A.L. Virto

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.

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 .

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.