Experimentelle Physik 5 21Nov2013 Experimentelle Physik 5 (Timing - PowerPoint PPT Presentation

Experimentelle Physik 5 21Nov2013

Experimentelle Physik 5 (Timing of) light propagation in fibre  2011  First simple simulation of scifi in Geant4 to evaluate time distribution of photons arriving at fibre end  2012  Measurement of timing in 2.5 m fibre with and without mirrored end  2012 and 2013  More sophisticated simulation of fibre in Geant4  more information used and stored, higher flexibility, …  studies beside timing possible  Simulation results used by electronics development group ( → choice of integration time window, spill-over) 21Nov2013 2

Experimentelle Physik 5 SiPM Studies  2010  Irradiation of SiPM arrays with protons in Nice and Munich  2011 and 2012  In situ irradiation in LHCb cavern (arrays and single channel SiPM, 2012 cooled and non-cooled)  2013  Further measurements with irradiated sensors (annealing test) and data evaluation  Measured quantities and parameters  LED and dark spectra → gain, relative pde, cross-talk, pedestal position and width  Dark current, dark count rate, dark count rate distribution → after-pulse probability (only possible with small dark count rates) 21Nov2013 3

Experimentelle Physik 5 Fibre Quality Control Light guidance test Loose spools for speed control of fibre spools Diameter check 21Nov2013 4

Experimentelle Physik 5 Fibre Quality Control  3 Spools tested, so far only diameter About one big blob (>300 mu) per km  Several small blobs (between 270 mu and 300 mu)   Next steps: Optimize Quality Control with SiPM   Compare the data with standard light attenuation measurements  Therefor build a dark box Simplify the handling  21Nov2013 5

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Experimentelle Physik 5 Winding  Winding on threaded wheel „Aachen style“, but Wheel is fixed, positioning spool moves  Tension and feeding spool speed controled by loose spool  Glue is placed by hand after each layer   Produced three good 7-9cm mats Quality and amount of human influence necessary depends on „blobiness“ of  fibre Winding speed: 10s/3m = 0.3m/s  One is in Heidelberg, one was cut in pieces for quality analysis, one is left   Produced one 14cm wide mat Winding speed: 5s/3m = 0.6m/s  Several different problems due to different reasons  21Nov2013 8

Experimentelle Physik 5 Winding  Gained some experience with glueing broke fibre in a layer -> might be possible  Online fibre laying check with video 21Nov2013 9

Experimentelle Physik 5 Cutting  Stone table with rail and milling head installed  Trying different parameters for best cut  Parallel cut to fibres will not be possible until alignment is implemented 21Nov2013 10

Experimentelle Physik 5 Fibre Mat Quality Control  Finished:  check the initial straigtness of the mat with an alignment wire -> mat to flexible  Ongoing:  optical check of crosssection (fit circles)  See next slides  Planned:  check light guidance (compare layers)  Test with radioactiv source (long term) 21Nov2013 11

Experimentelle Physik 5 Fibre Mat Quality Control  Cut a mat in 2.5cm long pieces (30 pieces)  Take a picture with high resolution (scanner, 9600 dpi)  C++ code for finding circles in picture (OpenCV)  As result you (will) get the radii and the centers of the detected circles in the picture  Check the uniformity and straigtness of the mat 21Nov2013 12

Experimentelle Physik 5 Fibre Mat Quality Control  Planned for the Futute: analysis with a microscope  Detectes circles automatically and is able to give you different parameters  For example: radius, position, circularity, ... 21Nov2013 13