CMS Tracker:CMS Tracker:

Detector Control Units Detector Control Units &&

Tracker MonitoringTracker Monitoring

My Summer Student project My Summer Student project

(A contribution to:)

Fatima Kajout

11th of August 2003 Student Session 2003

Silicon detectorsdetectors~10 000000 detectors strips~10 000000 detectors strips

=> A lot of temperature monitoring to do!=> A lot of temperature monitoring to do!

Front End Readout, Front End Readout, Control and Monitoring Control and Monitoring UnitsUnits

The CMS Tracker:The CMS Tracker:

Front End Control and MonitoringFront End Control and Monitoring

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MeasuresMeasures and and monitorsmonitors slowly varying analogue signals; slowly varying analogue signals; i.e.: Temperatures, low voltages, detector currents,…i.e.: Temperatures, low voltages, detector currents,…

2*22*2 mmmm22 chip; power consumption chip; power consumption 5050mWmW

Contains an Contains an 88-channel, -channel, 12 12 bit ADC,…bit ADC,…

Provides Provides 2 2 bias currents bias currents for powering temperature for powering temperature probesprobes

Will be mounted on every module hybrid where it Will be mounted on every module hybrid where it will monitor: - will monitor: - Internal temperature probes, externalInternal temperature probes, external temperature temperature probes, voltages and currents.probes, voltages and currents.

DCUDCUDetector Control UnitDetector Control Unit

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AgendaAgendaProject Outline

Hardware and Objectives

Software and Objectives (1)

Software and Objectives (2)

Architecture Validation

ConclusionsStudent Session 2003

Project OutlineProject Outline The project aimed to build the tools needed to The project aimed to build the tools needed to

collect DCU data, store them into a permanent collect DCU data, store them into a permanent database, retrieve all or part of the data, and database, retrieve all or part of the data, and finally display and analyze them. An evaluation of finally display and analyze them. An evaluation of the temperature and voltage measurement spread the temperature and voltage measurement spread was also made.was also made.

A prototype system with 12 DCU ASICs has been A prototype system with 12 DCU ASICs has been installed and used for tests.installed and used for tests.

Software technologies used are: Java, C++, SQL, Software technologies used are: Java, C++, SQL, mySQL and PAW.mySQL and PAW.

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Hardware and Objectives Hardware and Objectives

Prototype tests: no system of such size (“of the Prototype tests: no system of such size (“of the CMS Tracker”) can be assembled without CMS Tracker”) can be assembled without exhaustive prototype work, followed by scalability exhaustive prototype work, followed by scalability studies that should validate the proposed studies that should validate the proposed architecture even when the number of modules architecture even when the number of modules grows by orders of magnitude, as in our case. I grows by orders of magnitude, as in our case. I have set up a system with 12 DCU chips as a have set up a system with 12 DCU chips as a starting point. Performance measurements are starting point. Performance measurements are foreseen.foreseen.

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Measurements and calibration of 12 DCUsMeasurements and calibration of 12 DCUsWe used a set of 8 very-well measured resistors which simulated We used a set of 8 very-well measured resistors which simulated one thermistor at different temperatures (from –40 to 30 one thermistor at different temperatures (from –40 to 30 00C).C).

DCUcts

Rin

Temperature

Steinhart-Hart equation:1/T = a*ln(Rin)³ +b*ln(Rin)² + c*ln(Rin) +d

Calibration linear formula:

Rin = offset + scale*DCUcts

Converting from DCU counts to Ohm Converting from DCU counts to Ohm

Clearly, there is a non-negligible spread in the Clearly, there is a non-negligible spread in the offsetoffset values. It is still to be seen whether this values. It is still to be seen whether this influences the temperature measurement to the influences the temperature measurement to the point of requiring a set of separate calibration point of requiring a set of separate calibration constants for each DCU.constants for each DCU.

The present plots show the The present plots show the offsetoffset distribution and the distribution and the scalescale factor distribution for the 12 DCU under test. The formula used factor distribution for the 12 DCU under test. The formula used is, of course,is, of course, Counts = Counts = OffsetOffset + + ScaleScale * Resist * Resist

Although the spread is smaller, a non- Although the spread is smaller, a non- uniformity in this calibration constant is as uniformity in this calibration constant is as dangerous as one in the offset.dangerous as one in the offset.

At –30 and +30At –30 and +3000C, the RMS is ~ 1.2% of the mean value, i.e. for the same resistance value the C, the RMS is ~ 1.2% of the mean value, i.e. for the same resistance value the measurements would vary ~ 1.2% (which is ~.5 measurements would vary ~ 1.2% (which is ~.5 00C at +30C at +3000C and less at lower temperatures.)C and less at lower temperatures.)

Test temperature distributionTest temperature distribution This plot shows, for all This plot shows, for all 12 DCU12 DCU

chips tested, the reconstructed chips tested, the reconstructed temperature for the 8 resistors used temperature for the 8 resistors used to simulate thermistors. It is clear to simulate thermistors. It is clear from this plot that with increasing from this plot that with increasing temperatures the measurements temperatures the measurements become less accurate. This is due to become less accurate. This is due to the non-linearity of the thermistor the non-linearity of the thermistor characteristic: the higher the characteristic: the higher the temperature, the less the value of temperature, the less the value of the resistance changes for an equal the resistance changes for an equal temperature step.temperature step.

Note that we will operate the CMS Note that we will operate the CMS Tracker at –20Tracker at –20° C => nice!!!° C => nice!!!

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Software and Objectives (1)Software and Objectives (1)

Database design: a proper definition of the Database design: a proper definition of the tables and their relationships is mandatory tables and their relationships is mandatory in a project of this size. Therefore, I have in a project of this size. Therefore, I have studied the problem and derived tables in studied the problem and derived tables in the third normal form, as recommended by the third normal form, as recommended by IT literature. IT literature.

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Measurement

ValueTimestamp

1

1

1

1

Sensor Id Location Idref ref

1 1

N N

Each Each measurementmeasurement entity comprises:entity comprises:• a a ValueValue (an integer number produced by the analogue to (an integer number produced by the analogue to digital conversion process);digital conversion process);• a a TimestampTimestamp (an integer number encoding the date and time (an integer number encoding the date and time at at which the measurement was taken);which the measurement was taken);• a a Sensor IdSensor Id (a reference to a Sensor entity in a separate table); (a reference to a Sensor entity in a separate table);• a a Location IdLocation Id (a reference to a Location entity in a separate (a reference to a Location entity in a separate

table);table);

Database design

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Software and Objectives (2)Software and Objectives (2) Interface design: in order to be of any use, a database Interface design: in order to be of any use, a database

system must offer interfaces that are easy to use and system must offer interfaces that are easy to use and effective. Given the present database structure, the very effective. Given the present database structure, the very first interface needed will be the one that allows to read the first interface needed will be the one that allows to read the list of existing sensors and add to it. list of existing sensors and add to it.

We can:

• Consult

a=0.005;b=0.002;c=0.014;d=0.014

Sensor-Type Table

Current 1

Voltage 1

Thermistor 1

Description

AlgorithmSteinhart-hart equation

Thermistor 2

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Architecture ValidationArchitecture Validation

The DCU prototype system will be also The DCU prototype system will be also used to validate the proposed general used to validate the proposed general scheme for the monitoring of Tracker scheme for the monitoring of Tracker environmental parameters. In particular, environmental parameters. In particular, one should establish whether individual one should establish whether individual DCU chips need calibration constants, or a DCU chips need calibration constants, or a single set can be used without excessive single set can be used without excessive loss of accuracy.loss of accuracy.

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ConclusionsConclusionsWhat we wanted to do:What we wanted to do: Gather DCU DATA and Gather DCU DATA and

StoreStore RetrieveRetrieve DisplayDisplay AnalyzeAnalyze

How we accomplished it:How we accomplished it: Prototyping a system with 12 DCUs andPrototyping a system with 12 DCUs and

Performed measurements and calibration (used Performed measurements and calibration (used predevelopped software for the CMS Trackers)predevelopped software for the CMS Trackers)

Designed a new, improved databaseDesigned a new, improved database Designed a graphical interfaceDesigned a graphical interface

Next steps:Next steps: Performance evaluationPerformance evaluation Architecture validationArchitecture validation Finalize databaseFinalize database Student Session 2003

Any question?

Thank you!Thank you!

Student Session 2003