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Summer Student Presentation

Summer Student Presentation. Radiation Monitoring with commercial p-i-n diodes BPW34F Summer Student Project of Kim Temming Supervisors: Michael Moll Maurice Glaser. Outline. purpose of my project diode BPW34F / BPW 34 how to measure radiation with this diodes?

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Summer Student Presentation

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  1. Summer Student Presentation Radiation Monitoring with commercial p-i-n diodes BPW34F Summer Student Project of Kim Temming Supervisors: Michael Moll Maurice Glaser By Kim Temming

  2. Outline • purpose of my project • diode BPW34F / BPW 34 • how to measure radiation with this diodes? • history of my measurements • irradiations • first setup • measurements / results • problems • new setup • measurements • first results • problems • first conclusions • outlook Summer Student Presentation Kim Temming

  3. Purpose of my Project • investigate the possibility to use commercial BPW 34 p-i-n diodes as dosimeters for LHC experiments and irradiation facilities • advantages • commercial product: low costs (1.60 €) • robust and easy to handle • large fluence range (1012 – 1015 p/cm2) • measuring NIEL (displacement damage) • disadvantages • needs qualifying • temperature & fluence dependence • annealing • readout scheme • commercial product (no influence on production) Summer Student Presentation Kim Temming

  4. Diode BPW34F / BPW34 • commercial SI-pin-diode / cheap • BPW34 photosensitive from 400nm to 1100nm (BPW34F: 950nm) • applications: • IR remote controls • photointerruptors • control and drive circuits BPW34 - photosensitive area + BPW34F Summer Student Presentation Kim Temming

  5. How to measure radiation? • increase of voltage with fluence for constant current when biased in forward direction Summer Student Presentation Kim Temming

  6. My Work: Irradiations • 102 diodes were irradiated with 24 GeV/c PS proton beam • 50 BPW34F from USA • 1.0 E15, 0.5 E14, 0.3 E14, 1.0 E14, 0.5 E13, 0.3 E13, 1.0 E13, 0.5 E12, 0.3 E12, 1.0 E12 (all in p/cm2) • 22 BPW34F from MALAYSIA • 1.0 E15 ppcm2, 1.0 E14 p/cm2 • BPW34 Siemens, BPW34 Osram and BPW34FS • each 5 pieces 1.0 E13 p/cm2 • each 5 pieces 1.0 E14 p/cm2 • irradiations successful in limits of 20% discrepancies to wanted fluence (+ca. 8% errors on values) Summer Student Presentation Kim Temming

  7. First Setup • aluminium box / completely dark • (diodes are sensitive to daylight!) • Keithley 2400 • set current / read voltage • sensor for temperature • inside box / 2 cm beside diode • sensitivity: 0.1 degree celsius • labview program • option for constant current • option for pulsed current • displays graph: voltage time Summer Student Presentation Kim Temming

  8. Measurements / results first setup • VI measurements of all samples before irradiation • current between 0.1 A and 1 mA • results of VI measurements before irradiation: • nearly all samples show same characteristic • all differences between samples become larger with higher current • samples from Siemens: • old (some years) • vary more than 20% samples siemens Summer Student Presentation Kim Temming

  9. Measurements / results first setup • dependence of the voltage on readout frequency and readout pulse length • 10 samples together irradiated with 1.0 E14 protons/cm2 • applied current: 1 mA • pulse length varying between 1 ms and 1 s • pulse to pulse time between 60 s and 3 s • Results of dependence on readout frequency & pulse length • not very sensitive to pulse length (except of constant current) • not at all sensitive to time between pulses • but differences of more than 20 % between the different diodes Summer Student Presentation Kim Temming

  10. Measurements / results first setup • dependence on readout current • ONE diode irradiated with 1.0 E14 protons/cm2 • pulse to pulse 3 s, pulse length varying • current varying between 1 A and 100 mA • Results of dependence on readout current Summer Student Presentation Kim Temming

  11. Problems of first setup • diodes are very sensitive to temperature • measured voltage depends very much on the temperature of diode • temperature is measured 2 cm away from diode / isolated by plastic and air • possible sources of temperature differences • changes of room temperature (air condition!) • touching of diodes • opening of box • another possible explanation: diodes show peltier effect • cooling down by applying current • necessary to control temperature of diode very exactly Summer Student Presentation Kim Temming

  12. New setup • peltier element below socket of diode regulates temperature of diode to exactly 19.3  0.01 degree celsius • temperature read out by small temperature sensor (operated with Keithley 2410) • readout of diode still with Keithley 2400 • temperature displayed on web with webDAQ/100 Summer Student Presentation Kim Temming

  13. Measurements with new setup • ONE diode irradiated with 1.0 E14 protons/cm2 • always same end value with constant current • first no room temperature effects (outside box) visible because of the good temperature shielding • over night / weekend measurements • irradiated diode • non irradiated diode • very temperature stable resistor • measurements: • applied current: 100A, constant current • temperature measured inside and outside the box with 2 digits • voltage measured with labview-program and Keithley 2400 Summer Student Presentation Kim Temming

  14. First results (new setup) • irradiated diode: voltage still depending on temperature but very sensitive • not irradiated diode: same results but less amplitude • 1 k Ohm resistor Summer Student Presentation Kim Temming

  15. Problems of temperature / Keithleys • not completely clear yet: • effect of temperature in diode? • effect of room temperature in Keithleys? • limit of keithley accuracy! Summer Student Presentation Kim Temming

  16. First conclusions • before irradiations: • all diodes very close together, only few discrepancies on readout voltage • after irradiation: • diodes show discrepancies of up to 20% on readout voltage • diodes very temperature sensitive • temperature needs to be controlled • best readout scheme: • current: 100 A • pulse length: 1 ms • pulse to pulse: ~ 3s (not very sensitive) Summer Student Presentation Kim Temming

  17. End Outlook • continue measurement • more different devices (to get statistics) • more sensitive temperature control • dependence on the readout temperature • for fluences 1.0 E12...E15 p/cm2 • from –10 C to +30 C • dependence on the fluence • 1.0 E12 p/cm2 up to 1.0 E15 p/cm2 • annealing of samples in oven • 40, 60. 80, 100 degree celsius Summer Student Presentation Kim Temming

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