A method for detecting ντ\nu_\tau appearance in the spectra of quasielastic CC events

A method for detecting the transition \omutau in long-baseline accelerator experiments, that consists in comparing the far-to-near ratios of the spectra of quasielastic CC events generated by high- and low-energy beams of muon neutrinos, is proposed. The test may be accessible to big water Cherenkov detectors and iron--scintillator calorimeters, and is limited by statistics rather than systematics.Comment: 10 pages, 4 figure

Государственные награды

In the beginning of 2017 our colleagues and authors of Project Baikal received several state awards. Andrei Kaftanov received the Russian Federation Presidential Certificate of Honour for his active international and scientific work. Andrei introduced to PB the Swiss journalist Guy Mettan, who later became president of the Geneva Parliament. His valuable article on the Geneva-Lausanne agglomeration was published in PB 9. Guy Mettan was awarded the Order of Friendship. Andrei Bokov, who has also greatly contributed to PB (PB 5, PB 26, PB 50 and PB 51), was awarded the honorary title National Architect of the RF.Начало 2017 года ознаменовалось вручением сразу нескольких государственных наград нашим коллегам и авторам ПБ. Наш друг Андрей Кафтанов не раз посещал Иркутск, был гостем III межрегионального фестиваля ЗВС-2003, известен читателям ПБ как видный деятель Международного союза архитекторов, организатор многих международных выставок и конкурсов. Почетная грамота Президента Российской Федерации – достойная награда за активную международную и научную деятельность. Андрей в свое время познакомил нас с Ги Меттаном, журналистом, а впоследствии парламентарием из Швейцарии. Его рассказ об агломерации Женева – Лозанна был весомым вкладом специальный выпуск ПБ, посвященный агломерации (ПБ9). Высочайшего звания «Народный архитектор России» удостоен Андрей Боков, неоднократный автор и ньюсмейкер ПБ, гость главной темы этого номера (ПБ5, ПБ26, ПБ50, ПБ51)

Emulsion Chamber with Big Radiation Length for Detecting Neutrino Oscillations

A conceptual scheme of a hybrid-emulsion spectrometer for investigating various channels of neutrino oscillations is proposed. The design emphasizes detection of $\tau$ leptons by detached vertices, reliable identification of electrons, and good spectrometry for all charged particles and photons. A distributed target is formed by layers of low-Z material, emulsion-plastic-emulsion sheets, and air gaps in which $\tau$ decays are detected. The tracks of charged secondaries, including electrons, are momentum-analyzed by curvature in magnetic field using hits in successive thin layers of emulsion. The $\tau$ leptons are efficiently detected in all major decay channels, including \xedec. Performance of a model spectrometer, that contains 3 tons of nuclear emulsion and 20 tons of passive material, is estimated for different experimental environments. When irradiated by the $\nu_\mu$ beam of a proton accelerator over a medium baseline of $\sim 1$ km/GeV, the spectrometer will efficiently detect either the \omutau and \omue transitions in the mass-difference region of $\Delta m^2 \sim 1$ eV$^2$, as suggested by the results of LSND. When exposed to the neutrino beam of a muon storage ring over a long baseline of $\sim$ 10-20 km/GeV, the model detector will efficiently probe the entire pattern of neutrino oscillations in the region $\Delta m^2 \sim 10^{-2}-10^{-3}$ eV$^2$, as suggested by the data on atmospheric neutrinos.Comment: 34 pages, 8 figure

The Pipeline: Less is More, Slower is Better, and Smaller is Possible

Background and Purpose:Despite experience gained with the Pipeline Embolization Device (PED), the following remain unclear: the significance of intra-procedural aneurysm occlusion after PED placement, if PED’s should be used for treatment of smaller aneurysms, and whether multiple PED’s are needed to achieve occlusion.Methods: Between October 2009 and December 2015, 299 patients, with 342 aneurysms distributed at the internal carotid artery and posterior circulation underwent PED embolization by a single team. Data was collected prospectively and analyzed retrospectively. A new metric assessing flow into the aneurysm following PED placement was created: the Post Stenting Flow Scale (PSFs). It ranges from 0 (no residual flow) to 3 (no significant change in flow). Clinical complications, as well as aneurysm occlusion rates and their predictors, were calculated.Results: The overall peri-procedural clinical complication rate was 18/299 (6%) including 2.7% mortality. All mortality occurred in the giant and fusiform groups. Predictors of clinical complication were aneurysm location (posterior vs. anterior circulation) and the use of multiple PED’s. Clinical complications were more common in fusiform and giant aneurysms 15/168 (9%) than in other aneurysms 3/131 (2.2%). PSFs of 0 was a predictor of vascular complications. Occlusion rate was 77%. PSFs was its only significant predictor.Conclusions: Using a single PED for aneurysm embolization is enough. Rapid and total occlusion of the aneurysm following PED deployment is an ominous sign and warrants clinical attention. Expanding the use of PED’s to treat smaller aneurysms located at the internal carotid artery appears to be a valid strategy

Detecting the (Quasi-)Two-Body Decays of τ\tau Leptons in Short-Baseline Neutrino Oscillation Experiments

Novel detector schemes are proposed for the short-baseline neutrino experiments of next generation, aimed at exploring the large-$\Delta m^2$ domain of \omutau oscillations in the appearance mode. These schemes emphasize good spectrometry for charged particles and for electromagnetic showers and efficient reconstruction of \ypi_gg decays. The basic elements are a sequence of relatively thin emulsion targets, immersed in magnetic field and interspersed with electronic trackers, and a fine-grained electromagnetic calorimeter built of lead glass. These elements act as an integral whole in reconstructing the electromagnetic showers. This conceptual scheme shows good performance in identifying the $\tau$ (quasi-)two-body decays by their characteristic kinematics and in selecting the electronic decays of the $\tau$.Comment: 34 pages, 8 figure

Status of the CMS magnet (MT17)

The CMS experiment (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with a free bore of 6 m diameter and 12.5-m length, enclosed inside a 10 000-ton return yoke. The magnet will be assembled and tested in a surface hall at Point 5 of the LHC at the beginning of 2004 before being transferred by heavy lifting means to an experimental hall 90 m below ground level. The design and construction of the magnet is a common project of the CMS Collaboration. The task is organized by a CERN based group with strong technical and contractual participation from CEA Saclay, ETH Zurich, Fermilab, INFN Genova, ITEP Moscow, University of Wisconsin and CERN. The magnet project will be described, with emphasis on the present status of the fabrication. (15 refs)

Neutral currents and tests of three-neutrino unitarity in long-baseline experiments

We examine a strategy for using neutral current measurements in long-baseline neutrino oscillation experiments to put limits on the existence of more than three light, active neutrinos. We determine the relative contributions of statistics, cross section uncertainties, event misidentification and other systematic errors to the overall uncertainty of these measurements. As specific case studies, we make simulations of beams and detectors that are like the K2K, T2K, and MINOS experiments. We find that the neutral current cross section uncertainty and contamination of the neutral current signal by charge current events allow a sensitivity for determining the presence of sterile neutinos at the 0.10--0.15 level in probablility.Comment: 24 pages, Latex2e, uses graphicx.sty, 2 postscript figures. Submitted to the Neutrino Focus Issue of New Journal Physics at http://www.njp.or