A question of hierarchy: matter effects with atmospheric neutrinos and anti-neutrinos

It is by now established that neutrinos mix, have (different) non-zero masses, and therefore oscillate. The oscillation parameters themselves, however, are not all well-known. An open problem is that of the neutrino mass hierarchy. We study the possibility of determining the neutrino mass hierarchy with atmospheric neutrinos using an iron calorimeter detector capable of charge identification such as the proposed MONOLITH and ICAL/INO detectors. We find that such detectors are sensitive to the sign of the mass-squared difference, \delta_{32} = m_3^2 - m_2^2, provided the as-yet unknown mixing angle between the first and third generations, \theta_{13}, is greater than 6 degrees (\sin^2 2\theta_{13} > 0.04). A result with a significance greater than 90% CL requires large exposures (more than 500 kton-years) as well as good energy and angular resolution of the detected muons (better than 15%), especially for small \theta_{13}. Hence obtaining definitive results with such a detector is difficult, unless \theta_{13} turns out to be large. In contrast, such detectors can establish a clear oscillation pattern in atmospheric neutrinos in about 150 kton-years, therefore determining the absolute value of \delta_{32} and \sin^2 2 \theta_{23} to within 10%.Comment: 36 pages revtex with 14 eps figures; new section on statistical significance when detector resolution is include

The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals

We present the waveform digitiser used in the Double Chooz experiment. We describe the hardware and the custom-built firmware specifically developed for the experiment. The performance of the device is tested with regards to digitising low light level signals from photomultiplier tubes and measuring pulse charge. This highlights the role of quantisation effects and leads to some general recommendations on the design and use of waveform digitisers.Comment: 14 pages, 8 figures, accepted for publication in JINS

Global analysis of neutrino masses, mixings and phases: entering the era of leptonic CP violation searches

We perform a global analysis of neutrino oscillation data, including high-precision measurements of the neutrino mixing angle theta_13 at reactor experiments, which have confirmed previous indications in favor of theta_13>0. Recent data presented at the Neutrino 2012 Conference are also included. We focus on the correlations between theta_13 and the mixing angle theta_23, as well as between theta_13 and the neutrino CP-violation phase delta. We find interesting indications for theta_23< pi/4 and possible hints for delta ~ pi, with no significant difference between normal and inverted mass hierarchy.Comment: Updated version, including recent data released at the Neutrino 2012 Conference. Some references adde

The 3-D kinematics of water masers around the semiregular variable RT Virginis

We report observations of water masers around the semiregular variable RT Virginis (RT Vir), which have been made with the Very Long Baseline Array (VLBA) of the National Radio Astronomy Observatory (NRAO) at five epochs, each separated by three weeks of time. We detected about 60 maser features at each epoch. Overall, 61 features, detected at least twice, were tracked by their radial velocities and proper motions. The 3-D maser kinematics exhibited a circumstellar envelope that is expanding roughly spherically with a velocity of about 8 km/s. Asymmetries in both the spatial and velocity distributions of the maser features were found in the envelope, but less significant than that found in other semiregular variables. Systematic radial-velocity drifts of individual maser features were found with amplitudes of <= 2 km/s/yr. For one maser feature, we found a quadratic position shift with time along a straight line on the sky. This apparent motion indicates an acceleration with an amplitude of 33 km/s/yr, implying the passage of a shock wave driven by the stellar pulsation of RT Vir. The acceleration motion is likely seen only on the sky plane because of a large velocity gradient formed in the accelerating maser region. We estimated the distance to RT Vir to be about 220 pc on the basis of both the statistical parallax and model-fitting methods for the maser kinematics.Comment: 18 pages, 8 figures. Accepted to appear in the Astrophysical Journa

Optimal Testing Intervals in the Squatting Test to Determine Baroreflex Sensitivity

The recently introduced “squatting test” (ST) utilizes a simple postural change to perturb the blood pressure and to assess baroreflex sensitivity (BRS). In our study, we estimated the reproducibility of and the optimal testing interval between the STs in healthy volunteers. Thirty-four subjects free of cardiovascular disorders and taking no medication were instructed to perform the repeated ST at 30-sec, 1-min, and 3-min intervals in duplicate in a random sequence, while the systolic blood pressure (SBP) and pulse intervals were measured. Baroreflex sensitivity was estimated by plotting reflex increases and decreases in the SBP and succeeding pulse intervals during stand-to-squat and squat-to-stand maneuvers, respectively. Correlations between duplicate BRS data at each testing interval were analyzed by the Pearson’s correlation coefficient, while agreements were assessed by Bland-Altman plots. Two measurements of BRS during stand-to-squat and squat-to-stand maneuvers demonstrated significant correlations at both 1-min and 3-min intervals, while at 30-sec intervals correlation was poor. Correlation coefficients became considerably greater in each maneuver as the measurement interval was increased from 30 sec to 3 min. Our results suggest that the testing interval in the ST should be at least 1 min long, but ideally it should be longer than or equal to 3 min, to assess the baroreflex adequately.У нещодавно запропонованому «тесті присідання» (ТП) використовується проста зміна пози для індукції зрушення кров’яного тиску, що дозволяє визначити барорефлекторну чутливість (БРЧ). Ми оцінювали ступінь відтворюваності та оптимальні інтервали між ТП, що реалізовувалися здоровими випробуваними. Групу з 34 тестованих, які не мали будь-яких серцево-судинних розладів та не приймали якихось ліків, інструктували виконувати повторні подвійні ТП у випадковій послідовності з інтервалами 30 с, 1 та 3 хв; при цьому вимірювали систолічний кров’яний тиск (СКТ) та кардіоінтервали. Рефлекторні підвищення та зниження СКТ і послідовні кардіоінтервали під час рухів присідання та повернення у вертикальну позу представляли графічно. Залежність між повторними визначеннями БРЧ при кожному інтервалі між тестами аналізували, встановлюючи коефіцієнти кореляції Пірсона. Виміри БРЧ під час рухів присідання та підйому демонстрували істотну кореляцію при інтервалах 1 та 3 хв, а при інтервалах 30 с кореляція була слабшою. Коефіцієнти кореляції ставали помітно значнішими з кожним рухом і збільшенням інтервалів між вимірами від 30 с до 3 хв. Наші результати вказують на те, що адекватна оцінка барорефлексу може бути забезпечена при інтервалах між ТП не менше 1 хв (бажано 3 хв або більше)