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ZEUS

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The ZEUS experiment was located in the south hall of the HERA collider at DESY (Hamburg). HERA was the first and only lepton-proton collider, accelerating electrons or positrons at 27.5 GeV and protons at 920 GeV. Data were collected from 1992 to 2007. Since 2001 the HERA collider provided longitudinally polarized lepton beams to the experiment. During the last months of running, HERA also collided protons at 460 and 575 GeV.

The ZEUS detector was an almost hermetic multipurpose detector, designed to study the structure of the proton. ZEUS measured neutral and charged current deep inelastic scattering processes, as well as high energy photoproduction processes, in electron-proton and positron-proton interactions, both in inclusive and in exclusive channels, and searched for new interactions and new particles beyond the Standard Model.

The detector was capable of accurate identification and measurement of jets and leptons, as well as precision tracking. The main detector components were a high-resolution compensating uranium-scintillator calorimeter, a central tracking detector surrounded by a superconducting coil and a silicon micro-vertex detector. Drift chambers and straw tube trackers covered forward and backward regions. An instrumented iron absorber catched the tail of hadronic showers and identified muons. A large fraction of the solid angle was further covered by muon detectors.

The ZEUS Collaboration is now committed to data analysis, ensuring the publication of the final physics results.

The ZEUS Collaboration consists of about 450 physicists of more than 55 institutes from 18 countries around the world.

More information and physics results can be found on the ZEUS web page.

Attività di ricerca: 

The Torino group was responsible for the construction and running of the Leading Proton Spectrometer (LPS), together with the Bologna group and the Santa Cruz group. The LPS was located between 20 m and 90 m from the interaction point along the beamline in the direction of the outgoing protons. Nine stations of silicon microstrip detectors, together with the magnetic fields of the beamline, allowed the momentum measurement of protons scattered at very small angles inside the beampipe, having lost only a small fraction of their initial energy. Detectors could be moved into the beampipe to a few mm from the proton beam. The LPS was dismounted in 2001 for the HERA upgrade.

The Torino group also contributed to the Beam Pipe Tracker (BPT), installed in 1997, and to the MicroVertex Detector (MVD), which was installed after the HERA upgrade in 2001.

The main physics interest of the group has been, and is still today, diffractive physics. In diffractive ep interactions, the proton emerges intact from the collision, having lost only of the order of a percent of its energy. The study of these interactions gives access to the diffractive parton distribution functions (dPDF) and the generalised parton distribution functions (GPD) of the proton. Members of the group contributed to analyses of exclusive vector mesons production and inclusive diffractive cross sections. 

At present, an analysis is ongoing for the measurement of the diffractive structure functions F2D and FLD using 2006/07 data. Part of the group is also working at the final combination of the diffractive data of H1 and ZEUS.

Current members of the group: M.Arneodo, M.Costa, M.I.Ferrero, V.Monaco, M.Ruspa, R.Sacchi, V.Sola, A.Solano.

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Nome del responsabile: 

Michele Arneodo

arneodo@to.infn.it