longitudinal alignment $A_L$ of the recoil nucleus in the $μ^- + ^{14}$N$(1^+, 0)$ $\to$ $ν_μ + ^{14}$C$(2^+, 7012)$ transition. The experiment was performed on the M9B beamline at the TRIUMF cyclotron via the measurement of the Doppler lineshape of the subsequent $^{14}$C$(2^+, 7012)$ $\to$ $^{14}$C$(0^+, 0)$ gamma-rays. We compare our result $A_L = 0.60 \pm 0.11$ to various model calculations, and discuss the sensitivity to the induced pseudoscalar coupling, second-forbidden effects and $2 \hbar ω$ wavefunction admixtures.

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arXiv2002

Muon capture on Chlorine-35

We report measurements of $γ$--ray spectra from muon capture on $^{35}$Cl. For the allowed Gamow--Teller transitions to the $^{35}$S$(2939, 3/2^+)$ state and the $^{35}$S$(3421, 5/2^+)$ state we obtained their capture rates, hyperfine dependences and $γ$--$ν$ correlation coefficients. The capture rates and hyperfine dependences were compared to shell model calculations using the complete 1s--0d space and the universal SD interaction. With $g_p / g_a = 6.7$ and $g_a = -1.00$ (or $g_a = -1.26$) we found agreement of the model and the data at the 1--2 $σ$ level. However, we caution that the transitions are sensitive to $\ell = 2$ forbidden matrix elements.

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arXiv2001

Gamma-rays from Muon Capture in $^{14}$N

Many new $γ$-rays have been observed, following muon capture on $^{14}$N. One had been reported before, and the low yield is confirmed, indicating that the nuclear structure of $^{14}$N is still not understood. Gamma-rays from $^{13}$C resulting from the reaction $^{14}$N($μ^{-}$,$ν$n)$^{13}$C compare favourably with states observed in the reaction $^{14}$N($γ$,p)$^{13}$C. More precise energies are also given for the 7017 and 6730 keV $γ$-rays in $^{14}$C.

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arXiv2001

The hyperfine transition in light muonic atoms of odd Z

The hyperfine (hf) transition rates for muonic atoms have been re-measured for select light nuclei, using neutron detectors to evaluate the time dependence of muon capture. For $^{19}$F $Λ$$_{h}$ = 5.6 (2) $μ$s$^{-1}$ for the hf transition rate, a value which is considerably more accurate than previous measurements. Results are also reported for Na, Al, P, Cl, and K; that result for P is the first positive identification.

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