arXiv subjects

M. Goncharov

Publications and source records attributed to M. Goncharov.

At least 19 recordsLinked to original sources

arXiv2016

Direct determination of the atomic mass difference of Re187 and Os187 for neutrino physics and cosmochronology

For the first time a direct determination of the atomic mass difference of 187Re and 187Os has been performed with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. The obtained value of 2492(30stat)(15sys) eV is in excellent agreement with the Q values determined indirectly with microcalorimetry and thus resolves a long-standing discrepancy with older proportional counter measurements. This is essential for the determination of the neutrino mass from the beta-decay of 187Re as planned in future microcalorimetric measurements. In addition, an accurate mass difference of 187Re and 187Os is also important for the assessment of 187Re for cosmochronology.

nucl-ex↗

arXiv2016

Direct Measurement of the Mass Difference of Ho163 and Dy163 Solves the Q-Value Puzzle for the Neutrino Mass Determination

The atomic mass difference of 163Ho and 163Dy has been directly measured with the Penning trap mass spectrometer SHIPTRAP applying the novel phase imaging ion cyclotron resonance technique. Our measurement has solved the long standing problem of large discrepancies in the Q value of the electron capture in 163Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 [G. Audi et al., Chin. Phys. C 36, 1157 (2012)] by more than 7 sigma to 2833(30stat)(15sys) eV/c2. With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude.

physics.ins-det↗

arXiv2011

PENTATRAP: A novel cryogenic multi-Penning trap experiment for high-precision mass measurements on highly charged ions

The novel five-Penning trap mass spectrometer PENTATRAP is developed at the Max-Planck-Institut für Kernphysik (MPIK), Heidelberg. Ions of interest are long-lived highly charged nuclides up to bare uranium. PENTATRAP aims for an accuracy of a few parts in 10^12 for mass ratios of mass doublets. A physics program for PENTATRAP includes Q-values measurements of β-transitions relevant for neutrino physics, stringent tests of quantum electrodynamics in the regime of extreme electric fields, and a test of special relativity. Main features of PENTATRAP are an access to a source of highly charged ions, a multi-trap configuration, simultaneous measurements of frequencies, a continuous precise monitoring of magnetic field fluctuations, a fast exchange between different ions, and a highly sensitive cryogenic non-destructive detection system. This paper gives a motivation for the new mass spectrometer PENTATRAP, presents its experimental setup, and describes the present status.

physics.atom-ph↗

arXiv2005

The Timing System for the CDF Electromagnetic Calorimeters

We report on the design and performance of the electromagnetic calorimeter timing readout system (EMTiming) for the Collider Detector at Fermilab (CDF). The system will be used in searches for rare events with high energy photons to verify that the photon is in time with the event collision, to reject cosmic ray and beam halo backgrounds, and to allow direct searches for new heavy long-lived particles that decay to photons. The installation and commissioning of all 862 channels was completed in Fall 2004 as part of an upgrade to the Run II version of the detector. Using in-situ data, including electrons from W=>e nu and Z => ee decays, we measure the energy threshold for a time to be recorded to be 3.8 \pm 0.3GeV in the central portion of the detector and 1.9 \pm 0.1 GeV in the plug portion. Similarly, we measure a timing resolution of 600 \pm 10 ps and 610 \pm 10 ps for electrons above 10 GeV and 6 GeV respectively. There are very few system pathologies such as recording a time when no energy is deposited, or recording a second, fake time for a single energy deposit.

physics.ins-det↗

arXiv2005

Precise Measurement of Neutrino and Anti-neutrino Differential Cross Sections

The NuTeV experiment at Fermilab has obtained a unique high statistics sample of neutrino and anti-neutrino interactions using its high-energy sign-selected beam. We present a measurement of the differential cross section for charged-current neutrino and anti-neutrino scattering from iron. Structure functions, F_2(x,Q^2) and xF_3(x,Q^2), are determined by fitting the inelasticity, y, dependence of the cross sections. This measurement has significantly improved systematic precision as a consequence of more precise understanding of hadron and muon energy scales.

hep-ex↗

arXiv2003

Selection of Tau Leptons with the CDF II Trigger System

In Run II of the CDF experiment, traditional dilepton triggers are enriched by lepton (electrons or muons) plus track, di-tau and tau plus missing transverse energy triggers at Level-3 dedicated to physical processes including tau leptons. We describe these triggers, along with their physics motivations, implementation and cross-sections and report on their initial performance.

hep-ex↗

arXiv2003

A Departure from Prediction: Electroweak Physics at Nutev

The NuTeV experiment has performed precision measurements of the ratio of neutral-current to charged-current cross-sections in high rate, high energy neutrino and anti-neutrino beams on a dense, primarily steel, target. The separate neutrino and anti-neutrino beams, high statistics, and improved control of other experimental systematics, allow the determination of electroweak parameters with significantly greater precision than past neutrino-nucleon scattering experiments. Our null hypothesis test of the standard model prediction measures sin2thetaW=0.2277+/-0.0013(stat)+/-0.0009(syst), a value which is 3.0 standard deviations above the prediction. We discuss possible explanations for and implications of this discrepancy.

hep-ex↗

arXiv2003

A Precise Determination of Electroweak Parameters in Neutrino-Nucleon Scattering

The NuTeV collaboration has extracted sin^2theta_W from the ratios of neutral current to charged current neutrino and anti-neutrino cross-sections. Our value, sin^2theta_W(on-shell)=0.2277+/-0.0013(stat)+/-0.0009(syst), is three standard deviations above the standard model prediction. We also present a model independent analysis of the same data.

hep-ex↗

arXiv2002

Off the Mass Shell: Electroweak Physics at NuTeV

The NuTeV collaboration has performed precision measurements of the ratio of neutral current to charged current cross-sections in high rate, high energy neutrino and anti-neutrino beams on a dense, primarily steel, target. The separate neutrino and anti-neutrino beams, high statistics, and improved control of other experimental systematics, allow the determination of electroweak parameters with significantly greater precision than past neutrino-nucleon scattering experiments. Our null hypothesis test of the standard model prediction measures sin2thetaW=0.2277+/-0.0013(stat)+/-0.0009(syst), a value which is 3 sigma above the prediction. We discuss possible explanations for and implications of this discrepancy.

hep-ex↗

arXiv2002

A Search for Muon-neutrino to Electron-neutrino and Muon-antineutrino to Electron-antineutrino Oscillations at NuTeV

Limits on $ν_μ\to ν_e$ and $\barν_μ\to \barν_e$ oscillations are extracted using the NuTeV detector with sign-selected $ν_μ$ and $\nub_μ$ beams. In $\nub_μ$ mode, for the case of $\sin^2 2α= 1$, $Δm^2 > 2.6$ ${\rm eV^2}$ is excluded, and for $Δm^2 \gg 1000$ ${\rm eV^2}$, $\sin^2 2α> 1.1 \times 10^{-3}$. The NuTeV data exclude the high $Δm^2$ end of $\barν_μ\to \barν_e$ oscillations parameters favored by the LSND experiment without the need to assume that the oscillation parameters for $ν$ and $\nub$ are the same. We present the most stringent experimental limits for $ν_μ(\barν_μ) \to ν_e (\barν_e)$ oscillations in the large $Δm^2$ region.

hep-ex↗

arXiv2001

Observation of an Anomalous Number of Dimuon Events in a High Energy Neutrino Beam

A search for long-lived neutral particles (N^0's) with masses above 2.2 GeV/c^2 that decay into at least one muon has been performed using an instrumented decay channel at the NuTeV experiment at Fermilab. Data were examined for particles decaying into the final states mu mu, mu e, and mu pi. Three mu mu events were observed over an expected Standard Model background of 0.069 +/- 0.010 events; no events were observed in the other modes.

hep-ex↗

arXiv2001

Precise Measurement of Dimuon Production Cross-Sections in muon neutrino Fe and muon antineutrino Fe Deep Inelastic Scattering at the Tevatron

We present measurements of the semi-inclusive cross-sections for muon neutrino and muon antineutrino-nucleon deep inelastic scattering interactions with two oppositely charged muons in the final state. These events dominantly arise from production of a charm quark during the scattering process. The measurement was obtained from the analysis of 5102 muon neutrino-induced and 1458 muon antineutrino-induced events collected with the NuTeV detector exposed to a sign-selected beam at the Fermilab Tevatron. We also extract a cross-section measurement from a re-analysis of 5030 muon neutrino-induced and 1060 muon antineutrino-induced vents collected from the exposure of the same detector to a quad-triplet beam by the CCFR experiment. The results are combined to obtain the most statistically precise measurement of neutrino-induced dimuon production cross-sections to date. These measurements should be of broad use to phenomenologists interested in the dynamics of charm production, the strangeness content of the nucleon, and the CKM matrix element Vcd.

hep-ex↗

arXiv2000

New Measurements of Nucleon Structure Functions from CCFR/NuTeV

We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nub from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. Within 5% the F_2 (PMI) values measured in neutrino and muon scattering are in agreement with the predictions of Next-to-Leading-Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two measurements.

hep-ex↗

arXiv2000

New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration

We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The F_2 (PMI) values measured in neutrino and muon scattering are in good agreement with the predictions of Next to Leading Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two sets of data.

hep-ex↗

arXiv2000

Observation of Anomalous Dimuon Events in the NuTeV Decay Detector

A search for long-lived neutral particles (N^0) which decay into at least one muon has been performed using an instrumented decay channel at the E815 (NuTeV) experiment at Fermilab. The decay channel was composed of helium bags interspersed with drift chambers, and was used in conjunction with the NuTeV neutrino detector to search for N^0 decays. The data were examined for particles decaying into the muonic final states mu mu, mu e, and mu pi. Three mu mu events were observed over an expected background of 0.040 +/- 0.009 events; no events were observed in the other modes. Although the observed events share some characteristics with neutrino interactions, the observed rate is a factor of 75 greater than expected. No Standard Model process appears to be consistent with this observation.

hep-ex↗

arXiv1999

Search for a 33.9 MeV/c^2 Neutral Particle in Pion Decay

The E815 (NuTeV) neutrino experiment has performed a search for a 33.9 MeV/c^2 weakly-interacting neutral particle produced in pion decay. Such a particle may be responsible for an anomaly in the timing distribution of neutrino interactions in the KARMEN experiment. E815 has searched for this particle's decays in an instrumented decay region; no evidence for this particle was found. The search is sensitive to pion branching ratios as low as 10^-13.

hep-ex↗

arXiv1999

Evidence for Diffractive Charm Production in nu_mu Fe and nubar_mu Fe Scattering at the Tevatron

We present evidence for the diffractive processes nu_mu Fe -> mu^- D_s^+ (D_s^*+) Fe and nubar_mu Fe -> mu^+ D_s^- (D_s^*-) Fe using the Fermilab SSQT neutrino beam and the Lab E neutrino detector. We observe the neutrino trident reactions nu_mu Fe -> nu_mu mu^- mu^+ Fe and nubar_mu Fe -> nubar_mu mu^+ mu^- Fe at rates consistent with Standard Model expectations. We see no evidence for neutral-current production of J/psi via either diffractive or deep inelastic scattering mechanisms.

hep-ex↗

arXiv1999

Low Q^2 low x structure function analysis of CCFR data for F2

Analyses of structure functions (SFs) from neutrino and muon deep inelastic scattering data have shown discrepancies in F2 for x < 0.1. A new SF analysis of the CCFR collaboration data examining regions in x down to x=.0015 and 0.4 < Q^2 < 1.0 is presented. Comparison to corrected charged lepton scattering results for F2 from the NMC and E665 experiments are made. Differences between muon and neutrino scattering allow that the behavior of F2 from muon scattering could be different from F2 from neutrino scattering as Q^2 approaches zero. Comparisons between F2 muon and F2 neutrino are made in this limit.

hep-ex↗