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Monte Carlo Studies on Possible Calibration Sources

Monte Carlo Studies on Possible Calibration Sources. Kevin Kr öninger, MPI für Physik GERDA Collaboration Meeting, DUBNA, 06/27 – 06/29/2005. Introduction. External sources in the GERDA setup are needed in order calibrate the detectors

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Monte Carlo Studies on Possible Calibration Sources

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  1. Monte Carlo Studies on Possible Calibration Sources Kevin Kröninger, MPI für Physik GERDA Collaboration Meeting, DUBNA, 06/27 – 06/29/2005

  2. Introduction • External sources in the GERDA setup are needed in order • calibrate the detectors • Monte Carlo study done with different sources to test • Efficiencies • Allowed activities (no additional background source) • Homogenity • Accuracy of calibration Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  3. Geometry I • Phase II setup with 3 x 7 crystals and 3 x 6 fold segmentation • (378 segments in total) • Propose 3 sources at marked • positions and flexible in z • For MC study only one source • is simulated Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  4. Geometry II • Sources consist of small plastic sphere within a steel shield • Placed inside lead cylinder with 60° opening Lead cylinder Source Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  5. Sources • List of source used in the simulation: • 22Na T1/2 = 950.8 d β+ Lines: 511 keV, 1.3 MeV • 26Al T1/2 = 0.71 My EC, β+ Lines: 511 keV, 1.8 MeV • 57Co T1/2 = 271 d EC Lines: 122 keV, 136 keV • 60Co T1/2 = 5.3 y β- Lines: 1.2 MeV, 1.3 MeV • 88Y T1/2 = 106.65 d β+ Lines: 511 keV, 0.9 MeV, • 1.8 MeV Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  6. Efficiencies • Total efficiency = event efficiency x peak efficiency • Event efficiency is the fraction of events that deposits energy • in at least one segment • Peak efficiencyis calculated for each peak and corresponds • to the fraction of events within a 10 keV window around the • peak (averaged over all segments) Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  7. Activities • Demanding an error of 3% 1000 events are needed in the • peak region. • The minimum activity is • Allowing a background index of 10-3 cnts/kg/keV/y the • maximum activity is A = N / (T·3600·ε) A : activity in Bq N : number of events T : run duration in h ε : efficiency A = 0.001 / (3.15·107·r/10) A : activity in Bq r : suppression factor Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  8. Control Plots • Position of hits Source Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  9. Example: Co-60 Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  10. Segment Study • Calibration should be done homogenious, therefore test • different regions (central, left / right neighboring segments) • Repeat study with 120° opening angle of lead cylinder Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  11. Efficiencies and Activities Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

  12. Conclusion • Propose 3 calibration sources with one run of 1 hour per • crystal level • Simulated 5 different isotopes and calculated limits on the • activities • 60Co, 22Na and 88Y are good candidates for calibration sources • Note GSTR-05-005 is avaiable at MPI-K website Kevin Kröninger, MPI München GERDA Collaboration Meeting DUBNA, 06/27 – 06/29/2005

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