9/6/2014

1. CMS Pixel General meeting 14/02/2011 Introduction and detector status G. Bolla bolla@cern.ch 9/6/2014 1

2. Introduction • Highlits from 2010. • Understood the effect on pixel associated with beam-gas events that produce tracks grazing along the pixel layers • Implemented the BUSY mechanism in the FED. • Solved the problem of data-corruption (internal to the FED) by reducing the slew-rate in the FED’s fpgas. • No more fatal errors since August 2010. • Verified the functionality of the pixel detector and its DAQ during the extended period with Heavy ion collisions • Ongoing effort for high lumi HI. • Successfully opened the door to non expert for operation. • Several new people have been trained to handle the daily duties. Special thanks to all of them. 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 2

3. Introduction • 2010 has been a succesful year. • Here is a summary of what we foresee in 2011: • Take a snapshot of the health of the detector with the same conditions as in 2010. Done! • Calibrate the detector at a temperature lower than the one of 2010. (-10 deg C is the target) • This process will keep going during beam interruptions along the year until finished. • Join CMS in the cosmic campaign. Not yet started due to strips cooling. Likely not going to give the desired statistic (if any at all). • Start taking data with collision in the same configuration as last year (7.4 deg C at the cooling plant) • Once the detector is calibrated at -10 deg C we should: • `take 1 FILL of collisions data. • Go back to take data at +7.4 deg C • Wait for an offline validation of the data at -10 deg C before making it our default way to handle collisions • Deal with operations along the year (not a small effort) 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 3

4. Detector status Text view Pasquale 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 4

5. Detector status Graphical view 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 5

6. CMS Pixel General meeting 14/02/2011 Running colder Infrastructure G. Bolla bolla@cern.ch 9/6/2014 6

7. Pixel cooling Recently you might have heard of some problems with the strip systems leaking. The pixel still leaks as much as much as last year ~100 g/day 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 7

8. Let’s start with the problem POWER BPix BmI Sec5 L3 This BPIX power group developed an open circuit on the (positive wire) remote sensing of the ANALOG Voltage. Danek believes the detector can be retuned within the limit of the power supply to work (how well it will work is to be measured). Pasquale is working with CAEN to find a “permanent” solution. 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 8

9. Motivations1 to cool down: Leakage current L1 - ~10 uA increase But bigger volume of Si L1 - ~10 uA increase L3 - smaller increase bigger volume of Si. Is it the same volume for the two HV channels?

10. Leakage current calculations • At L1 we measured about 10 uA with ~50 pb^-1 • This is with the present temperature: • 7.4 deg C at the cooling plant • 16-18 deg C at the sensors • With 10 fb^-1 we expect a factor of 200 more  2 mA. • What did we expect? • The fluence (from simulation) is 5E12 per fb^-1  2.5E11 for the 50 pb^-1 we got • The volume at L1 is 0.81*0.81*0.027*64=1.2 cm^3 • DI = a*F * V Where a =4E-17 A*cm^-3  ~11 uA • Leakage current goes down a factor of 2 every 7 deg C. • We are at 7.4 deg C and nominal should be something like -20.6 (28 deg colder) • 28/7=4  2^4=16 • 10fb^-1 for the leakage current is equivalent to 160 fb^-1 at present temperature. • Potential for re-tuning leakage current compensation continuously (7-8 nA per pixel to be compensated). 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 10

11. Cooling. • The pixel cooling plant can run at -10 deg C. • The problem left is the temperature stability. • This problem is associated with the temperature regulation circuits between the brine and the chilled water. • Solution imply having people from different teams working together at the same time. • Difficult to find a time with all necessary expertise due to the work on the strips and in general all the work on cooling during the technical stop. • All indications are such that when SS1 and SS2 are working fine the temperature regulation should be OK. • To be verified. 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 11

12. Limit 1 (Pixel PP1s) ENVIRONMENT Relative humidity should not exceed 75% 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 12

13. Limit 2 (Outside the Bulkhead) ENVIRONMENT Temperature outside the bulkhead should not go below the measured dew point in UXC (available at: ) 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 13

14. Limit 1 (Inside the Bulkhead) ENVIRONMENT Relative humidity should not exceed 50% 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 14

15. Pixel humidities • Protection against too high humidities inside the pixel volume is granted by our Pixel PLC: • If any T is lower than (DP+5deg)  interlock • There is also another limit (RH>33%  interlock) for other reasons (protection against open circuit in the sensor side). • In the last week we triggered this interlock twice. 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 15

16. PX T PX T B FIELD CAVERN DP PX RH

17. Some final remarks • We are working hard on understanding the humidity problem. • We will take any available opportunity to lower the temperature and continue to calibrate the detector. • For the time being we are at 7.4 deg C and we invest our time trying to recover some of the channels that are out of the configuration. • We should discuss if it is worth re-starting the calibration process of our RH sensors 9/6/2014 Gino Bolla CMS Pixel Commissioning Meeting 17