N. V. Khomutov
A5056448992- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- High-Energy Particle Collisions Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Radioactive Decay and Measurement Techniques
- Noncommutative and Quantum Gravity Theories
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Nuclear Materials and Properties
- Particle accelerators and beam dynamics
- Scientific Research and Discoveries
- Astrophysics and Cosmic Phenomena
- Advanced NMR Techniques and Applications
- Nuclear reactor physics and engineering
- International Science and Diplomacy
- Distributed and Parallel Computing Systems
- Chemical and Physical Properties of Materials
Joint Institute for Nuclear Research
2013-2024
Dubna State University
1991-2024
Tbilisi State University
2009
University of Virginia
2009
Paul Scherrer Institute
1991-2009
National Centre for Nuclear Research
2009
University of Zurich
2009
Rudjer Boskovic Institute
2009
The final results of the search for lepton flavour violating decay $$\mathrm {\mu }^+ \rightarrow \mathrm {e}^+ {\gamma }$$ based on full dataset collected by MEG experiment at Paul Scherrer Institut in period 2009–2013 and totalling $$7.5\times 10^{14}$$ stopped muons target are presented. No significant excess events is observed with respect to expected background a new upper limit branching ratio this $$ \mathcal{B} (\mu ^+ \mathrm{e}^+ \gamma ) < 4.2 \times 10^{-13}$$ (90 % confidence...
The MEG experiment, designed to search for the mu+->e+ gamma decay at a 10^-13 sensitivity level, completed data taking in 2013. In order increase reach of experiment by an magnitude level 6 x 10-14 branching ratio, total upgrade, involving substantial changes has been undertaken, known as II. We present both motivation upgrade and detailed overview design expected detector performance.
The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency $ω_a$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run 2018. When combined a precision measurement magnetic field experiment's ring, determines anomaly $a_μ({\rm FNAL}) = 116\,592\,040(54) \times 10^{-11}$ (0.46 ppm). This article describes...
Abstract The MEG II experiment, based at the Paul Scherrer Institut in Switzerland, reports result of a search for decay $$\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>μ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:mtext>e</mml:mtext> </mml:mrow> <mml:mi>γ</mml:mi> </mml:math> from data taken first physics run 2021. No excess events over expected background is observed, yielding an...
The Fermi National Accelerator Laboratory has measured the anomalous precession frequency $a^{}_\mu = (g^{}_\mu-2)/2$ of muon to a combined precision 0.46 parts per million with data collected during its first physics run in 2018. This paper documents measurement magnetic field storage ring. is monitored by nuclear resonance systems and calibrated terms equivalent proton spin spherical water sample at 34.7$^\circ$C. weighted distribution resulting $\tilde{\omega}'^{}_p$, denominator ratio...
Abstract The MEG II experiment, located at the Paul Scherrer Institut (PSI) in Switzerland, is successor to which completed data taking 2013. started fully operational 2021, with goal of improving sensitivity $$\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma $$ <mml:math...
Using a large acceptance calorimeter and stopped pion beam we have made precise measurement of the rare ${\ensuremath{\pi}}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{e}^{+}\ensuremath{\nu}$ (${\ensuremath{\pi}}_{\ensuremath{\beta}}$) decay branching ratio. We evaluated ratio by normalizing number observed ${\ensuremath{\pi}}_{\ensuremath{\beta}}$ decays to ${\ensuremath{\pi}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\nu}$ (${\ensuremath{\pi}}_{e2}$) decays. find value...
In case a mirror world with copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, n', could potentially mix undergo nn' oscillations. The interaction an magnetic field lift degeneracy between partners, diminish n' amplitude in wave function and, thus, suppress observability. We report experimental comparison ultracold storage trap without superimposed field. No influence is found assuming negligible fields, limit on oscillation time taunn' > 103 s (95%...
A clock comparison experiment, analyzing the ratio of spin precession frequencies stored ultracold neutrons and 199Hg atoms, is reported. No daily variation this could be found, from which set an upper limit on Lorentz invariance violating cosmic anisotropy field b perpendicular < 2 x 10(-20) eV (95% C.L.). This first for free neutron. result also interpreted as a direct gravitational dipole moment neutron |gn| 0.3 eV/c2 m spin-dependent interaction with Sun. Analyzing Earth, based previous...
The MEG experiment took data at the Paul Scherrer Institute in years 2009–2013 to test violation of lepton flavor conservation law, which originates from an accidental symmetry that Standard Model elementary particle physics has, and published most stringent limit on charged violating decay μ+→e+γ: BR(μ+→e+γ) <4.2×10−13 90% confidence level. detector has been upgraded order reach a sensitivity 6×10−14. basic principle II is achieve highest possible using full muon beam intensity (7×107...
We have measured the pi+-->e+ nugamma branching ratio over a wide region of phase space, based on total 65 460 events acquired using PIBETA detector. Minimum-chi2 fits to (E(e+), E(gamma) energy distributions result in weak form factor value F(A)=0.0119(1) with fixed F(V)=0.0259. An unconstrained fit yields F(V)=0.0258(17) and F(A)=0.0117(17). In addition, we a=0.10(6) for dependence F(V) q2, e+ nu pair invariant mass squared, parametrized as F(V)(q2)=F(V)(0)(1+aq(2)). The kinematic...
We performed ultracold neutron storage measurements to search for additional losses due (n) mirror-neutron (n′) oscillations as a function of an applied magnetic field B. In the presence mirror B′, would be maximal B≈B′. did not observe any indication nn′ and placed lower limit on oscillation time τnn′>12.0 s at 95% C.L. B′ between 0 12.5 μT.Received 26 May 2009DOI:https://doi.org/10.1103/PhysRevD.80.032003©2009 American Physical Society
We present a precise measurement of the deuteron longitudinal spin asymmetry A1d and spin-dependent structure function g1d at Q2<1(GeV/c)2 4×10−5<x<2.5×10−2 based on data collected by COMPASS experiment CERN during years 2002 2003. The statistical precision is tenfold better than that previous in this region. measured are found to be consistent with zero whole range x.
The measurement of the neutron electric dipole moment (nEDM) constrains contribution CP-violating terms within both Standard Model and its extensions. experiment uses ultracold neutrons (UCN) stored in vacuum at room temperature. This technique provided last (and best) limit by RAL/Sussex/ILL collaboration 2006: dn < 2:9 × 10-26 e cm (90% C.L.). We aim to improve experimental sensitivity a factor 5 2-3 years, using an upgrade same apparatus. will take advantage increased density Paul...
Abstract We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X, $$\upmu ^+ \rightarrow \mathrm {e}^+\mathrm {X}, {X} \upgamma \ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>μ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:mi>e</mml:mi> </mml:mrow> <mml:mi>X</mml:mi> <mml:mo>,</mml:mo> <mml:mi>γ</mml:mi> <mml:mspace /> </mml:math> . This uses dataset resulting from...
We have studied radiative pion decays pi(+)-->e(+)nugamma in three broad kinematic regions using the PIBETA detector and a stopped beam. Based on Dalitz distributions of 41 601 events we evaluated absolute pi-->enugamma branching ratios regions. Minimum chi(2) fits to integral differential (E(e(+)),E(gamma)) result axial-to-vector weak form factor ratio gamma identical with F(A)/F(V)=0.443(15), or F(A)=0.0115(4) F(V)=0.0259. However, deviations from standard model predictions...
The anomalous magnetic moment of the muon is one most precisely measured quantities in experimental particle physics. Its latest measurement at Brookhaven National Laboratory deviates from Standard Model expectation by approximately 3.5 standard deviations. goal new experiment, E989, now under construction Fermilab, a fourfold improvement precision. Here, we discuss details future and its current status.
We studied the radiative muon decay $μ^+ \to e^+ν\barνγ$ by using for first time an almost fully polarized source. identified a large sample (~13000) of these decays in total 1.8x10^14 positive collected MEG experiment years 2009--2010 and measured branching ratio B($μ^+ e^+ν\barνγ$) = (6.03+-0.14(stat.)+-0.53(sys.))x10^-8 E_e > 45 MeV E_γ 40 MeV, consistent with Standard Model prediction. The precise measurement this mode provides basic tool timing calibration, normalization channel,...
We propose an original test of Lorentz invariance in the interaction between a particle spin and electromagnetic field report on first measurement using ultracold neutrons. used high-sensitivity neutron electric dipole moment (nEDM) spectrometer searched for direction dependence nEDM signal leading to modulation its magnitude at periods 12 24 hours. constrain such d12 < 10×10−25e cm d24 14×10−25e 95% C.L. The result translates into limit energy scale this type violation effect level εLV > 1010 GeV.
The MEG II experiment, based at the Paul Scherrer Institut in Switzerland, reports result of a search for decay $\mu^+\to e^+\gamma$ from data taken first physics run 2021. No excess events over expected background is observed, yielding an upper limit on branching ratio B($\mu^+\to e^+\gamma$) < $7.5 \times 10^{-13}$ (90% C.L.). combination this and obtained by gives $3.1 C.L.), which most stringent to date. A ten-fold larger sample being collected during years 2022-2023, data-taking will...
The MEG experiment makes use of one the world's most intense low energy muon beams, in order to search for lepton flavour violating process $\mu^{+} \rightarrow {\rm e}^{+} \gamma$. We determined residual beam polarization at thin stopping target, by measuring asymmetry angular distribution Michel decay positrons as a function energy. initial production is predicted be $P_{\mu} = -1$ Standard Model (SM) with massless neutrinos. estimated our -0.85 \pm 0.03 ~ (stat)} { }^{+ 0.04}_{-0.05}...