J.C. Oller

Construction and test of the final CMS Barrel Drift Tube Muon Chamber prototype

A prototype of the CMS Barrel Muon Detector incorporating all the features of the final chambers was built using the mass production assembly procedures and tools. The performance of this prototype was studied in a muon test beam at CERN and the results obtained are presented in this paper.

Semitransparent amorphous silicon sensors for the CMS alignment: an in-depth study

Abstract Semitransparent amorphous silicon sensors have been proposed as the 2D positioning sensors for the link system of the CMS alignment. An in-depth study of the actual performance of these sensors is here reported.

Spectrometric response of large volume CdZnTe coplanar detectors

In this paper, the spectroscopic performance of a new large volume coplanar detector is studied. Spectrometric results using classical techniques are presented. The new unit confirmed that this design of coplanar-grid anodes provided an acceptable balance between anode weighting potentials. The material of this detector is not as homogeneous as desirable. Nonetheless, the detector demonstrated a resolution of the order of 2.7% FWHM for 662 keV. The spectroscopic properties at different interaction depths were studied by making use of a multiparametric digital system. Depth sensing achievable resolution is quantified by making use of this setup. The interaction profile at different depths of the detector was compared with that expected in ideal detectors. An adaptation of the multiparametric digital system was applied to the study of the waveforms generated in the preamplifiers connected to the electrodes. Induced charge waveforms at selected interaction depths were analyzed in order to study the deviations in the interaction depth profiles found between simulation and theory. The causes are attributed to trapping effects in the detector bulk. Unexpected pulses are explained by modeling the charge drift in the detector. The mobility of electrons in these detectors was studied by digital signal analysis, which gave a value close to 950 cm/sup 2/ V/sup -1/ s/sup -1/ at room temperature. Results of the dependence of /spl mu//sub e/ with T are presented in the operation temperature range of these detectors.

Results on photon and neutron irradiation of semitransparent amorphous-silicon sensors

Abstract Semitransparent amorphous-silicon sensors are basic elements for laser 2D position reconstruction in the CMS multipoint alignment link system. Some of the sensors have to work in a very hard radiation environment. Two different sensor types have been irradiated with 60Co photons (up to 100 kGy) and fast neutrons (up to 10 15 cm −2 ), and the subsequent change in their performance has been measured.

First test of tiltmeters for the alignment system of CMS

Abstract In this note we present first tests done with the tiltmeters proposed as the key elements of the Laser Level systems to be used in the CMS alignment system. The response of the sensors under moderated longitudinal and transverse tilts is studied and intrinsic performance is extracted.

Study of CMOS image sensors for laser beam position detection

We report on the study made on commercial CMOS image sensors in order to determine their feasibility for light beam position reconstruction. Measurements of the intrinsic position resolution, sensor photoresponse and uniformity were done. The effect of eventual background illumination was evaluated. The precision on the spatial point reconstruction was determined from linearity measurements. First results on gamma-ray radiation tolerance are presented.

Effect of neutron and gamma-ray irradiation on the transmittance power of glasses and glues

Abstract LHC, working at the expected nominal luminosity, will induce an extremely high irradiation in the CMS experiment. The CMS alignment system uses optical elements to build the laser beams paths. Optical properties of basic components such as glasses and glues may result affected and their transmission power may degrade significantly. We have proceeded to a first test of various glasses and glues and identified some of them that can stand up to 150 kGy of gamma-rays plus 5×10 14 neutrons / cm 2 .

PERFORMANCE TEST OF THE CMS LINK ALIGNMENT SYSTEM

Abstract A first global test of the CMS Alignment System was performed at the I4 hall of the CERN ISR tunnel. Positions of the network, reproducing a set of points in the CMS detector monitored by the Link System, were reconstructed and compared to survey measurements. Spatial and angular reconstruction precisions reached in the present experimental set-up are already close to the CMS requirements.

Gamma irradiation of semitransparent amorphous silicon sensors

Abstract Semitransparent amorphous silicon sensors are the key elements for laser light 2D position reconstruction in the CMS alignment system. Some of them have to work in very extreme radiation environment. We have irradiated with gammas, up to 10 MRad, two different sensors and measured their change in performance.

First test results of semitransparent amorphous silicon sensors for the link system of the CMS alignment

Abstract Semitransparent amorphous silicon sensors have been proposed as the 2D positioning sensors for the link system of the CMS alignment. We have developed a general method to characterise these sensors, from the signal reconstruction to the beam distortion. First test results with a few sensors are here reported.