Browsing by Author "Lin, Guey-Lin"

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A new type of plasma wakefield accelerator driven by magnetowaves
(2009-02-01)
Chen, Pisin
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Chang, Feng-Yin
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Lin, Guey-Lin
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Noble, Robert J.
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Sydora, Richard
We present a new concept for a plasma wakefield accelerator driven by magnetowaves (MPWA). This concept was originally proposed as a viable mechanism for the 'cosmic accelerator' that would accelerate cosmic particles to ultra-high energies in the astrophysical setting. Unlike the more familiar plasma wakefield accelerator (PWFA) and the laser wakefield accelerator (LWFA) where the drivers, the charged-particle beam and the laser, are independently existing entities, MPWA invokes the high-frequency and highspeed whistler mode as the driver, which is a medium wave that cannot exist outside of the plasma. Aside from the difference in drivers, the underlying mechanism that excites the plasma wakefield via the ponderomotive potential is common. Our computer simulations show that under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over many plasma wavelengths. We suggest that in addition to its celestial application, the MPWA concept can also be of terrestrial utility. A proof-of-principle experiment on MPWA would benefit both terrestrial and celestial accelerator concepts.
Classifying and probing flavor transition mechanisms of astrophysical high energy neutrinos
(2012-01-01)
Lai, Kwang-Chang
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Lin, Guey-Lin
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Liu, T. C.
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物理研究所
;
Institute of Physics
The future neutrino telescopes are expected to identify the flavors of astrophysical neutrinos and therefore determine the flavor ratio. The flavor ratio of astrophysical neutrinos observed at the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during the propagations of these neutrinos. We propose a model-independent way to parameterize the above flavor transitions, including standard oscillations and beyond. A systematical way is also described to probe those mechanisms taking advantage of R equivalent to phi(mu)/(phi(e) + phi(tau)) and S equivalent to phi(e)/phi(tau) the observables in neutrino telescope measurements.
Complementary test of the dark matter self-interaction in dark U(1) model by direct and indirect dark matter detection
(2016-01-01)
Chen, Chian-Shu
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Lin, Guey-Lin
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Lin, Yen-Hsun
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物理研究所
;
Institute of Physics
The halo dark matter (DM) can be captured by the Sun if its final velocity after the collision with a nucleus in the Sun is less than the escape velocity. We consider a selfinteracting dark matter (SIDM) model where U(1) gauge symmetry is introduced to account for the DM self-interaction. Such a model naturally leads to isospin violating DM nucleon interaction, although isospin symmetric interaction is still allowed as a special case. We present the IceCube-PINGU 2a sensitivity to the parameter range of the above model with 5 years of search for neutrino signature from DM annihilation in the Sun. This indirect detection complements the direct detection by probing those SIDM parameter ranges which are either the region for very small rnx or the region opened up due to isospin violations.
Complementary Test of the Dark Matter Self-Interaction in Dark U(1) Model by Direct and Indirect Detection
(2016-01-01)
Chen, Chian-Shu
;
Lin, Yen-Hsun
;
Lin, Guey-Lin
;
物理研究所
;
Institute of Physics
The halo dark matter (DM) can be captured by the Sun if its final velocity after the collision with a nucleus in the Sun is less than the escape velocity. We consider a selfinteracting dark matter (SIDM) model where U(1) gauge symmetry is introduced to account for the DM self-interaction. Such a model naturally leads to isospin violating DM- nucleon interaction, although isospin symmetric interaction is still allowed as a special case. We present the IceCube-PINGU 2 sigma sensitivity to the parameter range of the above model with 5 years of search for neutrino signature from DM annihilation in the Sun. This indirect detection complements the direct detection by probing those SIDM parameter ranges which are either the region for very small m(chi) or the region opened up due to isospin violations.
Constraining dark matter capture and annihilation cross sections by searching for neutrino signature from the Earth's core
(2014-01-06)
Lee, Fei-Fan
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Lin, Guey-Lin
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Tsai, Yue-Lin Sming
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物理研究所
;
Institute of Physics
We study the sensitivity of IceCube/DeepCore detector to dark matter annihilations in the Earth's core. We focus on annihilation modes chi chi -> nu(nu) over cap, tau(+)tau(-), h (h) over cap, and W+W-. Both track and cascade events are considered in our analysis. By fixing the dark matter annihilation cross section at some nominal values, we study the sensitivity of the IceCube/DeepCore detector to dark matter spin- independent cross section sigma(SI)(p) for m(chi) ranging from few tens of GeV to 10 TeV. This sensitivity is compared with the existing IceCube 79-string constraint on the same cross section, which was obtained by searching for dark matter annihilations in the Sun. We compare this sensitivity to dark matter direct detection results as well, in particular the XENON100 (2012) limit and the parameter regions preferred by DAMA and CRESST- II experiments. We also present IceCube/DeepCore sensitivity to hs.i as a function of m(chi) by fixing sigma(SI)(p) at XENON100 (2012) and XENON1T limits, respectively. This sensitivity is compared with the preferred dark matter parameter range derived from the combined fitting to PAMELA and AMS02 positron fraction data. We conclude that the search for dark matter annihilations in the Earth's core provides competitive constraints on sigma(SI)(p) and in the case of low- mass dark matter. Particularly, the expected constraint on sigma(SI)(p) for 5 years of data taking in IceCube/DeepCore is more stringent than the current IceCube 79- string limit mentioned above.
Constraining the mass scale of a Lorentz-violating Hamiltonian with the measurement of astrophysical neutrino-flavor composition
(2017-12-26)
Lai, Kwang-Chang
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Lai, Wei-Hao
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Lin, Guey-Lin
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物理研究所
;
Institute of Physics
We study Lorentz violation effects on flavor transitions of high energy astrophysical neutrinos. It is shown that the appearance of a Lorentz-violating Hamiltonian can drastically change the flavor transition probabilities of astrophysical neutrinos. Predictions of Lorentz-violation effects on flavor compositions of astrophysical neutrinos arriving on Earth are compared with IceCube flavor composition measurement which analyzes astrophysical neutrino events in the energy range between 25 TeV and 2.8 PeV. Such a comparison indicates that the future IceCube-Gen2 will be able to place stringent constraints on a Lorentz-violating Hamiltonian in the neutrino sector. We work out the expected sensitivities by IceCube-Gen2 on dimension-3 CPT-odd and dimension-4 CPT-even operators in a Lorentz-violating Hamiltonian. The expected sensitivities can improve on the current constraints obtained from other types of experiments by more than two orders of magnitudes for certain ranges of the parameter space.
Dark Matter Induced Neutrino Signature in IceCube DeepCore Detector
(2014-01-01)
Lee, Fei-Fan
;
Lin, Guey-Lin
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Tsai, Yue-Lin Sming
;
物理研究所
;
Institute of Physics
The installation of DeepCore array significantly lowers IceCube\'s energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we discuss decays of the event rate in DeepCore array due to neutrino flux produced by annihilations and galactic dark matter. This event rate is calculated with a 10 GeV threshold energy, which is smaller than the threshold energy taken in previous works. Taking into account the background event rate due to the atmospheric neutrino flux, we evaluate the sensitivity of DeepCore array for probing dark matter annihilation cross section and decay time. We compare our results with corresponding constraints derived from observations of WMAP, ACT and Fermi-LAT.
Determination of the neutrino flavor ratio at the astrophysical source
(2009-11-01)
Lai, Kwang-Chang
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Lin, Guey-Lin
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Liu, T. C.
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物理研究所
;
Institute of Physics
We discuss the reconstruction of neutrino flavor ratios at astrophysical sources through the future neutrino-telescope measurements. Taking the ranges of neutrino mixing parameters theta(ij) as those given by the current global fit, we demonstrate by a statistical method that the accuracies in the measurements of energy-independent ratios R equivalent to phi(nu(mu))/(phi(nu(e))+phi(nu(tau))) and S equivalent to phi(nu(e))/phi(nu(tau)) among integrated neutrino flux should both be better than 10% in order to distinguish between the pion source and the muon-damped source at the 3 sigma level. The 10% accuracy needed for measuring R and S requires an improved understanding of the background atmospheric neutrino flux to a better than 10% level in the future. We discuss the applicability of our analysis to practical situations that the diffuse astrophysical neutrino flux arises from different types of sources and each point source has a neutrino flavor ratio varying with energies. We also discuss the effect of the leptonic CP phase on the flavor-ratio reconstruction.
Determination of the total absorption peak in an electromagnetic calorimeter
(2016-08-11)
Cheng, Jia-Hua
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Wang, Zhe
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Lebanowski, Logan
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Lin, Guey-Lin
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Chen, Shaomin
A physically motivated function was developed to accurately determine the total absorption peak in an electromagnetic calorimeter and to overcome biases present in many commonly used methods. The function is the convolution of a detector resolution function with the sum of a delta function, which represents the complete absorption of energy, and a tail function, which describes the partial absorption of energy and depends on the detector materials and structures. Its performance was tested with the simulation of three typical cases. The accuracy of the extracted peak value, resolution, and peak area was improved by an order of magnitude on average, relative to the Crystal Ball function. (C) 2016 Elsevier B.V. All rights reserved.
Determinations of flavor ratios and flavor transitions of astrophysical neutrinos
(2010)
Lin, Guey-Lin
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Liu, T. C.
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Lai, Kwang-Chang
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Huang, M. A.
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物理研究所
We argue that an effective flavor discrimination in neutrino telescopes is the key to probe the flavor ratios of astrophysical neutrinos at the source and flavor transition mechanisms of these neutrinos during their propagations from the source to the Earth. We first discuss how well one can reconstruct the flavor ratios of astrophysical neutrinos at the source. We then discuss how to probe flavor transition mechanisms of propagating astrophysical neutrinos. In this regard, we propose a model independent parametrization for neutrino flavor transitions, with the neutrino oscillation as a special case.
Flavor transition mechanisms of propagating astrophysical neutrinos: A model independent parametrization
(2010-11-05)
Lai, Kwang-Chang
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Lin, Guey-Lin
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Liu, T. C.
;
物理研究所
;
Institute of Physics
One of the important goals for future neutrino telescopes is to identify the flavors of astrophysical neutrinos and therefore determine the flavor ratio. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. We propose a model independent parametrization for describing the above flavor transitions. A few flavor transition models are employed to test our parametrization. The observational test for flavor transition mechanisms through our parametrization is discussed.
Heavy-flavor-conserving hadronic weak decays of heavy baryons
(2016-03-07)
Cheng, Hai-Yang
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Cheung, Chi-Yee
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Lin, Guey-Lin
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Lin, Yeu-Chung
;
Yan, Tung-Mow
More than two decades ago, we studied heavy-flavor-conserving weak decays of heavy baryons within the framework that incorporates both heavy-quark and chiral symmetries. In view of the first observation of Xi(-)(b) -> Lambda(0)(b)pi(-) by LHCb recently, we have reexamin Xi(-)(b) -> Lambda(0)(b)pi(-) in the MIT bag and diquark models are consistent with experiment. The major theoretical uncertainty stems from the evaluation of baryon matrix elements. The branching fraction of Xi(c)-> Lambda(c)pi is predicted to be of order 10(-4). It is suppressed relative to B(Xi(b) -> Lambda(b)pi) owing to the shorter lifetime of Xi(c) relative to Xi(b) and the destructive nonspectator W-exchange contribution. The kinematically accessible weak decays of the sextet heavy baryon Omega(Q) are Omega(Q) -> Xi(Q)pi. Due to the absence of the B-6 - B-(3) over bar transition in the heavy quark limit and the B-6 - B-6 transition in the model calculations, Omega(Q) -> Xi(Q)pi vanish in the heavy quark limit.
Magnetowave Induced Plasma Wakefield Acceleration for Ultrahigh Energy Cosmic Rays
(2009-03-20)
Chang, Feng-Yin
;
Chen, Pisin
;
Lin, Guey-Lin
;
Noble, Robert
;
Sydora, Richard
Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic astrophysical outflow has been proposed as a viable mechanism for the acceleration of cosmic particles to ultrahigh energies. Here we present simulation results that clearly demonstrate the viability of this mechanism for the first time. We invoke the high frequency and high speed whistler mode for the driving pulse. The plasma wakefield obtained in the simulations compares favorably with our newly developed relativistic theory of the MPWA. We show that, under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over hundreds of plasma skin depths. Invoking active galactic nuclei as the site, we show that MPWA production of ultrahigh energy cosmic rays beyond ZeV (10(21) eV) is possible.
Neutrino flavor ratio on Earth and at astrophysical sources
(2010-04-01)
Lai, Kwang-Chang
;
Lin, Guey-Lin
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Liu, T. C.
;
物理研究所
;
Institute of Physics
We present the reconstruction of neutrino flavor ratios at astrophysical sources. For distinguishing the pion source and the muon-damped source to the 3 a level, the neutrino flux ratios, R equivalent to phi(nu(mu))/(phi(nu(e)) + phi(nu(r))) and S equivalent to phi(nu(e))/(phi(nu(r))), need to be measured in accuracies better than 10%. (C) 2010 Elsevier B.V. All rights reserved.
NEUTRINO FLAVOR RATIOS ON EARTH UNDER DECAY AND OSCILLATION SCENARIOS
(2013)
Liu, T. C.
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Lai, Kwang-Chang
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Lin, Guey-Lin
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物理研究所
;
Institute of Physics
In the neutrino propagation mechanisms, both neutrino oscillation and decay mechanisms, the actual neutrinos flavor ratio at astrophysical sources can be quite different from observed ratios on Earth.(1) We introduce the recent global fitting result of the mixing angle values(2) into the analysis to point out the allowed neutrino flavor ratios on Earth for standard neutrino oscillation and general decay mechanisms. In this analysis, four types of the neutrino decay mechanisms can be separated from the oscillation case easily with arbitary initial neutrino flavor ratio and the other four types of neutrino decay mechanisms can be identified from the oscillation case with the specified source. The rest types of neutrino decays strongly overlape with the oscillation and cannot be identified.
NEUTRINO FLAVOR RATIOS ON THE EARTH FOR DECAY AND OSCILLATION SCENARIOS
(2013-01-20)
Liu, T. C.
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Lai, Kwang-Chang
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Lin, Guey-Lin
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物理研究所
;
Institute of Physics
Due to flavor transition mechanisms in neutrino propagations, both neutrino oscillation and decay, neutrinos flavor ratio at astrophysical sources can quite different from observed ratios on the Earth.(1) We use the recent global fitting result of the mixing angle values(2) to determine the allowed neutrino flavor ratios on the Earth for standard neutrino oscillation and general decay mechanisms. In this analysis, four types of the neutrino decay mechanisms can be distinguished from the oscillation case easily with arbitrary initial neutrino flavor ratio and the other four types of neutrino decay mechanisms can be distinguished from the oscillation case with the specified source. The rest types of neutrino decays strongly overlap with the oscillation and cannot be identified.
Neutrino physics with JUNO
(2016-03)
An, Fengpeng
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An, Guangpeng
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An, Qi
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Antonelli, Vito
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Baussan, Eric
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multipurpose underground liquid scintillator detector, was proposed with the determination of the neutrino mass hierarchy (MH) as a primary physics goal. The excellent energy resolution and the large fiducial volume anticipated for the JUNO detector offer exciting opportunities for addressing many important topics in neutrino and astro-particle physics. In this document, we present the physics motivations and the anticipated performance of the JUNO detector for various proposed measurements. Following an introduction summarizing the current status and open issues in neutrino physics, we discuss how the detection of antineutrinos generated by a cluster of nuclear power plants allows the determination of the neutrino MH at a 3-4 sigma significance with six years of running of JUNO. The measurement of antineutrino spectrum with excellent energy resolution will also lead to the precise determination of the neutrino oscillation parameters sin(2) theta(12), Delta m(21)(2), and vertical bar Delta m(ee)(2)vertical bar to an accuracy of better than 1%, which will play a crucial role in the future unitarity test of the MNSP matrix. The JUNO detector is capable of observing not only antineutrinos from the power plants, but also neutrinos/antineutrinos from terrestrial and extra-terrestrial sources, including supernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos, atmospheric neutrinos, and solar neutrinos. As a result of JUNO\'s large size, excellent energy resolution, and vertex reconstruction capability, interesting new data on these topics can be collected. For example, a neutrino burst from a typical core-collapse supernova at a distance of 10 kpc would lead to similar to 5000 inverse-beta-decay events and similar to 2000 all-flavor neutrino-proton ES events in JUNO, which are of crucial importance for understanding the mechanism of supernova explosion and for exploring novel phenomena such as collective neutrino oscillations. Detection of neutrinos from all past core-collapse supernova explosions in the visible universe with JUNO would further provide valuable information on the cosmic star-formation rate and the average core-collapse neutrino energy spectrum. Antineutrinos originating from the radioactive decay of uranium and thorium in the Earth can be detected in JUNO with a rate of similar to 400 events per year, significantly improving the statistics of existing geoneutrino event samples. Atmospheric neutrino events collected in JUNO can provide independent inputs for determining the MH and the octant of the theta(23) mixing angle. Detection of the Be-7 and B-8 solar neutrino events at JUNO would shed new light on the solar metallicity problem and examine the transition region between the vacuum and matter dominated neutrino oscillations. Regarding light sterile neutrino topics, sterile neutrinos with 10-(5) eV(2) < Delta m(41)(2) < 10(-2) and a sufficiently large mixing angle theta(14) could be identified through a precise measurement of the reactor antineutrino energy spectrum. Meanwhile, JUNO can also provide us excellent opportunities to test the eV-scale sterile neutrino hypothesis, using either the radioactive neutrino sources or a cyclotron-produced neutrino beam. The JUNO detector is also sensitive to several other beyondthe-standard-model physics. Examples include the search for proton decay via the p -> K++ <(v)over bar> decay channel, search for neutrinos resulting from dark-matter annihilation in the Sun, search for violation of Lorentz invariance via the sidereal modulation of the reactor neutrino event rate, and search for the effects of non-standard interactions. The proposed construction of the JUNO detector will provide a unique facility to address many outstanding crucial questions in particle and astrophysics in a timely and cost-effective fashion. It holds the great potential for further advancing our quest to understanding the fundamental properties of neutrinos, one of the building blocks of our Universe.
Physics prospects of the Jinping neutrino experiment
(2017-02-01)
Beacom, John F.
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Chen, Shaomin
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Cheng, Jianping
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Doustimotlagh, Sayed N.
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Gao, Yuanning
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.
Probing annihilations and decays of low-mass galactic dark matter in IceCube DeepCore array: Track events
(2012-01-25)
Lee, Fei-Fan
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Lin, Guey-Lin
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物理研究所
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Institute of Physics
The deployment of DeepCore array significantly lowers IceCube's energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we calculate the track event rate in DeepCore array due to neutrino flux produced by annihilations and decays of galactic dark matter. We also calculate the background event rate due to the atmospheric neutrino flux for evaluating the sensitivity of DeepCore array to galactic dark matter signatures. Unlike previous approaches, which set the energy threshold for track events at around 50 GeV (this choice avoids the necessity of including the oscillation effect in the estimation of atmospheric background event rate), we have set the energy threshold at 10 GeV to take full advantage of DeepCore array. We compare our calculated sensitivity with those obtained by setting the threshold energy at 50 GeV. We conclude that our proposed threshold energy significantly improves the sensitivity of DeepCore array to the dark matter signature for m (chi) < 100 GeV in the annihilation scenario and m (chi) < 300 GeV in the decay scenario.
Probing dark matter self-interaction in the Sun with IceCube-PINGU
(2014-10-01)
Chen, Chian-Shu
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Lee, Fei-Fan
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Lin, Guey-Lin
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Lin, Yen-Hsun
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物理研究所
We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 similar to 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels chi chi -> tau(+)tau(-), nu(nu) over bar as examples. The PINGU sensitivities to DM self-interaction cross section sigma(chi chi) are estimated for track and cascade events.