Thermal Modeling of Pixel Detector Brian Maynard Steven Blusk HEP Group SU

Material Constants Material Thermal Conductivity Thermal Conductivity (W/m*K) (W/m*K) Substrate (Diamond) 2000 Glue1 HDI2 RO Chip (Silicon) 150 Silicon Detector 150

Assumptions Cross-sectional modeling of detector Applied 0.5W/cm 2 heat generation on read out chips by taking into account the 3D geometry Also applied heat generation function on the silicon sensors Held end of substrate at -25 C 2

Sensor35mm RO Chip35mm HDI39mm Glue39mm Diamond40mm Aspect Ratio 1: in (mm)

If we reduced the sensor power by half we see that the Therm Runaway Temp increases from about -13.5C to -6.3C

3D Modeling We exceed our maximum number of allowable elements (32,000) after meshing 3 rd volume out of 9 We exceed our maximum number of allowable elements (32,000) after meshing 3 rd volume out of 9 32,000 is a limit set on this student version of ANSYS 32,000 is a limit set on this student version of ANSYS

Misc. Noticed that the sensor function does not take into account the 3D geometry like the RO Chips do Noticed that the sensor function does not take into account the 3D geometry like the RO Chips do Still figuring out how to model radiation Still figuring out how to model radiation

Therm Conduct X,Z: 2000 Y :10 TPG

Conclusions  Thermal gradient is less then 8 degrees  TPG and Diamond are comparable  (more crosschecks pending)  3D modeling on hold with current software  Still need to include radiation effects