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Status on 25 Mg(n, γ ) and neutron flux in 2012 Bologna, 27 November 2013

Status on 25 Mg(n, γ ) and neutron flux in 2012 Bologna, 27 November 2013 . C. Massimi. 2012 Flux Detectors & data Flux and its uncertainty Mg(n, γ ) RSA, examples MACS, preliminary Conclusions. Outline. 2012 Flux – Available data. Capture collimator (1.8 cm). Fission

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Status on 25 Mg(n, γ ) and neutron flux in 2012 Bologna, 27 November 2013

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  1. Status on 25Mg(n,γ) and neutron flux in 2012 Bologna, 27 November 2013 C. Massimi

  2. 2012 Flux Detectors & data Flux and its uncertainty Mg(n,γ) RSA, examples MACS, preliminary Conclusions Outline

  3. 2012 Flux – Available data Capture collimator (1.8 cm) Fission collimator (8 cm)

  4. 2012 Flux – Available data Capture collimator (1.8 cm) Fission collimator (8 cm)

  5. 2012 Flux – SiMon data DST version 11, an improved routine exists but not used yet Amplitude Spectrum Silicon 1 n+6Li  α + 3H TOF > 104 ns  No γ-flash

  6. 2012 Flux – SiMon data DST version 11, an improved routine exists but not used yet Amplitude Spectrum Silicon 2 n+6Li  α + 3H TOF > 104 ns  No γ-flash

  7. 2012 Flux – SiMon data DST version 11, an improved routine exists but not used yet Amplitude Spectrum Silicon 3 n+6Li  α + 3H TOF > 104 ns  No γ-flash

  8. 2012 Flux – SiMon data DST version 11, an improved routine exists but not used yet Amplitude Spectrum Silicon 4 n+6Li  α + 3H TOF > 104 ns  No γ-flash

  9. 2012 Flux – SiMon data TOF spectrum, gate on 3H peak Silicon 1 ~ 0.5 eV 260 keV 35 kev 87 kev

  10. 2012 Flux – SiMon data TOF spectrum, gate on 3H peak Silicon 2 0.5 - 2 eV

  11. 2012 Flux – SiMon data TOF spectrum, gate on 3H peak Silicon 3 ~ 0.5 eV

  12. 2012 Flux – SiMon data TOF spectrum, gate on 3H peak Silicon 4 ~ 0.5 eV

  13. 2012 Flux – SiMon data Rejection of radiofrequency(?)  signals in coincidence --- No conditions --- 1 signal --- No coincidences (30 ns)

  14. 2012 Flux – SiMon data Rejection of radiofrequency(?)  Energy deposition Solution Electronic noise not present in parasitic bunches

  15. 2012 Flux – SiMon data Beam stability  Ratio of beam monitors

  16. 2012 Flux – SiMon data Beam stability  Ratio of beam monitors --- Dedicated beam --- Parasitic beam R.M.S. ~ 4,3 % R.M.S. ~ 5,4 % “protons” / “pkup”

  17. 2012 Flux – SiMon data Detector stability  Ratios of Sili counts Vs … Conditions: Amplitude 3H peak TOF  thermal region

  18. 2012 Flux – SiMon data Detector stability  Ratios of Sili counts Vs … Conditions: Amplitude 3H peak TOF  thermal region

  19. 2012 Flux – SiMon data SiMon Counts normalized to protons

  20. 2012 Flux – SiMon data SiMon Counts normalized to pkup

  21. 2012 Flux – SiMon data SiMon Counts normalized to protons

  22. 2012 Flux – SiMon data Uncertainty due to counting statistic 87 kev 35 kev 6 kev En< 0.5 eV

  23. 2012 Flux – SiMon data From flux to capture LFLUX=182.35 m LCAPT=184.21 m

  24. 2012 Flux – SiMon data Comparison with previous years Difference at thermal > 10% Average difference 10%

  25. 2012 Flux – SiMon data Comparison with previous years 12 – 45 μs 1 MeV – 90 keV Difference at high energy ? 260 keV

  26. SiMon data not enough En > few keV SiMon efficiency not well known simulation or experimental ratio (2011 data)?

  27. SiMon Vs PPAC data 2012 PPAC data from Esther Leal Cidoncha

  28. SiMon Vs PPAC data Matching region PPAC – SIMON 3 – 25 keV 3% systematic uncertainty depending on the matching region

  29. SiMon Vs PPAC data

  30. SiMon + PPAC data --- Evaluated 2011 --- This work 2012 Flux from 0.03 eV < En< 1 MeV PPAC SiMon

  31. SiMon + PPAC data --- Evaluated 2011 --- This work 2012 Same shape 3% systematic uncertainty depending on the matching region

  32. Flux 2011 – 2012 Real situation ATTENTION to normalization --- Evaluated 2011 --- This work 2012 56Fe 197Au

  33. Flux 2011 – 2012 Real situation

  34. Sample MgO, powder sample Transmission experiment on natMg sample n_TOF facility Phase-I: Water as neutron moderator Measurement Few data collected New 25Mg(n,γ) measurement … why ? Because of the limitations in 2003 measurement Physical Review C 85 (2012) 044615

  35. Sample MgO, powder sample Transmission experiment on natMg sample n_TOF facility Phase-I: Water as neutron moderator Measurement Few data collected New 25Mg(n,γ) measurement … why ? Because of the limitations in 2003 measurement … did we improve? • Yes a lot • Metal sample • Transmission experiment on enriched 25Mg sample • Yes • Borated water • NO • Again few data collected

  36. 25Mg(n,γ) first resonance Recall: 2003 capture data normalized to this resonance

  37. 25Mg(n,γ) first resonance Recall: 2003 capture data normalized to this resonance Γγ=1.73±0.03 eV

  38. 25Mg(n,γ) first resonance Recall: 2003 capture data normalized to this resonance Γγ=1.73±0.03 eV Γγ=1.5±0.5 eV

  39. 25Mg(n,γ) first resonance Recall: 2003 capture data normalized to this resonance Γγ=1.73±0.03 eV Γγ=1.5±0.5 eV Γγ=1.28±0.03 eV

  40. 25Mg(n,γ) up to 100 keV Clean up resonances list

  41. 25Mg(n,γ) up to 100 keV Check with transmission data from GELINA

  42. 25Mg(n,γ) up to 300 keV … RSA ongoing

  43. 25Mg(n,γ) up to 100 keV Check with transmission data from GELINA

  44. 25Mg(n,γ) - MACS Maxwellian-averaged capture cross section ~ 10 - 20% lower than previously reported

  45. 25Mg(n,γ) - MACS Maxwellian-averaged capture cross section ~ 10 - 20% lower than previously reported

  46. Conclusions • 2012 flux, obtained from the combination of SiMon and PPAC data, available: • uncertainty due to counting statistic < 4% • systematic uncertainty ~ 3% for En > 30 keV • 25Mg(n,γ) measurement at n_TOF • RSA, check with transmission data • MACS 20% lower than previously reported  important astrophysical implication • Uncertainty reduced

  47. Cristian Massimi Dipartimento di Fisica e Astronomia massimi@bo.infn.it www.unibo.it

  48. Neutron Sensitivity Preliminary study: εN,BICRON ~ 10-4

  49. Silicon 2 - stability Ni campaign

  50. Silicon 2 - stability

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