1 Module produced with low R int sensors-Anthony AffolderSensor Meeting, Feb 11, 2004 Modules Produced With Low R int Sensors Anthony Affolder UCSB

2 Module produced with low R int sensors-Anthony AffolderSensor Meeting, Feb 11, 2004 Modules Produced with low R int sensors 5 modules were produced with a set of 10 sensors with low interstrip resistances  5036 (Sensors , ) Depletion Voltage 168 V  5041 (Sensors , ) Depletion Voltage 173 V  5077 (Sensors , ) Depletion Voltage 150 V  5187 (Sensors , ) Depletion Voltage 166 V  5100 (Sensors , ) Depletion Voltage 296 V

3 Module produced with low R int sensors-Anthony AffolderSensor Meeting, Feb 11, 2004 What we can(not) measure With the ARCS system, we can measure the isolation of the strips only through noise and calibration injection  Mostly a measure of the load capacitance on the channel We do not have the tools to measure other quantities which would be very important to the determination if these sensors are usable  Cannot measure R int vs V to know to what severity that the sensors have this problem  Cannot measure the charge collection efficiency, charge sharing, and single hit resolution with tools at UCSB Need a pinpoint penetrating laser/source scan

4 Module produced with low R int sensors-Anthony AffolderSensor Meeting, Feb 11, 2004 Results (I) With the previous caveats, all 5 modules look identical to other 10 modules made that day with unaffected sensors at 400 V bias voltage For the four modules with the low depletion voltage ( V), the modules showed regular noise response at the 10% level with a bias voltage as low as 20 V  In order to make a more strong statement, R int vs. bias voltage has to be known at low bias voltages  At such low voltages in becomes difficult to distinguish between under-depletion and R int effects

5 Module produced with low R int sensors-Anthony AffolderSensor Meeting, Feb 11, 2004 Result (II) For module 5100, a noise source on order of the same size as the other noise source can be seen on second half of module until 150 V bias applied  Since sensors have a depletion voltage of 300V, it is not possible with this measurement to know if increase noise is due to Rint effects or under-depletion To disentangle the two effects, measurements of signal are needed  Laser/source/beam

6 Module produced with low R int sensors-Anthony AffolderSensor Meeting, Feb 11, 2004 Conclusions 5 modules using low Rint sensors for Pisa have been built All 5 modules show regular performance in tests possible at 400 V 4 of the modules show regular noise down to 20 V 1 module shows increased noise up to 150 bias voltage  Not clear if it is R int or under depletion effect Karlsruhe has agreed to perform laser/source scans on modules 5100 and 5187 in order to address this issue and issues of charge sharing, hit resolution, etc.