"Measurement of Neutrino Oscillation with KamLAND: Evidence of Spectral Distortion"
by the KamLAND Collaboration (T. Araki et al.). Jun 2004. 5pp.
Paper | PostScript | PDF |
Proper reference for the data given below:
KamLAND collaboration, Phys.Rev.Lett.94:081801,2005
The following data file lists the prompt energies of the 258 observed neutrino candidate events.
The event energies are in MeV and show the positron energy including the annihilation energy (0 MeV kinetic energy positron appears as 1.022 MeV).
Event list | plain text |
Also monthly candidate events are listed, the monthly candidates are separated by #, the second column is year/month, and the third column is the monthly detector livetime (sec.).
Monthly event list | plain text |
The following data file provides the estimated energy spectra for
He8/Li9 events, accidental coincidences and C13(α,n) background events and are given
in arbitrary units. The first column is the mid-point of the energy bin using the positron
energy scale, the second column is the He8/Li9 background rate in that bin, the third is the accidental background rate
and the fourth is the C13(α, n) expected rate. The background spectra below 2.6 MeV are still
The total (integrated) backgrounds above 2.6 MeV have to be normalized to 4.8, 2.69 and 10.3 events, respectively, as given in the paper.
The beta-delayed neutron energy spectrum of the He8/Li9 background is not known very well and only a few of the beta-decay branches are modeled here.
Background spectrum | plain text |
The figure shows the integrated fission flux at the Kamioka site for the four main nuclei that have fission products contributing to the
anti-neutrino flux from reactors up to a distance of 1000km from the experimental site. The four
main fission nuclei are U-235, U-238, Pu-239 and Pu-241 and their fission fluxes, integrated over the total
detector livetime, are provided in the data file below. The total fission fluxes when including all
reactors up to 1000km are 1.2055e13, 1.6864e12, 6.4194e12 and 1.2143e12 fissions/cm2, respectively.
Neutrino spectra for the 4 fissile nuclei can be obtained from K.Schreckenbach et al., Phys.Lett. B 160, 325 (1985) for U235, A.A.Hahn et al., Phys.Lett.B 218, 365 (1989) for Pu239,Pu241 and P.Vogel et al., Phys.Rev.C 24, 1543 (1981) for U238.
For a more precise calculation, consideration of long-lived nuclei is necessary. See for example the calculation by V.I.Kopeikin et al., Physics of Atomic Nuclei 64, 849 (2001).
Fission flux | plain text |
The following file gives the χ2 map from the KamLAND rate+shape analysis. The minimum χ2 is 701.357 at (tan2θ, Δm2)=(0.457, 7.943×10-5).
χ2 Map | plain text |
Some numbers necessary for calculating expected number of neutrino events are given here.
|Total live time after spallation cut||515.1 days|
|Total number of target protons in the 5.5-m-radius fiducail volume||4.61e31|
|Approximated energy resolution|
|The analysis threshold to the positron energy||2.6 MeV|
|Total detection efficiency||89.8%|
|Total systematic uncertainty on number of neutrino events||6.5%|