The ANTARES optical beacon system (original) (raw)

Time calibration of the ANTARES neutrino telescope

Astroparticle Physics, 2011

The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of ∼1ns. The methods developed to attain this level of precision are described.

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

Astroparticle Physics, 2005

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 λ abs and an effective scattering length λ eff sct . The values for blue (UV) light are found to be λ abs ≃ 60(26) m, λ eff sct ≃ 265(122) m, with significant (∼15%) time variability. Finally, the results of ANTARES simulations showing the effect of these water properties on the anticipated performance of the detector are presented.

Background light in potential sites for the ANTARES undersea neutrino telescope

Astroparticle Physics, 2000

The ANTARES collaboration has performed a series of 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. W e 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 e ciency.

Nanobeacon: A time calibration device for the KM3NeT neutrino telescope

2021

The KM3NeT Collaboration is currently constructing a multi-site high-energy neutrino telescope in the Mediterranean Sea consisting of matrices of pressure-resistant glass spheres, each holding a set of 31 small-area photomultipliers. The main goals of the telescope are the observation of neutrino sources in the Universe and the measurement of the neutrino oscillation parameters with atmospheric neutrinos. Both extraterrestrial and atmospheric neutrinos are detected through the Cherenkov light induced in seawater by charged particles produced in neutrino interactions in the surrounding medium. A relative time synchronization between photomultipliers of the order of 1 ns is needed to guarantee the required angular resolution of the detector. Due to the large detector volumes to be instrumented by KM3NeT, a cost reduction of the different systems is a priority. To this end, the inexpensive Nanobeacon has been designed and developed by the KM3NeT Collaboration to be used for detector ti...

The High Altitude water Cherenkov (HAWC) Observatory

Nuclear and Particle Physics Proceedings, 2016

The High Altitude Water Cherenkov (HAWC) Observatory is a gamma-ray experiment being built in Mexico. It will be an array consisting of 300 water Cherenkov detectors (WCDs). Four photomultiplier tubes (PMTs) will be deployed on the bottom of each WCD to detect the Cherenkov light produced by the secondary particles in air showers caused by the interaction of cosmic particles and high-energy gamma rays with the atmosphere. The relative times between the PMT channels are crucial for reconstructing the direction of the primary particle. The response time of a PMT and electronics depends on the light intensity striking on the PMT. A laser calibration system was designed to accurately measure the relative timing among the PMT channels. Laser pulses with varying intensities are sent to each WCD through optical splitters, switches, and fibers. The time between the laser shot and the PMT signal is recorded to correct for the dependence on the light intensity. A time residual study is also performed to improve the angular reconstruction. The time residual is the difference between a fitted air shower front and the PMT readout time. This systematic time offset is then accounted for in an iterative shower reconstruction procedure to improve the determination of the incoming direction of the primary particle. A partial array of 30 WCDs began operation in Fall 2012. In this contribution, the first results of the timing calibration curves and time residual studies are presented.

First results of the Instrumentation Line for the deep-sea ANTARES neutrino telescope

Astroparticle Physics, 2006

In 2005, the ANTARES Collaboration deployed and operated at a depth of 2500 m a so-called Mini Instrumentation Line equipped with Optical Modules (MILOM) at the ANTARES site. The various data acquired during the continuous operation from April to December 2005 of the MILOM confirm the satisfactory performance of the Optical Modules, their front-end electronics and readout system, as well as the calibration devices of the detector. The in-situ measurement of the Optical Module time response yields a resolution better than 0.5 ns. The performance of the acoustic positioning system, which enables the spatial reconstruction of the ANTARES detector with a precision of about 10 cm, is verified. These results demonstrate that with the full ANTARES neutrino telescope the design angular resolution of better than 0.3 • can be realistically achieved.