The ultra-low mass cylindrical drift chamber designed for the MEG II experiment is a challenging apparatus made of 1728 Ø=20μm gold plated tungsten sense wires, 7680 Ø=40μm and 2496 Ø=50μm silver plated aluminium field wires. Because of electrostatic stability requirements all the wires have to be stretched at mechanical tensions of ~25, ~19 and ~29g respectively which must be controlled at a level better than 0.5g. This chamber is presently in acquisition, but during its construction ~100 field wires broke, because of chemical corrosion induced by the atmospheric humidity. On the basis of the experience gained with this chamber we decided to build a new one, equipped with a different type of wires less sensitive to corrosion. The choice of the new wire required a deep inspection of its characteristics and one of the main tools for doing this is a system for measuring the wire tension by means of the resonant frequency technique, which is described in this paper. The system forces the wires to oscillate by applying a sinusoidal signal at a known frequency, and then measures the variation of the capacitance between a wire and a common ground plane as a function of the external signal frequency. We present the details of the measuring system and the results obtained by scanning the mechanical tensions of two samples of MEG II cylindrical drift chamber wires and discuss the possible improvements of the experimental apparatus and of the measuring technique
The measuring systems of the wire tension for the MEG II Drift Chamber by means of the resonant frequency technique
Chiri, C.Membro del Collaboration Group
;Cocciolo, G.Membro del Collaboration Group
;Cuna, F.Methodology
;Grancagnolo, F.Methodology
;Panareo, M.Methodology
;Tassielli, G. F.Methodology
;
2023-01-01
Abstract
The ultra-low mass cylindrical drift chamber designed for the MEG II experiment is a challenging apparatus made of 1728 Ø=20μm gold plated tungsten sense wires, 7680 Ø=40μm and 2496 Ø=50μm silver plated aluminium field wires. Because of electrostatic stability requirements all the wires have to be stretched at mechanical tensions of ~25, ~19 and ~29g respectively which must be controlled at a level better than 0.5g. This chamber is presently in acquisition, but during its construction ~100 field wires broke, because of chemical corrosion induced by the atmospheric humidity. On the basis of the experience gained with this chamber we decided to build a new one, equipped with a different type of wires less sensitive to corrosion. The choice of the new wire required a deep inspection of its characteristics and one of the main tools for doing this is a system for measuring the wire tension by means of the resonant frequency technique, which is described in this paper. The system forces the wires to oscillate by applying a sinusoidal signal at a known frequency, and then measures the variation of the capacitance between a wire and a common ground plane as a function of the external signal frequency. We present the details of the measuring system and the results obtained by scanning the mechanical tensions of two samples of MEG II cylindrical drift chamber wires and discuss the possible improvements of the experimental apparatus and of the measuring techniqueI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
