A high stability light emitting diode system for monitoring lead glass electromagnetic calorimeters

We have designed, built and tested a high stability system based on blue light emitting diodes (LED) and current pulse generators fur calibration and monitoring of lead-glass calorimeters. This apparatus is presently being used for the electromagnetic calorimeter of the WA96 (NOMAD) experiment at CERN. The system was developed to minimize the sensitivity to temperature variations, different loadings, and ageing effects. Tests performed both in the laboratory and in the experiment showed that the response of the lead-glass calorimeter modules to LED light pulses could be kept within the precision of +/-1% for periods of several months

Test beam performance of the electromagnetic calorimeter of the NOMAD experiment

Test beam results of the NOMAD electromagnetic calorimeter are presented showing linearity, signal uniformity, energy and position resolution measured in an electron beam. Tests were also performed placing the calorimeter in a magnetic field of 0.4 T. Results on the pi rejection obtained using a combined measurement of preshower/electromagnetic calorimeter are found to be in good agreement with the project expectations. Finally the calorimeter response to the muons is discussed

The electromagnetic calorimeter of the NOMAD experiment RID C-6672-2008

A description is given of the NOMAD electromagnetic calorimeter, consisting of 875 lead-glass counters read out by two-stage photomultipliers and a low noise electronic chain. The detector operates in a 0.4 T magnetic field transverse to the counter axis. The paper discusses the design criteria, the lead-glass characteristics, the properties of the read out chain and provides a summary of the calorimeter performance

Parameterization of e and γ initiated showers in the NOMAD lead-glass calorimeter

A description of the response of the NOMAD electromagnetic calorimeter to electrons and photons is discussed. In particular, the dependence of the two-dimensional shower shape on the angle and energy of the incident particle is parametrized by analytical functions. Some applications to the neutrino event reconstruction are also reported

The CERN Axion Solar Telescope (CAST)

A decommissioned LHC test magnet is being prepared as the CERN Axion Solar Telescope (CAST) experiment. The magnet has a field of 9.6 Tesla and length of 10 meters. It is being mounted on a platform to track the sun over +/-8(0) vertically and +/-45(0), horizontally. A sensitivity in axion-photon coupling g(agammagamma) < 5 x 10(-11)GeV(-1) can be reached for m(a) less than or equal to 10(-2) eV, and with a gas filled tube-can reach g(agammagamma) less than or equal to 10(-10)GeV(-1) for axion masses m(a) < 2eV

Search for a new gauge boson in pi(0) decays RID B-6634-2009 RID C-6672-2008

A search was made for a new light gauge boson X which might be produced in pi(0) -->, gamma + X decay from neutral pions generated by 450 GeV protons in the CERN SPS neutrino target. The X's would penetrate the downstream shielding and be observed in the NOMAD detector via the Primakoff effect, in the process of X --> pi(0) conversion in the external Coulomb field of a nucleus. With 1.45 x 10(18) protons on target, 20 candidate events with energy between 8 and 140 GeV were found from the analysis of neutrino data. This number is in agreement with the expectation of 18.1 +/- 2.8 background events from standard neutrino processes. A new 90% C.L. upper limit on the branching ratio Br(pi(0) --> Y + X)< (3.3 to 1.9)X 10(-5) for X masses ranging from 0 to 120 MeV/c(2) is obtained. (C) 1998 Elsevier Science B.V. All rights reserved