The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is under construction 4100 meters above sea level at Sierra Negra, Mexico. We describe the design and cabling of the detector, the characterization of the photomultipliers, and the timing calibration system. We also outline a next-generation detector based on the water Cherenkov technique.

Using the CLEO detector, we have measured the branching ratios for the exclusive decays of the Ds+ meson into K*0K+, K0K+, and K*+K0 relative to the decay Ds+→φπ+ to be close to unity. We have also measured the mass diference between the Ds+ and D+ meson to be 98.5±1.5 MeV/c2. © 1989.

Using the CLEO detector at the Cornell Electron Storage Ring, we have searched for two-photon production of charmonium in four-track final states. We have measured Γγγ(ηc)=5.9+2.1-1.8±1.9 keV, and we have obtained 95% CL upper limits of Γγγ(Xc0)<6.2 keV and Γγγ(Xc2)<1.0 keV. © 1990.

The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is designed to record air showers produced by cosmic rays and gamma rays between 100 GeV and 100 TeV. Because of its large field of view and high livetime, HAWC is well-suited to measure gamma rays from extended sources, diffuse emission, and transient sources. We describe the sensitivity of HAWC to emission from the extended Cygnus region as well as other types of galactic diffuse emission; searches for flares from gamma-ray bursts and active galactic nuclei; and the first measurement of the Crab Nebula with HAWC-30.

The High Altitude Water Cherenkov (HAWC) observatory is an array of large water Cherenkov detectors sensitive to gamma rays and hadronic cosmic rays in the energy band between 100 GeV and 100 TeV. The observatory will be used to measure high-energy protons and cosmic rays via detection of the energetic secondary particles reaching the ground when one of these particles interacts in the atmosphere above the detector. HAWC is under construction at a site 4100 meters above sea level on the northern slope of the volcano Sierra Negra, which is located in central Mexico at 19 N latitude. It is scheduled for completion in 2014. In this paper we estimate the sensitivity of the HAWC instrument to point-like and extended sources of gamma rays. The source fluxes are modeled using both unbroken power laws and power laws with exponential cutoffs. HAWC, in one year, is sensitive to point sources with integral power-law spectra as low as 5×10-13 cm-2sec-1 above 2 TeV (approximately 50 mCrab) over 5 sr of the sky. This is a conservative estimate based on simple event parameters and is expected to improve as the data analysis techniques are refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources. © 2013 Elsevier B.V. All rights reserved.

Using the CLEO detector at the Cornell Electron Storage Ring, we have found evidence for L=1 charmed mesons in e+e- annihilations. We observe a D**0 state at mass 2461±3±1 MeV/c2 and width 20-12-10+9+9 MeV/c2 decaying to D+-. We also see an enhancement in the m(D*+-)-m(D*+) mass-difference spectrum and by examining D*+ decay-angle dependence, we see structure consistent with two states decaying to D*+-. We observe a lower-mass state, at mass (2428±3±2) MeV/c2 and width (23-6-4+8+10) MeV/c2, assuming that the higher-mass component is from the decay D**0(2461)D*+-. We present arguments for the spin-parity assignments of these states. We also report observation of candidate L=1 cs» state decaying to D*+Ks0. © 1990 The American Physical Society.

The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is designed to perform a synoptic survey of the TeV sky. The high energy coverage of the experiment will enable studies of fundamental physics beyond the Standard Model, and the large field of view of the detector will enable detailed studies of cosmologically significant backgrounds and magnetic fields. We describe the sensitivity of the full HAWC array to these phenomena in five contributions shown at the 33rd International Cosmic Ray Conference in Rio de Janeiro, Brazil (July 2013).

We describe measurements of GeV and TeV cosmic rays with the High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC. The measurements include the observation of the shadow of the moon; the observation of small-scale and large-scale angular clustering of the TeV cosmic rays; the prospects for measurement of transient solar events with HAWC; and the observation of Forbush decreases with the HAWC engineering array and HAWC-30.

We have searched for neutrinoless decays into three charged particles. Evidence of such decays would demonstrate nonconservation of lepton flavor and, in some cases, lepton number. We see no signal for any such neutrinoless decays and set upper limits on their branching fractions. © 1990 The American Physical Society.

Using the CLEO detector, we present a measurement of the mass of the charged charmed strange baryon Ξ+c and its neutral counterpart the Ξ0c. The Ξ+c is observed through its decay to Ξ-π+π+, and its mass is measured to be (2467±3±4) MeV. The isospin mass splitting of the Ξc system is found to be M(Ξ+c)-M(Ξ0c)=(-5±4±1)MeV. © 1989.