“ The Response of Mo Isotopes to Supernova Neutrino Spectra "

1. Physics of Massive Neutrinos Annual Meeting of ENTApP N6/WP1 Milos Island, Greece, May 20-22, 2008 “ The Response of MoIsotopes to Supernova Neutrino Spectra" V.A.TSAKSTARA Division of Theoretical Physics, University of Ioannina,Greece Collaborators:T.S.Kosmas V.C.Chasioti J.D.Sinatkas P.C.Divari H. Ejiri

2. Outline Introduction Astrophysical Neutrino Sources Supernova Neutrino production Neutrino detection experiments ( MOON,SNO, SK ) Nuclear Response to various neutrino Spectra Convolution (folding) Method Response of Mo- isotopes to SN-neutrino spectra Flux averaged cross sections <σ> Convolution of differential cross sections <dσ/dΩ> Summary - Conclusions - Outlook

3. INTRODUCTION

4. Neutrino Production Sources 1)Astrophysical Neutrino Sources • Solar Neutrinos(νe) • Supernova Neutrinos(νe, νμ, ντ) • Atmospheric Neutrinos • Cosmological Neutrinos 2)Laboratory Neutrinos Sources • In Nuclear reactors ( β-decay of fission fragments) • In Accelerators (muon factory (π±,μ ±decay in flight produce)(νμ, ντ))

5. Massive Star Evolution • High mass stars produce elements up to iron by absorbing 4He • When the mass of the iron core exceeds the 1.4Msun, the core of the star starts to collapse. • The explosion is initiated by a dynamical instability inside the star. • All the other chemical elements are produced during the collapse by neutron capture mechanism. • The final stages are the birth of a neutron star or black hole depending on the mass of the star.

6. SN- v Spectra • ~99% of the gravitational binding energy is released as neutrinos • All the three- flavor (ve, vτ, vμ, )neutrinos and antineutrinos are radiated • The number of emitted neutrinos is ~ 1058 of all types • The energy per flavor is ~ 0,5x1053 erg • The energy spectrum of emitted neutrinos can approximately be described by Fermi-Dirac distribution

7. SN-v energy spectra H. Ejiri, Phys. Rep. 338 (2000)265.

8. Nuclear Response to SN-v spectra

9. Nuclear Response to SN-v Spectra The Convolution Method in SN-v Searches • In the case of differential nucleus cross-sections dσ(Εν,ω)/dωthe folding is defined by the expression : ω = Εi- Εf = εi – εf :excitation energy of the nucleus • In the case of total neucleus cross-sections σ(Εν)the folding is defined by the expression : Εthres:the energy-threshold of the nuclear detector

10. Nuclear Response to SN-v Spectra TheFermi-Diracdistribution for Supernova Neutrinospectra f(Eν)isnormalized to unity as F2(α) =Normalization factorα =chemical potential Τ = Neutrino TemperatureEν = neutrino energy

11. Energy-spectra of SN-v Nuclear Response to various SN-v Spectra

12. 98Mo as a SN-ν detector Neutral current reactions

13. Results for 98Mo SN- v Spectrafor0 ≤ Ev ≤ 100 MeV

14. Results for 98Mo

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

16. Summary – Conclusions - Outlook • We have studied the response of 98Mo isotope to SN- ν spectra for the range of Temperatures: 2.5 < T < 8 MeV and degeneracy-parameter α values: α = 0, 3 by evaluating the averaged cross-sections for neutral current reaction 98Mo(ve,v’e)98Mo* • We used the convolution method and employed Fermi-Dirac neutrino energy distribution which is appropriate for neutrinos produced by a Supernova explosion. • Currently we study the response of other Mo-isotopes toSN-ν spectra and alsocharged-current ν–nucleus processes. • We have also obtained convoluted differential cross sections dσ/dΩ for this isotope and the results have the same picture like those of Haxton. Acknowledgments:I wish to acknowledge financial support from the ΠΕΝΕΔ-03/807, Hellenic GSRT Project