SNO+

Abstract:

We present the discovery of gamma-ray emission greater than 350 GeV from the BL Lacertae (BL Lac) object 1ES 2344 + 514 with the Whipple Observatory 10 m gamma-ray telescope. This is the third BL Lac object detected at very high energies (VHE, E > 300 GeV), the other two being Markarian 421 (Mrk 421) and Mrk 501. These three active galactic nuclei are all X-ray selected and have the lowest known redshifts of any BL Lac objects currently identified with declination greater than 0°. The evidence for emission from 1ES 2344 + 514 comes mostly from an apparent flare on 1995 December 20 (UT) during which a 6 σ excess was detected with an average flux of I(> 350 GeV) = 6.6 ± 1.9 × 10-11 photons cm-2 s-1. This is approximately 63% of the VHE emission from the Crab Nebula, the standard candle in this field. Observations taken between 1995 October and 1996 January, excluding the night of the flare, yield a 4 σ detection indicating a flux level of I(> 350 GeV) = 1.1 ± 0.4 × 10-11 photons cm-2 s-1, or about 11% of the VHE Crab Nebula flux. Observations taken between 1996 September and 1997 January on this object did not yield a significant detection of a steady flux or any evidence of flaring activity. The 99.9% confidence level upper limit from these observations is I(> 350 GeV) < 8.2 × 10-12 photons cm-2 s-1, ≲8% of the Crab Nebula flux. The low baseline emission level and variation in the nightly and yearly flux of 1ES 2344 + 514 are the same as the VHE emission characteristics of Mrk 421 and Mrk 501.

Abstract:

The evidence for supersymmetric dark matter annihilations presented by Strausz is based on both an analysis of data from the JACEE balloon-borne emulsion experiment which ignores systematic uncertainties and on a flawed analysis of background data from the Whipple gamma-ray observatory. When the latter analysis is corrected, it is found that there is no evidence for a peak in the 3.5–4.0 TeV regime in the Whipple data. Furthermore, were any such excess seen in the Whipple data, it would indicate a flux in gross conflict with the JACEE upper limits. It is therefore concluded that no evidence exists for an annihilation line due to supersymmetric dark matter. © 1998 The American Physical Society.

Abstract:

The average bottom-hadron and individual (Formula presented), (Formula presented), and (Formula presented) meson lifetimes have been determined using decays with a (Formula presented) in the final state. The data sample consists of 110 pb(Formula presented) of (Formula presented) collisions at (Formula presented) TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992–1995. For the average lifetime of (Formula presented) hadrons decaying into (Formula presented)+X, we obtain (Formula presented) For the (Formula presented) and (Formula presented) meson lifetimes, we determine (Formula presented) (Formula presented) and (Formula presented) For the (Formula presented) meson lifetime, we find (Formula presented) ps. © 1998 The American Physical Society.