A sample of 1.53 x 10 super(9) cosmic-ray-induced single muon events has been recorded at 225 m water equivalent using the MINOS near detector. The underground muon rate is observed to be highly ...correlated with the effective atmospheric temperature. The coefficient alpha sub(T), relating the change in the muon rate to the change in the vertical effective temperature, is determined to be 0.428 + or - 0.003(stat.) + or - 0.059(syst.). An alternative description is provided by the weighted effective temperature, introduced to account for the differences in the temperature profile and muon flux as a function of zenith angle. Using the latter estimation of temperature, the coefficient is determined to be 0.352 + or - 0.003(stat.) + or - 0.046(syst.).
The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay K(L)-->pi(0)e(+)e(-). This mode is expected to have a significant CP violating component. The measurement of its branching ...ratio could support the standard model or could indicate the existence of new physics. This Letter reports new results from the 1999-2000 data set. One event is observed with an expected background at 0.99+/-0.35 events. We set a limit on the branching ratio of 3.5x10(-10) at the 90% confidence level. Combining with the previous result based on the data set taken in 1997 yields the final KTeV result: BR(K(L)-->pi(0)e(+)e(-))<2.8x10(-10) at 90% C.L.
We report the final measurement of the neutrino oscillation parameters \(\Delta m^2_{32}\) and \(\sin^2\theta_{23}\) using all data from the MINOS and MINOS+ experiments. These data were collected ...using a total exposure of \(23.76 \times 10^{20}\) protons on target producing \(\nu_{mu}\) and \(\overline{\nu_\mu}\) beams and 60.75 kt\(\cdot\)yr exposure to atmospheric neutrinos. The measurement of the disappearance of \(\nu_{\mu}\) and the appearance of \(\nu_e\) events between the Near and Far detectors yields \(|\Delta m^2_{32}|=2.40^{+0.08}_{-0.09}~(2.45^{+0.07}_{-0.08}) \times 10^{-3}\) eV\(^2\) and \(\sin^2\theta_{23} = 0.43^{+0.20}_{-0.04} ~(0.42^{+0.07}_{-0.03})\) at 68% C.L. for Normal (Inverted) Hierarchy.
A search for mixing between active neutrinos and light sterile neutrinos has been performed by looking for muon neutrino disappearance in two detectors at baselines of 1.04 km and 735 km, using a ...combined MINOS and MINOS+ exposure of \(16.36\times10^{20}\) protons-on-target. A simultaneous fit to the charged-current muon neutrino and neutral-current neutrino energy spectra in the two detectors yields no evidence for sterile neutrino mixing using a 3+1 model. The most stringent limit to date is set on the mixing parameter \(\sin^2\theta_{24}\) for most values of the sterile neutrino mass-splitting \(\Delta m^2_{41} > 10^{-4}\) eV\(^2\).
The temperature of the upper atmosphere affects the height of primary cosmic ray interactions and the production of high-energy cosmic ray muons which can be detected deep underground. The MINOS far ...detector at Soudan, MN, has collected over 67×106 cosmic ray induced muons. The underground muon rate measured over a period of five years exhibits a 4% peak-to-peak seasonal variation which is highly correlated with the temperature in the upper atmosphere. The coefficient, αT, relating changes in the muon rate to changes in atmospheric temperature was found to be αT=0.873±0.009(stat)±0.010(syst). Pions and kaons in the primary hadronic interactions of cosmic rays in the atmosphere contribute differently to αT due to the different masses and lifetimes. This allows the measured value of αT to be interpreted as a measurement of the K/π ratio for Ep≳7TeV of 0.12-0.05+0.07, consistent with the expectation from collider experiments.
Measurements of the Decay KL-->e+ e- mu+ mu Alavi-Harati, A; Alexopoulos, T; Arenton, M ...
Physical review letters,
2003-Apr-11, 20030411, Letnik:
90, Številka:
14
Journal Article
Recenzirano
The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined ...to be 2.69+/-0.24(stat)+/-0.12(syst)x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation.
Phys. Rev. D 100, 032003 (2019) We present a measurement of $B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0
\rightarrow \gamma\gamma)$, the Dalitz branching ratio, using data taken in
1999 by the E832 ...KTeV experiment at Fermi National Accelerator Laboratory. We
use neutral pions from fully reconstructed $K_L$ decays in flight; the
measurement is based on about 60 thousand $K_L \rightarrow \pi^0\pi^0\pi^0
\rightarrow \gamma\gamma~\gamma\gamma~e^+e^-\gamma$ decays. We normalize to
$K_L \rightarrow \pi^0\pi^0\pi^0 \rightarrow 6\gamma$ decays. We find $B(\pi^0
\rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma)$ $(m_{e^+e^-}$ >
15 MeV/$c^2)$ = $3.920 \pm 0.016(stat) \pm 0.036 (syst) \times 10^{-3}$.
Using the Mikaelian and Smith prediction for the $e^+e^-$ mass spectrum, we
correct the result to the full $e^+e^-$ mass range. The corrected result is
$B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma) = 1.1559
\pm 0.0047(stat) \pm 0.0106 (syst)$%. This result is consistent with previous
measurements and the uncertainty is a factor of three smaller than any previous
measurement.
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