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We present an empirical investigation of the correcting coils behavior used to homogenize the field distribution of the race-track microtron accelerator end magnets. These end magnets belong to the second stage of the 30.0 MeV cw electron accelerator under construction at IFUSP, the race-track microtron booster, in which the beam energy is raised from 1.97 to 5.1 MeV. The correcting coils are attached to the pole faces and are based on the inhomogeneities of the magnetic field measured. The performance of these coils, when operating the end magnets with currents that differ by ±10% from the one used in the mappings that originated the coils copper leads, is presented. For one of the magnets, adjusting conveniently the current of the correcting coils makes it possible to homogenize field distributions of different intensities, once their shapes are practically identical to those that originated the coils. For the other one, the shapes are changed and the coils are less efficient. This is related to intrinsic factors that determine the inhomogeneities. However, we obtained uniformity of 0.001% in both cases.

This work deals with the design of the Institute of Physics of the University of São Paulo (IFUSP) main racetrack microtron accelerator end magnets. This is the last stage of acceleration, comprised of an accelerating section (1.04 m) and two end magnets (0.1585 T), in which a 5.10 MeV beam, produced by a racetrack microtron booster has its energy raised up to 31.15 MeV after 28 accelerations. Poisson code was used to give the final configuration that includes auxiliary pole pieces (clamps) and auxiliary homogenizing gaps. The clamps create a reverse fringe field region and avoid the vertical defocusing and the horizontal displacement of the beam produced by extended fringe fields; Ptrace code was used to perform the trajectory calculations in the fringe field region. The auxiliary homogenizing gaps improve the field uniformity as they create a “magnetic shower” that provides uniformity of ±0.3% , before the introduction of the correcting coils that will be attached to the pole faces. This method of correction, used in the IFUSP racetrack microtron booster magnets, enabled uniformity of ±0.001% in an average field of 0.1 T and will also be employed for these end magnets.

The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) < 1.0 x 10^{-10} and Br(KL->pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \\bar{d}sX0 coupling is completely real.

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\\).

We report on a new measurement of the branching ratio B(KL -> pi0 e+ e- gamma) using the KTeV detector. This analysis uses the full KTeV data set collected from 1997 to 2000. We reconstruct 139 events over a background of 14, which results in B(KL -> pi0 e+ e- gamma) = (1.62 +/- 0.14 (stat) +/- 0.09 (syst)) x 10^{-8}. This result supersedes the earlier KTeV measurement of this branching ratio.

We report new constraints on the size of large extra dimensions from data collected by the MINOS experiment between 2005 and 2012. Our analysis employs a model in which sterile neutrinos arise as Kaluza-Klein states in large extra dimensions and thus modify the neutrino oscillation probabilities due to mixing between active and sterile neutrino states. Using Fermilab's NuMI beam exposure of \\(10.56 \\times 10^{20}\\) protons-on-target, we combine muon neutrino charged current and neutral current data sets from the Near and Far Detectors and observe no evidence for deviations from standard three-flavor neutrino oscillations. The ratios of reconstructed energy spectra in the two detectors constrain the size of large extra dimensions to be smaller than \\(0.45\\,\\mu\\text{m}\\) at 90% C.L. in the limit of a vanishing lightest active neutrino mass. Stronger limits are obtained for non-vanishing masses.

We report results of a search for oscillations involving a light sterile neutrino over distances of 1.04 and \\(735\\,\\mathrm{km}\\) in a \\(\\nu_{\\mu}\\)-dominated beam with a peak energy of \\(3\\,\\mathrm{GeV}\\). The data, from an exposure of \\(10.56\\times 10^{20}\\,\\textrm{protons on target}\\), are analyzed using a phenomenological model with one sterile neutrino. We constrain the mixing parameters \\(\\theta_{24}\\) and \\(\\Delta m^{2}_{41}\\) and set limits on parameters of the four-dimensional Pontecorvo-Maki-Nakagawa-Sakata matrix, \\(|U_{\\mu 4}|^{2}\\) and \\(|U_{\\tau 4}|^{2}\\), under the assumption that mixing between \\(\\nu_{e}\\) and \\(\\nu_{s}\\) is negligible (\\(|U_{e4}|^{2}=0\\)). No evidence for \\(\\nu_{\\mu} \\to \\nu_{s}\\) transitions is found and we set a world-leading limit on \\(\\theta_{24}\\) for values of \\(\\Delta m^{2}_{41} \\lesssim 1\\,\\mathrm{eV}^{2}\\).

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.

The charge ratio, \\(R_\\mu = N_{\\mu^+}/N_{\\mu^-}\\), for cosmogenic multiple-muon events observed at an under- ground depth of 2070 mwe has been measured using the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly continuously from August 2003 until April 2012, comprise two independent data sets imaged with opposite magnetic field polarities, the comparison of which allows the systematic uncertainties of the measurement to be minimized. The multiple-muon charge ratio is determined to be \\(R_\\mu = 1.104 \\pm 0.006 {\\rm \\,(stat.)} ^{+0.009}_{-0.010} {\\rm \\,(syst.)} \\). This measurement complements previous determinations of single-muon and multiple-muon charge ratios at underground sites and serves to constrain models of cosmic ray interactions at TeV energies.