Neutrino-nucleus interaction and its role in supernova dynamics and nucleosynthesis Karlheinz Langanke GSI Helmholtzzentrum Darmstadt Technische Universität.
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Neutrino-nucleus interaction and its role in supernova dynamics and nucleosynthesis
Karlheinz LangankeGSI Helmholtzzentrum DarmstadtTechnische Universität DarmstadtFrankfurt Institute for Advanced Studies
Erice, September 21, 2014
Neutrino spectra
collapse phase: after bounce
electron captures on nuclei
(Juodagalvis, Martinez-Pinedo.. )
cooling of neutron star by nu pairs
energy hierarchy due to opacity
(Raffelt, Janka, Liebendoerfer,...)
Experiment vs shell modelCole, Zegers et al., PRC 86 (2012) 015809
Iron-nickel mass range under control
With increasing density, less sensitivity to details of GT distribution-> models less sophisticated than shell model suffice, e.g. QRPA
Describing neutrino-nucleus reactions
Neutrino energies (and momentum transfer) is low enough that allowed transitions dominate. However, forbidden contributions become important at higher neutrino energies.
Hybrid model (Martinez-Pinedo, Kolbe):
allowed transitions: shell model
forbidden transitions: RPA
Validation: charged-current reaction
shell model vs (p,n) data
Martinez-PinedoRapaport et al.
hybrid model vs QRPA
differences at small neutrino energies(sensitivity to GT details)
Paar, Marketin, Vretenar
Validation: charged-current reactions
anti-electron neutrino cross sections more sensitive to nuclear structure effects
(like in electron capture)
Zegers, Brown et al.
Neutrino-nucleus reactions in supernova simulations
charged-current reactions (nu+A, nubar+A) are inverse of electron and positron captures and areconsidered via detailed balance
neutral-current reactions (inelastic scattering):not considered until recently
Inelastic neutrino-nucleus scattering at finite temperature
• Approach 1 (based on hybrid model):
T=0 cross section +
Gamow-Teller from (a few) excited states +
contributions from inverted GT transitions
(Juodagalvis, Martinez-Pinedo, Sampaio,...)
* Approach 2:
Thermal Quasiparticle RPA
consistent QRPA at finite temperature
(Dzhioev, Wambach, Ponomarev)
Approach 1: Hybrid model
validation from high-precisionelectron scattering datascattering on excited statesdominates at low energies(Martinez-Pinedo, Richter, vonNeumann-Cosel)
Approach 2: Tthermal QRPA
Dzhioev, Wambach, Ponomarev)
GT dominates, finite T effects onlyimportant at low neutrino energies
Neutrino spectra from inelastic neutrino-nucleus scattering at finite T
Nuclear deexcitation only important at low neutrino neutrino energies
(from Juodagalvis, Martinez-Pinedo, Sampaio..)
Effect of inelastic neutrino-nucleus scattering on in supernova simulations
neutrino scattering on nuclei acts asadditional obstacle – in particularfor high-energy neutrinossupernova neutrino spectrum shiftsto lower energiessmaller event rates for earthboundsupernova neutrino detectors
(Janka, Hix, Mueller, Martinez-Pinedo,Juogadalvis, Sampaio)
little effect on collapse dynamics, thermalization dominated by nu+electron
no preheating of shock material
BUT:
Consequences for supernova detectors
Change in supernova neutrino spectra reduces neutrino detection rates
Neutrino-nucleus reactions and its role in nucleosynthesis
neutrino-driven wind on top ofproto-neutron star:neutrino absorption on nucleonssets proton/neutron ratio Ye
if Ye > 0.5: vp processif Ye < 0.5: r-process
modern simulations predict onlyconditions for weak r-process(up to A~130)
neutrino process in outer burningshells
Possible consequences of high neutrino flux in shock-front
Neutrino capture on protons1H(+,e+)n, neutron production which influence the reaction path by neutron capture.
•Anti-neutrino capture on protons produce neutrons at late times•(n,p) reactions simulate beta decays and overcome waiting points
p-process in hydrogen rich, high neutron flux environments
On-site neutron production through neutrino induced interaction: 1H(+,e+)n!
By-passing waiting point nuclei 64Ge, 68Se by n-capture reactions.
Producing 138La
138La is being produced by (v,e) reaction on 138Ba, which has beenpreviously produced by s-process. The respective GT cross sectionshave been measured at RCNP in Osaka.
HegerWoosleyKolbeMartinez-PinedoHaxton
Neutrino nucleosynthesis
Neutrino nucleosynthesis is sensitive to those neutrino typesnot observed from SN1987a
(Heger, Woosley, Kolbe, Martinez-Pinedo, Haxton)
Detecting supernova neutrinos
carbon (scintillator): BOREXINO, KamLAND,...large Q values, transition to T=1 states fixed by experiment
oxygen: SuperKamiokandelarge Q values, Gamow-Teller strongly suppressed
argon (liquid scintillator): ICARUShybrid model calculation for nu_e, nuclear challenge for anti nu_e
lead: HALOlarge cross sections as (N-Z) large, fixed by sum rules and positionsof giant resonances, neutron signal difficult to predict as GT strengthresides around (2n) threshold
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