Diamond Sensor Tests for the Diamond Sensor Tests for the CMS BCMCMS BCM

Alexandr IgnatenkoAlexandr Ignatenko

FCAL collaboration meetingMay 7, 2008

22May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting 22

OverviewOverview

BRM system overviewBRM system overviewStandard set of measurements in ZeuthenStandard set of measurements in Zeuthen

Thickness Thickness CapacitanceCapacitanceI-V characteristicI-V characteristicCharge collection distanceCharge collection distance

ResultsResultsUsual behaviorUsual behaviorAbnormal casesAbnormal cases

ConclusionConclusion

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting 33

The components:

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting 44

BCM1, 1.8m

BCM2+BSC2, 14.4m

55May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting 55

Thickness and capacitance measurements Thickness and capacitance measurements

Thickness: mechanically with 10 µm precisionValues 400-430 µm

A sensor assembled in the frame

Capacitance: with LCR meter HP 4263A10.7-12.1 pF

66

I-V characteristicI-V characteristic

NN22 atmosphere 0-500-0 V 50V/30 sec steps atmosphere 0-500-0 V 50V/30 sec steps

Voltage source and picoamperemeter: Keithley 487 Voltage source and picoamperemeter: Keithley 487

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

77

Charge collection efficiency = Qmeas/Qind

Charge collection distance CCD = × d

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

Detection mechanism

traps

Charge collection distance (CCD)Charge collection distance (CCD)

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting 88

CCD setup

9999

~ CCD

CCD = (Mean-Ped)×calib×corr/Nexp

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

Typical spectrum

CCD = (MPV-Ped)*calib/Nexp

10101010

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

CCD setup

Source holder with collimator

Sensor box

Trigger box

Low voltage power supply

HV supply and picoampearmeter

ResultsNormal behaviorNormal behavior

P28

depumped

pumped

negative positiveMay 7, 2008May 7, 2008 1111FCAL collaboration meetingFCAL collaboration meeting

12121212

CCD vs dose, pumping

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

The current in the sensor circuit was The current in the sensor circuit was monitoredmonitored

CCD dependence on dose, irradiationCCD dependence on dose, irradiation @ 0.7 Gy/h@ 0.7 Gy/h

irradiation started

1313

1313

CCD dependence on time for the fully pumped sensors

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

The current in the sensor circuit was The current in the sensor circuit was monitoredmonitored

After additional 60 mGy

200 V applied

400 V applied

Abnormal casesAbnormal cases

P18

Depumped state Pumped state

Currents up to hundreds of nA at high

bias voltagesMay 7, 2008May 7, 2008 1414FCAL collaboration meetingFCAL collaboration meeting

P 45

depumped

pumped

May 7, 2008May 7, 2008 1515FCAL collaboration meetingFCAL collaboration meeting

16161616

Currents had changed in time even without irradiation

May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

17171717May 7, 2008May 7, 2008 FCAL collaboration meetingFCAL collaboration meeting

ConclusionConclusion 25 samples have been investigated25 samples have been investigated

The characterization of each sample The characterization of each sample has been givenhas been given

6 sensors have shown unstable 6 sensors have shown unstable

currentscurrents

The parameters of the sensor were The parameters of the sensor were reproduciblereproducible