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Status of 54 Fe and 56 Fe(n, g ) analysis Giuseppe Giubrone Instituto de Fisica Corpuscular

Status of 54 Fe and 56 Fe(n, g ) analysis Giuseppe Giubrone Instituto de Fisica Corpuscular Valencia n_ToF Analysis meeting, CERN 2011. Outline. Experimental details Energy and width calibration Polynomial WF Neutron fluence and Resolution Function SAMMY analysis

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Status of 54 Fe and 56 Fe(n, g ) analysis Giuseppe Giubrone Instituto de Fisica Corpuscular

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  1. Status of 54Fe and 56Fe(n,g) analysis Giuseppe Giubrone Instituto de Fisica Corpuscular Valencia n_ToF Analysis meeting, CERN 2011

  2. Outline • Experimental details • Energy and width calibration • Polynomial WF • Neutron fluence and Resolution Function • SAMMY analysis • Neutron Sensitivity • Summary G.Giubrone n_TOF Analysis meeting 2011, CERN

  3. Experimental Details • In 2009 @ nToF started a campaign to measure isotopes with a relevant interest in astrophysics. • In 2009 the measurement was made for the 56Fe isotope • In 2010 the measurement was made for 54Fe isotope and the new lead target allows the use of borated water moderator to reduce beam g-rays scattered background. • The measurements for the 56Fe and 54Fe were performed using two deuterated benzene(C6D6) scintillation detectors with a low neutron sensitivity. Experimental setup for 54Fe (2010) Borated water moderator Experimental setup for 56Fe (2009) Water moderator

  4. Experimental Details • The two setups had different geometries and different detectors: • 2009 – two K6D6 detectors • 2010 – One K6D6 and one St. Gobain/Bicron commercial detector (Al housing, smaller volume). G.Giubrone n_TOF Analysis meeting 2011, CERN

  5. Experimental Details Samples 2009 2010 Isotopic Analysis

  6. Experimental Details Data Reduction • We call data reduction the transformation of the registered • number of counts into yield. Yield: Fraction of neutronbeam wich undergoes a capture reaction in the sample G.Giubrone n_TOF Analysis meeting 2011, CERN

  7. ENERGY AND WIDTH CALIBRATION • A calibration is needed because the weighting function is obtained from a MC simulation as function of deposited energy. • The C6D6 detectors were calibrated using three different radioactive sources: • 137Cs with g=662 keV • 88Y with g =0.898 keV and 1.4MeV • Am/Be source with g=4.4MeV • Linear energy calibration with the pulse height: E= a0+a1*Amplitude. G.Giubrone n_TOF Analysis meeting 2011, CERN

  8. ENERGY AND WIDTH CALIBRATION • Quadratic width calibration withs2=b0E+b1E2The instrumental resolution was found different for each detector.56Fe b0=3.277keV and b1=2.859keV for det#1 b0=3.270187keV and b1=4.6016keV for det#2 • 54Fe • b0=6.01496keV and b1=9.7422keV for K6D6 b0=1.74132keV and b1=0 for Bicron G.Giubrone n_TOF Analisys meeting 2011, CERN

  9. ENERGY AND WIDTH CALIBRATION 2010 #2 2010 G.Giubrone n_TOF Analysis meeting 2011, CERN

  10. ENERGY AND WIDTH CALIBRATION • During the 2009 measurement which lasted from August 20 till September 23,the gain of the detectors was drifting • The total measurement period was divided in six periods with a constant energy calibration: To check the calibration we have recalibrate all calibration runs,choosen as reference the last calibration runs: 88Y source G.Giubrone n_TOF Analysis meeting 2011,CERN

  11. ENERGY AND WIDTH CALIBRATION • During the 2010measurement which lasted from July 13 (after the final setup) till July 30, the gain of the detectors was stable. The total measurement period was divided in six periods with a constant energy calibration BICRON K6D6 Am/Be Am/Be

  12. ENERGY AND WIDTH CALIBRATION BICRON K6D6 Experimental spectrum Simulated spectrum Experimental spectrum Simulated spectrum G.Giubrone n_TOF Analysis meeting 2011,CERN

  13. Polynomial weighting function Geometrical setup defined in the GEANT4 simulations The geometries have been modeled in high detail: detectors, samples, supports.... Experimental setup for 56Fe Experimental setup for 54Fe

  14. Polynomial weighting function • Monoenergetic gamma-rays were MC simulated using the Geant 4 code and a detailed geometrical description of the setup. • To simulate a gamma-ray we assumed that the beam has a gaussian profile (based on MicroMegas result 100keV-1MeV) • We also took into account the exponential depth profile. Only relevant for the 4.9eV Au reference resonance (λ= 0.001cm) G.Giubrone n_TOF Analisys meeting 2011, CERN

  15. Polynomial Weighting Function • A set of 34 monoenergetic gamma-rays with energies 0.05, 0.1, 0.15, 0.2, ...2, 2.5, 3, ….8 MeV were simulated. For each energy 5 e+6 photons were simulated. To verify the correctness of the shape of the WF we calculate the ratio: Simulated response Weighting function

  16. Plolynomial Weighting Function 2009 and 2010 WF G.Giubrone n_TOF Analysis meeting 2011, CERN

  17. Data reduction statistics and parameters 56Fe 54Fe To process the data we applied well defined software threshold of 300 keV (low energy cut) ,9MeV(56Fe) and12MeV(54Fe)(high energy cut). G.Giubrone n_TOF Analysis meeting 2011,CERN

  18. Data reduction statistics and parameters Det#1 vs Det#2 56 Fe 54 Fe

  19. Data reduction statistics and parameters 56 Fe DET#1 DET#2 54 Fe BICRON FZK

  20. 54 Fe G.Giubrone n_TOF Analysis meeting 2011,CERN

  21. Sammy Analysis The total weighted spectrum has to converted into yield using the relation: • However due to the deep holes in the flux distribution we decided to analyze whenever is possible the weighted spectrum with a single normalization factor (calculated at the neutron resonance energy) • For the flux we are using the MCNPX simulation with 100bpd from M. Calviani (with spline interpolation) G.Giubrone n_TOF Analysis meeting 2011,CERN

  22. Sammy Analysis Flux Raw Spectra Weighted Spectra 56Fe Flux Raw Spectra Weighted Spectra 54Fe

  23. Sammy Analysis • As Resolution Function we have taken provisionally the RPI parametrization of the old target RF done by the Bari group

  24. Sammy Analysis Normalization of neutron flux was obtained with saturated resonace method Normalization= 0.649 (~ beam-interception-factor) 197Au Preliminary FIT ToF calibration with Gold and Iron resonance: Flight path in 2010 =184m This spectrum was obtained from the En in the ROOT data file. We have re processed the data using ToF G.Giubrone n_TOF Analysis meeting 2011,CERN

  25. Sammy Analysis In this first analysis I take into all resonances tabulated in ENDF and Suchkorushkin library Sukhoruchkin ENDF G.Giubrone n_TOF Analysis meeting 2011,CERN

  26. Sammy Analysis Examples of s and p wave ENDF Sukhoruchkin n_ToF G.Giubrone n_TOF Analysis meeting 2011,CERN

  27. Sammy Analysis Sukhoruchkin n_ToF G.Giubrone n_TOF Analysis meeting 2011,CERN

  28. Sammy Analysis 2=1.279 “”A slight improvement in the fit is obteined when a second resonance is added, thus might be a doublet” 2=1.215 G.Giubrone n_TOF Analysis meeting 2011, CERN

  29. Sammy Analysis Some Fit

  30. Sammy Analysis First Results (*) Present in the previous last but not in the last Suchoruchkin compilation (**) Probably a doublet G.Giubrone n_TOF Analysis meeting 2011,CERN

  31. Sammy Analysis In average, n_TOF is in better agreement with Suckhoruchkin than with ENDF G.Giubrone n_TOF Analysis meeting 2011,CERN

  32. Sammy Analysis G.Giubrone n_TOF Analysis meeting 2011,CERN

  33. Sammy Analysis Zoom in y "No clear dependence of Gn/Gg versus the resonance energy, thus no neutron sensitivity effect noticeable". G.Giubrone n_TOF Analysis meeting 2011,CERN

  34. Neutron Sensitivity • The neutron sensitivity for the experimental setup used for 54Fe and 57Fe will be analized by detalaited MC simulation using Geant4 4.9.3version • A preliminary result was obtained using the new neutron library developed by D. Cano and E. Mendoza from CIEMAT. 10X10e+6 events

  35. Energy and width calibrations as a function of run number were obtained. A first round of consistency checks has been done, but new detailed check is necessary • The weighting functions have been obtained with realistic MC simulations and taking into account the real shape of the neutron beam profile. • The ToF/Energy preliminary calibration done. • To proceed with the analysis (extract the yield), a good shape of the neutron flux is necessary for both H2O and borated H2O moderator. For this first analysis a shape of the flux provided by Calviani is used. • A preliminary analysis of the 2010 54Fe(n,g) measurement • (with borated water moderator) has been completed Summary G.Giubrone n_TOF Analysis meeting 2011,CERN

  36. Summary • The Resolution Function from the old target (at least in Bari RPI parameterization) seems (nearly) adequate also for the new target • Statistics seems limited: only a careful, complete analysis will tell us how much improvement on existing resonance parameters will be obtained • Resonance analysis for few resonances was performed using SAMMY • Neutron sensitivity for FZK and BICRON detector is under study using a new neutron library implemented for GEANT4. G.Giubrone n_TOF Analysis meeting 2011,CERN

  37. 57Fe Status 359 keV(3.36% 58Fe) 230 keV (3.36% 58Fe) G.Giubrone n_TOF Analysis meeting 2011,CERN

  38. 57Fe(1-10keV)

  39. 57Fe(10-100keV)

  40. To solve the problem due to some point with a standard deviation more than ±2 we made a rebinning in the region before and after the resonance energy

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