Detection of neutrinos from supernovae in nearby galaxies

While existing detectors would see a burst of many neutrinos from a Milky Way supernova, the supernova rate is only a few per century. As an alternative, we propose the detection of approximately 1 neutrino per supernova from galaxies within 10 Mpc, in which there were at least 9 core-collapse supernovae since 2002. With a future 1 Mton scale detector, this could be a faster method for measuring the supernova neutrino spectrum, which is essential for calibrating numerical models and predicting the redshifted diffuse spectrum from distant supernovae. It would also allow a > or approximately 10(4) times more precise trigger time than optical data alone for high-energy neutrinos and gravitational waves.     

Resonant oscillations of massless neutrinos in matter

Oscillations of neutrinos propagating in matter do not require that neutrinos are massive, at a fundamental level. Even if neutrinos are massless as a consequence of an exact symmetry - such as total lepton number - they can oscillate into one another if the weak interaction has a small non-universal component, whose existence would signal physics beyond the standard model. The experimental constraints and theoretical plausibility of the mechanism are discussed. Coherent neutrino and antineutrino scattering could substantially affect the late thermal phase neutrino signal from a supernova explosion.     

Oscillation of Dirac and Majorana neutrinos from muon decay in the case of a general interaction

We analyse the possibility of distinguishing Dirac and Majorana neutrinos in future neutrino factory experiments in which neutrinos are produced in muon decay when, in addition to a vector type as in the SM, there are also scalar interactions. We check this possibility in an experiment with a near detector, where the observed neutrinos do not oscillate, and in a far detector, after the neutrino oscillations. Neglecting higher-order corrections, even neutrino observation in the near detector does not give a chance to differentiate their character. However, this possibility appears in the leading-order after the neutrino oscillations observed in far detector.     

TeV neutrinos and GeV photons from shock breakout in supernovae

We show that as a Type II supernova shock breaks out of its progenitor star, it becomes collisionless and may accelerate protons to energies >10 TeV. Inelastic nuclear collisions of these protons produce an approximately 1 h long flash of TeV neutrinos and 10 GeV photons, about 10 h after the thermal (10 MeV) neutrino burst from the cooling neutron star. A Galactic supernova in a red supergiant star would produce a photon and neutrino flux of approximately 10(-4) erg cm(-2) s(-1). A km(2) neutrino detector will detect approximately 100 muons, thus allowing to constrain both supernova models and neutrino properties.     

Prospects of the search for neutrino bursts from supernovae with Baksan large volume scintillation detector

Observing a high-statistics neutrino signal from the supernova explosions in the Galaxy is a major goal of low-energy neutrino astronomy. The prospects for detecting all flavors of neutrinos and antineutrinos from the core-collapse supernova (ccSN) in operating and forthcoming large liquid scintillation detectors (LLSD) are widely discussed now. One of proposed LLSD is Baksan Large Volume Scintillation Detector (BLVSD). This detector will be installed at the Baksan Neutrino Observatory (BNO) of the Institute for Nuclear Research, Russian Academy of Sciences, at a depth of 4800 m.w.e. Low-energy neutrino astronomy is one of the main lines of research of the BLVSD.     

利用大亚湾中微子实验装置探测超新星中微子

在利用大亚湾中微子实验装置研究超新星中微子探测过程中, 需要考虑到中微子传播过程中受到各种效应的影响, 包括超新星震荡效应、中微子集体效应、 Mikheyev Smirnov Wolfenstein (MSW)效应和地球物质效应等。 由于超新星中微子受到这些效应, 不同味道的中微子之间振荡会发生变化, 因而利用探测某些超新星中微子事例数之比, 就有可能确定中微子的质量层次,得到中微子混合角θ13和中微子绝对质量的信息。 While detecting supernova neutrinos in the Daya Bay neutrino laboratory, several supernova neutrino effects need to be considered, including the supernova shock effects, the neutrino collective effects, the Mikheyev Smirnov Wolfenstein (MSW) effects, and the Earth matter effects. The phenomena of neutrino oscillation is affected by the above effects. Using some ratios of the event numbers of different supernova neutrinos, we propose some possible methods to identify the mass hierarchy and acquire information about the neutrino mixing angle θ13 and neutrino masses.     

Detection of supernova neutrinos at spallation neutron sources

After considering supernova shock effects, Mikheyev-Smirnov-Wolfenstein effects, neutrino collective effects, and Earth matter effects, the detection of supernova neutrinos at the China Spallation Neutron Source is studied and the expected numbers of different flavor supernova neutrinos observed through various reaction channels are calculated with the neutrino energy spectra described by the Fermi-Dirac distribution and the "beta fit"distribution respectively. Furthermore, the numerical calculation method of supernova neutrino detection on Earth is applied to some other spallation neutron sources, and the total expected numbers of supernova neutrinos observed through different reactions channels are given.     

Effects of matter oscillations on supernova neutrino flux

If neutrinos have mass it is likely that, as a result of the effect of matter, neutrino flavor eigenstates are converted to mass eigenstates as they emerge from a supernova. In the case of large neutrino mixing angles there can be a significant increase in the mean energy and detected flux of neutrinos from a supernova.     

Contributed report: Flavor anarchy for Majorana neutrinos

We argue that neutrino flavor parameters may exhibit features that are very different from those of quarks and charged leptons. Specifically, within the Proggatt-Nielsen (FN) framework, charged fermion parameters depend on the ratio between two scales, while for neutrinos a third scale — that of lepton number breaking — is involved. Consequently, the selection rules for neutrinos may be different. In particular, if the scale of lepton number breaking is similar to the scale of horizontal symmetry breaking, neutrinos may become flavor-blind even if they carry different horizontal charges. This provides an attractive mechanism for neutrino flavor anarchy.     

On the possibility to determine neutrino mass hierarchy via supernova neutrinos with short-time characteristics

In this paper, we investigate whether it is possible to determine the neutrino mass hierarchy via a high-statistics and real-time observation of supernova neutrinos with short-time characteristics. The essential idea is to utilize distinct times-of-flight for different neutrino mass eigenstates from a core-collapse supernova to the Earth, which may significantly change the time distribution of neutrino events in the future huge water-Cherenkov and liquid-scintillator detectors. For illustration, we consider two different scenarios. The first case is the neutronization burst of emitted in the first tens of milliseconds of a core-collapse supernova, while the second case is the black hole formation during the accretion phase for which neutrino signals are expected to be abruptly terminated. In the latter scenario, it turns out only when the supernova is at a distance of a few Mpc and the fiducial mass of the detector is at the level of gigaton, might we be able to discriminate between normal and inverted neutrino mass hierarchies. In the former scenario, the probability for such a discrimination is even less due to a poor statistics.     

Neutrino-nucleus reaction in supernovae

Neutrino reactions play an important role at various stages of core-collapse supernova. During infall, neutrinos are produced by electron capture mainly on nuclei and contribute significantly to the cooling of the collapsing core. After core bounce the nascent neutron star cools by neutrino emission. It is a major goal to observe such neutrinos from a future supernova by earthbound detectors and to establish their spectra. Recently it has been shown that the spectrum of electron neutrinos from the early neutrino burst is significantly altered if inelastic neutrino-nucleus scattering is considered in supernova simulations. Finally spallation reactions induced by neutrinos when passing through the outer burning shells can produce certain nuclides in what is called neutrino nucleosynthesis.     

The rich neutrino programme of the SNO+ experiment

The SNO+ experiment is a multi-faceted neutrino experiment re-using the existing infrastructure and detector hardware of the Sudbury Neutrino Observatory located in Vale Inco’s Creighton mine, Sudbury (ON), Canada. The main aim of this, now fully-funded, experiment is the search for neutrinoless double-beta decay, however, it has access to other, very interesting, measurements involving neutrinos, such as lower energy solar neutrinos, geo- and reactor-antineutrinos and supernova neutrinos.     

Twisted flavors and tribimaximal neutrino mixing

A new framework for handling flavor symmetry breaking in the neutrino sector is discussed where the source of symmetry breaking is traced to the global property of right-handed neutrinos in extra-dimensional space. Light neutrino phenomenology has rich and robust predictions such as the tribimaximal form of generation mixing, controlled mass spectrum, and no need of flavor mixing couplings in the theory.     

Physics prospects of the Jinping neutrino experiment

The China Jinping Underground Laboratory(CJPL), which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detectors and a total fiducial mass of 2000 tons for solar neutrino physics(equivalently, 3000 tons for geo-neutrino and supernova neutrino physics), the Jinping neutrino experiment will have the potential to identify the neutrinos from the CNO fusion cycles of the Sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the Th/U ratio. These goals can be fulfilled with mature existing techniques. Efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the Jinping discovery potential in the study of solar neutrinos,geo-neutrinos, supernova neutrinos, and dark matter.     

Supernova-neutrino studies with Mo

We show that supernova neutrinos can be studied by observing their charged-current interactions with ¹⁰⁰Mo, which has strong spin–isospin giant resonances. Information about both the effective temperature of the electron–neutrino sphere and the oscillation into electron neutrinos of other flavors can be extracted from the electron (inverse β) spectrum. We use measured hadronic charge-exchange spectra and the Quasiparticle Random Phase Approximation to calculate the charged-current response of ¹⁰⁰Mo to electron neutrinos from supernovae, with and without the assumption of oscillations. A scaled up version of the MOON detector for ββ and solar-neutrino studies could potentially be useful for spectroscopic studies of supernova neutrinos as well.     

利用超新星爆发测量电子中微子静止质量

综述了中微子静止质量ｍυｅ的测量方法与结果,侧重介绍了超新星ＳＮ８７Ａ中微子测量的结果,即得到具有能量为８ＭｅＶ和３６ＭｅＶ的中微子飞行时间差,对于Ｋａｍｉｏｋａｎｄｅ,ＩＭＢ,Ｂａｋｓｏｎ分别为１．９ｓ,６ｓ和９ｓ,由此给出电子中微子静止质量上限为１４ｅＶ「９５％置信水平（Ｃ．Ｌ．）」,并且描述了计划建造的新型太阳中微子能谱仪,该谱仪在观测太阳中微子能谱的同时,将兼测超新星中微子,提供了在ｍυｅ〈１ｅＶ范围内测量中微子静止质量的可能性。     

Neutrino mass and mixing implied by underground deficit of low energy muon-neutrino events

Recent observations of a deficit of cosmic ray muon-neutrino interactions in underground detectors suggest that the muon neutrinos may have oscillated to another state. We examine possible neutrino mass and mixing patterns, and their implications for vacuum and matter effects on solar neutrinos, on neutrinos passing through the earth, and on terrastrial neutrino beams. By invoking the see-saw mechanism of neutrino mass generation, we draw inferences on closure of the universe with neutrino masses, on the number of generations, on t-quark and fourth generation masses, and on the Peccei-Quinn symmetry breaking scale. Testable predictions are suggested.     

Neutrino masses in astrophysics and cosmology

Cosmology yields the most restrictive limits on neutrino masses and conversely, massive neutrinos would contribute to the cosmic dark-matter density and would play an important role for the formation of structure in the universe. Neutrino oscillations may well solve the solar neutrino problem and can have a significant impact on supernova physics. The neutrino signal from a future galactic supernova could provide evidence for cosmologically interesting neutrino masses or set interesting limits.     

Working group report: Neutrino and astroparticle physics

This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed.     

The response of Mo to supernova neutrinos

Knowledge about nuclear responses to neutrinos is essential for both astrophysical applications and studies of neutrino properties. We perform in this paper calculations of the cross sections for neutral-current neutrino scattering off the odd A=95,97 Mo isotopes for energies appropriate for the detection of supernova neutrinos. Both the incoherent and coherent contributions to the cross sections are evaluated. The prominently contributing nuclear final states are identified and analysed. We employ the microscopic quasiparticle-phonon model (MQPM) to construct the wave functions of the initial and final nuclear states. The response of the aforementioned nuclei to supernova neutrinos are computed by folding the obtained cross sections with a two-parameter Fermi-Dirac distribution. The sensitivity of the calculated nuclear responses to the adopted supernova model is also discussed.