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Abstract: The response of the ZEUS sampling calorimeter has been studied over a period of 17 years using a moving 60Co source. The aim was to monitor the stability of the calorimeter with respect to radiation damage, ageing and mechanical damage. The measurements started in 1990 during the installation of the first calorimeter modules and ended in 2007 after the last HERA run. Within the experimental uncertainties, the longitudinal uniformity of the polymethylmethacrylate (PMMA) based wavelength shifters (Y7) did not change. There is also no evidence for radiation damage in the polystyrene (PS) based scintillators (SCSN-38) due to particle losses of the electron and proton beams. On the other hand, the investigations clearly indicate that the attenuation length of the SCSN-38 scintillators decreased continuously over the years. A comparison with data obtained from a test calorimeter showed that the same effect observed in the ZEUS calorimeter after 17 years would require a uniform exposure of all scintillators by a dose of of rays. However, it can be excluded that the degradation observed in the ZEUS calorimeter can be attributed to the radioactivity of the uranium plates of the calorimeter. Thus we expect that the decrease of the attenuation length is due to ageing of the scintillators. The ageing effects observed in SCSN-38 are compared to data taken from the literature. [Copyright &y& Elsevier]

The influence of radiation damage on energy resolution, linearity and uniformity of an electromagnetic lead/scintillator calorimeter was studied experimentally with 1–6 GeV electrons. Plastic scintillators and wavelength shifter bars were irradiated uniformly with γ rays. Both were identical with those of the ZEUS uranium calorimeter. The attenuation length of the scintillators was determined from bench tests of single scintillator tiles and from beam tests of the whole calorimeter. After exposure to a dose of 10 kGy the attenuation length of the scintillators decreased by a factor of 2. The experimental results show that the irradiation of the nearly 2 m long wavelength shifter bars affects the calorimeter much more than the damage of the scintillators which were only 19 cm long. Damaged and undamaged sections of the calorimeter were scanned with a moving radioactive γ source (60Co). The results demonstrate that the 60Co monitor system is a very precise tool to detect radiation damage in a sampling calorimeter. [Copyright &y& Elsevier]

The Photo Injector Test Facility at DESY Zeuthen (PITZ) was built to test and optimize electron sources for Free Electron Lasers and future linear colliders. The focus is on the production of intense electron beams with minimum transverse emittance and short bunch length as required for FEL operation. The experimental setup includes a 1.5 cell L-band gun cavity with coaxial RF coupler, a solenoid for space charge compensation, a laser capable to generate long pulse trains with variable temporal and spatial pulse shape, an UHV photo cathode exchange system, and an extensive diagnostics section. This contribution will give an overview on the facility and will mainly discuss the measurements of the electron beam transverse phase space. This will include measurements of the transverse and longitudinal laser profile, beam charge as a function of RF phase, and transverse emittance as a function of different parameters. The corresponding measurements of momentum and momentum spread as well as the RF commissioning results will be summarized. As a first application of the PITZ electron source it will be installed at the TESLA Test Facility Free Electron Laser at DESY Hamburg in autumn 2003. [Copyright &y& Elsevier]

The Photo Injector Test facility at DESY Zeuthen (PITZ) was built to develop electron sources for the TESLA Test Facility Free Electron Laser and future linear colliders. The main goal is to study the production of minimum transverse emittance beams with short bunch length at medium charge (∼1 nC). The facility includes a 1.5 cell L-band cavity with coaxial RF coupler, a solenoid for space charge compensation, a laser capable to generate long pulse trains, an UHV photo cathode exchange system, and different diagnostics tools. Besides an overview of the facility, its main components and their commissioning, this contribution will concentrate on the first measurements at PITZ with photoelectrons. This will include measurements of the transverse and longitudinal laser profile, charge and quantum efficiency, momentum and momentum spread, transverse electron beam profiles at different locations and first results on transverse emittance. [Copyright &y& Elsevier]