1 / 15

Craig Buttar, University of Sheffield collaborators P Booth, I Dawson, PJ Dervan, C Grigson,

Si-detector macroscopic damage parameters during irradiation from measurements of dark current evolution of with fluence. Craig Buttar, University of Sheffield collaborators P Booth, I Dawson, PJ Dervan, C Grigson, RS Harper, R Nicholson, University of Sheffield

elkan
Download Presentation

Craig Buttar, University of Sheffield collaborators P Booth, I Dawson, PJ Dervan, C Grigson,

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. Si-detector macroscopic damage parameters during irradiation from measurements of dark current evolution of with fluence Craig Buttar, University of Sheffield collaborators P Booth, I Dawson, PJ Dervan, C Grigson, RS Harper, R Nicholson, University of Sheffield Maurice Glaser, CERN, Alick Macpherson, PSI/CERN

  2. Outline • Radiation damage in Si • ATLAS SCT PS irradiation facility • Current evolution with fluence • Results from proton irradiation • Pion irradiation at PSI • Results from pion irradiation • Summary of results-comparison to NIEL Craig Buttar NSS 2002

  3. Radiation effects • Irradiation by heavy particles: s, ps,… results in displacement of atoms from their lattice sites. • Linear increase in leakage current with fluence: I=D • Change in effective doping due to donor removal and acceptor creation • type inversion np at ~1013-1014neqcm-2 • Change in depletion voltage, primarily due to • At the Large Hadron Collider • Expect levels ~1.4x1014(1MeV)neqcm-2 in regions closest to interactions-central tacking region of ATLAS and CMS • Detector irradiation programme at CERN PS Craig Buttar NSS 2002

  4. PS Irradiation setup • Irradiate detectors with voltage applied at ~-70C • Monitor temperature and current during the irradiation between beam spills • Small beam spot requires scanning of detectors • Monitor fluence and uniformity of irradiation • Measure fluence by activating Al foils • measure 24Na  peak at 1369keV, T1/2=16hrs • Calibrate counter from secondary emission counter Craig Buttar NSS 2002

  5. Silicon Microstrip Detectors Craig Buttar NSS 2002

  6. At high fluences, depletion depth~ =>I~ Model of bulk current during irradiation Assume no annealing at ~-7oC Current damage: I=afD Change in effective carrier concentration Depletion depth, d At low fluences, depletion depth is constant => I~ Craig Buttar NSS 2002

  7. Current evolution with proton fluence Vb=100V Craig Buttar NSS 2002

  8. High fluence gives good agreement with: Low fluence agreement is less good with fluence rising sublinearly: Proton Results-power laws Results based 90 full-size ATLAS detectors Craig Buttar NSS 2002

  9. Proton Results-Damage parameters Craig Buttar NSS 2002

  10. Module currents 4 detectors in Module Use for on-line dosimetry Craig Buttar NSS 2002

  11. PSI-pion irradiation • Πe1 beamline, T=191MeV • Different operation due to beamstructure-switch-off beam to take I-Vs19ns beam with 1ns spacing • Use ATLAS mini-detectors1cm2, from wafer with full-size detector • ‘Portable’ cold box, chiller, monitoring system • Guard and bulk biased seperately Craig Buttar NSS 2002

  12. Pion Irradiation Results Craig Buttar NSS 2002

  13. Summary of results Craig Buttar NSS 2002

  14. Summary • A model for current evolution with fluence based on bulk current has been used to analyse detectors currents during irradiations with protons and pions • The model appears to work well but there are deviations from the expected power laws • Values of a and b have been extracted from the dataa and b are larger than other results, but care required when comparing. • Ratio of alpha agrees with relative NIEL-but need to reduce errors from fluence on pion measurements. Craig Buttar NSS 2002

  15. More work • Improve model, why are there deviations from the power law ? • Investigate effect of annealing • Make measurements at other sites with a range of particle and energies Craig Buttar NSS 2002

More Related