1 / 33

Collaborators: University of Ioannina , Greece:

5 th Annual Meeting ENTApP WP1 ‘‘Neutrinos in Particle, in Nuclear and in Astrophysics’’ Trento, Italy, November 17 th – 20 st , 2008.

karah
Download Presentation

Collaborators: University of Ioannina , Greece:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 5th Annual Meeting ENTApP WP1 ‘‘Neutrinos in Particle, in Nuclear and in Astrophysics’’ Trento, Italy, November 17th – 20st, 2008 ‘‘Charged-current neutrino-nucleus reactionsand their impact to astrophysics’’T.S. KosmasDivision of Theoretical Physics, University of Ioannina, GR-45110, Greece Collaborators: University of Ioannina, Greece: V. Tsikoudi, J. Sinatkas, P. Divari, Th. Liolios, V. Stavrou K. Balasi, V. Tsakstara, G. Karathanou, P. Giannaka, J. Kardaras Univ. of Jyvaskyla, Finland : Group of J. Suhonen T.Univ. of Darmstadt, Germany: Group of J. Wambach Univ. of Tuebingen, Germany :Group of A. Faessler Univ. of Valencia, Spain : Group of J.W.F. Valle RCNP, Univ. of Osaka, Japan : H. Ejiri (MOON-experiment)

  2. Motivation Reliable ν-Nucleus reaction cross sections (for NC and CC reactions) are needed for various nuclear isotopes • In the modeling of stellar evolution [Janka et al, PR 442(07)38] 16O, 32Si, 56Fe, etc. • In terrestrial experiments [H.Ejiri, Phys.Rep. 338 (00)265] • For solar neutrino-detection experiments(Eν < 20 MeV) 115In, 127I, etc. • Supernova neutrino-detection experiments (Eν < 60 -70MeV) • Neutrinoless double-beta-decay experiments (0νββ-decay) (i) MOON-Experiment: 92,94,95,96,97,98,100Mo (ii)Cobra-Experiment: 116Cd

  3. Outline of the talk • Introduction Nuclear Structure Calculations for One-body semi-leptonic nuclear processes (standard & exotic) non-accelerator physics • ν-NucleusCross Section Formalism Walecka-Donnelly-Haxton (multipole expansion) method • Results of realistic calculations for ν-N reactions CC 1. Use of Quasi-Particle RPA and QPM for Nuclear States 2. Differential, integrated and total ν-N cross sections 3. Nuclear response to Astrophysical ν-spectra (solar, SN) for :16O,56Fe, 92,94,96,98,100Mo,40Ar, 116Cd • Summary - Conclusions- Outlook

  4. 1-body semi-leptonic electroweak processes in nuclei A unified description of semi-leptonic 1-body processes in nuclei has been provided long ago (Walecka-Donnely-Haxton method) Standard (observed) 1-body semi-leptonic electroweak processes in nuclei

  5. Exotic 1-body Semi-leptonic Nuclear Processes 1). LF violating process: Conversion of a bound μ-b to e-in nuclei μ-b+ (Α, Ζ) e- + (Α,Ζ)* • a) Coherent (g.s => g.s.) and Incoherent i> => f> transitions occur • b) Both Fermi and Gammow-Teller type transitions exist • Dominance of Coherent channel, ‘measured’ by experiments : • Best upper limits: (i) PSI 197Au Rμe < 10-13 • (ii) MECO (Brookhaven) 27AlRμe < 2x 10-17(Cancelled) • (iii) PRIME (at PRISM) 48TiRμe < 10-18 • Shaaf, J.Phys.G (2003); Kuno, AIP Conf.Proc. (2000); Molzon, Spr. Trac. Mod. Phys., (2000) • Scwienger,Kosmas,Faessler,PLB (1998);Kosmas,NPA (2001);Deppisch,Kosmas,Valle,NPB (2006)

  6. 2). Scattering of Cold Dark Matter particles off nuclei (Direct detection) LSP-nucleus scattering The Content of the universe: Dark Energy ≈ 74%, Atoms ≈ 4% Cold Dark Matter ≈ 22%( Χ + (Α, Ζ) χ’ + (Α,Ζ)* • Coherent - Incoherent event rates : Vector & Axial-Vector Currents • Dominance of Axial-Vector contributions • (Odd-A nuclear targets : 73Ge, 127I, 115In, 129,131Xe) • C) Theoretical study: SM, MQPM, etc. 73Ge, 127I, 115In, 81Ga • Kosmas & Vergados, PRD 55(97)1752, Korteleinen, TSK, Suhonen, Toivanen, PLB 632(2006)226; Holmlund et. al., PLB 584 (2004) 31; Phys.At.Nuc. 67 (2004)1198.

  7. νμ CC Event νeCC Event NC Event Neutrino-nucleus interactions Neutral current (NC) processes (mediated by Z-bozon) Charged-currents processes (mediated by Z-bozon)

  8. Reactor-Neutrino energy-Spectra

  9. Neutrino Supernova energy-spectra The Energy of neutrinos emitted in a core collapse SN can be described by Fermi- Dirac type distribution

  10. Supernova-neutrino spectra α = Chemical Potential T = Neutrino Temperature

  11. Parametrization of SN-v spectra Recent results showed that the SN neutrino energy spectra can be accurately parametrized with a power- law(PL-distibution) <εν >isthe averaged neutrino energy αistheamount of spectral pinching The parameters n and αallow to adjust the width w

  12. Semi-leptonic Effective Interaction Hamiltonian The effective interaction Hamiltonian reads Matrix Elements between initial and final Nuclear states are needed for partial transition rates : (leptonic current ME) (momentum transfer)

  13. Nucleon-level hadronic current for neutrino processes The effective nucleon level Hamiltonian takes the form For charged-current ν-nucleus processes For neutral-current ν-nucleus processes The form factors, for neutral-current processes, are given by

  14. One-nucleon matrix elements of hadronic current 1). Neglecting second class currents : Polar-Vector current: Axial-Vector current: 2). Assuming CVC theory 3). Use dipole-type q-dependent form factors: Fi, i=1, 2, A, as 4. Static parameters, q=0, for nucleon form factors (i) Polar-Vector (i) Axial-Vector

  15. Neutral-Current ν–Nucleus Cross sections In Walecka-Donnely-Haxton method [PRC 6 (1972)719, NPA 201(1973)81] where The Coulomb-Longitudinal (1st sum), and Transverse (2nd sum) are: ==============================================================================================================

  16. Nuclear Matrix Elements - The Nuclear Model The initial and final states, |Ji>, |Jf>, in the ME <Jf ||T(qr)||Ji>2are determined by using QRPA j1, j2run over all active single-particle levels(coupled to J) D(j1, j2; J)one-body transition densitiesdetermined by the model • 1). Interactions: • Woods-Saxon + Coulomb corrections (as Field) • Bonn-C Potential (as two-body interaction) • 2). Parameters: • In the BCS level: the pairing parameters gnpair , gppair • In the QRPA level: the strength parameters gpp,gph • 3). Testing the reliability of the Method: • Low-lying nuclear excitations (up to about 5 MeV) • magnetic moments(separate spin, orbital contributions)

  17. Low-lying Nuclear Spectra (up to about 5 MeV) 98Mo experimental theoretical

  18. State-by-state calculations of multipole contributions to the differential cross section dσ/dΩ 56Fe

  19. State-by-state calculations of dσ/dΩ 98Mo

  20. Angular dependence of the differential cross-section 56Fe Chasioti,TSK,Divari,,Prog.Part.Nucl.Phys.,59(07)481

  21. Angular dependence of the differential cross-section 98Mo

  22. Dominance of Axial-Vector contributions in σ 56Fe

  23. Dominance of Axial-Vector contributions in σ 98Mo

  24. Total Cross section: Coherent & Incoherent contributions 56Fe g.s.g.s. g.s.f_exc

  25. Coherent and Incoherent 98Mo

  26. Results for C-C ν-nucleus reactions • Total cross sections for the CC56Fe(νe,e-)56Co • B) Comparison with CRPA-results byKolbe-Langanke, PRC 55(97)1752

  27. Nuclear response to SN-ν The SN-νenergies are between few MeV < Eν< few tenths of MeV) This is the region of nuclear excitations where G-T and F Giant Resonances, and isospin and spin-isospin Dipole Resonances play crucial role. For NC processes, importantGR associated with nuclear responses are : Isospin and isospin-spin resonances with Jπ = 1+ , 1-, etc Mo-isotopes as SN-νdetectors H. Ejiri, Phys. Rep. 338 (2000)265; H. Ejiri et a., Phys.Lett. B 530 (02)265; H. Ejiri, Proc. MEDEX-07, Prague, June 11-14, 2007. 100Mo is appropriate for ββ-decay and SN-ν (MOON) 98Mo is appropriate for SN-ν (2-3 MeV < Eν < 40-60 MeV)

  28. Nuclear response to SN-νfor various targets Assuming Fermi-Dirac distribution for the SN-νspectra f(Eν) isnormalized to unity as Using our results, we calculated for various ν–nucleus reaction channels the flux-averaged cross sections F2(α) = Normalisation factor α = degeneracy parameter Τ = Neutrino Temperature Eν = neutrino energy

  29. Flux averaged Cross Sections for SN-ν α = 0, 3 2.5 < Τ < 8 (in MeV) A= <σ>_A V= <σ>_V 56Fe

  30. Folded differential cross sections of 98Mo

  31. W.C.Haxton, Phys. Rev,VOL 36,1987

  32. Concluding Remarks • UsingQRPA, we performed state-by-state calculations for ν–nucleus NC and CC processes (J-projected states) for currently interesting nuclei like: 16O , 40Ar,56Fe, Mo-isotopes (MOON exp.), 116Cd (COBRA exp.) •The QRPA method is tested on the reproducibility of : a) the low-lying nuclear spectrum (up to about 5 MeV) b)the nuclear magnetic moments • From the evaluated Differential and Total cross sections we studied the response to solar and SN-ν spectra (even-even Mo-isotopes, MOON experiment, etc.) in the temperature range 2.5 < T < 8 MeV. The power-law distribution is currently used. • Our results for the CC reaction 56Fe(νe,e-)56Cr and 40Ar(νe,e-)40Kr are in good agreement with recent Continuum RPA calculations. Acknowledgments: I wish to acknowledge financial support from ΠΕΝΕΔ-03/807 (Hellenic G.S.R.T.) projects to participate and speak in the present meeting.

More Related