Are there sterile neutrinos at the eV scale?

New predictions for the anti-neutrino flux emitted by nuclear reactors suggest that reactor experiments may have measured a deficit in the anti-neutrino flux, which can be interpreted in terms of oscillations between the known active neutrinos and new sterile states. Motivated by this observation, we perform a re-analysis of global short-baseline neutrino oscillation data in a framework with one or two sterile neutrinos. While one sterile neutrino is still not sufficient to reconcile the signals suggested by reactor experiments and by the LSND and MiniBooNE experiments with null results from other searches, we find that, with the new reactor flux prediction, the global fit improves considerably when the existence of two sterile neutrinos is assumed.Comment: 5 pages, 5 figures, v2: reference and acknowledgements adde

Implications of sterile neutrinos for medium/long-baseline neutrino experiments and the determination of θ13\theta_{13}

We revisit some of the recent neutrino observations and anomalies in the context of sterile neutrinos. Based on a general parametrization motivated in the presence of sterile neutrinos, the consistency of the MINOS disappearance data with additional sterile neutrinos is discussed. We also explore the implications of sterile neutrinos for the measurement of $|U_{\mu3}|$ in this case. Regarding the determination of $|U_{e3}|$, we observe that the existence of sterile neutrinos may induce a significant modification of the $\theta_{13}$ angle in neutrino appearance experiments like T2K and MINOS, over and above the ambiguities and degeneracies that are already present in 3-neutrino parameter extractions. The modification is less significant in reactor neutrino experiments like Double-CHOOZ, Daya Bay and RENO and therefore the extracted $|U_{e3}|$ value when sterile neutrinos are present is close to the one that would be obtained in the 3-neutrino case. We also conclude that the results from T2K imply a 90% C.L. lower-bound on $|U_{e3}|$, in the "$\,3+2$" neutrino case, which is still within the sensitivity of future reactor neutrino experiments like Daya Bay, and consistent with the one-$\sigma$ range of $\sin^22\theta_{13}$ recently reported by the Double-CHOOZ experiment. Finally, we argue that for the recently determined best-fit parameters, the results in the "$\,3+1$" scenario would be very close to the medium/long baseline results obtained in the "$\,3+2$" case analyzed in this work.Comment: 25 pages, 9 figures, revtex4-1. Typos corrected, published versio

Global neutrino data and recent reactor fluxes: status of three-flavour oscillation parameters

We present the results of a global neutrino oscillation data analysis within the three-flavour framework. We include latest results from the MINOS long-baseline experiment (including electron neutrino appearance as well as anti-neutrino data), updating all relevant solar (SK II+III), atmospheric (SK I+II+III) and reactor (KamLAND) data. Furthermore, we include a recent re-calculation of the anti-neutrino fluxes emitted from nuclear reactors. These results have important consequences for the analysis of reactor experiments and in particular for the status of the mixing angle $\theta_{13}$. In our recommended default analysis we find from the global fit that the hint for non-zero $\theta_{13}$ remains weak, at 1.8$\sigma$ for both neutrino mass hierarchy schemes. However, we discuss in detail the dependence of these results on assumptions concerning the reactor neutrino analysis.Comment: 15 pages, 10 figures and 2 tables, v2: corrected version, main conclusions unchanged, references adde

Reactor-based Neutrino Oscillation Experiments

The status of neutrino oscillation searches employing nuclear reactors as sources is reviewed. This technique, a direct continuation of the experiments that proved the existence of neutrinos, is today an essential tool in investigating the indications of oscillations found in studying neutrinos produced in the sun and in the earth's atmosphere. The low-energy of the reactor \nuebar makes them an ideal tool to explore oscillations with small mass differences and relatively large mixing angles. In the last several years the determination of the reactor anti-neutrino flux and spectrum has reached a high degree of accuracy. Hence measurements of these quantities at a given distance L can be readily compared with the expectation at L = 0, thus testing \nuebar disappearance. While two experiments, Chooz and Palo Verde, with baselines of about 1 km and thus sensitive to the neutrino mass differences associated with the atmospheric neutrino anomaly, have collected data and published results recently, an ambitious project with a baseline of more than 100 km, Kamland, is preparing to take data. This ultimate reactor experiment will have a sensitivity sufficient to explore part of the oscillation phase space relevant to solar neutrino scenarios. It is the only envisioned experiment with a terrestrial source of neutrinos capable of addressing the solar neutrino puzzle.Comment: Submitted to Reviews of Modern Physics 34 pages, 39 figure

НЕОПРЕДЕЛЕННОСТЬ РЕЗУЛЬТАТОВ КОНТРОЛЯ РАДОНА В ПОМЕЩЕНИЯХ. ЧАСТЬ 1. ПРОБЛЕМА ОЦЕНКИ СОДЕРЖАНИЯ РАДОНА И СОВРЕМЕННЫЙ ПРИНЦИП КОНТРОЛЯ

Radon control in buildings is being performed for decades in different countries of the world, including Russia. However, there is a lack of unified standard for the assessment of the uncertainty of the results of the control, considering the protocol and duration of the measurements. It is obvious that the uncertainty of the control increases with the reduction of the duration of the measurements. The lack of data on confidence interval for the average annual radon concentration in housings does not allow correct and precise comparison with the regulatory level, both for the commissioned and operated buildings. Additionally, it complicates a development of the effective method, mass control strategy and identification of buildings with high radon concertations. A reliable method of control, considering time variations of radon and duration of exposure, was developed in Russia several years ago, but it is not well-known and not applied on practice. This paper is focused on a novel principle of radon control, based on simple criteria, widely used in metrology and complying to the modern standards. This principle introduces a new parameter – the radon time variation coefficient KV(t), which reflects main constituent of the uncertainty of the average annual radon concentration depending on the protocol and duration of the measurements. A novel algorithm for the estimation of KV(t) is proposed, developed on the base of the results of continuous annual radon monitoring in representative experimental housings. Additionally, the structure of the correcting coefficient is presented, considering an impact of the temperature on the radon behavior. The use of the corrective coefficient allows lowering the KV(t)value, but its application is limited.Контроль радона в зданиях проводится уже многие десятилетия в разных странах мира, включая Россию. Однако до сих пор отсутствует единый стандарт, позволяющий оценивать значение неопределенности результата контроля с учетом режима и продолжительности измерений. Очевидно, что с уменьшением продолжительности измерений увеличивается неопределенность контроля. Отсутствие данных о доверительном интервале величины среднегодового содержания радона в помещении не позволяет выполнять корректное и надежное сравнение с нормативным уровнем как на стадии приемки зданий в эксплуатацию, так и в эксплуатируемых зданиях. Это также существенно затрудняет развитие эффективного метода, стратегии массового контроля и выявление зданий с высоким содержанием радона. В России несколько лет назад был разработан надежный метод контроля, учитывающий временные вариации радона и продолжительность измерений, однако он до сих пор малоизвестен и не имеет практического применения. В статье приводится принцип контроля радона, основанный на простых критериях, широко используемых в метрологии и отвечающих требованиям современных стандартов. Этот принцип вводит новый параметр – коэффициент временных вариаций радона KV(t), который выражает основную составляющую неопределенности среднегодового уровня радона в зависимости от режима и продолжительности измерений. Предложен оригинальный алгоритм определения значений KV(t), разработанный на основе результатов непрерывных годовых мониторингов радона в представительных экспериментальных помещениях. Кроме того, показана структура поправочного коэффициента, учитывающего влияние температуры на поведение радона. Использование поправочного коэффициента позволяет снизить величину KV(t), однако его применение ограничено

Оценка доз внешнего облучения населения с учетом структуры аппаратурного обеспечения для контроля мощности дозы фотонного излучения в организациях Роспотребнадзора

This paper provides review of equipment and methodology for measurement of photon radiation dose; analysis of possible reasons for considerable deviation between the Russian Federation population annual effective external irradiation doses and the relevant average global value. Data on Rospotrebnadzor bodies dosimetry equipment used for measurement of gamma radiation dose are collected and systematized. Over 60 kinds of dosimeters are used for monitoring of population external irradiation doses. Most of dosimeters used in the country have gas-discharge detectors (Geiger-Mueller counters, minor biochemical annunciators, etc.) which have higher total values of own background level and of space radiation response than the modern dosimeters with scintillation detectors. This feature of dosimeters is apparently one of most plausible reasons of a bit overstating assessment of population external irradiation doses. The options for specification of population external irradiation doses assessment are: correction of gamma radiation dose measurement results with consideration of dosimeters own background level and space radiation response, introduction of more up-to-date dosimeters with scintillation detectors, etc. The most promising direction of research in verification of population external irradiation doses assessment is account of dosimetry equipment.Рассматриваются вопросы аппаратурно-методического обеспечения измерений мощности дозы фотонного излучения, анализируются возможные причины значительной разницы между годовыми эффективными дозами внешнего облучения населения Российской Федерации и среднемировым значением этих величин. Собраны и систематизированы сведения о парке дозиметрического оборудования, которое используется для измерений мощности дозы гамма-излучения в организациях Роспотребнадзора. Установлено, что для контроля доз внешнего облучения населения используются более 60 типов дозиметров. Большая часть применяемых в стране дозиметров имеют газоразрядные детекторы (счетчики Гейгера – Мюллера, СБМ и т.п.), которые характеризуются более высокими суммарными значениями уровня собственного фона и отклика на космическое излучение, чем современные дозиметры со сцинтилляционными детекторами. Показано, что эта характеристика дозиметров является, по-видимому, одной из наиболее вероятных причин того, что оценки доз внешнего облучения населения оказываются несколько завышенными. Рассматриваются возможные варианты уточнения оценки доз внешнего облучения населения: введение поправки в результаты измерений мощности дозы гамма-излучения с учетом уровня собственного фона дозиметров и отклика на космическое излучение, применение более современных дозиметров со сцинтилляционными детекторами и др. Показано, что учет структуры парка дозиметрического оборудования является наиболее перспективным направлением исследований по верификации оценки доз внешнего облучения населения

The minimal 3+2 neutrino model versus oscillation anomalies

We study the constraints imposed by neutrino oscillation experiments on the minimal extension of the Standard Model that can explain neutrino masses, which requires the addition of just two singlet Weyl fermions. The most general renormalizable couplings of this model imply generically four massive neutrino mass eigenstates while one remains massless: it is therefore a minimal 3+2 model. The possibility to account for the confirmed solar, atmospheric and long-baseline oscillations, together with the LSND/MiniBooNE and reactor anomalies is addressed. We find that the minimal model can fit oscillation data including the anomalies better than the standard 3ν model and similarly to the 3+2 phenomenological models, even though the number of free parameters is much smaller than in the latter. Accounting for the anomalies in the minimal model favours a normal hierarchy of the light states and requires a large reactor angle, in agreement with recent measurements. Our analysis of the model employs a new parametrization of seesaw models that extends the Casas-Ibarra one to regimes where higher order corrections in the light-heavy mixings are significant

Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment

Included in the papers for the Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment: Introduction by Milton Katz and Richard R. Baxter, p. 1 Freedom of Scientific Research in the World Ocean by A.F. Vysotsky, p. 7 The International Law of Scientific Research in the Oceans by Richard R. Baxter, p. 27 Responsibility and Liability for Harm to the Marine Environment by Robert E. Stein, p. 41 Liability for Marine Environment Pollution Damage in Contemporary International Sea Law by A. L. Makovsky, p. 59 Protection of the Marine Environment from Pollution by Richard A. Frank, p. 73 The Freedom of Navigation and the Problem of Pollution of the Marine Environment by V. A. Kiselev, p. 93 The Freedom of Navigation Under International Law by William E. Butler, p. 107 International Fisheries Management Without Global Agreement: United States Policies and Their Impact on the Soviet Union by H. Gary Knight, p. 119 Some Biological Background for International Legal Acts on Rational Utilization of the Living Resources of the World Ocean by P. A. Moiseev, p. 143 An International Regime for the Seabed Beyond National Jurisdiction by Thomas M. Franck, p. 151 Settlement of Disputes Under the Law of Ocean Use, with Particular Reference to Environmental Protection by John Lawrence Hargrove, p. 18