R. L. Talaga

Beam tests of the ZEUS barrel calorimeter

Abstract A fully compensating uranium—scintillator calorimeter was constructed for the ZEUS detector at HERA. Several of the barrel calorimeter modules were subjected to beam tests at Fermilab before shipping them to DESY for installation. The calibrations of the modules used beams of electrons and hadrons, measuring the uniformity of the response, and checking the resolution. The runs also provided opportunity to test a large fraction of the actual ZEUS calorimeter readout system in an integrated beam environment more than one year before HERA turn on. The experiment utilized two computer controlled mechanical structures, one of which was capable of holding up to four modules in order to study shower containment, and a magnetic spectrometer with a high resolution beam tracking system. During two running periods, beams of 6 to 110 GeV containing e, μ, π, and p were used. The results show energy resolutions of 35%/ E for hadrons and 19%/ E for electrons, uniformities at the 1% level, energy nonlinearity less than 1%, and equal response for electrons and hadrons.

Experimental constraints on a dark matter origin for the DAMA annual modulation effect

A claim for evidence of dark matter interactions in the DAMA experiment has been recently reinforced. We employ a new type of germanium detector to conclusively rule out a standard isothermal galactic halo of weakly interacting massive particles as the explanation for the annual modulation effect leading to the claim. Bounds are similarly imposed on a suggestion that dark pseudoscalars might lead to the effect. We describe the sensitivity to light dark matter particles achievable with our device, in particular, to next-to-minimal supersymmetric model candidates.

Cosmic ray tests of the Zeus barrel calorimeter modules

Abstract The ZEUS barrel calorimeter consists of 32 wedge-shaped modules constructed using alternate layers of depleted uranium and scintillator with one radiation length sampling. In this paper we summarize tests made on 22 of these modules by measuring their response to hardened cosmic rays. We describe the cosmic ray facility, the data taking, the track reconstruction, the data analysis and the module testing. These tests include the uniformity, both tower-to-tower and module-to-module, in the response to minimum ionizing particles, the mapping of this response as a function of lateral position of the particles inside a given tower, and the measurement of the number of photoelectrons produced by a minimum ionizing particle. In addition, we present data on the stability of the current in the photomultiplier tube generated by the natural radioactivity of the uranium.