Journal articles: 'High energy neutrino conversion'

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CHIU, S. H. "RESONANT FLAVOR CONVERSION OF SUPERNOVA NEUTRINOS AND NEUTRINO PARAMETERS." Modern Physics Letters A 24, no. 34 (November 10, 2009): 2741–59. http://dx.doi.org/10.1142/s0217732309031855.

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The unknown neutrino parameters may leave detectable signatures in the supernova (SN) neutrino flux. However, even the contribution from the MSW flavor transition alone could cause ambiguity in the interpretation to the neutrino signals because of the uncertain local density profile of the SN matter and the model-dependent SN neutrino spectral parameters. A specific parametrization to the unknown local density profile is proposed in this work, and the contribution from the standard MSW effect is investigated through a multi-detector analysis of the SN neutrinos. In establishing the model-independent scheme, results based on the existing spectral models are included. The limitation of the analysis is also discussed.

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IBRAHIM, UNGKU FERWANI SALWA UNGKU, NOR SOFIAH AHMAD, NORHASLIZA YUSOF, and HASAN ABU KASSIM. "NEUTRINO ENERGY LOSS AT MATTER-RADIATION DECOUPLING PHASE." Modern Physics Letters A 24, no. 11n13 (April 30, 2009): 1051–54. http://dx.doi.org/10.1142/s0217732309000577.

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Neutrinos are produced copiously in the early universe. Neutrinos and antineutrinos ceased to be in equilibrium with radiation when the weak interaction rate becomes slower than the rate expansion of the universe. The ratio of the temperature of the photon to the temperature of the neutrino at this stage is Tγ/Tν = (11/4)1/3. We investigate the neutrino energy loss due to the oscillation of the electron neutrino into a different flavor in the charged-current interaction of νe-e- based on the work of Sulaksono and Simanjuntak. The energy loss from the neutrinos ΔEν during the decoupling of the neutrinos with the rest of the matter would be a gain in the energy of the electrons and can be obtained from the integration of stopping power equation ΔEν = (dEν/dT-1)dT-1 where Eν and T are the energy of the neutrinos and the temperature respectively. When the universe expands and matter-radiation decouples, an extra energy will be transferred to the photons via the annihilation of the electron-positron pairs, e++e-→γ+γ. This consequently will increase the temperature of the photons. The net effect to the lowest order is an increase in the ratio of the photon temperature to the neutrino temperature. The magnitude of energy loss of the neutrino is ∼10-4-10-5 MeV for the probability of conversion of νe → νi (i = μ,τ) between 0 to 1.0.

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Peres, O. L. G., and A. Yu Smirnov. "Testing the solar neutrino conversion with atmospheric neutrinos." Physics Letters B 456, no. 2-4 (June 1999): 204–13. http://dx.doi.org/10.1016/s0370-2693(99)00487-6.

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Blennow, Mattias, and Alexei Yu Smirnov. "Neutrino Propagation in Matter." Advances in High Energy Physics 2013 (2013): 1–33. http://dx.doi.org/10.1155/2013/972485.

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We describe the effects of neutrino propagation in the matter of the Earth relevant to experiments with atmospheric and accelerator neutrinos and aimed at the determination of the neutrino mass hierarchy and CP violation. These include (i) the resonance enhancement of neutrino oscillations in matter with constant or nearly constant density, (ii) adiabatic conversion in matter with slowly changing density, (iii) parametric enhancement of oscillations in a multilayer medium, and (iv) oscillations in thin layers of matter. We present the results of semianalytic descriptions of flavor transitions for the cases of small density perturbations, in the limit of large densities and for small density widths. Neutrino oscillograms of the Earth and their structure after determination of the 1–3 mixing are described. A possibility to identify the neutrino mass hierarchy with the atmospheric neutrinos and multimegaton scale detectors having low energy thresholds is explored. The potential of future accelerator experiments to establish the hierarchy is outlined.

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Vergados, J. D., and Y. Giomataris. "Neutral current coherent cross-sections — Implications on detecting SN and earth neutrinos with gaseous spherical TPC’s." International Journal of Modern Physics E 26, no. 01n02 (January 2017): 1740030. http://dx.doi.org/10.1142/s0218301317400304.

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The detection of galactic supernova (SN) neutrinos represents one of the future frontiers of low energy neutrino physics and astrophysics. The neutron coherence of neutral currents (NCs) allows quite large cross-sections in the case of neutron rich targets, which can be exploited in detecting earth and sky neutrinos by measuring nuclear recoils. They are relatively cheap and easy to maintain. These (NC) cross-sections are not dependent on flavor conversions and, thus, their measurement will provide useful information about the neutrino source. In particular, they will yield information about the primary neutrino fluxes and perhaps about the spectrum after flavor conversions in neutrino sphere. They might also provide some clues about the neutrino mass hierarchy. The advantages of large gaseous low threshold and high resolution time projection counters (TPC) detectors are discussed.

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BERNARDINI, A. E., and M. M. GUZZO. "INFLUENCE OF SECOND-ORDER CORRECTIONS TO THE ENERGY-DEPENDENCE OF NEUTRINO FLAVOR CONVERSION FORMULAS." Modern Physics Letters A 23, no. 23 (July 30, 2008): 1949–60. http://dx.doi.org/10.1142/s0217732308026066.

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We discuss the intermediate wave-packet formalism for analytically quantifying the energy dependence of the two-flavor conversion formula that is usually considered for analyzing neutrino oscillations and adjusting the focusing horn, target position and/or detector location of some flavor conversion experiments. Following a sequence of analytical approximations where we consider the second-order corrections in a power series expansion of the energy, we point out a residual time-dependent phase which, in addition to some well-known wave-packet effects, can subtly modify the oscillation parameters and limits. In the present precision era of neutrino oscillation experiments where higher precision measurements are required, we quantify some small corrections in neutrino flavor conversion formulas which lead to a modified energy-dependence for νμ ↔ νe oscillations.

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Zoller, V. R. "Coherent neutrino magnetic conversion in crystals." Physics Letters B 416, no. 3-4 (January 1998): 447–51. http://dx.doi.org/10.1016/s0370-2693(97)01177-5.

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TOTANI, TOMONORI, and KATSUHIKO SATO. "EFFECTS OF NEUTRINO OSCILLATION ON THE SUPERNOVA RELIC NEUTRINO BACKGROUND." International Journal of Modern Physics D 05, no. 05 (October 1996): 519–27. http://dx.doi.org/10.1142/s0218271896000321.

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We investigate to what extent the oscillation or conversion of neutrinos enhances the expected event rate of the supernova relic neutrino background (SRN) at the SuperKamiokande detector (SK). The SRN [Formula: see text] can be almost completely exchanged with vμ-like neutrinos by the MSW oscillation under the inverse mass hierarchy with Δm2~ 10−8–105[eV2], or by the magnetic moment of Majorana neutrinos with μv≳10−12μB and Δm2~10−4–10° [eV2]. In the standard calculation of the SRN flux, the event rate of the SRN [Formula: see text] at the SK in the observable energy range of 15–40 MeV can be enhanced from 1.2 yr−1 to 2.4 yr−1 if all [Formula: see text] are exchanged with vμ-like neutrinos. The enhancement is prominent especially in the high energy range (≳ 25 MeV). In the astrophysically optimistic calculation, the event rate becomes as high as 9.4 yr−1. Because the theoretical upper bound of the SRN events without oscillation is about 5 yr−1 taking into account the various astrophysical uncertainties, we might have to resort to the neutrino oscillation if more than 5 events in a year, as well as a significantly harder spectrum, were observed in the SK.

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Delepine, David, Vannia González Macías, Shaaban Khalil, and Gabriel López Castro. "Probing Majorana neutrino CP phases and masses in neutrino–antineutrino conversion." Physics Letters B 693, no. 4 (October 2010): 438–42. http://dx.doi.org/10.1016/j.physletb.2010.08.068.

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DVORNIKOV, MAXIM. "NEUTRINO SPIN RELAXATION IN MEDIUM WITH STOCHASTIC CHARACTERISTICS." International Journal of Modern Physics A 21, no. 11 (April 30, 2006): 2403–13. http://dx.doi.org/10.1142/s0217751x06028497.

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The helicity evolution of a neutrino propagating in randomly moving and polarized matter is studied. The type of the neutrino interaction with background fermions is arbitrary. We derive the equation for the description of the averaged neutrino helicity evolution. In the particular case of a τ-neutrino interacting with ultrarelativistic electron–positron plasma, we obtain the expression for the neutrino helicity relaxation rate in the explicit form. We study the neutrino spin relaxation in the relativistic primordial plasma. Supposing that the conversion of left-handed neutrinos into right-handed ones is suppressed at the early stages of the Universe evolution, we get the upper limit on the τ-neutrino mass.

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Grasso, Dario, and Anna Rossi. "Macroscopic forces driven by resonant neutrino conversion." Physics Letters B 483, no. 1-3 (June 2000): 157–62. http://dx.doi.org/10.1016/s0370-2693(00)00594-3.

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BRAMANTE, JOSEPH. "STERILE NEUTRINO PRODUCTION THROUGH A MATTER EFFECT ENHANCEMENT AT LONG BASELINES." International Journal of Modern Physics A 28, no. 16 (June 28, 2013): 1350067. http://dx.doi.org/10.1142/s0217751x1350067x.

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If sterile neutrinos have a neutral coupling to standard model fermions, matter effect resonant transitions to sterile neutrinos and excess neutral-current events could manifest at long baseline experiments. Assuming a single sterile neutrino with a neutral coupling to fermionic matter, we re-examine bounds on sterile neutrino production at long baselines from the MINOS result Pνμ →νs < 0.22 (90% CL). We demonstrate that sterile neutrinos with a neutral vector coupling to fermionic matter could evade the MINOS limit, allowing a higher fraction of active to sterile neutrino conversion at long baselines. Scanning the parameter space of sterile neutrino matter effect fits of the LSND and MiniBooNe data, we show that in the case of a vector singlet coupling of sterile neutrinos to matter, some favored parametrizations of these fits would create neutral-current event excesses above standard model predictions at long baseline experiments (e.g. MINOS and OPERA).

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PALAZZO, ANTONIO. "PHENOMENOLOGY OF LIGHT STERILE NEUTRINOS: A BRIEF REVIEW." Modern Physics Letters A 28, no. 07 (March 6, 2013): 1330004. http://dx.doi.org/10.1142/s0217732313300048.

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An increasing number of anomalous experimental results are emerging, which cannot be described within the standard three-neutrino framework. We present a concise discussion of the most popular phenomenological interpretation of such findings, based on a hypothetical flavor conversion phenomenon of the ordinary "active" neutrinos into new light "sterile" species having mass [Formula: see text].

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SAHU, SARIRA, and VISHNU M. BANNUR. "NEUTRINO PROPAGATION IN AGN ENVIRONMENT." Modern Physics Letters A 15, no. 11n12 (April 20, 2000): 775–81. http://dx.doi.org/10.1142/s021773230000075x.

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Assuming the violation of equivalence principle (VEP) by ultra high energy AGN neutrinos we study the effect of random magnetic field fluctuation on conversion of electron neutrinos to tau anti-neutrinos.

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KUZNETSOV, A. V., and N. V. MIKHEEV. "PLASMA INDUCED NEUTRINO RADIATIVE DECAY INSTEAD OF NEUTRINO SPIN LIGHT." Modern Physics Letters A 21, no. 23 (July 30, 2006): 1769–75. http://dx.doi.org/10.1142/s0217732306021104.

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The conversion νL→νRγ* of a neutrino with a magnetic moment is considered, caused by the additional Wolfenstein energy acquired by a left-handed neutrino in medium, with an accurate account of the photon γ* dispersion in medium. It is shown that the threshold arises in the process, caused by the photon (plasmon) effective mass. This threshold leaves no room for the so-called "neutrino spin light" in the most of astrophysical situations.

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Lee, MyeongJae, and Michael MacKenzie. "Muon to Positron Conversion." Universe 8, no. 4 (April 7, 2022): 227. http://dx.doi.org/10.3390/universe8040227.

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Lepton-flavor violation (LFV) has been discovered in the neutrino sector by neutrino oscillation experiments. The minimal extension of the Standard Model (SM) to include neutrino masses allows LFV in the charged sector (CLFV) at the loop level, but at rates that are too small to be experimentally observed. Lepton-number violation (LNV) is explicitly forbidden even in the minimally extended SM, so the observation of an LNV process would be unambiguous evidence of physics beyond the SM. The search for the LNV and CLFV process μ−+N(A,Z)→e++N′(A,Z−2) (referred to as μ−→e+) complements 0νββ decay searches, and is sensitive to potential flavor effects in the neutrino mass-generation mechanism. A theoretical motivation for μ−→e+ is presented along with a review of the status of past μ−→e+ experiments and future prospects. Special attention is paid to an uncertain and potentially dominant background for these searches, namely, radiative muon capture (RMC). The RMC high energy photon spectrum is theoretically understudied and existing measurements insufficiently constrain this portion of the spectrum, leading to potentially significant impacts on current and future μ−→e+ work.

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KRASTEV, P. I., and A. YU SMIRNOV. "DENSITY PERTURBATIONS AND RESONANT CONVERSION OF NEUTRINOS." Modern Physics Letters A 06, no. 11 (April 10, 1991): 1001–9. http://dx.doi.org/10.1142/s0217732391001056.

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The influence of local density perturbations on the resonant neutrino conversion is studied. General relations are established between the features of the perturbations and the changes in the conversion probabilities. In the extreme case of very fast changes of density in a thin layer, the problem is solved analytically. We consider the possibility of appearance or shift of local ρ-perturbations in the sun to induce appreciable variations of the solar neutrino signals, in particular in the Cl-Ar experiment.

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PULIDO, JOÃO. "ON THE LEFT TO RIGHT HAND TRANSITION PROBABILITY OF NEUTRINOS IN THE SUN." Modern Physics Letters A 04, no. 23 (November 10, 1989): 2243–50. http://dx.doi.org/10.1142/s0217732389002525.

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The transition probability of left to right solar neutrinos in the sun is calculated in the adiabatic approximation as a function of the neutrino magnetic moment μν and the solar magnetic field depth and strength. We concentrate in the parameter regions compatible with the experimental upper limit μν<1.52×10−10μB and capable of providing a maximum VL→VR conversion. It is found that in the most favorable case (large innermost solar field B~104 G, small convective zone ~105 km and μν at its upper limit), this conversion is about 43% and decreases rapidly with decreasing μν.

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Kato, Chinami, Hiroki Nagakura, and Taiki Morinaga. "Neutrino Transport with the Monte Carlo Method. II. Quantum Kinetic Equations." Astrophysical Journal Supplement Series 257, no. 2 (December 1, 2021): 55. http://dx.doi.org/10.3847/1538-4365/ac2aa4.

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Abstract Neutrinos have a unique quantum feature as flavor conversions. Recent studies suggested that collective neutrino oscillations play important roles in high-energy astrophysical phenomena. The quantum kinetic equation (QKE) is capable of describing the neutrino flavor conversion, transport, and matter collision self-consistently. However, we have experienced many technical difficulties in their numerical implementation. In this paper, we present a new QKE solver based on a Monte Carlo (MC) approach. This is an upgraded version of our classical MC neutrino transport solver; in essence, a flavor degree of freedom including mixing state is added into each MC particle. This extension requires updating numerical treatments of collision terms, in particular for scattering processes. We deal with the technical problem by generating a new MC particle at each scattering event. To reduce statistical noise inherent in MC methods, we develop the effective mean free path method. This suppresses a sudden change of flavor state due to collisions without increasing the number of MC particles. We present a suite of code tests to validate these new modules with comparison to the results reported in previous studies. Our QKE-MC solver is developed with fundamentally different philosophy and design from other deterministic and mesh methods, suggesting that it will be complementary to others and potentially provide new insights into physical processes of neutrino dynamics.

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Abbar, Sajad, and Maria Cristina Volpe. "On fast neutrino flavor conversion modes in the nonlinear regime." Physics Letters B 790 (March 2019): 545–50. http://dx.doi.org/10.1016/j.physletb.2019.02.002.

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Boyarkin, O. M., and I. O. Boyarkina. "Solar neutrinos as indicators of the Sun’s activity." International Journal of Modern Physics A 34, no. 33 (November 30, 2019): 1950227. http://dx.doi.org/10.1142/s0217751x19502270.

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Opportunity of the solar flares (SFs) prediction observing the solar neutrino fluxes is investigated. In three neutrino generations, the evolution of the neutrino flux traveling the coupled sunspots (CSs) which are the SF source is considered. It is assumed that the neutrinos possess both the dipole magnetic moment and the anapole moment while the magnetic field above the CSs may reach the values [Formula: see text] Gs, display the twisting nature and posses the nonpotential character. The possible resonance conversions of the solar neutrino flux are examined. Since the [Formula: see text] resonance takes place before the convective zone, its existence can in no way be connected with the SF. However, when the solar neutrino flux moves through the CSs in the preflare period, then it may undergo the additional resonance conversions and, as a result, depleting the electron neutrinos flux may be observed.

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Lunardini, C. "Neutrino flavor conversion in a neutrino background: coherent scattering and many body effects." Nuclear Physics B - Proceedings Supplements 138 (January 2005): 353–55. http://dx.doi.org/10.1016/j.nuclphysbps.2004.11.082.

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BENVENUTO, O. G., M. I. KRIVORUCHENKO, and B. V. MARTEMYANOV. "POSSIBLE SIGNATURES OF THE CONVERSION OF A NEUTRON STAR TO A STRANGE STAR." International Journal of Modern Physics D 03, no. 03 (September 1994): 653–64. http://dx.doi.org/10.1142/s0218271894000794.

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The problem of the identification of strange stars is discussed. We suggest some characteristic signatures for the search for strange stars: a two-step mechanism for supernova explosions accompanied by the occurrence of strange stars and two neutrino bursts; microstructure analysis in the profile of pulsar emission; and unusual stability in the rotation of millisecond pulsars due to the absence of internal crust in strange stars. The cooling of strange stars is faster than the cooling of ordinary neutron stars, so low surface temperature of pulsars can indicate the existence of massive quark cores in observed pulsars. Low mass strange stars as bursters and/or X-ray sources have peculiar observable features: low luminosity and (for bursters) high recurrence rate, large duration of bursts, low ratio of energy emitted between two bursts and energy emitted during the burst.

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Beise, J., and C. Glaser. "Simulation study for an in-situ calibration system for the measurement of the snow accumulation and the index-of-refraction profile for radio neutrino detectors." Journal of Instrumentation 18, no. 01 (January 1, 2023): P01036. http://dx.doi.org/10.1088/1748-0221/18/01/p01036.

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Abstract Sensitivity to ultra-high-energy neutrinos (E > 17 eV) can be obtained cost-efficiently by exploiting the Askaryan effect in ice, where a particle cascade induced by the neutrino interaction produces coherent radio emission that can be picked up by antennas. As the near-surface ice properties change rapidly within the upper 𝒪(100 m), a good understanding of the ice properties is required to reconstruct the neutrino properties. In particular, continuous monitoring of the snow accumulation (which changes the depth of the antennas) and the index-of-refraction n(z) profile are crucial for an accurate determination of the neutrino's direction and energy. We present an in-situ calibration system that extends the radio detector station with two radio emitters to continuously monitor the firn properties within the upper 40 m by measuring the time differences between direct and reflected (off the surface) signals (D'n'R). We determine the optimal positions of two transmitters at all three sites of current and future in-ice radio detectors: Greenland, Moore's Bay, and the South Pole. For the South Pole we find that the snow accumulation Δh can be measured with a resolution of 3 mm and the parameters of an exponential n(z) profile α and z 0 with 0.04% and 0.14% precision respectively, which constitutes an improvement of more than a factor of 10 as compared to the inference of the n(z) profile from density measurements. Additionally, as this technique is based on the measurement of the signal propagation times we are not bound to the conversion of density to index-of-refraction. We quantify the impact of these ice uncertainties on the reconstruction of the neutrino vertex, direction, and energy and find that the calibration device measures the ice properties to sufficient precision to have negligible influence.

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FUKUGITA, M., and T. YANAGIDA. "IMPLICATIONS OF THE RECENT SOLAR NEUTRINO EXPERIMENT FOR PARTICLE PHYSICS." Modern Physics Letters A 06, no. 08 (March 14, 1991): 645–57. http://dx.doi.org/10.1142/s021773239100066x.

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Physical implications of the results of recent solar neutrino experiments from the Homestake, Kamioka and Baksan Laboratories are discussed. We argue that the results from Homestake and Kamioka, if the two data sets are combined, strongly suggest some unusual neutrino properties rather than the modification of astrophysical models of the sun. If the time variation of neutrino captures, as observed at Homestake, is a statistical fluke, the neutrino conversion in matter proposed by Mikheyev and Smirnov among several possibilities yields the most attractive explanation for the neutrino flux deficit. We remark that the solution includes the possibility predicted by simple SO(10) models and it is tested by the gallium experiment. If the time variation at Homestake is true, on the other hand, one must explain why such an effect is not seen at Kamiokande. We stress that it is still possible to make a particle physics model which explains the two apparently contradictory observations.

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EngviSt, Kari, Jukka Maalampi, and V. .B. Semikoz. "Neutrino conversions in hot plasma." Nuclear Physics B 456, no. 1-2 (December 1995): 339–54. http://dx.doi.org/10.1016/0550-3213(98)00480-5.

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BERNARDINI, A. E., and M. M. GUZZO. "THEORETICAL CORRELATION BETWEEN POSSIBLE EVIDENCES OF NEUTRINO CHIRAL OSCILLATIONS AND POLARIZATION MEASUREMENTS." Modern Physics Letters A 23, no. 15 (May 20, 2008): 1141–50. http://dx.doi.org/10.1142/s0217732308025723.

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Reporting about the formalism with the Dirac equation we describe the dynamics of chiral oscillations for a fermionic particle non-minimally coupling with an external magnetic field. For massive particles, the chirality and helicity quantum numbers represent different physical quantities of representative importance in the study of chiral interactions, in particular, in the context of neutrino physics. After solving the interacting Hamiltonian (Dirac) equation for the corresponding fermionic Dirac-type particle (neutrino) and quantifying chiral oscillations in the Dirac wave packet framework, we avail the possibility of determining realistic neutrino chirality conversion rates by means of (helicity) polarization measurements. We notice that it can become feasible for some particular magnetic field configurations with large values of B orthogonal to the direction of the propagating particle.

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Liu, Yiheng, Kai He, Gang Wang, Guilong Gao, Xin Yan, Yanhua Xue, Ping Chen, et al. "Simulation of the impact of using a novel neutron conversion screen on detector time characteristics and efficiency." AIP Advances 12, no. 4 (April 1, 2022): 045206. http://dx.doi.org/10.1063/5.0073025.

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To directly measure the DT neutrons from inertial confinement fusion with a high time resolution, a new type of neutron conversion composed of a CH2 conversion layer, a metal moderation layer, and a CsI secondary electron emission layer is proposed. The conversion screen is based on the principle that recoil protons produced by elastic scattering of the neutrons in CH2 interact with CsI to generate secondary electrons. The moderation layer can filter the energy spectrum of protons to prevent low-energy protons from reaching CsI, which shortens the duration of the secondary electron pulse and improves the temporal resolution of the conversion screen. Based on the Monte Carlo method, both the neutron impulse and background γ-rays response of this conversion screen were calculated. The simulation indicates that the temporal resolution of the conversion screen can reach up to 4.9 ps when the thickness of the gold layer is 100 µm. The detection efficiency of secondary electrons/neutrons can reach 7.4 × 10−3. The detection efficiency of the neutron conversion screen for secondary electrons/γ-rays is an order of magnitude lower than the neutron impulse response, and the response time of γ-rays is 20 ps earlier than the neutron pulses. This means that using this conversion screen is beneficial to distinguish between neutrons and γ-rays and has a good signal-to-noise ratio.

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Lambiase, G. "MSW Effect in Loop Quantum Gravity and Constraints on Parameters from Neutrino–Antineutrino Transitions." Modern Physics Letters A 18, no. 20 (June 28, 2003): 1397–401. http://dx.doi.org/10.1142/s0217732303011150.

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The MSW effect is studied in the context of loop quantum gravity. In this theory the dispersion relation of fermion depends on the helicity of particles. Bounds on parameters related to helicity-terms, which violate the Lorentz invariance, are derived in the framework of spin-flip conversion of neutrino flavors.

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GNINENKO, S. N., M. M. KIRSANOV, N. V. KRASNIKOV, and V. A. MATVEEV. "PROBING LEPTON FLAVOUR VIOLATION IN νμ + N → τ + ⋯ SCATTERING AND μ → τ CONVERSION ON NUCLEONS." Modern Physics Letters A 17, no. 22 (July 20, 2002): 1407–17. http://dx.doi.org/10.1142/s0217732302007855.

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We study lepton flavour-violating interactions which could result in the τ-lepton production in the νμN scattering or in μ → τ conversion on nucleons at high energies. Phenomenological bounds on the strength of [Formula: see text] interactions are extracted from the combined result of the NOMAD and CHORUS experiments on searching for νμ - ντ oscillations. Some of these bounds supersede limits from rare decays. We also propose a "missing energy" type experiment searching for μ → τ conversion on nucleons. The experiment can be performed at a present accelerator or at a future neutrino factory.

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YAGUNA, CARLOS E. "CONSTRAINING MSUGRA PARAMETERS WITH μ→eγ AND μ–e CONVERSION IN NUCLEI." International Journal of Modern Physics A 21, no. 06 (March 10, 2006): 1283–89. http://dx.doi.org/10.1142/s0217751x06025377.

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We show that, in the MSSM with msugra boundary conditions and seesaw induced neutrino masses, the values of BR (μ→eγ) and the μ–e conversion rate in a nucleus constrain msugra parameters in a model independent way.

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CIRIGLIANO, VINCENZO. "NEUTRINOLESS DOUBLE BETA DECAY AND LEPTON FLAVOR VIOLATION." International Journal of Modern Physics A 20, no. 15 (June 20, 2005): 3340–42. http://dx.doi.org/10.1142/s0217751x05026510.

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I argue that muon lepton flavor violating (LFV) processes (such as μ → eγ and μ → e conversion in nuclei) provide a useful diagnostic tool to determine whether or not the effective neutrino mass can be safely extracted from the rate of neutrinoless double beta decay.

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Kargiantoulakis, Manolis. "A search for charged lepton flavor violation in the Mu2e experiment." Modern Physics Letters A 35, no. 19 (April 24, 2020): 2030007. http://dx.doi.org/10.1142/s0217732320300074.

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The Mu2e experiment will search for the neutrino-less conversion of a muon into an electron in the field of an aluminum nucleus. An observation would be the first signal of charged lepton flavor violation and de facto evidence for new physics beyond the Standard Model. The clean signature of the conversion process offers an opportunity for a powerful search: Mu2e will probe four orders of magnitude beyond current limits, with real discovery potential over a wide range of well-motivated new physics models. This goal requires an integrated system of solenoids that will create the most intense muon beam in the world, and suppression of all possible background sources. The Mu2e components are currently being constructed, with the experiment planned to begin operations in the Fermilab Muon Campus within the next few years.

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Sagatova, Andrea, Bohumir Zatko, Katarina Sedlackova, Marius Pavlovic, Vladimir Necas, Marko Fulop, Michael Solar, and Carlos Granja. "Semi-insulating GaAs detectors with HDPE layer for detection of fast neutrons from D–T nuclear reaction." International Journal of Modern Physics: Conference Series 44 (January 2016): 1660233. http://dx.doi.org/10.1142/s2010194516602337.

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Bulk semi-insulating (SI) GaAs detectors optimized for fast-neutron detection were examined using mono-energetic neutrons. The detectors have an active area of 7.36 mm2 defined by a multi-pixel structure of a AuZn Schottky contact allowing a relatively high breakdown voltage (300 V) sufficient for full depletion of the detector structure. The Schottky contact is covered by a HDPE (high density polyethylene) conversion layer, where neutrons transfer their kinetic energy to hydrogen atoms through elastic nuclear collisions. The detectors were exposed to mono-energetic neutrons generated by a deuterium (D)–tritium (T) nuclear reaction at a Van de Graaff accelerator. Neutrons reached a kinetic energy of 16.8 MeV when deuterons were accelerated by 1 MV potential. The influence of the HDPE layer thickness on the detection efficiency of the fast neutrons was studied. The thickness of the conversion layer varied from 50 [Formula: see text]m to 1300 [Formula: see text]m. The increase of the HDPE layer thickness led to a higher detection efficiency due to higher conversion efficiency of the HDPE layer. The effect of the active detector thickness modified by the detector reverse bias voltage on the detection efficiency was also evaluated. By increasing the detector reverse voltage, the detector active volume expands to the depth and also to the sides, slightly increasing the neutron detection efficiency.

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Zhu, Cui, Xia Zhou, and Na Wang. "Rotational energy conversion and thermal evolution of neutron stars." Chinese Physics C 41, no. 12 (November 30, 2017): 125104. http://dx.doi.org/10.1088/1674-1137/41/12/125104.

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PAVLOVIČ, MÁRIUS, KATARÍNA SEDLAČKOVÁ, ANDREA ŠAGÁTOVÁ, and IVAN STRAŠÍK. "APPLICATION OF THE S3M AND MCNPX CODES IN PARTICLE DETECTOR DEVELOPMENT." International Journal of Modern Physics: Conference Series 27 (January 2014): 1460153. http://dx.doi.org/10.1142/s2010194514601537.

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Semiconductor detectors can be used to detect neutrons if they are covered by a conversion layer. Some neutrons transfer their kinetic energy to hydrogen via elastic nuclear scattering in the conversion layer, and protons are produced as recoils. These protons enter the sensitive volume of the detector and are detected. In the process of detector development, Monte Carlo computer codes are necessary to simulate the detection process. This paper presents the main features of the S3M code (SRIM Supporting Software Modules) and shows its application potential. Examples are given for the neutron detectors with a conversion layer and for CVD (Chemical Vapor Deposition) diamond detectors for beam-condition monitors at the LHC (Large Hadron Collider). Special attention is paid to the S3M statistical modules that can be of interest also for other application areas like beam transport, accelerators, ion therapy, etc. The results are generated by MCNPX (Monte Carlo N-Particle eXtended) simulations used to optimize the thickness of the HDPE (high density polyethylene) conversion layer.

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Prelas, M. A., and E. J. Charlson. "Synergism in inertial confinement fusion: a total direct energy conversion package." Laser and Particle Beams 7, no. 3 (August 1989): 449–66. http://dx.doi.org/10.1017/s0263034600007412.

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The products of fusion reactions have unique properties which can be used for direct energy conversion. These products are neutrons and ions. Neutrons can be transported very long distances through solid materials and can interact with certain elements which have a very high absorption cross section. Ions on the other hand have a very short transport length even in a gaseous medium. It is possible to utilize these products in an inertial confinement fusion reactor with two different direct energy conversion devices: a nuclear-pumped laser using neutrons from the fusion reaction; a photon generator material combined with a photovoltaic converter using the ionic fusion products.It will be argued that a nuclear-pumped laser can be more efficient than a conventional laser. It will also be shown that an advanced energy conversion concept based on photon production and photovoltaics can produce ICF system efficiencies of 56%.

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Kurup, A. "Muon to electron conversion: how to find an electron in a muon haystack." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1924 (August 13, 2010): 3645–55. http://dx.doi.org/10.1098/rsta.2010.0058.

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The standard model (SM) of particle physics describes how the Universe works at a fundamental level. Even though this theory has proven to be very successful over the past 50 years, we know it is incomplete. Many theories that go beyond the SM predict the occurrence of certain processes that are forbidden by the SM, such as muon to electron conversion. This paper will briefly review the history of muon to electron conversion and focus on the high-precision experiments currently being proposed, COMET (Coherent Muon to Electron Transition) and Mu2e, and a next-generation experiment, PRISM. The PRISM experiment intends to use a novel type of accelerator called a fixed-field alternating-gradient (FFAG) accelerator. There has recently been renewed interest in FFAGs for the Neutrino Factory and the Muon Collider, and because they have applications in many areas outside of particle physics, such as energy production and cancer therapy. The synergies between these particle physics experiments and other applications will also be discussed.

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Likta, Emmanuel Wana, David I. Malgwi, and Nura Yakubu. "Evaluation of deep inelastic scattering of nucleon in the gluon structure functions." Gadau Journal of Pure and Allied Sciences 1, no. 2 (October 16, 2022): 153–59. http://dx.doi.org/10.54117/gjpas.v1i2.33.

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It is known that between quarks the basic particle acts as the conversation particle for the strong force is gluon and the gluon have two separation states due to gauge invariance. Inside hadron the baryons such as proton and neutrons uses electron, muons and neutrino the process is deep inelastic scattering. Deep is considered to be the high energy of lepton that gives very short wavelength which penetrates a small size target. The goal of this paper is to obtain the following reality evaluation of Deep Inelastic scattering of nucleon in the gluon structure, to observe the agreement between the electron and muon. The method initiate is the cross section. The deep inelastic scattering of nucleon in the gluon structure has been achieved and it has been observed that the electron and muon are in agreement with each other. For electron, muon and neutrino disagree to each other. The bound and pseudo free nucleon within the nucleus do not behave in the same way. Measurement production has been carried out. Small dependent on nuclear dependence has been achieved.

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Giovannella, S. "Status of the Mu2e experiment." EPJ Web of Conferences 179 (2018): 01003. http://dx.doi.org/10.1051/epjconf/201817901003.

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The Mu2e experiment at Fermilab searches for the charged-lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. The dynamics of such a process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed, in three years of running Mu2e will improve the current limit by four orders of magnitude. Such a charged lepton flavor-violating reaction probes new physics at a scale inaccessible with direct searches at either present or planned high energy colliders. The experiment both complements and extends the current search for muon decay to electron-photon at MEG and searches for new physics at the LHC. This paper focuses on the physics motivation, the design and the status of the experiment.

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Yoshizawa, Nobuaki, Osamu Sato, Shunji Takagi, Shiori Furihata, Jun Funabiki, Satoshi Iwai, Takashi Uehara, Shun-ichi Tanaka, and Yukio Sakamoto. "Fluence to Dose Conversion Coefficients for High-Energy Neutron, Proton and Alpha Particles." Journal of Nuclear Science and Technology 37, sup1 (March 2000): 865–69. http://dx.doi.org/10.1080/00223131.2000.10875013.

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Li, Wei, Yu-Rong Bai, Hao-Xuan Guo, Chao-Hui He, and Yong-Hong Li. "Geant4 simulation of neutron displacement damage effect in InP." Acta Physica Sinica 71, no. 8 (2022): 082401. http://dx.doi.org/10.7498/aps.71.20211722.

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As the second-generation compound semiconductor material, indium phosphide (InP) has strong irradiation resistance and high photoelectric conversion efficiency. It has advantages in the field of photonics and radio frequency. In atmospheric space, high-energy cosmic rays enter into the earth's atmosphere and interact with nitrogen (N), oxygen (O) and other elements to produce secondary cosmic rays. The irradiation particles in the atmosphere are mainly neutrons because the penetration of charged particles is weak. The InP semiconductor devices are affected by atmospheric neutron irradiation of various energy from all directions, which results in the internal defects in InP crystals, the degradation of device performance and the reduction of device lifetime. In this paper, Monte Carlo simulation software Geant4 is used to simulate the neutron irradiation effect, and the initial state distribution of displacement damage caused by neutrons with different energy is obtained, including the distribution of non-ionized energy loss (NIEL) with depth, the relationship between NIEL and the energy of incident neutrons, and the type, number and energy of primary knock-on atoms (PKA). The results show that (1) the NIEL is uniformly distributed when material thickness is on the order of μm and for the material thickness on the order of cm and more, the NIEL decreases as the depth increases and can be reduced to zero when the target material is thick enough; (2) by analyzing the NIEL produced by 1–20 MeV neutrons incident on 3-μm InP and their distribution with depth, it is found that the NIEL first increases and then decreases with incident neutron energy increasing. This trend is caused mainly by PKA produced through the inelastic scattering reaction; (3) by analyzing the type and the energy of PKA produced by 1–20 MeV neutrons incident on 3 μm InP, it is found that the PKA of In/P accounts for a large proportion, which causes displacement damage mainly, and the higher the neutron energy, the richer the variety of PKA is and the greater the maximum kinetic energy of PKA, but the PKAs mainly distribute in the low energy part. The present research has theoretical and guiding value for the long-term application of InP-based 5G devices in atmospheric neutron irradiation environment.

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Karcher, N., D. Richter, F. Ahrens, R. Gartmann, M. Wegner, O. Krömer, S. Kempf, C. Enss, M. Weber, and O. Sander. "SDR-Based Readout Electronics for the ECHo Experiment." Journal of Low Temperature Physics 200, no. 5-6 (April 30, 2020): 261–68. http://dx.doi.org/10.1007/s10909-020-02463-w.

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Abstract Due to their excellent energy resolution, the intrinsically fast signal rise time, the huge energy dynamic range, and the almost ideally linear detector response, metallic magnetic calorimeters (MMC)s are very well suited for a variety of applications in physics. In particular, the ECHo experiment aims to utilize large-scale MMC-based detector arrays to investigate the mass of the electron neutrino. Reading out such arrays is a challenging task which can be tackled using microwave SQUID multiplexing. Here, the detector signals are transduced into frequency shifts of superconducting microwave resonators, which can be deduced using a high-end software-defined radio (SDR) system. The ECHo SDR system is a custom-made modular electronics, which provides 400 channels equally distributed in a 4 to 8 GHz frequency band. The system consists of a superheterodyne RF frequency converter with two successive mixers, a modular conversion, and an FPGA board. For channelization, a novel heterogeneous approach, utilizing the integrated digital down conversion (DDC) of the ADC, a polyphase channelizer, and another DDC for demodulation, is proposed. This approach has excellent channelization properties while being resource-efficient at the same time. After signal demodulation, on-FPGA flux-ramp demodulation processes the signals before streaming it to the data processing and storage backend.

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Kirichek, O., C. R. Lawson, G. L. Draper, D. M. Jenkins, D. J. Haynes, and S. Lilley. "Solid methane moderators: Thermodynamics and chemistry." Journal of Neutron Research 22, no. 2-3 (October 20, 2020): 281–86. http://dx.doi.org/10.3233/jnr-190132.

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The unique properties of solid methane enable the conversion of hot, energetic neutrons into cold neutrons, with an efficiency approximately 3.5 times that of liquid hydrogen based moderators. However, practical applications of solid methane in neutron moderators turned out to be much more challenging than initially expected. Exposure of solid methane at low temperatures to neutron radiation leads to a build-up of radiolysis products in the solid methane matrix. Accumulation of defects beyond some critical number can result in a spontaneous self-accelerated recombination process, which in combination with the expansion of hydrogen built up in bulk solid methane during irradiation, was believed to be responsible for the moderator’s breakdown. Here we present results of our thermodynamic model, based on the theory of thermal explosion. Our model agrees well with the test data obtained using methane moderators developed at the IPNS neutron source, based at Argonne National Laboratory and the data acquired during commissioning of the ISIS Target Station 2 solid methane moderator. We also discuss the products of radiolysis reactions generated by exposure of the condensed methane to neutron radiation. The succession of radiolysis reactions may lead to the production of long chain hydrocarbons, which can contaminate the moderator system and significantly reduce efficiency of the heat-exchanger. The possible solutions for cleaning moderators using targeted solvents are considered. In the conclusion we give some practical recommendations, based on our simulation results and operational experience.

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Zimmer, Oliver, Thierry Bigault, Skyler Degenkolb, Christoph Herb, Thomas Neulinger, Nicola Rizzi, Valentina Santoro, Alan Takibayev, Richard Wagner, and Luca Zanini. "In-beam superfluid-helium ultracold neutron source for the ESS." Journal of Neutron Research 24, no. 2 (January 5, 2023): 95–110. http://dx.doi.org/10.3233/jnr-220045.

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This paper discusses design principles and possible performances of an “in-beam” ultracold neutron (UCN) source for the European Spallation Source (ESS). The key components of the proposed neutron delivery system are nested-mirror optics (NMO), which image the bright neutron emission surface of the large liquid-deuterium moderator, studied within the HighNESS project, onto a remotely located superfluid-helium converter. Bandpass supermirrors, with optional polarization capability, enable the selective transport of those neutrons that are most effective for UCN production, exploiting the single-phonon conversion process that is possible for neutrons having wavelengths within a narrow range centered on 8.9 A ˚. NMO are capable of extracting and refocusing neutrons with small transport losses under the large solid angle available at the ESS Large Beam Port (LBP), allowing the converter to be placed far away from the high-radiation area in the ESS shielding bunker, where the source stays accessible for trouble-shooting while facilitating a low-background environment for nearby UCN experiments. Various configurations of the beam and converter are possible, including a large-volume converter – with or without a magnetic reflector – for a large total UCN production rate, or a beam focused onto a small converter for highest possible UCN density. The source performances estimated by first simulations of a baseline version presented in this paper, including a saturated UCN density on the order of 10 5 cm − 3 , motivate further study and the development of NMO beyond the first prototypes that have been recently investigated experimentally.

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Ferrari, A., and M. Pelliccioni. "Fluence to Dose Equivalent Conversion Data and Effective Quality Factors for High Energy Neutrons." Radiation Protection Dosimetry 76, no. 4 (April 1, 1998): 215–24. http://dx.doi.org/10.1093/oxfordjournals.rpd.a032267.

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Chuirazzi, William, Aaron Craft, Burkhard Schillinger, Jesus Mendoza, Steven Cool, and Adrian Losko. "Fast Neutron Scintillator Screens for Neutron Imaging Using a Layered Polymer-Phosphor Architecture." Quantum Beam Science 6, no. 2 (April 1, 2022): 14. http://dx.doi.org/10.3390/qubs6020014.

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Fast neutrons enable a nondestructive examination of dense, large, and highly attenuating samples due to their lower interaction probability compared to thermal neutrons. However, this also creates a challenge in fast neutron imaging, as the thicker sensors necessary to detect fast neutrons degrade an image’s spatial resolution due to scattering within the sensor and the indeterminate depth of interaction in the sensor. This work explores the advantages of a fast neutron imaging screen with a layered polymer-phosphor screen approach as opposed to a mixed polymer-phosphor screen typically used in fast neutron imaging. Proton recoil is the primary conversion mechanism for fast neutron imaging. Simulations showed that the recoil proton range of typical fast neutrons is approximately 200 µm, however, tests at Idaho National Laboratory revealed that the light output of these screens increased at much greater polymer thicknesses. The NECTAR fast neutron beamline at FRM II was used to test the imaging performance of layered fast neutron imaging screens. Distinguishing between the fast-neutron and γ-ray signals is a major challenge in fast neutron imaging because all fast neutron sources also produce γ-rays. A relative comparison between a control plate and the fast neutron screen was made to distinguish between a γ-ray and fast neutron signals. MCNP modeling quantified the γ-ray and fast neutron contributions to the images measured at NECTAR, which were approximately a 75% γ-ray image.

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NAZARUK, V. I. "$n\bar{n}$ CONVERSION IN FINITE NUCLEI." International Journal of Modern Physics E 20, no. 05 (May 2011): 1203–12. http://dx.doi.org/10.1142/s0218301311018368.

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The [Formula: see text] transitions for the neutrons in bound state are studied. The |in〉-state of nucleus is described by single-particle shell model. The dynamical process part is calculated by means of field-theoretical approach with finite time interval. The results are the same as for nuclear matter.

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Shishido, Hiroaki, The Dang Vu, Kazuya Aizawa, Kenji M. Kojima, Tomio Koyama, Kenichi Oikawa, Masahide Harada, et al. "Neutron Imaging toward Epithermal Regime using a Delay Line Current-Biased Kinetic-Inductance Detector." Journal of Physics: Conference Series 2323, no. 1 (August 1, 2022): 012029. http://dx.doi.org/10.1088/1742-6596/2323/1/012029.

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Abstract Wide energy range neutron imaging and spectroscopy in a single experiment without changing the setup is available by a combination of a high-power pulsed neutron source and fast operating neutron detector. The delay-line current-biased kinetic-inductance detector (CB-KID) is a two-dimensional superconducting detector with high spatial and temporal resolutions, and multi-hit tolerance. We demonstrate that the delay-line CB-KID with 10B neutron conversion layer is applicable for neutron imaging and spectroscopy up to the neutron energy of 100 eV. High spatial neutron transmission image for a Sm-Sn mixed metal is successfully constructed below 0.3 eV. Concomitantly, we examine the neutron transmission up to 100 eV and identify observed resonance dips by Sm nuclei.

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Sannikov, A. V., and E. N. Savitskaya. "Ambient Dose Equivalent Conversion Factors for High Energy Neutrons Based on the ICRP 60 Recommendations." Radiation Protection Dosimetry 70, no. 1 (April 1, 1997): 383–86. http://dx.doi.org/10.1093/oxfordjournals.rpd.a031982.

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Journal articles on the topic 'High energy neutrino conversion'

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