700 research outputs found
Bruno Pontecorvo and solar neutrinos
Bruno Pontecorvo had a very substantial impact on measurements of solar neutrinos, proposing a technique in 1948 that led to measurements by Davis and proposing that neutrinos could oscillate, a process that has been found to influence observed fluxes substantially. The past history and future prospects of solar neutrino measurements are reviewed, including a discussion of the contributions by
Pontecorvo
Decay of the first isobaric analog state in Ge69
The alpha-decay branching ratio for the lowest isobaric analog state in Ge69 has been measured to be less than 1.0Ă—10-2. Transitions to this level contribute significantly to the cross section for the capture of high-energy neutrinos by Ga69. Since the analog state decays almost exclusively by gamma-ray emission, induced Ge69 radioactivity may be used for the detection of high-energy neutrinos in large-scale gallium neutrino detectors
Are solar neutrino oscillations robust?
The robustness of the large mixing angle (LMA) oscillation (OSC)
interpretation of the solar neutrino data is considered in a more general
framework where non-standard neutrino interactions (NSI) are present. Such
interactions may be regarded as a generic feature of models of neutrino mass.
The 766.3 ton-yr data sample of the KamLAND collaboration are included in the
analysis, paying attention to the background from the reaction ^13C(\alpha,n)
^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration
are included. In addition to the solution which holds in the absence of NSI
(LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70,
essentially degenerate with the former, and another light-side solution (LMA-0)
allowed only at 97% CL. More precise KamLAND reactor measurements will not
resolve the ambiguity in the determination of the solar neutrino mixing angle
theta_Sol, as they are expected to constrain mainly Delta m^2. We comment on
the complementary role of atmospheric, laboratory (e.g. CHARM) and future solar
neutrino experiments in lifting the degeneracy between the LMA-I and LMA-D
solutions. In particular, we show how the LMA-D solution induced by the
simplest NSI between neutrinos and down-type-quarks-only is in conflict with
the combination of current atmospheric data and data of the CHARM experiment.
We also mention that establishing the issue of robustness of the oscillation
picture in the most general case will require further experiments, such as
those involving low energy solar neutrinos.Comment: 13 pages, 6 figures; Final version to appear in JHE
Gamma decays of isobaric analog states relevant to neutrino detection
Measurements have been made of the gamma ray branching ratios for the decay of the lowest isobaric analog states of Ge71 and Kr81. These states could be populated by high-energy neutrinos in gallium- and bromine-based detectors. Although these states are unbound to particle decay, all channels with significant penetrabilities are isospin forbidden, so that gamma decay is a possibility. Our results indicate that these states decay mainly by neutron emission and therefore contribute very little to detection sensitivities for Ga71 and Br81
Probing Non-Standard Neutrino Interactions with Neutrino Factories
We discuss the sensitivity reach of a neutrino factory measurement to
non-standard neutrino interactions (NSI), which may exist as a low-energy
manifestation of physics beyond the Standard Model. We use the muon appearance
mode \nu_e --> \nu_\mu and consider two detectors, one at 3000 km and the other
at 7000 km.
Assuming the effects of NSI at the production and the detection are
negligible, we discuss the sensitivities to NSI and the simultaneous
determination of \theta_{13} and \delta by examining the effects in the
neutrino propagation of various systems in which two NSI parameters
\epsilon_{\alpha \beta} are switched on. The sensitivities to off-diagonal
\epsilon's are found to be excellent up to small values of \theta_{13}.
We demonstrate that the two-detector setting is powerful enough to resolve
the \theta_{13}-NSI confusion problem. We believe that the results obtained in
this paper open the door to the possibility of using neutrino factory as a
discovery machine for NSI while keeping its primary function of performing
precision measurements of the lepton mixing parameters.Comment: 47 pages, 22 figures. Color version of Figs. 18, 19 and 22 can be
found in the article published in JHE
I127(3He,t)127Xe reaction with relevance to neutrino detection
The I127(3He,t)127Xe reaction has been measured for low-lying states in Xe127 which may play a role in neutrino capture by I127. High-spin states at excitation energies Ex=309 and 646 keV are found to be much more strongly populated than the JĎ€=((3/2-(7/2)+ states relevant to neutrino capture by I127
PACIFIC-R: First real-world study of patients with unresectable, stage III NSCLC treated with durvalumab after chemoradiotherapy
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The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources
The production and analysis of distributed sources of 24Na and 222Rn in the
Sudbury Neutrino Observatory (SNO) are described. These unique sources provided
accurate calibrations of the response to neutrons, produced through
photodisintegration of the deuterons in the heavy water target, and to low
energy betas and gammas. The application of these sources in determining the
neutron detection efficiency and response of the 3He proportional counter
array, and the characteristics of background Cherenkov light from trace amounts
of natural radioactivity is described.Comment: 24 pages, 13 figure
Constrained Supersymmetric Flipped SU(5) GUT Phenomenology
We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT
model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are
constrained to be universal at some input scale, , above the GUT scale,
. We analyze the parameter space of CFSU(5) assuming that the lightest
supersymmetric particle (LSP) provides the cosmological cold dark matter,
paying careful attention to the matching of parameters at the GUT scale. We
first display some specific examples of the evolutions of the SSB parameters
that exhibit some generic features. Specifically, we note that the relationship
between the masses of the lightest neutralino and the lighter stau is sensitive
to , as is the relationship between the neutralino mass and the masses
of the heavier Higgs bosons. For these reasons, prominent features in generic
planes such as coannihilation strips and rapid-annihilation
funnels are also sensitive to , as we illustrate for several cases with
tan(beta)=10 and 55. However, these features do not necessarily disappear at
large , unlike the case in the minimal conventional SU(5) GUT. Our
results are relatively insensitive to neutrino masses.Comment: 23 pages, 8 figures; (v2) added explanations and corrected typos,
version to appear in EPJ
Evidence for Neutrino Oscillations I: Solar and Reactor Neutrinos
This paper discusses evidence for neutrino oscillations obtained from
measurements with solar neutrinos and reactor neutrinos.Comment: Invited Paper for the International Confenence on Nuclear Physics
INPC2004, Goteborg, Sweden, June 27-July 2, 2004, 14 pages, 7 fig
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