1 Comparison of MIRAC-4 array with Cornell test array, both warm ver 3 Bill Hoffmann November 10, 2009 Test configuration Array: MIRAC-4 array or Cornell test array Controller: NIC electronics box with new preamp, backplane, FPGA, bias, and clocks Software: Linux version Cornell server and gui’s plus UA filter and other gui’s Power supply: Original MIRAC-4 power supply Power cable: Original MIRAC-4 long Cable from backplane to cryostat: Original MIRAC-4 cable or Cornell test cable Cable bulkhead to fanout board: Second edition MIRAC-4 cable or Cornell test cable Bulkhead connectors: Original MIRAC-4 cryostat hermetic bulkhead connectors or Cornell test connectors Fanout board: MIRAC-4 or Cornell test board Ground interconnects: Chosen by Paul Arbo for best operation Results: The Cornell test assembly gives clean images without digital pickup (flash bars). The Cornell array in the MIRAC fanout board with the Cornell cryo signal cable gives the same results. The MIRAC array in the MIRAC fanout board with the Cornell cryo signal cable has slightly more noise but no flash bars. Both the MIRAC and Cornell arrays in the MIRAC fanout board with the MIRAC cryo signal cable have flash bars. Pickup from the motor power supply is large with the MIRAC system. It is small with the Cornell warm test assembly and the same with the MIRAC or Cornell array in the MIRAC fanout board with the Cornell cryo signal cable.

2 On the following page the upper two images are for the MIRAC fanout board and MIRAC cryo signal cable. The MIRAC array is on the left and the Cornell array on the right. Both show “flash bars”. Three or so show on each image with the warm arrays. With the MIRAC system cold, these bars frequently appear all over the images. The lower images are for the Cornell cryo signal cable. The two images on the left use the MIRAC fanout board. The leftmost image is the MIRAC array and the center image the Cornell array. The image on the right is with the Cornell warm test assembly including the the Cornell fanout board. The flash bars are absent from all three images. The defects along the left and right side of the MIRAC images are debonding of the indium pads.

3 MIRAC array; MIRAC fanoutCornell array; MIRAC fanout MIRAC array; MIRAC fanout MIRAC cryo signal cable Cornell cryo signal cable Cornell array; MIRAC fanoutCornell array; Cornell fanout

4 The top table is with the MIRAC fanout board and various combinations of warm and cryogenic cables, fanout board mounting hardware, array, and motor power supply off and on. The lower table is for the Cornell warm test cable and array test assembly.

5 The red lines for the Cornell warm assembly and fanout board. The dashed line is for the motor power on. This is our baseline for no “flash bars” and minimum motor power pickup. The blue lines are for the MIRAC fanout board. Significant reduction in motor power pickup occurs with isolating the array cold finger from ground and using the Cornell cryo signal cable. These have little effect on the motor-off standard deviation. But with the MIRAC cryo signal cable both the MIRAC and Cornell arrays show flash bars. These are eliminated with the Cornell cryo signal cable. The filled orange triangles are the Cornell array in the MIRAC fanout board. The Cornell array has slightly lower noise in either the Cornell or MIRAC fanout board than the MIRAC array.