Search

We have searched for correlations between the pointing directions of ultrahigh energy cosmic rays observed by the High Resolution Fly's Eye experiment and Active Galactic Nuclei (AGN) visible from its northern hemisphere location. No correlations, other than random correlations, have been found. We report our results using search parameters prescribed by the Pierre Auger collaboration. Using these parameters, the Auger collaboration concludes that a positive correlation exists for sources visible to their southern hemisphere location. We also describe results using two methods for determining the chance probability of correlations: one in which a hypothesis is formed from scanning one half of the data and tested on the second half, and another which involves a scan over the entire data set. The most significant correlation found occurred with a chance probability of 24%., 13 pages, 1 table, 5 figures

Air fluorescence detectors traditionally determine the dominant chemical composit ion of the ultrahigh energy cosmic ray flux by comparing the averaged slant depth of the shower maximum, $X_{max}$, as a function of energy to the slant depths expect ed for various hypothesized primaries. In this paper, we present a method to make a direct measurement of the expected mean number of protons and iron by comparing the shap es of the expected $X_{max}$ distributions to the distribution for data. The advantages of this method includes the use of information of the full distribution and its ability to calculate a flux for various cosmic ray compositi ons. The same method can be expanded to marginalize uncertainties due to choice of spectra, hadronic models and atmospheric parameters. We demonstrate the technique with independent simulated data samples from a parent sample of protons and iron. We accurately predict the number of protons and iron in the parent sample and show that the uncertainties are meaningful., 11 figures, 22 pages, accepted by Astroparticle Physics

We present preliminary results of the search for the pentaquark candidates Θ(1540) and Ξ(1862) using data from Fermilab experiment E690 in the reaction pp → pX at 800 GeV/c. We find that production of pentaquark resonances is heavily suppressed with respect to the production of normal baryon and antibaryon resonances.

Air fluorescence measurements of cosmic ray energy must be corrected for attenuation of the atmosphere. In this paper we show that the air-showers themselves can yield a measurement of the aerosol attenuation in terms of optical depth, time-averaged over extended periods. Although the technique lacks statistical power to make the critical hourly measurements that only specialized active instruments can achieve, we note the technique does not depend on absolute calibration of the detector hardware, and requires no additional equipment beyond the fluorescence detectors that observe the air showers. This paper describes the technique, and presents results based on analysis of 1258 air-showers observed in stereo by the High Resolution Fly's Eye over a four year span., Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics Journal

Data taken in stereo mode by the High Resolution Fly's Eye (HiRes) air fluorescence experiment are analyzed to search for correlations between the arrival directions of ultra--high-energy cosmic rays with the positions of BL Lacertae objects. Several previous claims of significant correlations between BL Lacs and cosmic rays observed by other experiments are tested. These claims are not supported by the HiRes data. However, we verify a recent analysis of correlations between HiRes events and a subset of confirmed BL Lacs from the 10th Veron Catalog, and we study this correlation in detail. Due to the a posteriori nature of the search, the significance level cannot be reliably estimated and the correlation must be tested independently before any claim can be made. We identify the precise hypotheses that will be tested with statistically independent data., Comment: 5 pages, 1 figure, submitted to ApJ

We present the results of a search for cosmic ray point sources at energies above 40 EeV in the combined data sets recorded by the AGASA and HiRes stereo experiments. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather than requiring an a priori choice of a fixed angular bin size. No statistically significant clustering of events consistent with a point source is found.

The composition of Ultra High Energy Cosmic Rays (UHECR) is measured with the High Resolution Fly's Eye cosmic ray observatory (HiRes) data using the Xmax technique. Data were collected in stereo between 1999 November and 2001 September. The data are reconstructed with well-determined geometry. Measurements of the atmospheric transmission are incorporated in the reconstruction. The detector resolution is found to be 30 g cm^-2 in Xmax and 13% in Energy. The Xmax elongation rate between 10^18.0 eV and 10^19.4 eV is measured to be 54.5 +/- 6.5 (stat) +/- 4.5 (sys) g cm^-2 per decade. This is compared to predictions using the QGSJet01 and SIBYLL 2.1 hadronic interaction models for both protons and iron nuclei. CORSIKA-generated Extensive Air Showers (EAS) are incorporated directly into a detailed detector Monte Carlo program. The elongation rate and the Xmax distribution widths are consistent with a constant or slowly changing and predominantly light composition. A simple model containing only protons and iron nuclei is compared to QGSJet and SIBYLL. The best agreement between the model and the data is at 80% protons for QGSJet and 60% protons for SIBYLL., Comment: 52 pages, 27 figures. Revised Fig. 10 caption, improved Fig. 23, resubmitted to ApJ. (Previously revised to address referee's comments.) (Originally 37 pages, 13 figures. Submitted to ApJ)

The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of 06 and is sensitive to cosmic rays with energies above 1018 eV. The HiRes cosmic-ray detector is thus an excellent instrument for the study of the arrival directions of ultra-high-energy cosmic rays. We present the results of a search for anisotropies in the distribution of arrival directions on small scales ( 1019 eV). The search is based on data recorded between 1999 December and 2004 January, with a total of 271 events above 1019 eV. No small-scale anisotropy is found, and the strongest clustering found in the HiRes stereo data is consistent at the 52% level with the null hypothesis of isotropically distributed arrival directions.

Λ 0 polarization from pp → p diffracted Λ 0 K + at 800 GeV / c in the average depends linearly on Λ 0 K + invariant mass: Λ 0 polarization is 0.635 ± 0.036 at 1.64 GeV , consistent with zero at ≈ 2.195 GeV , and −0.586 ± 0.072 at 3.200 GeV . The origin of this Λ 0 polarization is, probably, the interference of at least two Λ 0 K + resonances, created from the excitation of the target proton, due to the diffracted proton transfered momentum.

The high resolution Fly’s Eye (HiRes) detector in Dugway, Utah, is an air fluorescence detector designed for the measurement of the energy and arrival direction of cosmic ray particles with energy E >10 18 eV. HiRes monitors the night sky for fluorescence light from air shower cascades induced by cosmic ray primaries. The light is collected by mirrors and projected onto arrays of photomultiplier tubes that provide an image of the air shower. HiRes is an astronomical instrument, and the accuracy of the mirror pointing and understanding of the optical properties of the mirror–camera units is crucial. We present a method to cross-check and monitor the mirror pointing by using star light. A star crossing the field of view of a photomultiplier tube causes a temporary increase in the total light detected by the tube. Using UV bright stars, we analyze the pointing accuracy of the HiRes 2 detector, and evaluate the shape of a point-like object as a function of distance to the mirror axis.

This paper describes a data acquisition system for optical telescopes studying extensive air showers for the High Resolution Fly's Eye Project at Dugway Proving Grounds, Utah. The measurements are based entirely on flash-analog-to-digital conversion of phototube signals, digitized continuously at 10 MHz, and stored in a deep (820 μs) pipeline, for deadtimeless readout following a parallel pipeline trigger. The massive parallel processing by digital signal processors and programmable logic devices is distributed site-wide, with 42 telescopes and a central facility linked by optical fiber. The system was designed and built at Columbia University, Nevis Laboratories.

We study the spectrum and average mass composition of cosmic rays with primary energies between 10^{17} eV and 10^{18} eV using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum as a function of energy. A complete Monte Carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic ray intensity is changing f rom a heavier to a lighter composition in this energy range. The spectrum is consistent with earlier Fly's Eye measurements and supports the previously found steepening near 4 \times 10^{17} eV .

This article describes the fiber-optic-based calibration system installed at the High Resolution Fly's Eye (HiRes) astro-particle physics observatory. The HiRes detectors measure ultra violet scintillation light from distant extensive air showers. This automated calibration system delivers light from a frequency tripled 355 nm YAG laser to the 10,752 photo-multiplier tubes of the 42 HiRes-II detectors.

The High-Resolution Fly's Eye (HiRes) is an observatory for the highest energy cosmic rays. It detects the nitrogen fluorescence light induced by the passage of giant cosmic ray extensive air showers through the atmosphere. A two-site prototype of the observatory was operated from September 1994 to November 1996. In this paper we describe the components of that detector, and the procedures used to calibrate the detector and characterise the atmosphere. Data collected by the HiRes prototype are being used for physics studies, including an analysis of the cosmic ray mass composition in the energy range from 1017 to 10 18 eV .

The average mass composition of cosmic rays with primary energies between ${10}^{17}$ and ${10}^{18}\mathrm{eV}$ has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases.

The High Resolution Fly's Eye EHE cosmic ray detector (HiRes) was operated for over two years (prior to November 1996) in a two-site prototype configuration. This paper describes the development and testing of an event reconstruction method for extensive air showers (EAS) viewed in coincidence by both sites (stereo viewing). The reconstruction accuracy was directly measured through the use of a UV laser mounted on a telescope that generated airshower-like events with known geometries. For events observed with stereo opening angles greater than about 10° (most events) the median error in the reconstructed laser direction was 0.4° with 95% of events being reconstructed with errors of less than 0.9° (which degrade to 0.8° and 1.8°, respectively, for smaller opening angles). A limited investigation of the likely performance of the HiRes Stage 1.0 detector was undertaken. Reconstruction accuracy is likely to be only slightly degraded compared with the prototype results.

Results are presented from an analysis of a large sample of centrally produced mesons in the reaction $\mathrm{pp}\ensuremath{\rightarrow}{p}_{\mathrm{slow}}({K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}){p}_{\mathrm{fast}}$ with $800\mathrm{GeV}/c$ protons incident on liquid hydrogen. Two resonances dominate the final state, the ${f}_{1}(1285)$, decaying into ${a}_{0}\ensuremath{\pi}$, and the ${f}_{1}(1420)$, decaying into ${K}^{*}K$. Both mesons are produced with equal amounts of $|{J}_{z}{|}^{\ensuremath{\eta}}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1}^{\ifmmode\pm\else\textpm\fi{}}$, and no ${J}_{z}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$.

Stable, robust ultraviolet light sources for atmospheric monitoring and calibration pose a challenge for experiments that measure air #uorescence from cosmic ray air showers. One type of light source in use at the High Resolution Fly’s Eye (HiRes) cosmic ray observatory features a xenon #ashbulb at the focal point of a spherical mirror to produce a 1 ls pulse of collimated light that includes a strong UV component. A computer-controlled touch tone radio system provides remote operation of bulb triggering and window heating. These devices, dubbed ‘#ashersa, feature stand-alone operation, $5% shot-to-shot stability, weather proof construction and are well suited for long-term"eld use. This paper describes the #ashers, the radio control system, and a 12-unit array in operation at the HiRes cosmic ray observatory ( 1999 Elsevier Science B.V. All rights reserved.

Results are presented from a partial wave analysis of a sample of centrally produced mesons in the reaction $\mathrm{pp}\ensuremath{\rightarrow}{p}_{\mathrm{slow}}({K}_{S}{K}_{S}){p}_{\mathrm{fast}}$, with 800 GeV/c protons incident on a liquid hydrogen target. The meson system is found to be predominantly $S$ wave in the mass range between ${K}_{S}{K}_{S}$ threshold and $1.55\mathrm{GeV}{/c}^{2}$. The ${f}_{0}(1500)$ is observed in this region. Above $1.55\mathrm{GeV}{/c}^{2}$ two solutions are possible, one with mainly $S$ wave and another with mainly $D$ wave. This ambiguity prevents a unique determination of the spin of the ${f}_{J}(1710)$ meson.

We have obtained precise measurements of the {Sigma}{sup 0} mass and the {Sigma}{sup 0}-{Lambda}{sup 0} mass difference from a fit to the {Lambda}{sup 0}{gamma} invariant mass distribution of 3327 {Sigma}{sup 0}{r_arrow}{Lambda}{sup 0}+{gamma} decays. Our measurements yield M{sub {Sigma}{sup 0}}=1192.65{plus_minus}0.020{plus_minus}0.014 MeV/c{sup 2} and M{sub {Sigma}{sup 0}}{minus}M{sub {Lambda}{sup 0}}=76.966{plus_minus}0.020{plus_minus}0.013 MeV/c{sup 2}, where the uncertainties are statistical and systematic in that order. This represents a significant improvement over all previous determinations and is the first direct measurement of the {Sigma}{sup 0} mass itself. {copyright} {ital 1997} {ital The American Physical Society}

A study of hyperon production in fully reconstructed proton-proton interactions at 28 GeV/c (\ensuremath{\surd}s=7.3 GeV) is presented. Features of the data are presented with the aid of a phenomenological model, the LPM, that was developed to study \ensuremath{\Lambda} production reactions. We note the similarities between \ensuremath{\Lambda} reactions and other families of reactions, and show that this surprisingly simple model can be easily adapted to ${\mathrm{\ensuremath{\Xi}}}^{\mathrm{\ensuremath{-}}}$ production reactions. The only significant difference between the \ensuremath{\Lambda} and ${\mathrm{\ensuremath{\Xi}}}^{\mathrm{\ensuremath{-}}}$ data is the observation that \ensuremath{\Lambda} hyperons are produced as leading particles, whereas ${\mathrm{\ensuremath{\Xi}}}^{\mathrm{\ensuremath{-}}}$ hyperons are not. Production cross sections for eight high-multiplicity hyperon reactions are presented. \textcopyright{} 1996 The American Physical Society.

We measured the polarization of 51195 {Lambda}{sup 0}{close_quote}s produced in the specific reaction {ital pp}{r_arrow}{ital p}{Lambda}{sup 0}{ital K}{sup +}{pi}{sup +}{pi}{sup {minus}}{pi}{sup +}{pi}{sup {minus}} with 27.5GeV/{ital c} protons incident on a liquid hydrogen target. Because the reaction was measured completely, the polarization was studied versus the following: {ital x}{sub {ital F}}({minus}1to+1), {Lambda}{sup 0} transverse momentum (0 to 1.32GeV/{ital c}), correlations with the momentum vectors of the other particles in the reaction, and the invariant mass of combinations of particles in the final state. The dependence of the polarization on these variables does not always agree with theoretical expectations. {copyright} {ital 1995 The American Physical Society.}

During the last Fermilab fixed-target run experiment E690 wrote on tape five billion events in the reaction pp→Xpfast. The beam momentum was 800 GeV/c, the target liquid hydrogen and pfast was a-t

Fermilab experiment 690 [1], a study of target dissociation reactions pp → pX using an 800 GeV/c proton beam and a liquid hydrogen target, collected data in late 1991. The incident beam and 600–800 GeV/c scattered protons were measured using a system of six 6 in. × 4 in. and two 15 in. × 8 in. pressurized drift chambers spaced over 260 m. These chambers provided precise measurements at rates above 10 MHz (2 MHz per cm of sense wire). The measurement resolution of the smaller chambers was 90 μm, and the resolution of the larger chambers was 125 μm. Construction details and performance results, including radiation damage, are presented.

We have measured the momentum correlation of pion pairs produced in the collisions of 27.5 GeV/c protons in liquid hydrogen. By considering events for which all final state particles have been measured, we have succeeded in reducing backgrounds due to particle misidentification below 5% for ${\ensuremath{\pi}}^{+}$ and 1% for ${\ensuremath{\pi}}^{\ensuremath{-}}$. Our use of a precision magnetic spectrometer has provided an accurate determination of particle momenta and excellent acceptance for particle pairs with small relative momentum essential for correlations studies. A large data sample of fully reconstructed events (1 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$) allows us to analyze the correlations for ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$ pairs separately, and also as a function of the final state multiplicity. We find that the pion pair correlations scale 0.98 fm describes the data well. We do not find any indication of multiplicity dependence of the correlation scale for multiplicities from 6 to 14 final state particles.

A precision measurement of the masses of the ${\mathrm{\ensuremath{\Lambda}}}^{0}$ and \ensuremath{\Lambda}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$ hyperons is obtained from Gaussian fits to the invariant mass distributions for 20 138 ${\mathrm{\ensuremath{\Lambda}}}^{0}$'s and 18 309 \ensuremath{\Lambda}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$'s. The Gaussians have standard deviations of 0.49 and 0.51 MeV/${\mathit{c}}^{2}$ for the ${\mathrm{\ensuremath{\Lambda}}}^{0}$ and \ensuremath{\Lambda}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$, respectively. Systematic errors were reduced by calibrating the spectrometer with 60 000 exclusive events containing a ${\mathit{K}}_{\mathit{S}}^{0}$. We find ${\mathit{M}}_{\mathrm{\ensuremath{\Lambda}}}$=1115.678\ifmmode\pm\else\textpm\fi{}0.006\ifmmode\pm\else\textpm\fi{}0.006 MeV/${\mathit{c}}^{2}$ and ${\mathit{M}}_{\mathrm{\ensuremath{\Lambda}}\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}$=1115.690\ifmmode\pm\else\textpm\fi{}0.008\ifmmode\pm\else\textpm\fi{}0.006 MeV/${\mathit{c}}^{2}$. The ${\mathrm{\ensuremath{\Lambda}}}^{0\mathrm{\ensuremath{-}}}$\ensuremath{\Lambda}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$ mass difference testing CPT invariance is -0.012\ifmmode\pm\else\textpm\fi{}0.010 MeV/${\mathit{c}}^{2}$.

In a study of collisions of 27.5 GeV/{ital c} protons in liquid hydrogen we have observed enhanced production of oppositely charged hadron pairs when the relative velocity of the two hadrons in the pair rest frame approaches {alpha}{ital c}. The scale and velocity dependence of the enhancement agree well with the effect of the attractive Coulomb interaction as described by the Gamow factor.

It is an experimental evidence that all baryons are created polarized from unpolarized p—nucleus collisions. So far, the origin of this polarization remains unexplained in spite of the experimental evidences accumulated in the past thirty years. Up to these days, Λ0 is the most studied baryon for polarization, for it is copiously produced in p—nucleus collisions at the energies of the principal high energy physics accelerators of the world. This paper is an overview of the experimental evidences accumulated on the polarization of Λ0 from unpolarized exclusive pp collisions as function of xF, PT, and M(Λ0K+) in the past fifteen years inside Fermilab e690 experiment, in the particular reactions pp→pΛ0K0π+, pp→ppΛ0Λ−0, pp→pΛ0K+, produced at 800 GeV.

We determined Λ0 polarization as function of XF, PT, MX, and EΛ, with respect to the normal of the following two different production planes: The first one defined by the momentum of the 800 GeV/c proton beam and the moment of Λ0; the second one, by the momentum of the transferred object and the momentum of Λ0, from the sample created in the FNAL E690 experiment. We present results, compare and discuss them.

Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultrahigh energy electron-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current electron-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular dataset has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for electron-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going electron-neutrino-induced cascades and present an upper limit on the flux of electron-neutrinos., Comment: 13 pages, 3 figures. submitted to Astrophysical Journal

The properties and principles of the data acquisition and track processing of Fermilab E690 and BNL766 are outlined. A simple example is presented, and followed by speculations about the future at LHC and SSC experiments.

In this paper ultra-high energy cosmic rays UHECRs data observed by the HiRes fluorescence detector in stereo mode is analyzed to search for events in the sky with an arrival direction lying on a great circle. Such structure is known as the arc structure. The arc structure is expected when the charged cosmic rays pass through the galactic magnetic field. The arcs searched for could represent a broad or a small scale anisotropy depending on the proposed source model for the UHECRs. The arcs in this paper are looked for using Hough transform were Hough transform is a technique used to looking for patterns in images. No statistically significant arcs were found in this study.

The preliminary results of a Λ0 and anti‐Λ0 polarization study as functions of the M(Λ‐bΛ), XF and their corresponding PT are reported in this work.

We report the results of the search for the pentaquark candidates Θ(1540) and Ⅺ(1862) using data from Fermilab experiment E690 in the reaction pp → pX at 800 GeV/c. We find no evidence for narrow baryon resonances near 1862 MeV decaying to Ⅺπ. Also, we find no evidence of a narrow resonance near 1540 MeV decaying to pKs0.

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to ${\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$, ${\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$, ${\overline{\ensuremath{\Xi}}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and ${\overline{\ensuremath{\Xi}}}^{+}{\ensuremath{\pi}}^{+}$. The only resonances observed are the well known ${\ensuremath{\Xi}}^{0}(1530)$ and ${\overline{\ensuremath{\Xi}}}^{0}(1530)$. No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with $\ensuremath{\sigma}=7.6\text{ }\text{ }\mathrm{MeV}$ in the ${\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$ effective mass spectrum to be 0.3% of the number of observed ${\ensuremath{\Xi}}^{0}(1530)\ensuremath{\rightarrow}{\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the ${\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$, ${\overline{\ensuremath{\Xi}}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and ${\overline{\ensuremath{\Xi}}}^{+}{\ensuremath{\pi}}^{+}$ mass spectra.

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to Xi-pi-, Xi-pi+, Xi+pi-, and Xi+pi+. The only resonances observed are the well known Xi0(1530) and Xi0(1530). No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with sigma=7.6 MeV in the Xi-pi- effective mass spectrum to be 0.3% of the number of observed Xi0(1530)--Xi-pi+. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the Xi-pi+, Xi+pi-, and Xi+pi+ mass spectra.

We present preliminary results of the analysis of the centrally produced φφ system at 800 GeV/c in the reaction pp → pslow(φφ)pfast. A partial wave analysis of the data up to 2.6 GeV/c2 shows that three waves with JPCLS = 2++02 and with different Jz and reflectivity are needed to describe the data. A fit to the wave amplitudes using Jost functions gives two resonances, one above and one below the φφ threshold. The resonance above threshold has a Breit‐Wigner structure with MR = 2.243 ± 0.015(stat) ± 0.010(syst) GeV and ΓR = 0.368 ± 0.033(stat) ± 0.030(syst) GeV.

We report physics results of charm diffractive production, light meson spectroscopy, and baryon polarization, from studies carried out with data from experiment E690 of Fermilab.

We present preliminary results of a Partial Wave Analysis of the centrally produced φφ system at 800 GeV/c in the reaction pp → pslow(φφ)pfast. Our preliminary results with one and two M = 0 waves, indicate that most of the cross section can be described by two waves, with JPC LSη = 2++02−1, 0++00−1.

We report the first observation of diffractively produced open charm in 800-GeV/c pp collisions of the type pp{yields}pD{sup *}X. We measure cross sections of {sigma}{sub diff}(D{sup *+})= (0.185{+-}0.044{+-}0.054) {mu}b and {sigma}{sub diff}(D{sup *-})= (0.174{+-}0.034{+-}0.029) {mu}b. Our measurements are based on 4.3 x 10{sup 9} events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.

We report results from a study of Lambda(0) polarization in the exclusive reaction pp --p(f)(Lambda0K+) at 800-GeV/c. We observe a dependence of the polarization on the Lambda0K+ invariant mass with large (+71%) positive polarization at small mass (1.63-GeV/c(2)) and large (-43%) negative polarization at large mass (2.75-GeV/c(2)). This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed. The strong dependence of the polarization on the Lambda0K+ invariant mass suggests that the origin of the polarization is closely related to the production dynamics of the diffractively produced Lambda0K+ system.

We report the first observation of diffractively produced open charm in 800-GeV/c pp collisions of the type pp--pD*X. We measure cross sections of sigma(diff)(D*+) = (0.185+/-0.044+/-0.054) (mu)b and sigma(diff)(D(*-)) = (0.174+/-0.034+/-0.029) (mu)b. Our measurements are based on 4.3x10(9) events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.

We present some preliminary measurements of Λ0 polarization, in the final state pp→p{Λ0K+} created at 800 GeV/c, as a function of PT,xF, and the diffractive mass of the object {Λ0K+}.

We present evidence of the observation of the centrally produced φφ system at 800 GeV/c in the reaction pp→pslow(φφ)pfast. A clear bump is observed over low φK+K− and K+K−K+K− background. Statistics are comparable to those previously obtained in π−p interactions, where three 2++ waves were found to comprise all cross section.

Monitoring the aerosol component of the lowest 10 km of the atmosphere at UV wavelengths (300 - 400 nm) is an important part of the High Resolution Fly's Eye astrophysics experiment. Our method of atmospheric monitoring uses a frequency tripled YAG laser and a steering system that can point the beam anywhere in the sky. The same detector that measures scintillation light from high energy cosmic rays also measures light scattered from this laser system over a range of laser energies, geometries, and polarizations. This paper describes the technique, the laser system, and some recent measurements.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Results are presented from a partial wave analysis of a sample of centrally produced mesons in the reaction pp {yields} p{sub slow}(K{sub s} K{sub s})p{sub fast} , with 800 GeV/c protons incident on a liquid hydrogen target. The meson system is found to be predominantly S-wave in the mass range between K{sub s} K{sub s} threshold and 1.58 GeV/c{sup 2} . The f{sub 0}(1500) is clearly observed in this region. Above 1.58 GeV/c{sup 2} two solutions are possible, one with mainly S-wave and another with mainly D-wave. This ambiguity prevents a unique determination of the spin of the f{sub J} (1710) meson.

Partial wave analysis results of centrally produced mesons in the reaction pp {yields} P{sub slow}(X)P{sub fast}, with 800 GeV/c protons incident on a liquid hydrogen target are presented. In the reactions considered in this paper the (X) system decays into: a) K{sup 0}{sub s}K{sup {+-}}{pi}{sup {-+}}, b) K{sub s}K{sub s}, and c) {pi}{sup +}{pi}{sup -}.