1 / 17

Annealing effects in irradiated HPK strip detectors measured with SCT128 chip

Annealing effects in irradiated HPK strip detectors measured with SCT128 chip Igor Mandić 1 , Vladimir Cindro 1 , Andrej Gorišek 1 , Gregor Kramberger 1 , Marko Milovanović 1 , Marko Mikuž 1,2 , Marko Zavrtanik 1 1 Jožef Stefan Institute, Ljubljana, Slovenia

ban
Download Presentation

Annealing effects in irradiated HPK strip detectors measured with SCT128 chip

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Annealing effects in irradiated HPK strip detectors measured with SCT128 chip Igor Mandić1, Vladimir Cindro1, Andrej Gorišek1,GregorKramberger1, Marko Milovanović1,Marko Mikuž1,2, Marko Zavrtanik1 1Jožef Stefan Institute, Ljubljana, Slovenia 2 Faculty of Mathematics and Physics,University of Ljubljana, Slovenia I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June 2010

  2. Setup: • SCTA128VG chip • VME module SEQSI (for clock, commands...) • Tektronix digital scope for data acquisition • 90Sr source, photomultiplier, scintillator, • power supplies, coincidence circuit ...... • Most probablevalue (MPV) fromfitofLandau + Gaus to • distributionofmeasured signal clusterheights •  scale defined with signals from non-irradiated detector • Detectors: • p-type, FZ, 320 µm thick, 75 µm strip pitch, 1x1 cm2, producedbyHamamatsu • 1) ATLAS07-PSSSSD_Series I, W16, BZ3-P21: Φ = 5∙1015 n/cm2 • 2) ATLAS07-PSSSSD_Series I, W22, BZ3-P3: Φ = 1∙1015 n/cm2 • detectors irradiated with neutrons in reactor in Ljubljana I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June 2010

  3. Motivation • large rise of collected charge with annealing time at high bias voltage • measured with detector (ATLAS07A, Z3, W44) irradiated to 5∙1015 n/cm2 Plot showed at the last RD50 workshop at CERN: Φ = 5·1015 n/cm2  repeat this measurement with new detector and new SCT128 chip I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June 2010

  4. Φ =5∙1015 n/cm2, MPV vs time, newmeasurement • because of problems with test board, annealing measurements made • only up to 1000 V. rise of MPV with annealing time confirmed 4 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June 2010

  5. Φ =5∙1015 n/cm2, comparison with old measurement black: new blue: old  Good agreement with first measuremnt 5 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June 2010

  6. Φ =5∙1015 n/cm2, comparison with old measurement black: new blue: old Noise: black: new blue: old Signal/Noise: 6 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  7. Φ =5∙1015 n/cm2, current: New measurement:  rise of leakage current with annealing time black: new blue: old • Good agreement with previous • measuremenet 7 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June 2010

  8. Φ =5∙1015 n/cm2: • problem on test board was fixed, • measurements up to 1400 V • good agreement with old data also • at high voltage • at high voltages spectra not Landau • multiplication Bias = 900 V Bias = 1400 V 8 8 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May - 2 June2010

  9. Measurements with detector irradiated to Φeq =1∙1015 n/cm2 Space charge anneals, electric field drops: high voltage: less multiplication  less charge lower voltages: larger depleted region, less trapping  more charge • rise of MPV at long annealing times at high voltage: • space charge concentration rises => higher electric field => more multiplication • the highest voltage at which measurements can be taken falls with increasing • annealing time: too much multiplication 9 9 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  10. Φ =1∙1015n/cm2 • agreement with Liverpool measurements if annealing acceleration factor t60/t20 ~ 500 •  1000 days at 20 C ~ 3000 minutes at 60C Plotsshowed by G. Casse at Trento 2010 workshop: 10 10 10 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  11. Φeq =1∙1015 n/cm2, Current: • increase of current with annealing at high voltages • agreement with Liverpool measurements G. Casse, Trento 2010: 11 11 11 11 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  12. Φeq =1∙1015 n/cm2, Noise: • after certain annealing time sharp increase of noise at bias above 800 V • signal becomes very unstable, measurements not possible at this or • higher voltage any more 12 12 12 12 12 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  13. Φeq =1∙1015 n/cm2 Bias = 800 V: Bias = 1400 V: Not used Typical event at t = 2480 min: Normal event: 13 13 13 13 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  14. Φeq =5∙1015n/cm2 • noise vs. current, measured at different annealing times • at same current higher noise measured in more annealed detector •  after annealing: more multiplication, larger noise at same current •  if multiplication not large noise scales with current as expected 14 14 14 14 14 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  15. Φeq =5∙1015n/cm2, annealdfor 5040 min. • distribution of hits measured in dedicated • noise run (no 90Sr source): •  pedestals and common mode subtracted • cumulative distribution of noise  measures • probability to find a noise hit above given voltage •  no significant change of shape with bias • calculated from fit of Landau + Gauss •  estimate of signal efficiency Log scale 22 mV = 1 fC Lin scale 15 15 15 15 15 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  16. Φeq =1∙1015n/cm2, annealedfor 5040 min. • no lagre multiplication at these voltages • (no increase of leakage current, no increase • of MPV) • if noise distribution Gaussian (no significant • tails), good signal efficiency achieved at low • noise occupancy already at modest bias voltages • in real application many noise sources •  good to have large signals 20 mV = 1 fC Log scale Lin scale 16 16 16 16 16 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

  17. Conclusions • at high fluences and high bias voltages multiplication effects influenceannealing • behavior: • multiplication effects increase withannealing time larger than • ~ 500 minutes @ 60°C (~170 days @ 20°C) • increase of space charge concentration  higher electric fields  more multiplication • with detector irradiated to 5∙1015 n/cm2 measurements could be done up to Bias = 1400 V • at all annealing times • with detector irradiated to 1∙1015 n/cm2 bias voltage at which output gets unstable • lowers with increasing annealing time •  at lower fluences operation in high multiplication regime not stable • higher collected charge can be measured with more irradiated detectors after annealing • because running in high multiplication mode possible • noise increases because of multiplication •  shape of noise distribution does not change significantly 17 17 17 17 17 17 I. Mandić, 16th RD50 Workshop, Barcelona, Spain, 31 May-2 June 2010

More Related