1. Impurities in MuCAP Bernhard Lauss Berkeley Analysis Meeting Feb 27 - Mar 1, 2006

2. We see CHUPS cleaning Unexplained yield from gas-chromatographic analysis suspect water outgassing

3. We see CHUPS cleaning Unexplained yield from gas-chromatographic analysis suspect water outgassing

4. Determination of Impurity Detection Efficiency of Tom’s impurity finder for nitrogen Comparison to filling / gas-chromatographic analysis

5. Determination of Impurity Detection Efficiency of Tom’s impurity finder for nitrogen via Yield Comparison to filling / gas-chromatographic analysis 8.1 N2-doped fill in Run7 (based on Tom’s analysis result page April 13, 2004 / production pass 3 file) Yield determination: Yield_N = 1180  2.2 From this measurement we calculated the respective concentration to be c Y = Yield_N / Y2C = 118 / 115 = 10.30  0.1 ppm Concentrations (Run7 Elog 631): Malte & Claude N2 doped run contains c = 18  1 ppm  Efficiency:Eff_N = c Y / c = 0.573  0.032 8.2 N2-doped fill in Run 8 (based on Tom’s CalibN2-mu-.root) Yield determination: Yield_N = 730.5  2.3 From this measurement we calculated the respective concentration to be c Y = Yield_N / Y2C = 6.38  0.7 ppm Concentrations (Ref.7): one of the big disagreements in Run 8 ! Claude and Malte via filling procedure: 11  0.22 ppm (  2%) gas-chromatographic analysis: 21  0.8 ppm  Efficiency: Eff_N (CM-value) = 0.580  0.013 Eff_N (GCA-value) = 0.304  0.012 Consistent data from GCA and Claude

6. Simple Determination of the N2 concentration in the doped N2 run8 measurement Lifetime fit with simple exponential (has systematic problems)

7. time (100ns)

8. start/stop time scan with fixed 5  s gate start time (100ns)

9. start/stop time scan with fixed 10  s gate start time (100ns)

10. start/stop time scan with fixed 15  s gate time (100ns) start time (100ns)

11. Simple Determination of the N2 concentration in the doped N2 run8 measurement Lifetime fit with simple exponential 1) Fit lifetime N2 doped and clean fill N2456150 ± 60 s-1457000 ± 60 s-1clean fill455425 ± 12 s-1 457600 ± 60 s-1 2) calculate difference Difference N2 - clean fill (min/max): D1 = 725 ± 65 s-1D2 = 1575 ± 65 s-1 D3 = 2175 ± 65 s-1 3) per ppm N we expect a lifetime change of  r = 190.6 ppm (Table) D1 /dr = 3.8 ± 0.4 ppm D2/dr = 8.3 ± 0.4 ppm D3/dr = 11.4 ± 0.4 ppm confirm Claude’s filling and yield method disagree with GCA

12. Analysis of Impurity events in Run 9 Special Runs CHUPS at 2 flow rates

13. Measurement with 2 CHUPS flow rates

15. measurements correct for N2 assume impurity finder efficiency

16. Measurement with 2 CHUPS flow rates the difference measurement of the humidity sensor should be pretty accurate: assume 2ppb we can explain all 3 values consistently with a single PURA offset = 12 ppb

17. Measurement with 2 CHUPS flow rates Solution via the determination of an effective muon transfer rate from hydrogen to oxygen for the MuCAP target conditions

18.  ZZ pp lam_tr_Z *c Z *phi lam_0 c=1 cZcZ lam_cap_H lam_cap_Z

19. Determination of an effective muon transfer rate from hydrogen to oxygen for the MuCAP target conditions Table 2: Main characteristics of MuCAP relevant impurities at the MuCAP target density of phi = 0.0116 of liquid hydrogen density (LHD). These table uses atomic rates. r_tr = muon transfer rate [10 11 s -1 ], r_cap muon capture rate [10 6 s -1 ] x = transfer fraction in ppm for c = 1ppm, x = r_tr*phi*c/r_0, y = capture fraction in  Z atom, y = r_cap/(r_0+r_cap), r_0 = 0.455 [10 6 s -1 ] Y = x*y capture yield in ppm at 1 ppm concentration, del_r = relative change of observed decay rate, del_r = x y (2+y)/(1+y) 2, del_r / Y = is the relative decay rate change per observed pp impurity yield c = impurity concentration in ppm, Argon rates are from Ref. 3 and 5. O eff = describes the effective muon-to-oxygen transfer rate for the MuCAP conditions measured at phi=0.0116 of LHD. Note that the quantity relevant for the lifetime fit, del_r/Y, does not change between the 2 target densities, as it only depends on the capture rate. Y2C = 897 =Y@C=1

20. Implementing our Impurity knowledge from Run7/8/9 for the high Z capture correction of Run8

21. Implementing our Impurity knowledge from Run7/8/9 for the high Z capture correction of Run8 B.Lauss Tom’s Run8 clean fill analysis: capture events = 36376 capture control candidates = 47 muon stops (25PP) = 3.052337171 x 10 9  Observed Impurity Yield = 11.90 ± 0.07 ppm Let’s take the nitrogen contamination from the 3 gas-chromatographic measurements during the clean fill and average it over the measurement period (discard the data of the furst 29 hours of cleaning): hours2897516 Total 614 N contamination36.2519.2510.55 This results in a mean N concentration over the clean fill of 13.56 ± 2 ppb From this we calculate a Yield contribution of 0.01356 x 114.57 = 1.55 ± 0.23 ppm x N_eff = 0.9 ± 0.14 for an impurity finder efficiency of N_eff = 0.58 ± 0.02 The corrected Yield = 11.9 - 0.9 = 11.0 ± 0.16 ppm which were during run8 unexplained, but water was the prime suspect now from our Run 9 measurements we can suppose this is true

22. Let’s take the effective transfer rate to Oxygen which was estimated from Run9 data = 1.92 10 11 s -1 and also assume that the efficiency to detect an oxygen impurity capture event is probably similar to nitrogen N_eff = 0.58 but for sure not larger than 1. (Y2C = 896 ± 123) various methods how one could asses the impurity finder efficiency  11 / 0.58 / 896 = 0.0212 ± 0.003 ppm or 11 / 1 / 896 = 0.0123 ± 0.002 ppm (lower concentration limit) assume 50% error on Eff  11 / 0.58 / 896 = 0.0212 ± 0.011 ppm these values are perfectly matching the values which we have measured with the humidity sensor in Run9 where the offset corrected value at the standard hydrogen flow rate was 20 ± 10 ppb This determines the oxygen concentration to be ElementConcentration [ppm]lifetime correction [ppm] from tableO11398. best guessO0.0212 ± 0.003 29.6 ± 4.2 mean O0.01675 ± 0.004523.4 ± 6.3 50%O0.0212 ± 0.011 29.6 ± 15.4 from tableN1190.6 N0.01356 ± 0.0022.6 ± 0.4 We conclude: lifetime correction using an extraordinary conservative error32.2 ± 15.4 ppm using a conservative mean error26.0 ± 6.3ppm using a best guess error 32.2 ± 4.2 ppm

23. Can one understand this large effective oxygen transfer rate with a wrong concentration in the published experiment ?

25. Can one understand this large effective oxygen transfer rate with a Simple two-component Model Description ?

26. Simple 2 component model for the description of muon transfer

27. Physics Explanation ? lam_e_o = 2.08 · 10 5  s -1 epithermal muon transfer rate from hydrogen to oxygen lam_t_o = 0.85 · 10 5  s -1 ground state muon transfer rate from hydrogen to oxygen lam_r = 8 · 10 2  s -1  p atoms thermalization rate lam_0 = 0.455  s -1 muon decay rate phi = 0.01target density in LHD coxygen concentration also lam_e_o = 3.9 · 10 5  s -1 from Adamzcak lam_r is the important rate which changes the epithermal to thermal distribution

28. Physics Explanation ? calculate yield for the 2 populations

29. Physics Explanation ? Rates: o ep = 2.08  10 11 s -1 o t = 0.85  10 11 s -1 0.87  o ep + 0.13  o = o eff = 1.92  10 11 s -1

30. Yields with standard rates / from Peter

31. Yields with effective O rate Werthmueller rates : 37% epithermal (assuming Eff_O =1) 87 % epithermal  p (assuming Eff_O = 0.58) Adamczak Rates lam_e_o = 3.9 · 10 5  s -1 35% epithermal  p