Manuel Calderon De La Barca Sanchez

The Atmospheric Neutrino Flavor Ratio from a 3.9 Fiducial Kiloton-Year Exposure of Soudan 2

Abstract We report a measurement of the atmospheric neutrino flavor ratio, R, using a sample of quasi-elastic neutrino interactions occurring in an iron medium. The flavor ratio (tracks/showers) of atmospheric neutrinos in a 3.9 fiducial kiloton-year exposure of Soudan 2 is 0.64±0.11(stat.)±0.06(syst.) of that expected. Important aspects of our main analysis have been checked by carrying out two independent, alternative analyses; one is based upon automated scanning, the other uses a multivariate approach for background subtraction. Similar results are found by all three approaches.

Measurement of the L/E distributions of atmospheric neutrinos in Soudan 2 and their interpretation as neutrino oscillations

The effects of oscillations of atmospheric muon neutrinos are observed in the 5.90 fiducial kiloton-year exposure of the Soudan 2 detector. An unbinned maximum likelihood analysis of the neutrino L/E distribution has been carried out using the Feldman-Cousins prescription. The probability of the no oscillation hypothesis is 5.8x10-4. The 90% confidence allowed region in the sin**(2theta), Delta m**2 plane is presented.

Observation of atmospheric neutrino oscillations in Soudan 2.

The effects of oscillations of atmospheric �µ are observed in the 5.90 fiducial kiloton-year exposure of the Soudan 2 detector. An unbinned maximum likelihood analysis of the neutrino L/E distribution has been carried out using the Feldman-Cousins prescription. The probability of the no oscillation hypothesis is 5.8×10 4 . The 90% confidence allowed region in the sin 2 2�,�m 2 plane is presented.

Neutrino oscillation effects in Soudan-2 upward-stopping muons

Upward-going stopping muons initiated by atmospheric {nu}{sub {mu}} and {nu}{sub {mu}} interactions in the rock below the Soudan 2 detector have been isolated, together with a companion sample of neutrino-induced single muons, created within the detector, which travel downwards and exit. The downward-going sample is consistent with the atmospheric-neutrino flux prediction, but the upward-going sample exhibits a sizable depletion. Both are consistent with previously reported Soudan 2 neutrino-oscillation results. Inclusion of the two samples in an all-event likelihood analysis, using recent 3D-atmospheric-neutrino-flux calculations, reduces both the allowed oscillation parameter region and the probability of the no-oscillation hypothesis.

Search for neutron anti-neutron oscillations using multiprong events in Soudan 2

We have searched for neutron-antineutron oscillations using the 5.56 fiducial kiloton-year exposure of the Soudan 2 iron tracking calorimeter. We require candidate n-nbar occurrences to have .GE. 4 prongs (tracks and showers) and to have kinematics compatible with nbar-N annihilation within a nucleus. We observe five candidate events, with an estimated background from atmospheric neutrino and cosmic ray induced events of 4.5 \pm 1.2 events. Previous experiments with smaller exposures observed no candidates, with estimated background rates similar to this experiment. We set a lifetime lower limit for oscillation time in iron: T_A(Fe) > 7.2x10^{31} years. The corresponding lower limit for oscillation of free neutrons is \tau_{n-nbar} > 1.3x10^8 seconds.

AN ERROR ANALYSIS OF THE GEOMETRIC BAADE-WESSELINK METHOD

We derive an analytic solution for the minimization problem in the geometric Baade-Wesselink method. This solution allows deriving the distance and mean radius of a pulsating star by fitting its velocity curve and angular diameter measured interferometrically. The method also provides analytic solutions for the confidence levels of the best-fit parameters and accurate error estimates for the Baade-Wesselink solution. Special care is taken in the analysis of the various error sources in the final solution, among which are the uncertainties due to the projection factor, the limb darkening, and the velocity curve. We also discuss the importance of the phase shift between the stellar light curve and the velocity curve as a potential error source in the geometric Baade-Wesselink method. We finally discuss the case of the classical Cepheid ζ Gem, applying our method to the measurements derived with the Palomar Testbed Interferometer. We show how a careful treatment of the measurement errors can be used to discriminate between different models of limb darkening by using interferometric techniques.

CHerenkov detectors In mine PitS (CHIPS) Letter of Intent to FNAL

This Letter of Intent outlines a proposal to build a large, yet cost-effective, 100 kton fiducial mass water Cherenkov detector that will initially run in the NuMI beam line. The CHIPS detector (CHerenkov detector In Mine PitS) will be deployed in a flooded mine pit, removing the necessity and expense of a substantial external structure capable of supporting a large detector mass. There are a number of mine pits in northern Minnesota along the NuMI beam that could be used to deploy such a detector. In particular, the Wentworth Pit 2W is at the ideal off-axis angle to contribute to the measurement of the CP violating phase. The detector is designed so that it can be moved to a mine pit in the LBNE beam line once that becomes operational.

MINOS+: a Proposal to FNAL to run MINOS with the medium energy NuMI beam

This is a proposal to continue to expose the two MINOS detectors to the NuMI muon neutrino beam for three years starting in 2013. The medium energy setting of the NuMI beam projected for NO{nu}A will deliver about 18 x 10{sup 20} protons-on-target during the first three years of operation. This will allow the MINOS Far Detector to collect more than 10,000 charged current muon neutrino events in the 4-10 GeV energy range and provide a stringent test for non-standard neutrino interactions, sterile neutrinos, extra dimensions, neutrino time-of-flight, and perhaps more. In addition there will be more than 3,000 neutral current events which will be particularly useful in extending the sterile neutrino search range.

A k-NN METHOD TO CLASSIFY RARE ASTRONOMICAL SOURCES: PHOTOMETRIC SEARCH OF BROWN DWARFS WITH SPITZER/IRAC

We present a statistical method for the photometric search of rare astronomical sources based on the weighted k-Nearest Neighbors method. A metric is defined in a multidimensional color-magnitude space based only on the photometric properties of template sources and the photometric uncertainties of both templates and data, without the need to define ad hoc color and magnitude cuts which could bias the search. The metric is defined as a function of two parameters, the number of neighbors k and a threshold distance D th that can be optimized for maximum selection efficiency and completeness. We apply the method to the search of L and T dwarfs in the Spitzer Extragalactic First Look Survey and the Bootes field of the Spitzer Shallow Survey, as well as to the search of substellar mass companions around nearby stars. With high level of completeness, we confirm the absence of late-T dwarfs detected in at least two bands in the First Look Survey, and only one in the Shallow Survey (previously discovered by Stern et al.). This result is in agreement with the expected statistics for late-T dwarfs. One L/early-T candidate is found in the First Look Survey, and three in the Shallow Surveys, currently undergoing follow-up spectroscopic verification. Finally, we discuss the potential for brown dwarf searches with this method in the Spitzer warm mission Exploration Science programs.

Electron Neutrino Appearance in the MINOS Experiment

MINOS is a long‐baseline neutrino oscillation experiment tasked to make a precision measurement of the neutrino mixing parameters associated with the atmospheric neutrino mass splitting. Using a high powered neutrino beam from the Main Injector (NuMI) facility at Fermilab, it compares the neutrino energy spectrum for neutrino interactions observed in two large detectors located at Fermilab and in the Soudan mine in northern Minnesota at a distance of 735 km. We have recently presented muon‐neutrino disappearance results after two years of data taking. Beyond those results there is the possibility that for a mixing angle related to electron‐neutrino appearance in the vicinity of the current experimental limit, MINOS could make an initial measurement of this parameter. We present a method for particle identification of electron neutrinos and show several techniques being used to study the background contributions for this analysis in the non‐oscillated data at the Near Detector.