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A. Bodek

Publications and source records attributed to A. Bodek.

At least 199 records · Page 11Linked to original sources
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

Fiber R and D for the CMS HCAL

This paper documents the fiber R and D for the CMS hadron barrel calorimeter (HCAL). The R and D includes measurements of fiber flexibility, splicing, mirror reflectivity, relative light yield, attenuation length, radiation effects, absolute light yield, and transverse tile uniformity. Schematics of the hardware for each measurement are shown. These studies are done for different diameters and kinds of multiclad fiber.

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↗
arXiv2000

Physics at a Neutrino Factory

In response to the growing interest in building a Neutrino Factory to produce high intensity beams of electron- and muon-neutrinos and antineutrinos, in October 1999 the Fermilab Directorate initiated two six-month studies. The first study, organized by N. Holtkamp and D. Finley, was to investigate the technical feasibility of an intense neutrino source based on a muon storage ring. This design study has produced a report in which the basic conclusion is that a Neutrino Factory is technically feasible, although it requires an aggressive R&D program. The second study, which is the subject of this report, was to explore the physics potential of a Neutrino Factory as a function of the muon beam energy and intensity, and for oscillation physics, the potential as a function of baseline.

hep-ex↗
arXiv2000

Studies of the Response of the Prototype CMS Hadron Calorimeter, Including Magnetic Field Effects, to Pion, Electron, and Muon Beams

We report on the response of a prototype CMS hadron calorimeter module to charged particle beams of pions, muons, and electrons with momenta up to 375 GeV/c. The data were taken at the H2 and H4 beamlines at CERN in 1995 and 1996. The prototype sampling calorimeter used copper absorber plates and scintillator tiles with wavelength shifting fibers for readout. The effects of a magnetic field of up to 3 Tesla on the response of the calorimeter to muons, electrons, and pions are presented, and the effects of an upstream lead tungstate crystal electromagnetic calorimeter on the linearity and energy resolution of the combined calorimetric system to hadrons are evaluated. The results are compared with Monte Carlo simulations and are used to optimize the choice of total absorber depth, sampling frequency, and longitudinal readout segmentation.

hep-ex↗
arXiv2000

Measurements of F2, xF3nu-xF3nub from CCFR neutrino-Fe and antineutrino-Fe data in a model independent way

We report on the extraction of the structure functions F2 and Delta xF3 = xF3nu-xF3nub 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 xF3 which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The F2 (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

Performance of the NuTeV Fe-Scintillator Sampling Calorimeter and Implications for Thin Calorimeters

NuTeV is a neutrino-nucleon deep inelastic scattering experiment at Fermilab. The NuTeV detector is a traditional heavy target neutrino detector which consists of an iron/liquid scintillator sampling calorimeter followed by a muon spectrometer. The calorimeter response to hadrons, muons and electrons has been measured in an in situ calibration beam over the energy range from 4.5 to 190 GeV. The small non-linearity of the response to hadrons is compared to the expectation from the measured ratio of responses between electrons and hadrons combined with the energy dependence of the fractional electromagnetic energy deposition in the form of neutral pions in hadronic showers $f_{π^{0}}(E_π)$. The predictions use $f_{π^{0}}(E_π)$ from the Monte Carlo simulations by GHEISHA, GFLUKA and GCALOR and also from the parameterizations of Wigmans and Groom. In addition, a study based on the NuTeV hadron calibration data of the effectiveness of a thin calorimeter is presented. The results of this study have important consequences for the energy resolution of calorimeters used in other applications; for example, measuring the cosmic ray flux in space or with balloon-based experiments.

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

Studies of Higher Twist and Higher Order Effects in NLO and NNLO QCD Analysis of Lepton-Nucleon Scattering Data on F_2 and R =sigma_L/sigma_T

We report on the extraction of the higher twist contributions to F_2 and R = sigma_L/sigma_T from the global NLO and NNLO QCD fits to lepton nucleon scattering data over a wide range of Q^2. The NLO fits require both target mass and higher twist contributions at low Q^2. However, in the NNLO analysis, the data are described by the NNLO QCD predictions (with target mass corrections) without the need for any significant contributions from higher twist effects. An estimate of the difference between NLO and NNLO parton distribution functions is obtained.

hep-ex↗
arXiv1999

Nuclear Structure Functions in the Large x Large Q^2 Kinematic Region in Neutrino Deep Inelastic Scattering

Data from the CCFR E770 Neutrino Deep Inelastic Scattering (DIS) experiment at Fermilab contain events with large Bjorken x (x>0.7) and high momentum transfer (Q^2>50 (GeV/c)^2). A comparison of the data with a model based on no nuclear effects at large x, shows a significant excess of events in the data. Addition of Fermi gas motion of the nucleons in the nucleus to the model does not explain the excess. Adding a higher momentum tail due to the formation of ``quasi-deuterons'' makes some improvement. An exponentially falling F_2 \propto e^-s(x-x_0) at large x, predicted by ``multi-quark clusters'' and ``few-nucleon correlations'', can describe the data. A value of s=8.3 \pm 0.7(stat.)\pm 0.7(sys.) yields the best agreement with the data.

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↗
arXiv1999

A Study of an Acrylic Cerenkov Radiation Detector

An experiment investigating the angle of Cerenkov light emitted by 3-MeV electrons traversing an acrylic detector has been developed for use in the advanced physics laboratory course at the University of Rochester. In addition to exploring the experimental phenomena of Cerenkov radiation and total internal reflection, the experiment introduces students to several experimental techniques used in actual high energy and nuclear physics experiments, as well as to analysis techniques involving Poisson statistics. [to be published in Am. J. Phys. 67 (Oct/Nov 1999).]

physics.ed-ph↗
arXiv1999

Parton Distributions, d/u, and Higher Twist Effects at High X

A re-analysis of the NMC and SLAC data leads to a great improvement in our knowledge of the valence d and u parton distribution functions at high x. Standard parton distributions with our modifications are in good agreement with QCD predictions for d/u at x=1, and with the CDHSW nu p and nubar p data, the HERA charged current cross section data, the collider high-P_t jet data, and the CDF W asymmetry data. With the inclusion of target mass and higher twist corrections, the modified PDF's also describe all DIS data up to x = 0.98 and down to Q^2 = 1 GeV^2.

hep-ph↗
arXiv1999

Implication of W-boson Charge Asymmetry Measurements in p-pbar Collisions for Models of Charge Symmetry Violations in Parton Distributions

A surprisingly large charge symmetry violation of the sea quarks in the nucleon has been proposed in a recent article by Boros et al. as an explanation of the discrepancy between neutrino (CCFR) and muon (NMC) nucleon structure function data at low x. We show that these models are ruled out by the published CDF W charge asymmetry measurements, which strongly constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34. This constraint also limits the systematic error from possible charge symmetry violation in the determination of sin^2(theta) from nu-N scattering experiments.

hep-ex↗