Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope

The ANTARES collaboration has performed a series of {\em in situ} measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by $^{40}$K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to $^{40}$K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40~m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle Physic

The ANTARES project

The ANTARES project is an international collaboration with the aim of building a deep-sea large area neutrino telescope within the next decade. The achievements and status of the project as at the time of the conference are briefly discussed, and short term steps as well as longer term plans are described

Performance of the ALEPH upgraded silicon vertex detector

The ALEPH Vertex Detector (VDET) has been upgraded for the second phase of LEP running. The new version still uses double sided silicon strip detectors, fabricated with the same technology as the previous one, but the upgraded one is twice as long and has about half passive material in the tracking volume. Furthermore the readout electronics is now radiation hard (MX7-RH chips). An almost complete version of the upgraded VDET was installed in ALEPH during a three week LEP technical stop and took data in November 1995 during the LEP run at 130 GeV. The new detector worked well showing high signal over noise ratio and good efficiency. The point resolution measured during this run, using high momentum muons, 13 μm in the τ - φ view and 21 μm in the τ - z view, is dominated by the alignment precision, due to the low statistics available for this short LEP run. This result is however acceptable, since for lower momentum charged particle, the multiple scattering gives a significant contribution to the final impact parameter resolution. A better resolution has been achieved in the next run, when an initial period at the Z peak has been foreseen to calibrate and align the whole detector

Construction and performance of the new ALEPH vertex detector

A new Silicon Vertex Detector was developed for the ALEPH experiment and first installed for the high energy run at 130 GeV at the end of 1995. The detector has an active length of 40 cm and consists of two concentric layers of silicon wafers with double-sided readout. It extends the angular coverage, has only half the passive material as the former detector in the tracking volume and is radiation hard to cope with the higher level of radiation background expected for the LEP2 phase. The construction and the performance of the detector is described. (C) 1998 Elsevier Science B.V. All rights reserved

Transmission of light in deep sea water at the site of the ANTARES neutrino telescope

The Antares neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the Antares site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length λabs and an effective scattering length λscteff. The values for blue (UV) light are found to be λabs ≃ 60(26) m, λscteff ≃ 265(122)m , with significant (∼15%) time variability. Finally, the results of A ntares simulations showing the effect of these water properties on the anticipated performance of the detector are presented. © 2004 Elsevier B.V. All rights reserved

Transmission of Light in Deep Sea Water at the Site of the ANTARES Neutrino Telescope

The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length;,ab, and an effective scattering length lambda(sct)(eff). The values for blue (UV) light are found to be lambda(abs) similar or equal to 60(26) m, lambda(sct)(eff similar or equal to) 265(122) m, with significant (similar to15%) time variability. Finally, the results of ANTARES simulations showing the effect of these water properties on the anticipated performance of the detector are presented