Electromagnetic Dipole Strength distribution in 124,128,134 Xe below the neutron separation energy

Transcription

1 Electromagnetic Dipole Strength distribution in 124,128,134 Xe below the neutron separation energy Ralph Massarczyk Helmholtz-Zentrum Dresden-Rossendorf R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

2 Outlook my original idea introduction experiment my results other results R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

3 Outlook Oh oh I got 40 minutes talk... introduction experiment my results other results R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

4 Outlook R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

5 Outlook new idea My Hitchhiker's Guide to a PhD in nuclear physics......trails and o the beaten track R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

6 Outlook new idea My Hitchhiker's Guide to a PhD in nuclear physics......trails and o the beaten track How would such a book look like? R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

7 Part I - Maps and Overview R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

8 2 2 Part I - Maps and Overview Moller Chart of Nuclides 2000 Quadrupole Deformation Deformation < to to to to 0.3 >0.3 Stable How eects nuclear deformation nuclear reactions? R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

9 Part Ib - A closer view Xe β= Xe β= Xe β= 0.11 cross section (mb) energy (MeV) deformation changes shape of the Giant Dipole Resonance dierent parameterizations available R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

10 Part Ib - A closer view Xe β= Xe β= Xe β= 0.11 cross section (mb) energy (MeV) deformation changes shape of the Giant Dipole Resonance dierent parameterizations available R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

11 Part Ib - A closer view Xe 128 Xe 134 Xe Triple Lorentzian Model RIPL3 theoretical prediction cross section (mb) energy (MeV) deformation changes shape of the Giant Dipole Resonance dierent parameterizations available R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

12 Part Ib - A closer view Xe 128 Xe 134 Xe 40 Triple Lorentzian Model RIPL3 theoretical prediction cross section (mb) energy (MeV) deformation changes shape of the Giant Dipole Resonance dierent parameterizations available R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

13 Part Ic - some background photo-absorption cross-section vs. strength function f0λxl J = σj 0αXL (Eγ) (MeV ) (2L+1) g J Eγ 2L 1 σ f is what we can measure starts from ground state often includes E1, M1, E2 transitions as well as (γ,γ ), (γ,n) and other reactions (γ,x) is needed to describe deexcitations of excited states splits up in E1, M1, E2... should be independent from excitation energy, spin, parity, excitation mechanism an idea based on statistical assumptions R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

14 A short why-to-visit the energy region below the threshold interesting for a lot of nuclear reactions cross-over from a system dominated to a statistical dominated system new resonances (pygmy, M1, soft pole), new picture of nuclear matter? fascinating how small scale eects can change big things R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

15 A short why-to-visit the energy region below the threshold interesting for a lot of nuclear reactions cross-over from a system dominated to a statistical dominated system new resonances (pygmy, M1, soft pole), new picture of nuclear matter? fascinating how small scale eects can change big things 1 1 gure by D.Savran R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

16 A short why-to-visit the energy region below the threshold interesting for a lot of nuclear reactions cross-over from a system dominated to a statistical dominated system in heavy nuclei new resonances (pygmy, M1, soft pole), new picture of nuclear matter? fascinating how small scale eects can change big things R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

17 A short why-to-visit the energy region below the threshold interesting for a lot of nuclear reactions cross-over from a system dominated to a statistical dominated system in heavy nuclei new resonances (pygmy, M1, soft pole), new picture of nuclear matter? fascinating how small scale eects can change big things R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

18 A short why-to-visit the energy region below the threshold interesting for a lot of nuclear reactions cross-over from a system dominated to a statistical dominated system in heavy nuclei new resonances (pygmy, M1, soft pole), new picture of nuclear matter? fascinating how small scale eects can change big things 2 2 S.Goriely Phys. Lett. B 436 (1998) 1018 R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

19 My personal walking tour measure the photo-absorption cross section in a chain of stable isotopes recently published results of chain with neutron number N = 50 1 What happens if neutron excess and nuclear deformation go in dierent directions? measurements of Xenon isotopes learn something about the general behavior R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

20 My personal walking tour measure the photo-absorption cross section in a chain of stable isotopes recently published results of chain with neutron number N = 50 1 What happens if neutron excess and nuclear deformation go in dierent directions? measurements of Xenon isotopes learn something about the general behavior 1 R. Schwengner PRC 87 (2013) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

21 My personal walking tour measure the photo-absorption cross section in a chain of stable isotopes recently published results of chain with neutron number N = 50 1 What happens if neutron excess and nuclear deformation go in dierent directions? measurements of Xenon isotopes learn something about the general behavior 1 R. Schwengner PRC 87 (2013) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

22 My personal walking tour measure the photo-absorption cross section in a chain of stable isotopes recently published results of chain with neutron number N = 50 1 What happens if neutron excess and nuclear deformation go in dierent directions? measurements of Xenon isotopes learn something about the general behavior 1 R. Schwengner PRC 87 (2013) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

23 My personal walking tour measure the photo-absorption cross section in a chain of stable isotopes recently published results of chain with neutron number N = 50 1 What happens if neutron excess and nuclear deformation go in dierent directions? measurements of Xenon isotopes learn something about the general behavior 1 R. Schwengner PRC 87 (2013) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

24 pro and cons of Xenon noble gas interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe ratios important in solar system studies and planetary dierentiation Pro and Contra rarest not radioactive element on earth noble gas R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

25 pro and cons of Xenon Pro and Contra noble gas interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe ratios important in solar rarest not radioactive element on earth noble gas R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

26 pro and cons of Xenon Pro and Contra noble gas interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe ratios important in solar rarest not radioactive element on earth noble gas (High-pressure gas targets 80 bar) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

27 pro and cons of Xenon Pro and Contra noble gas, generally nonreactive interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe rarest not radioactive element on earth noble gas (High-pressure gas targets 80 bar) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

28 pro and cons of Xenon Pro and Contra noble gas, generally nonreactive interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe ratios important in solar system studies and planetary dierentiation R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

29 pro and cons of Xenon Pro and Contra noble gas, generally nonreactive interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe ratios important in solar system studies and planetary dierentiation 1 1 J. Kunz Sciene 280 (1998) 877 R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

30 pro and cons of Xenon Pro and Contra noble gas interesting for reactor physics acts as the most important reactor poison Xe(n,γ) 129 Xe/ 130 Xe, 136 Xe/ 130 Xe ratios important in solar system studies and planetary dierentiation 1 1 J. Kunz Sciene 280 (1998) 877 R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

31 Part II - Sites The (new) ELBE at Dresden Electron Linac for secondary radiation purposes (neutrons,positrons, FEL, activation experiments, bremsstrahlung) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

32 Part II - Sites photon excitation at the bremsstrahlung setup at the electron accelerator ELBE electron energies from 5 to 20 MeV with up to 1mA electron beam dump BGO shielded HPGe detectors electron beam on thin niobium foil produces bremsstrahlung setup contains high purity Germanium detectors with BGO shielding Nb radiator electrons purging magnet Al hardener collimator bremsstrahlung deuterised PE target Si detectors photon beam dump scattering target empty target measurements necessary R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

33 Part II - Sites photon excitation at the bremsstrahlung setup at the electron accelerator ELBE electron energies from 5 to 20 MeV with up to 1mA electron beam dump BGO shielded HPGe detectors electron beam on thin niobium foil produces bremsstrahlung setup contains high purity Germanium detectors with BGO shielding Nb radiator electrons purging magnet Al hardener collimator bremsstrahlung deuterised PE target Si detectors photon beam dump scattering target empty target measurements necessary R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

34 Part II - Sites photon excitation at the bremsstrahlung setup at the electron accelerator ELBE electron energies from 5 to 20 MeV with up to 1mA electron beam on thin niobium foil produces bremsstrahlung setup contains high purity Germanium detectors with BGO shielding empty target measurements necessary R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

35 Part II - Sites photon excitation at the bremsstrahlung setup at the electron accelerator ELBE electron energies from 5 to 20 MeV with up to 1mA electron beam on thin niobium foil produces bremsstrahlung setup contains high purity Germanium detectors with BGO shielding empty target measurements necessary R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

36 Part III - A walk through the analysis subtraction of the background from target container correction for eciency and deconvolution of detector response (GEANT4) 1 subtraction of atomic background R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

37 Part III - A walk through the analysis subtraction of the background from target container correction for e ciency and deconvolution of detector response (GEANT4) 1 subtraction of atomic background R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

38 Part III - A walk through the analysis subtraction of the background from target container correction for eciency and deconvolution of detector response (GEANT4) 1 subtraction of atomic background Efficiency (%) E γ (kev) 1 R. Massarczyk PRC 86 (2012) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

39 Part III - A walk through the analysis subtraction of the background from target container correction for eciency and deconvolution of detector response (GEANT4) 1 subtraction of atomic background 1 R. Massarczyk PRC 86 (2012) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

40 beaten track and an alternative way to go R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

41 beaten track and an alternative way to go R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

42 beaten track and an alternative way to go R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

43 beaten track and an alternative way to go Level spacing or FWHM (kev) E γ (kev) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

44 beaten track and an alternative way to go Level spacing or FWHM (kev) E γ (kev) continuum analysis... R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

45 beaten track and an alternative way to go Level spacing or FWHM (kev) E γ (kev) continuum analysis standard tool in (n,γ) analysis (e.g. Two-Step-Cascades) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

46 beaten track and an alternative way to go Level spacing or FWHM (kev) E γ (kev) continuum analysis standard tool in (n,γ) analysis (e.g. Two-Step-Cascades)... but not in nuclear resonance uorescence experiments R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

47 beaten track and an alternative way to go In this continuum of unresolvable states... R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

48 beaten track and an alternative way to go In this continuum of unresolvable (not overlapping) states... R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

49 beaten track and an alternative way to go In this continuum of unresolvable (not overlapping) states we have distributions for strength and level densities, their means, their deviations... R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

50 beaten track and an alternative way to go In this continuum of unresolvable (not overlapping) states we have distributions for strength and level densities, their means, their deviations Why do we still use random numbers and waste computational power? R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

51 γdex based on the idea of DICEBOX 1 rst step: scheme of levels = scheme of energy bins 2, 3 second step: remove the random numbers, by distributions, mean values, deviations and covariances 1 F. Be cvá NIM A 417 (1998) 434 R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

52 γdex based on the idea of DICEBOX 1 rst step: scheme of levels = scheme of energy bins 2, 3 second step: remove the random numbers, by distributions, mean values, deviations and covariances 1 F. Be cvá NIM A 417 (1998) T. Kawano Journal of Nucl. Science and Tech. 47 (2010) G. Schramm PRC 85 (2012) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

53 γdex based on the idea of DICEBOX 1 rst step: scheme of levels = scheme of energy bins 2, 3 second step: remove the random numbers, by distributions, mean values, deviations and covariances 1 F. Be cvá NIM A 417 (1998) T. Kawano Journal of Nucl. Science and Tech. 47 (2010) G. Schramm PRC 85 (2012) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

54 γdex off the beaten path change computer time to computer power! new calculation method: R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

55 γdex off the beaten path change computer time to computer power! new calculation method: - dene Histogram of 1st bin: H 1 = δ(e 1 ) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

56 γdex off the beaten path change computer time to computer power! new calculation method: - dene Histogram of 1st bin: H 1 = δ(e 1 ) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

57 γdex off the beaten path change computer time to computer power! new calculation method: - dene Histogram of 1st bin: H 1 = δ(e 1 ) - dene Histogram of 2nd bin: H 2 = Γ 2 0 Γ tot δ(e 2 ) + Γ 2 1 Γ tot H 1 R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

58 γdex off the beaten path change computer time to computer power! new calculation method: - dene Histogram of 1st bin: H 1 = δ(e 1 ) - dene Histogram of 2nd bin: H 2 = Γ 2 0 Γ tot δ(e 2 ) + Γ 2 1 Γ tot H 1 R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

59 γdex off the beaten path change computer time to computer power! new calculation method: - dene Histogram of 1st bin: H 1 = δ(e 1 ) - dene Histogram of 2nd bin: H 2 = Γ 2 0 Γ tot δ(e 2 ) + Γ 2 1 Γ tot H 1 - dene Histogram of nth bin: H n = Γ n 0 Γ tot δ(e n ) + i=n 1 Γ n i i=1 Γ tot H n R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

60 γdex off the beaten path change computer time to computer power! new calculation method: - dene Histogram of 1st bin: H 1 = δ(e 1 ) - dene Histogram of 2nd bin: H 2 = Γ 2 0 Γ tot δ(e 2 ) + Γ 2 1 Γ tot H 1 - dene Histogram of nth bin: H n = Γ n 0 Γ tot δ(e n ) + i=n 1 Γ n i i=1 Γ tot H n R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

61 γdex off the beaten path Problems Uncertainty propagation much more complicated statistical assumption not true for low energies R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

62 γdex off the beaten path Problems Uncertainty propagation much more complicated statistical assumption not true for low energies Solutions Uncertainty by error propagation Use discrete level scheme for low energies R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

63 γdex off the beaten path Problems Uncertainty propagation much more complicated statistical assumption not true for low energies Solutions Uncertainty by error propagation Use discrete level scheme for low energies Advantages TIME...TIME...TIME, calculation within a minute Test with dierent model combinations R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

64 Back to the experiment Correction of inelastic scattered events and branching Calculation and subtraction with γdex 1, 2 Selfconsistent: Input PSF is Output PSF R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

65 Back to the experiment Correction of inelastic scattered events and branching Calculation and subtraction with γdex 1, 2 Selfconsistent: Input PSF is Output PSF 1 G. Schramm PRC 85 (2012) R. Massarczyk PRC 87 (2013) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

66 1 G. Schramm PRC 85 (2012) R. Massarczyk PRC 87 (2013) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22 Back to the experiment Correction of inelastic scattered events and branching Calculation and subtraction with γdex 1, 2 Selfconsistent: Input PSF is Output PSF cross section (mb) cross section (mb) st Input (TLO) 50 12th Input 12th Output 25 1st Input (TLO) 1st Output == 2nd Input 2nd Output Energy (kev)

67 last chapter - results Complete dipole strength below the neutron separation energy in gas targets cross section (mb) QRPA calculations 20 performed TLO RIPL (2Lorentz) ELBE data 124 Xe 128 Xe 134 Xe E x (MeV) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

68 last chapter - results QRPA ELBE data 124 Xe QRPA RIPL3 TLO Complete dipole strength below the neutron separation energy in gas targets cross section (mb) Xe QRPA calculations performed Xe R.Massarczyk (HZDR) dipole strength 0 in 124,128,134 Xe / 22

69 results and theory this work ( 124,128,134 Xe Ba) 1 Deviation to other results 1 Follows the trend of theory in N/Z plot, extra strength observed Σ BE1 6 8MeV ( e 2 fm 2 ) N/Z R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

70 results and theory 1 this work ( 124,128,134 Xe Ba) Savran et al. ( N = 82 series) Deviation to other results 1 Follows the trend of theory in N/Z plot, extra strength observed Σ BE1 6 8MeV ( e 2 fm 2 ) N/Z 1 D. Savran PRL 100 (2008) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

71 results and theory 1 this work ( 124,128,134 Xe Ba) Savran et al. ( N = 82 series) this work (QRPA) Savran et al. (QPM) Deviation to other results 1 Follows the trend of theory in N/Z plot, extra strength observed Σ BE1 6 8MeV ( e 2 fm 2 ) N/Z 1 D. Savran PRL 100 (2008) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

72 results and theory Deviation to other results 1 Follows the trend of theory in N/Z plot, extra strength observed Σ BE1 6 8MeV ( e 2 fm 2 ) this work ( 124,128,134 Xe Ba) Savran et al. ( N = 82 series ) this work (QRPA) Savran et al. (QPM) β 2 1 D. Savran PRL 100 (2008) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

73 results and theory Deviation to other results 1 Follows the trend of theory in N/Z plot, extra strength observed extra strength (pygmy resonance? ) seems to be more dependent on (triaxial) deformation than known so far. Σ BE1 6 8MeV ( e 2 fm 2 ) this work ( 124,128,134 Xe Ba) Savran et al. ( N = 82 series ) this work (QRPA) Savran et al. (QPM) β 2 1 D. Savran PRL 100 (2008) R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

74 Conclusions determination of dipole strength functions below the neutron separation energy we are able to measure gaseous targets fast reaction code γdex for correction R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

75 Conclusions determination of dipole strength functions below the neutron separation energy we are able to measure gaseous targets fast reaction code γdex for correction Outlook additional measurement on 130 Xe analysis of HIγS Data additional work with γdex in (n,γ) experiments at GEELINA R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

76 Thank you for your attention. R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22

77 one last slide Announcement The 15 th International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics (CGS15) will take place in Dresden, Germany, from August 25 to August 29, We are looking forward to seeing you there. R.Massarczyk (HZDR) dipole strength in 124,128,134 Xe / 22