R. López

ACORDE a Cosmic Ray Detector for ALICE

ACORDE is one of the ALICE detectors, presently under construction at CERN. It consists of an array of plastic scintillator counters placed on the three upper faces of the ALICE magnet. It will act as a cosmic ray trigger, and, together with other ALICE sub-detectors, will provide precise information on cosmic rays with primary energies around 1015–1017eV. Here we describe the design of ACORDE along with the present status and integration into ALICE.

Cosmic Ray Physics at CERN

In recent decades, cosmic ray air showers initiated by high‐energy proton or nucleus collisions in the atmosphere have been studied with large area experiments on the surface of the Earth or with muon measurements deep underground. In principle, these cosmic ray experiments explore two completely different realms of physics, particle astrophysics and particle interaction physics, which are, however, intimately related by the interpretation of the data. In this paper we briefly review the cosmic ray physics activities developed at CERN in the last years. In particular we present some results from a small underground cosmic ray experiment and we discuss the capabilities of ALICE to detect high multiplicity muon events arising from cosmic ray air showers and some other astroparticle phenomena.

Geomagnetic effects on the PMT tubes of the Pierre Auger surface detectors

In this paper we report the geomagnetic field effect on three photomultiplier tube (PMT) candidates for their massive use in the Pierre Auger Observatory surface detector array. The geomagnetic field effect could be manifest in the variation of the response of the PMT after this has been rotated with respect to its own axis on top of the surface detector. We measured the signal given by secondary cosmic rays and by a LED installed in the interior of the tank with one PMT. Data were digitized using a digital oscilloscope and an ADC-CAMAC module. We found no significant variation of the PMT response when the dynode axis direction changes with respect to the geomagnetic field orientation.