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M. Danilov

Publications and source records attributed to M. Danilov.

160 records · Page 9Linked to original sources
arXiv2010

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.

physics.ins-det↗
arXiv2010

First Measurement of Inclusive B -> X_s eta Decays

We report a first measurement of inclusive B -> X_s eta decays, where X_s is a charmless state with unit strangeness. The measurement is based on a pseudo-inclusive reconstruction technique and uses a sample of 657 x 10^6 BB-bar pairs accumulated with the Belle detector at the KEKB e^+e^- collider. For M_{X_s} < 2.6 GeV/c^2, we measure a branching fraction of (26.1 +/- 3.0 (stat) +1.9 -2.1 (syst) +4.0 -7.1 (model)) x 10^-5 and a direct CP asymmetry of A_{CP} = -0.13 +/- 0.04 +0.02 -0.03. Over half of the signal occurs in the range M_{X_s} > 1.8 GeV/c^2.

hep-ex↗
arXiv2010

Study of the interactions of pions in the CALICE silicon-tungsten calorimeter prototype

A prototype silicon-tungsten electromagnetic calorimeter for an ILC detector was tested in 2007 at the CERN SPS test beam. Data were collected with electron and hadron beams in the energy range 8 to 80 GeV. The analysis described here focuses on the interactions of pions in the calorimeter. One of the main objectives of the CALICE program is to validate the Monte Carlo tools available for the design of a full-sized detector. The interactions of pions in the Si-W calorimeter are therefore confronted with the predictions of various physical models implemented in the GEANT4 simulation framework.

physics.ins-det↗
arXiv2008

Novel Photo-Detectors and Photo-Detector Systems

Recent developments in photo-detectors and photo-detector systems are reviewed. The main emphasis is made on Silicon Photo-Multipliers (SiPM) - novel and very attractive photo-detectors. Their main features are described. Properties of detectors manufactured by different producers are compared. Different applications are discussed including calorimeters, muon detection, tracking, Cherenkov light detection, and time of flight measurements.

physics.ins-det↗
arXiv2008

sBelle Design Study Report

In this note, we compile results of various simulation studies for the upgrade of the Belle detector. Based on these studies, we propose a set of optimum or appropriate parameters of the detector.

hep-ex↗
arXiv2008

Design and Electronics Commissioning of the Physics Prototype of a Si-W Electromagnetic Calorimeter for the International Linear Collider

The CALICE collaboration is studying the design of high performance electromagnetic and hadronic calorimeters for future International Linear Collider detectors. For the electromagnetic calorimeter, the current baseline choice is a high granularity sampling calorimeter with tungsten as absorber and silicon detectors as sensitive material. A ``physics prototype'' has been constructed, consisting of thirty sensitive layers. Each layer has an active area of 18x18 cm2 and a pad size of 1x1 cm2. The absorber thickness totals 24 radiation lengths. It has been exposed in 2006 and 2007 to electron and hadron beams at the DESY and CERN beam test facilities, using a wide range of beam energies and incidence angles. In this paper, the prototype and the data acquisition chain are described and a summary of the data taken in the 2006 beam tests is presented. The methods used to subtract the pedestals and calibrate the detector are detailed. The signal-over-noise ratio has been measured at 7.63 +/- 0.01. Some electronics features have been observed; these lead to coherent noise and crosstalk between pads, and also crosstalk between sensitive and passive areas. The performance achieved in terms of uniformity and stability is presented.

physics.ins-det↗
arXiv2008

Systematic study of trace radioactive impurities in candidate construction materials for EXO-200

The Enriched Xenon Observatory (EXO) will search for double beta decays of 136Xe. We report the results of a systematic study of trace concentrations of radioactive impurities in a wide range of raw materials and finished parts considered for use in the construction of EXO-200, the first stage of the EXO experimental program. Analysis techniques employed, and described here, include direct gamma counting, alpha counting, neutron activation analysis, and high-sensitivity mass spectrometry.

physics.ins-det↗
arXiv2007

Study of Scintillator Strip with Wavelength Shifting Fiber and Silicon Photomultiplier

The performance of the $200\times2.5\times1$ cm$^3$ plastic scintillator strip with wavelength shifting fiber read-out by two novel photodetectors called Silicon PhotoMultipliers (SiPMs) is discussed. The advantages of SiPM relative to the traditional multichannel photomultiplier are shown. Light yield and light attenuation measurements are presented. This technique can be used in muon or calorimeter systems.

physics.ins-det↗
arXiv2007

Experimental Review on Pentaquarks

The experimental evidence for pentaquarks is reviewed and compared with the experiments that do not see any sign of pentaquarks. This paper is based on a lecture given at the 33rd ITEP Winter School of Physics in the beginning of 2005. Results obtained since then are summarized in the epilogue.

hep-ex↗
arXiv2007

Scintillator Tile Hadron Calorimeter with Novel SiPM Readout

The CALICE collaboration is presently constructing a test hadron calorimeter (HCAL) with 7620 scintillator tiles read out by novel photo-detectors - Silicon Photomultipliers (SiPMs). This prototype is the first device which uses SiPMs on a large scale. We present the design of the HCAL and report on measured properties of more than 10 thousand SiPMs. We discuss the SiPM efficiency, gain, cross-talk, and noise rate dependence on bias voltage and temperature, including the spread in these parameters. We analyze the reasons for SiPM rejection and present the results of the long term stability studies. The first measurements of the SiPM radiation hardness are presented. We compare properties of SiPM with the properties of similar devices, MRS APD and MPPC. A possibility to make the tiles thinner and to read them out without WLS fibers has been studied.

physics.ins-det↗
arXiv2003

Correlated Fluctuations between Luminescence and Ionization in Liquid Xenon

The ionization of liquefied noble gases by radiation is known to be accompanied by fluctuations much larger than predicted by Poisson statistics. We have studied the fluctuations of both scintillation and ionization in liquid xenon and have measured, for the first time, a strong anti-correlation between the two at a microscopic level, with coefficient $ -0.80 < ρ_{ep} < -0.60 $. This provides direct experimental evidence that electron-ion recombination is partially responsible for the anomalously large fluctuations and at the same time allows substantial improvement of calorimetric energy resolution.

hep-ex↗
arXiv2002

Aging tests of the proportional wire chambers using Ar/CF4/CH4 (74:20:6), Ar/CF4/CH4 (67:30:3), Ar/CF4/CO2 (65:30:5) mixtures for the HERA-B Muon Detector

The Muon Detector of the HERA-B experiment at DESY is a gaseous detector that provides muon identification in a high-rate hadronic environment. We present our studies on the properties of several fast gases, Ar/CF4/CH4 (74:20:6), Ar/CF4/CH4 (67:30:3) and Ar/CF4/CO2 (65:30:5), which have been found to fulfill muon detection requirements. The severe radiation environment of the HERA-B experiment leads to the maximum charge deposit on a wire, within the muon detector, of 200 mC/cm per year. For operation in such an environment, the main criteria for the choice of gas turned out to be stability against aging. An overview of aging results from laboratory setups and experimental detectors for binary and ternary mixtures of Ar, CH4, CF4 and CO2 is presented and the relevance of the various aging results is discussed. Since it is not clear how to extrapolate aging results from small to large areas of irradiation, the lifetime of aluminum proportional chambers was studied under various conditions. In this paper we provide evidence that aging results depend not only upon the total collected charge. It was found that the aging rate for irradiation with $Fe^{55}$ X-rays and 100 MeV $α$-particles may differ by more than two orders of magnitude.

hep-ex↗
arXiv2001

Aging Studies of Large Area Proportional Chambers under High-Rate Irradiation with $CF_4$-based Mixtures (Part 2)

Experimental conditions at the HERA-B experiment impose very strong requirements for gaseous detectors. The charged particle fluxes through the HERA-B tracking system, varying with the radial distance R from the beam line, are about $2 \times 10^{7}/R^{2}$ particles per second, and comparable to those that will be encountered by LHC experiments. The severe radiation environment of the HERA-B experiment leads to a maximum charge deposit on a wire, within the muon detector, of 200 mC/cm per year. We report recent results of aging studies performed by irradiating proportional wire chambers filled with $Ar/CF_4/CH_4$ (74:20:6), $Ar/CF_4/CH_4$ (67:30:3), $Ar/CF_4/CO_2$ (65:30:5), $Ar/CF_4$ (70:30), $CF_4/CH_4$ (90:10), $CF_4/CH_4$ (80:20) mixtures in a three different experimental setups. The size of the irradiation zone varied in the tests from 1 cm up to 500 cm. Our experience shows that the aging rate depends not only on the total collected charge, but, in addition, on the mode of operation and area of irradiation. The possible application of these results to the construction of a large area gaseous detectors for operation in high rate environments is presented.

hep-ex↗
arXiv2001

Aging Studies of Large Area Proportional Chambers under High-Rate Irradiation with $CF_4$-based Mixtures (PART 1)

Experimental conditions at the HERA-B experiment impose very strong requirements for gaseous detectors. The charged particle fluxes through the HERA-B tracking system, varying with the radial distance $R$ from the beam line, are about $2 \times 10^{7}/R^{2}$ particles per second, and comparable to those that will be encountered by LHC experiments. The severe radiation environment of the HERA-B experiment leads to a maximum charge deposit on a wire, within the muon detector, of 200 mC/cm per year. We report recent results of aging studies performed by irradiating proportional wire chambers filled with $Ar/CF_4/CH_4$ (74:20:6), $Ar/CF_4/CH_4$ (67:30:3), $Ar/CF_4/CO_2$ (65:30:5), $Ar/CF_4$ (70:30), $CF_4/CH_4$ (90:10), $CF_4/CH_4$ (80:20) mixtures in a three different experimental setups. The size of the irradiation zone varied in the tests from 1 cm up to 500 cm. Our experience shows that the aging rate depends not only on the total collected charge, but, in addition, on the mode of operation and area of irradiation. The possible application of these results to the construction of a large area gaseous detectors for operation in high rate environments is presented.

hep-ex↗
arXiv2000

Detection of very small neutrino masses in double-beta decay using laser tagging

We describe an approach to the study of neutrino masses that combines quantum optics techniques with radiation detectors to obtain unprecedented sensitivity. With it the search for Majorana neutrino masses down to $\sim$10 meV will become accessible. The experimental technique uses the possibility of individually detecting $\rm Ba^+$-ions in the final state of $\rm ^{136}Xe$ double-beta decay via resonant excitation with a set of lasers aimed at a specific location in a large Time Projection Chamber. The specificity of the atomic levels provides tagging and, together with more traditional event recognition parameters, greatly suppresses radioactive backgrounds.

hep-ex↗