arXiv subjects

Yu. V. Mikhailov

Publications and source records attributed to Yu. V. Mikhailov.

23 records · Page 2Linked to original sources

arXiv2017

High purity 100 GeV electron identification with synchrotron radiation

In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV $π^-$ beam is used to test the method in the NA64 experiment resulting in a suppression factor of $10^{-5}$ while the efficiency for electron detection is $\sim$95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved.

physics.ins-det↗

arXiv2016

Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS

We report on a direct search for sub-GeV dark photons (A') which might be produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The A's would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75\cdot 10^{9} electrons on target. We set new limits on the γ-A' mixing strength and exclude the invisible A' with a mass < 100 MeV as an explanation of the muon g_μ-2 anomaly.

hep-ex↗

arXiv2014

A search for decay $η' \rightarrow 4 π^{0}$ with GAMS-$4π$ Setup

A search for rare decay $η' \rightarrow 4 π^{0}$ has been performed with GAMS-4$π$ Setup. The new upper limit for decay was established $BR(η' \rightarrow 4 π^{0}) < 3.2 \cdot 10^{-4}$ at 90\% confidence level. The $π^{-} p$ charge-exchange reaction at 32.5 GeV/c was used as a source of $1.3\cdot 10^{6}$ $ η'$ mesons. Experiment carried out at the IHEP U-70 accelerator.

hep-ex↗

arXiv2013

Proposal for an Experiment to Search for Light Dark Matter at the SPS

Several models of dark matter suggest the existence of dark sectors consisting of SU(3)_C x SU(2)_L x U(1)_Y singlet fields. These sectors of particles do not interact with the ordinary matter directly but could couple to it via gravity. In addition to gravity, there might be another very weak interaction between the ordinary and dark matter mediated by U'(1) gauge bosons A' (dark photons) mixing with our photons. In a class of models the corresponding dark gauge bosons could be light and have the $γ$-A' coupling strength laying in the experimentally accessible and theoretically interesting region. If such A' mediators exist, their di-electron decays A' -> e+e- could be searched for in a light-shining-through-a-wall experiment looking for an excess of events with the two-shower signature generated by a single high energy electron in the detector. A proposal to perform such an experiment aiming to probe the still unexplored area of the mixing strength 10^-5 < $ε$ < 10^-3 and masses M_A' < 100 MeV by using 10-300 GeV electron beams from the CERN SPS is presented. The experiment can provide complementary coverage of the parameter space, which is intended to be probed by other searches. It has also a capability for a sensitive search for A's decaying invisibly to dark-sector particles, such as dark matter, which could cover a significant part of the still allowed parameter space. The full running time of the proposed measurements is requested to be up to several months, and it could be taken at different SPS secondary beams.

hep-ex↗

arXiv2013

Measurement of the $η$ -$η'$ mixing angle in $π^{-}$ and $K^{-}$ beams with GAMS-$4π$ Setup

The results of mixing angle measurement for $η'$, $η$ mesons generated in charge exchange reactions with $π^{-}$ and $K^{-}$ beams are preseneted. When the $η'$, $η$ mesons are described in nonstrange(NS)--strange(S) quark basis the $π^{-}$ and $K^{-}$ beams allow to study $|η_{q}>$ and $|η_{s}>$ parts of the meson wave function. The cross section ratio at $t'=0$ (GeV/c)$^{2}$ in the $π^{-}$ beam is $R_π(η'/η)= 0.56 \pm 0.04$, results in mixing angle $ϕ_{P} = (36.8 \pm 1.)^{o} $. For $K^{-}$ beam the ratio is $R_{K}(η'/η)= 1.30 \pm 0.16$. It was found that gluonium content in $η'$ is $\sin^{2}ψ_{G}= 0.15 \pm 0.06$. The experiment was carried out with GAMS-4$π$ Setup.

hep-ex↗