Emile de Rijk, EE mechanics meeting, 26/08/2004, 1 Alveola Measurements Report on the external dimension measurements Wolfgang Funk and Emile de Rijk August 2004

Emile de Rijk, EE mechanics meeting, 26/08/2004, 2 Tolerances and measuring points In total we measured 73 alveolas tolerances Y X

Emile de Rijk, EE mechanics meeting, 26/08/2004, 3 Use of the Mandrels –The mandrels were normally used to measure the external dimensions and to obtain information about the dimension of the crystal holes. –After measurements on the touch-column with and without mandrels we only saw less then 60 microns of difference after having measured 3 alveolas in both dimensions. –We came to the conclusion that the mandrels were not required anymore for the external dimensions –We did not measure the interior dimensions with mandrels without mandrels difference with mandrels without mandrels difference with mandrels without mandrels difference y1145,44145,460,02145,7145,710,01145,69145,710,02 y2145,47145,44-0,03145,68145,70,02145,66145,61-0,05 y3154,07154,05-0,02154,28154,290,01154,26154,25-0,01 y4154,06154,080,02154, ,320,02 x1145,5145,49-0,01145,94145,950,01145,69145,66-0,03 x2145,66145,64-0,02145,78145,76-0,02145,91145,86-0,05 x3154,34154,29-0,05154,23154,17-0,06154,37 0 x4154,23154,19-0,04154,44154,450,01154,26154,270,01

Emile de Rijk, EE mechanics meeting, 26/08/2004, 4 The touch-column (absolute measuring device) –The alveola and the measuring device are placed on a marble table. –The measuring device is a column along which a pin can move vertically and measure distances –The machine is calibrated so that the needle measures the distance between the point measured and the table. –The standard deviation of the reproducibility was tested to be better than 20 microns

Emile de Rijk, EE mechanics meeting, 26/08/2004, 5 The relative measurements device -The alveola is fixed on a bench with a pump -4 sensors measure front and rear values separately at 1 cm of the edge of the alveola. -The calibration is made with a reference module which has been measured with the touch-column. -A zero is set for each sensor. The zero for each sensor is different for front and rear measurements. -The relative values are added to the external dimensions of the reference module -The results are directly saved in a file -The reproducibility is better than 50 microns -Mechanics : José Mulon -Software : Xavier Pons

Emile de Rijk, EE mechanics meeting, 26/08/2004, 6 Relative measurement device results (in absolute values)

Emile de Rijk, EE mechanics meeting, 26/08/2004, 7 Touch column results

Emile de Rijk, EE mechanics meeting, 26/08/2004, 8 Touch column - relative measurement device

Emile de Rijk, EE mechanics meeting, 26/08/2004, 9 Comparison between the Russian and the touch-column results

Emile de Rijk, EE mechanics meeting, 26/08/2004, 10 Accepted alveolas (using touch-column results) Considering our results we looked at the number of alveolas that were within the tolerances We first made a table of refused and accepted alveolas with the standard tolerances. As our reproducibility was of 50 microns we decided to make a new table with enlarged tolerances of 50 microns for lower and upper limit. With initial tolerances AcceptedRefused X155%45% X244%56% X377%23% X478%22% Y196%4% Y296%4% Y386%14% Y492%8% Combined results: 100% alveola refused With corrected tolerances AcceptedRefused X163%37% X259%41% X392%8% X486%14% Y199%1% Y297%3% Y396%4% Y497%3% Combined results: 87% alveola refused

Emile de Rijk, EE mechanics meeting, 26/08/2004, 11 Conclusions: –The mandrels are not needed for external dimension measurements at the edges of the alveola –The touch column and the Russian measurements are correlated although there is a 125 micron systematic shift observed in X1 and X2 –The relative measurement device gives results that are often uncorrelated with the absolute measurement results, especially in X1 and X2 –The fact that the results of the relative measurement device deviate is partly due to the fact that the faces of the alveola are not flat. –If we assume that our measurements are correct, we notice that the alveolas have some problems especially in the X1 and X2 dimensions. –As in the X1 and X2 dimensions a good percentage of the alveolas are too big, all alveolas will probably have to be measured at CERN. –Should we refuse some of the alveolas? –The polished alveolas will have to be inspected to see if they don’t suffer from structural problems. Note: a full report is being written and will be made available