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Preliminary Study of 214 Bi Background in Mo foils

Preliminary Study of 214 Bi Background in Mo foils. Leo Jenner, UCL. In Brief…. Analysis developed to identify 214 Bi events from foils Apply to MC, extract efficiency, apply to data Look for 214 Po decay T 1/2 spectrum as cross-check Rather higher rate than expected….

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Preliminary Study of 214 Bi Background in Mo foils

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  1. Preliminary Study of 214Bi Background in Mo foils Leo Jenner, UCL Nemo Collaboration Meeting

  2. In Brief… • Analysis developed to identify 214Bi events from foils • Apply to MC, extract efficiency, apply to data • Look for 214Po decay T1/2 spectrum as cross-check • Rather higher rate than expected… Nemo Collaboration Meeting

  3. Principle decay: e- with delayed a • Nemo 5.5: 150,000 MC foil events generated • Compare to 1,400,000 data events ( Apr 2003, Runs 2010-2019 = 107 hours ) Nemo Collaboration Meeting

  4. MC :1 track , >1 delayed hits High energy tail…(reconstruction?) Nemo Collaboration Meeting

  5. Monte Carlo Nemo Collaboration Meeting

  6. Monte Carlo Nemo Collaboration Meeting

  7. List of Cuts • 1 track only • 1 scintillator hit only (associated to track) • 1st layer of geigers hit (fast) • 4+ delayed geiger hits, >60 msec • Mo foil sectors • Track and delayed geiger start in same sector and IO • Prob circle, line fit > 0.1 • Qtrack < 0 • 2.08 msec < fast hits < 3.9 msec Nemo Collaboration Meeting

  8. MC: Most fast hits appear in 2.08 – 3.9 msec window Nemo Collaboration Meeting

  9. Data: humpy? 140 msecs 300 msecs Nemo Collaboration Meeting

  10. All cuts MC: 498/150,000 remain Efficiency : 0.332% Data: 2106 events Nemo Collaboration Meeting

  11. All cuts MC: 498/150,000 remain Efficiency : 0.332% Data: 2106 events 34,364 mBq/kg !!! Nemo Collaboration Meeting

  12. p2 offset in data corresponds to constant noise level? (20%) After noise removal… Nemo Collaboration Meeting

  13. Summary… • Far too many events remain after cuts… • Noise (geigers?), a sources in detector? • High Energy tail of MC distribution? • c2int / c2ext • Larger MC sample, gas, wires • Nemos 6.0 Nemo Collaboration Meeting

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