Proc. Neutrino Astrophysics - MPP Theory Group

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162 Figure 1: Calorimetric β − spectrum of 187 Re plus a multi-lines X-ray fluorescence spectrum due to an external calibration source (see text). The isotope 163 Ho decays by electron capture (EC) with the subsequent emission of an electron neutrino. The EC decay is followed by the emission of Auger electrons and X-rays due to the electronic cloud excitation of the daughter atom. For each occupied energy level from which the electron capture is energetically allowed, there is a line in the calorimetric energy spectrum. The effect of a finite neutrino mass should manifest itself as a variation of the ratios of the relative EC probabilities. Measuring N lines of the calorimetric spectrum, it is possible to set N − 1 simultaneous constraints on the neutrino mass and the end-point value Q from the relative ratios of the integral value of each spectral line. Enclosing the 163 Ho source in a suitable absorber of a micro-calorimeter it has been possible to measure [2, 3] four lines of the calorimetric spectrum (see Fig. 2.a), but the statistics of this measurement is not high enough to set a significant limit on the neutrino mass. Considering a zero value of the neutrino mass, the end-point energy has been calculated by a fit procedure and it is turned out to be Eend−point = (2800 ±50)eV. Taking into account this end-point value it should be possible to set a kinematical limit to the neutrino mass by means of this calorimetric method lower than 170 eV/c 2 in 50 days of data taking. Running more than one detector at the same time it will be possible to further improve the achievable mass limit. Although the limit on neutrino mass could not be competitive with the achievable limit on electron anti-neutrino mass, we believe it is meaningful to set independent limits on the masses of the electron neutrino and anti-neutrino. Another important application of this kind of detector is the measurement of the solar neutrino flux in radiochemical solar neutrino experiments. In these experiments the integrated value of the solar neutrino flux is measured counting the extracted isotope which is
produced in the target by neutrino capture. The use of a detector characterized by a low energy threshold and a good energy resolution can improved the results obtained so far with proportional counters. A prototype of a new radiochemical lithium detector is now under development at the Institute for Nuclear Research at Moscow [4]. The interest in this new experiment is related to the fact that it could provide new data about the solar neutrino flux at intermediate energy. Even taking into account the hypothesis of a strong attenuation of the neutrino flux of intermediate energies, this experiment can measure the flux with an accuracy of 12% in only one year of measurement time. The full scale experiment will have a target mass of only 10 tons, which is the absolutely minimal mass among all detectors of solar neutrinos. This experimental scale will be possible only if 7 Be can be detected with an efficiency close to 100%. The counting of the 7 Be isotope can be performed measuring the electron capture decay of this isotope to 7 Li, but in the 90% of the cases 7 Be decays into 7 Li ground state with the subsequent emission of a very low detectable energy, of the order of 100 eV. The only possible way to solve this problem appears to be the use of cryogenic detectors for 7 Be counting. The detection of the 7 Be EC decay by means of cryogenic detector with an efficiency close to 100% has been successfully realised [2, 5]. Counts / 8 eV 500 450 400 350 300 250 200 150 100 50 0 NII NI MII MI 0 250 500 750 1000 1250 1500 1750 2000 2250 Energy (eV) Counts / 1eV 225 200 175 150 125 100 75 50 25 0 163 0 20 40 60 80 100 120 140 160 180 200 Energy (eV) Figure 2: (a) Calorimetric EC spectrum of a 163 Ho source enclosed in a superconductive tin absorber. (b) Calorimetric 7 Be EC spectrum. The source has been produced by proton irradiation of a BeO absorber. As an absorber a beryllium oxide crystal of mass 3 µg has been used, as this is one of the possible forms in which Be can be chemically extracted form the Li target. The energy resolution has been found to be 24 eV FWHM for the 112 eV 7 Be line (see Fig. 2.b), which would enable one to discriminate the background of the counting system in the lithium Solar <strong>Neutrino</strong> Experiment.
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arXiv:astro-ph/9801320v1 30 Jan 199
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Preface This was the fourth worksho
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vi S.J. Hardy Quasilinear Diffusion
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viii
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History of Neutrino Physics: Pauli
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Brief an Oskar Klein, Stockholm, vo
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Recent observations with the Hubble
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MACHO sample of ∼100,000 light cu
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Solar Neutrinos
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14 In the depth range where an abun
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16 as follows: (1) All the detector
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18 [3] J.N. Bahcall and H.A. Bethe,
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20 the opacity has a very slowly ch
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22 Status of the Radiochemical Gall
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24 known true source activity. The
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26 Solar Neutrino Observation with
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28 Events/day/kton/bin 0.3 0.25 0.2
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30 log(Δm 2 (eV 2 log(Δm )) 2 (eV
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32 Table 1: Neutrino event rates in
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34 tank and sphere high purity wate
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36 Measurements of Low Energy Nucle
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38 Figure 1: The S(E) factor of 3 H
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40 Solar Neutrinos: Where We Are an
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42 [9] B. Pontecorvo, Chalk River R
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44 Figure 2: The difference between
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Phenomenology of Supernova Explosio
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Figure 2: Theoretical classificatio
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Supernova Rates Bruno Leibundgut Eu
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galaxies, however, and the statisti
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Figure 1: The motions of pulsars re
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Convection in Newly Born Neutron St
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a b Figure 2: Panel a shows the rec
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ference). The angular variations of
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Figure 1: Neutrino luminosity and e
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[9] G.S. Bisnovatyi-Kogan, Astron.
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and the mass-to-luminosity ratio of
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Figure 1: Time variation of superno
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Figure 3: Energy spectra of the sup
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Supernova Neutrino Opacities G.G. R
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Quasilinear Diffusion of Neutrinos
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Assuming a saturated thermal distri
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Anisotropic Neutrino Propagation in
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So far the damping rate corresponds
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Cherenkov Radiation by Massless Neu
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on ω so that they are well approxi
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2 2 / meff,e m eff 1.0 0.5 0.0 elec
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Gamma-Ray Burst Observations D.H. H
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Figure 1: The cumulative distributi
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[7] Lilly, S., in Critical Dialogue
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) Phase Transitions in Neutron Star
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after the collapse began (nb., no e
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Models of Coalescing Neutron Stars
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Figure 2: Contour plots of the mass
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From our torus models we find that
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High-Energy Neutrinos
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110 in gamma-rays. However, the acc
Page 120 and 121: 112 Atmospheric Muons and Neutrinos
Page 122 and 123: 114 Today, however, charm productio
Page 124 and 125: 116 Atmospheric Neutrinos in Super-
Page 126 and 127: 118 number of events 300 200 100 (a
Page 128 and 129: 120 Acknowledgements D.K. is suppor
Page 130 and 131: 122 Key signatures for νµ nucleon
Page 132 and 133: 124 (a.u) 0.5 0.4 0.3 0.2 0.1 0 0 1
Page 134 and 135: 126 However, in order to operate th
Page 136 and 137: 128 could be gravitationally captur
Page 138 and 139: 130 Ground-Based Observation of Gam
Page 140 and 141: 132 Figure 2: Sensitivities in unit
Page 142 and 143: 134 Crab flux Figure 4: Gamma-ray f
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Page 147 and 148: Helium Absorption and Cosmic Reioni
Page 149 and 150: Non-Standard Big Bang Nucleosynthes
Page 151 and 152: ) Non-standard Neutrino Properties
Page 153 and 154: some heating of the plasma. In cont
Page 155 and 156: Big Bang Nucleosynthesis With Small
Page 157 and 158: Neutrinos and Structure Formation i
Page 159 and 160: Photon and Neutrino Backgrounds The
Page 161 and 162: The (photon) temperature at aeq is
Page 163 and 164: spectrum has therefore changed to 1
Page 165 and 166: Figure 4: Growth of structure in CD
Page 167: Future Prospects
Page 172 and 173: 164 References [1] F. Gatti: Procee
Page 174 and 175: 166 The frequency of Galactic super
Page 176 and 177: 168 Table 1: Comparison of proposed
Page 178 and 179: 170 Neutrinos in Astrophysics José
Page 180 and 181: 172 N eq 7 6.5 6 5.5 5 4.5 4 3.5 3
Page 182 and 183: 174 Figure 4: SN 1987A bounds on FC
Page 184 and 185: 176 [5] A. Joshipura and J. W. F. V
Page 186 and 187: 178 Some Neutrino Events of the 21s
Page 188 and 189: 180 2099: Relic Neutrinos And last
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Page 192 and 193: 184 Tuesday, Oct. 21: Supernova Neu
Page 194 and 195: 186 Michael Altmann Technische Univ
Page 196 and 197: 188 Paolo Gondolo Max-Planck-Instit
Page 198 and 199: 190 Patrizia Meunier Max-Planck-Ins
Page 200 and 201: 192 Torsten Soldner Technische Univ
Page 202 and 203: 194 A Experimental Particle Physics
Page 204: 196 C Astrophysics and Cosmology C1
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