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11 Mar 2004Nemo Collaboration Meeting1 Preliminary Study of 214 Bi Background in Mo foils Preliminary Study of 214 Bi Background in Mo foils Leo Jenner,

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Presentation on theme: "11 Mar 2004Nemo Collaboration Meeting1 Preliminary Study of 214 Bi Background in Mo foils Preliminary Study of 214 Bi Background in Mo foils Leo Jenner,"— Presentation transcript:

1 11 Mar 2004Nemo Collaboration Meeting1 Preliminary Study of 214 Bi Background in Mo foils Preliminary Study of 214 Bi Background in Mo foils Leo Jenner, UCL

2 11 Mar 2004Nemo Collaboration Meeting2 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…

3 11 Mar 2004Nemo Collaboration Meeting3  Principle decay: e - with delayed   Nemo 5.5: 150,000 MC foil events generated  Compare to 1,400,000 data events ( Apr 2003, Runs = 107 hours )

4 11 Mar 2004Nemo Collaboration Meeting4 MC :1 track, >1 delayed hits High energy tail…(reconstruction?)

5 11 Mar 2004Nemo Collaboration Meeting5 Monte Carlo

6 11 Mar 2004Nemo Collaboration Meeting6 Monte Carlo

7 11 Mar 2004Nemo Collaboration Meeting7 List of Cuts 1 track only 1 scintillator hit only (associated to track) 1 st layer of geigers hit (fast) 4+ delayed geiger hits, >60  sec Mo foil sectors Track and delayed geiger start in same sector and IO Prob circle, line fit > 0.1 Q track <  sec < fast hits < 3.9  sec

8 11 Mar 2004Nemo Collaboration Meeting8 MC: Most fast hits appear in 2.08 – 3.9  sec window

9 11 Mar 2004Nemo Collaboration Meeting9 300  secs 140  secs Data: humpy?

10 11 Mar 2004Nemo Collaboration Meeting10 All cuts MC: 498/150,000 remain Efficiency : 0.332% Data: 2106 events

11 11 Mar 2004Nemo Collaboration Meeting11 All cuts MC: 498/150,000 remain Efficiency : 0.332% Data: 2106 events 34,364  Bq/kg !!!

12 11 Mar 2004Nemo Collaboration Meeting12 p2 offset in data corresponds to constant noise level? (20%) After noise removal…

13 11 Mar 2004Nemo Collaboration Meeting13 Summary… Far too many events remain after cuts… Noise (geigers?),  sources in detector? High Energy tail of MC distribution?  2 int /  2 ext Larger MC sample, gas, wires Nemos 6.0


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