arXiv subjects

M. Misiaszek

Publications and source records attributed to M. Misiaszek.

86 records · Page 5Linked to original sources

arXiv2011

Neutrinos Polarimetry in Muon Decay

We consider massive Dirac electron antineutrino to be observed in the muon decay, $μ^{-} \rightarrow e^- +\barν_{e} + ν_μ$, at rest in the LAB reference frame. A computation of $\barν_{e}$ differential direct spectral shape and angular distribution was performed. This has resulted in transverse component of the neutrino polarization emerging from the nonstandard S, T sector of the Lorentz structure in the Fermi leptonic charged weak interaction. The calculation is based on empirical values of the coupling parameters.

hep-ph↗

arXiv2011

Muon and Cosmogenic Neutron Detection in Borexino

Borexino, a liquid scintillator detector at LNGS, is designed for the detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear reactors, and the Earth. The feeble nature of these signals requires a strong suppression of backgrounds below a few MeV. Very low intrinsic radiogenic contamination of all detector components needs to be accompanied by the efficient identification of muons and of muon-induced backgrounds. Muons produce unstable nuclei by spallation processes along their trajectory through the detector whose decays can mimic the expected signals; for isotopes with half-lives longer than a few seconds, the dead time induced by a muon-related veto becomes unacceptably long, unless its application can be restricted to a sub-volume along the muon track. Consequently, not only the identification of muons with very high efficiency but also a precise reconstruction of their tracks is of primary importance for the physics program of the experiment. The Borexino inner detector is surrounded by an outer water-Cherenkov detector that plays a fundamental role in accomplishing this task. The detector design principles and their implementation are described. The strategies adopted to identify muons are reviewed and their efficiency is evaluated. The overall muon veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction algorithms developed are presented. Their performance is tested against muon events of known direction such as those from the CNGS neutrino beam, test tracks available from a dedicated External Muon Tracker and cosmic muons whose angular distribution reflects the local overburden profile. The achieved angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending on the impact parameter of the crossing muon. The methods implemented to efficiently tag cosmogenic neutrons are also presented.

physics.ins-det↗

arXiv2011

Polarized Muon Decay at Rest with V+A Interaction

In this paper, we analyze the polarized muon decay at rest (PMDaR) and elastic neutrino-electron scattering (ENES) admitting the non-standard V+A interaction in addition to standard V-A interaction. Considerations are made for Dirac massive muon neutrino and electron antineutrino. Moreover, muon neutrinos are transversely polarized. It means that the outgoing muon-neutrino beam is a mixture of the left- and right-chirality muon neutrinos and has a fixed direction of transverse spin polarization with respect to production plane. We show that the angle-energy distribution of muon neutrinos contains the interference terms between the standard V-A and exotic V+A couplings, which are proportional to the transverse components of muon neutrino spin polarization. They do not vanish in a limit of massless neutrino and include the relative phases to test the CP violation. In consequence, it allows to calculate a neutrino flux and an expected event number in the ENES (detection process) both for the standard model prediction and the case of neutrino left-right mixture.

hep-ph↗

arXiv2009

CP Violation in Antineutrino-Electron Elastic Scattering

Elastic scattering of transversely polarized electron antineutrino beam off unpolarized electrons can be used to detect the CP-violating effects by measuring the azimuthal asymmetry of recoil electrons caused by the interference terms between the standard vector $c_{V}^{L}$, axial $c_{A}^{L}$ couplings of left-chirality antineutrinos and exotic scalar $c_{S}^{R}$ coupling of right-chirality ones in the differential cross section. It would be a positive evidence for the existence of the exotic antineutrino states. Moreover, we also show that the differential cross section for the $\overlineν e^- $ scattering can be obtained from the one for the $νe$ scattering, if one makes the substitution $c_{T}^{R} \to -c_{T}^{R}$, $c_{A}^{L} \to -c_{A}^{L}$, ${\bf q}\to -{\bf q}$, ${\boldmath $\hatη_ν$}\to -{\boldmath $\hatη_ν$}$.

hep-ph↗

arXiv2007

Decay of polarized muon at rest as a source of polarized neutrino beam

In this paper, we indicate the theoretical possibility of using the decay of polarized muons at rest as a source of the transversely polarized electron antineutrino beam. Such a beam can be used to probe new effects beyond standard model. We mean here new tests concerning CP violation, Lorentz structure and chirality structure of the charged current weak interactions. The main goal is to show how the energy and angular distribution of the electron antineutrinos in the muon rest frame depends on the transverse components of the antineutrino beam polarization. Our analysis is model-independent and consistent with the current upper limits on the non-standard couplings. The results are presented in a limit of infinitesimally small mass for all particles produced in the decay.

hep-ph↗

arXiv2006

Thermal neutrinos from pre-supernova

We would like to discuss prospects for neutrino observations of the core-collapse supernova progenitor during neutrino-cooled stage. We will present new theoretical results on thermal neutrino and antineutrino spectra produced deep inside the pre-supernova core. Three competing processes: pair-, photo and plasma-neutrino production, are taken into account. The results will be used to estimate signal in existing and future neutrino detectors. Chance for supernova prediction is estimated, with possible aid to core-collapse neutrino and gravitational wave detectors in the form of early warning.

astro-ph↗

arXiv2006

Neutrino spectrum from the pair-annihilation process in the hot stellar plasma

An new method of calculating the energy spectrum of neutrinos and antineutrinos produced in the electron-positron annihilation processes in hot stellar plasma is presented. Detection of these neutrinos, produced copiously in the presupernova which is evolutionary advanced neutrino-cooled star, may serve in future as a trigger of pre-collapse early warning system. Also, observation of neutrinos will probe final stages of thermonuclear burning in the presupernova. The spectra obtained with the new method are compared to Monte Carlo simulations. To achieve high accuracy in the energy range of interest, determined by neutrino detector thresholds, differential cross-section for production of the antineutrino, previously unknown in an explicit form, is calculated as a function of energy in the plasma rest frame. Neutrino spectrum is obtained as a 3-dimensional integral, computed with the use of the Cuhre algorithm of at least 5% accuracy. Formulae for the mean neutrino energy and its dispersion are given as a combination of Fermi-Dirac integrals. Also, useful analytical approximations of the whole spectrum are shown.

astro-ph↗

arXiv2005

The polarized electron target as a new solar-neutrino detector

In this paper, we analyze the scattering of solar neutrinos on the polarized electron target, and predict how the effect of parity violation in weak interactions may help to distinguish neutrino signal from detector background. We indicate that the knowledge of the Sun motion across the sky is sufficient to predict the day/night asymmetry in the $(ν_ee^-)$ scattering on the polarized electron target. To make this detection feasible, the polarized electron target for solar neutrinos needs to be build from magnetic materials, e.g. from ferromagnetic iron foils, paramagnetic scintillator crystals or scintillating ferrofluids.

astro-ph↗

arXiv2005

Scattering of neutrinos on a polarized electron target as a test for new physics beyond the Standard Model

In this paper, we analyze the scattering of the neutrino beam on the polarized electron target, and predict the effects of two theoretically possible scenarios beyond the Standard Model. In both scenarios, Dirac neutrinos are assumed to be massive. First, we consider how the existence of CP violation phase between the complex vector V and axial A couplings of the Left-handed neutrinos affects the azimuthal dependence of the differential cross section. The future superbeam and neutrino factory experiments will provide the unique opportunity for the leptonic CP violation studies, if the large magnetized sampling calorimeters with good event reconstruction capabilities are build. Next, we take into account a scenario with the participation of the exotic scalar S coupling of the Right-handed neutrinos in addition to the standard vector V and axial A couplings of the Left-handed neutrinos. The main goal is to show how the presence of the R-handed neutrinos, in the above process changes the spectrum of recoil electrons in relation to the expected Standard Model prediction, using the current limits on the non-standard couplings. The interference terms between the standard and exotic couplings in the differential cross section depend on the angle $α$ between the transverse incoming neutrino polarization and the transverse electron polarization of the target, and do not vanish in the limit of massless neutrino. The detection of the dependence on this angle in the energy spectrum of recoil electrons would be a signature of the presence of the R-handed neutrinos in the neutrino-electron scattering. To make this test feasible, the polarized artificial neutrino source needs to be identified.

hep-ph↗

arXiv2004

Problem of neutrino handedness in weak interactions

In this paper we show that the neutrino observables, including an information about the transverse neutrino spin polarization, can be sensitive to the effects coming from the interference terms between the standard vector V, axial A couplings of L-handed neutrinos and exotic scalar S coupling of R-handed ones in the differential cross section. Our analysis is based on the electron neutrino-electron elastic scattering. This reaction is considered at the level of the four-fermion point interaction. Neutrinos are assumed to be massive and to be polarized Dirac fermions coming from the Sun.

astro-ph↗

arXiv2004

Neutrinos from pre-supernova star

Analysis of the massive star properties during C, Ne, O and Si burning i.e. the neutrino-cooled stage, leads to the simplified neutrino emission model. In the framework of this model we have simulated spectrum of the antineutrinos. Flux normalized according to the massive star model with explicitly given neutrino luminosity allow us to predict signal produced in water Cherenkov detectors. The results are discussed from the point of view of the possibility of the core-collapse supernova event prediction in advance of a few days.

astro-ph↗

arXiv2004

Detection possibility of the pair-annihilation neutrinos from the neutrino-cooled pre-supernova star

The signal produced in neutrino observatories by the pair-annihilation neutrinos emitted from a 20 $M_{\odot}$ pre-supernova star at the silicon burning phase is estimated. The spectrum of the neutrinos with an average energy $\sim$2 MeV is calculated with the use of the Monte Carlo method. A few relevant reactions for neutrinos and anti-neutrinos in modern detectors are considered. The most promising results are from $\barν_e + p \longrightarrow n + e^{+}$ reaction. During the Si-burning phase we expect 1.27 neutrons/day/kiloton of water to be produced by neutrinos from a star located at a distance of 1 kpc. Small admixture of effective neutron-absorbers as e.g. NaCl or GdCl$_{3}$ makes these neutrons easily visible because of Cherenkov light produced by electrons which were hit by $\sim$8 MeV photon cascade emitted by Cl or Gd nuclei. The estimated rate of neutron production for SNO and Super-Kamiokande is, respectively, 2.2 and 41 events per day for a star at 1 kpc. For future detectors UNO and Hyper-Kamiokande we expect 5.6 and 6.9 events per day even for a star 10 kpc away. This would make it possible to foresee a massive star death a few days before its core collapse. Importance of such a detection for theoretical astrophysics is discussed.

astro-ph↗

arXiv2003

Core-Collapse Supernova Mechanism - Importance of Rotation

An attempt is made to assess the significance of rotation in the core-collapse supernova phenomenon, from both observational and theoretical point of view. The data on supernovae particularly indicative of the role of rotation in the collapse-triggered explosion is emphasized. The problem of including the rotation of presupernova core into the supernova theory is considered. A two-dimensional classification scheme of core-collapse supernovae is proposed which unifies 'classical' supernovae of type Ib/c and type II, 'hypernovae' and some GRB events.

astro-ph↗

arXiv2003

Right-handed Dirac Neutrinos in $νe^{-}$ Scattering and Azimuthal Asymmetry in Recoil Electron Event Rates

In this paper a scenario with the participation of the exotic scalar S, tensor T and pseudoscalar couplings of the right-handed neutrinos in addition to the standard vector V, axial A couplings of the left-handed neutrinos in the low-energy $(ν_μe^{-})$ and $(ν_{e}e^{-})$ scattering processes is considered. Neutrinos are assumed to be massive Dirac fermions and to be polarized. Both reactions are studied at the level of the four-fermion point interaction. The main goal is to show that the physical consequence of the presence of the right-handed neutrinos is an appearance of the azimuthal asymmetry in the angular distribution of the recoil electrons caused by the non-vanishing interference terms between the standard and exotic couplings, proportional to the transverse neutrino polarization vector. The upper limits on the expected effect of this asymmetry for the low-energy neutrinos $(E_ν < 1 MeV)$ are found. We also show that if the neutrino helicity rotation $(ν_{eL} \to ν_{eR})$ in the solar magnetic field takes place, the similar effect of the azimuthal asymmetry of the recoil electrons scattered by the solar neutrinos should be observed. This effect would also come from the interference terms between the standard $(V, A)_{L}$ and exotic $(S, T, P)_{R}$ couplings. New-type neutrino detectors with good angular resolution could search for the azimuthal asymmetry in event number.

hep-ph↗