Search For Neutrinos Research Articles

Searches for Massive Neutrinos with Mechanical Quantum Sensors

The development of quantum optomechanics now allows mechanical sensors with femtogram masses to be controlled and measured in the quantum regime. If the mechanical element contains isotopes that undergo nuclear decay, measuring the recoil of the sensor following the decay allows reconstruction of the total momentum of all emitted particles, including any neutral particles that may escape detection in traditional detectors. As an example, for weak nuclear decays the momentum of the emitted neutrino can be reconstructed on an event-by-event basis. We present the concept that a single nanometer-scale, optically levitated sensor operated with sensitivity near the standard quantum limit can search for heavy sterile neutrinos in the keV-MeV mass range with sensitivity significantly beyond existing constraints. We also comment on the possibility that mechanical sensors operated well into the quantum regime might ultimately reach the sensitivities required to provide an absolute measurement of the mass of the light neutrino states.

Impact of wave packet separation in low-energy sterile neutrino searches

Light sterile neutrinos have been motivated by anomalies observed in short-baseline neutrino experiments.Among them, radioactive-source and reactor experiments have provided evidence and constraints, respectively, for electron neutrino disappearance compatible with an eV-scale neutrino. The results from these observations are seemingly in conflict. This letter brings into focus the assumption that the neutrino wave packet can be approximated as a plane wave, which is adopted in all analyses of such experiments. We demonstrate that the damping of oscillations, e.g., due to a finite wave packet size, solve the tension between these electron-flavor observations and constraints.

Gamma-Ray Emission from Galaxies Hosting Molecular Outflows

Many star-forming galaxies and those hosting active galactic nuclei show evidence of massive outflows of material in a variety of phases including ionized, neutral atomic, and molecular. Molecular outflows in particular have been the focus of recent interest as they may be responsible for removing gas from the galaxy, thereby suppressing star formation. As material is ejected from the cores of galaxies, interactions of the outflowing material with the interstellar medium can accelerate cosmic rays and produce high-energy gamma rays. In this work, we search for gamma-ray emission from a sample of local galaxies known to host molecular outflows using data collected by the Fermi Large Area Telescope. We employ a stacking technique in order to search for and characterize the average gamma-ray emission properties of the sample. Gamma-ray emission is detected from the galaxies in our sample at the 4.4σ level with a power-law photon index of Γ ≈ 2 in the 1–800 GeV energy range. The emission is found to correlate with tracers of star formation activity, namely the 8–1000 μm infrared luminosity. We also find that the observed signal can be predominantly attributed to H ii galaxies hosting energy-driven outflows. While we do not find evidence suggesting that the outflows are accelerating charged particles directly, galaxies with molecular outflows may produce more gamma rays than galaxies without outflows. In particular, the set consisting of gamma-ray-detected galaxies with molecular outflows are nearly perfect calorimeters and may be future targets for searches of high-energy neutrinos.

Multi-messenger implications of the Pierre Auger Observatory measurements

The Pierre Auger Observatory is not only the world’s largest cosmic-ray observatory, but also an efficient detector of cosmic particles other than nuclei. Using its enormous exposure, the Observatory is a competitive player in searches for ultra-high energy neutrinos, photons, and even particles that could be predicted by theories beyond the standard model of particle physics. We present our recent results of such searches, targeting both the diffuse fluxes of particles and specific transient events. Special attention is given to the potential of the Observatory to support or constrain the observations of the ANITA experiment interpreted as upward-going air showers. The search for correlations of arrival directions of ultra-high energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array with high-energy neutrinos detected by IceCube and ANTARES experiments is also discussed.

Hyper-Kamiokande detector and its capabilities in astrophysical neutrino search

Hyper-Kamiokande (Hyper-K) is a next generation underground large water Cherenkov detector. Its tank will be filled with 260000 metric tons of ultra-pure water with a fiducial volume of 0.19 Mtons, which is about 8 times larger than that of its predecessor Super-Kamiokande. In its water volume, Cherenkov light will be produced by neutrino interactions and detected by newly developed photo sensors installed in a dedicated frame.Two different kinds of photo-detectors systems are considered for Hyper-K: 20-inch PMT and multi-PMT (mPMT). In particular, the mPMT system consists of a pressure sealed vessel with 19 3-inch PMTs installed inside. This configuration was implemented for the first time in the KM3NeT experiment, and has been demonstrated to improve the Hyper-K physics capabilities [1, 2].Hyper-K will be located in the Kamioka mine (Japan), where a dedicated cavern under a 600m-high mountain is being excavated for the installation of the detector. With its fruitful physics research program, Hyper-K will play a highly significant role in the next neutrino physics frontier, in particular for the CP violation, and including the neutrino astrophysics program, providing important information from its measurements.The physics potential of the Hyper-K neutrino astrophysics program will be discussed in this contribution.

Model Constraints Based on the IceCube Neutrino Nondetection of GRB 221009A

GRB 221009A is a bright gamma-ray burst (GRB) with isotropic energy larger than 1054 erg. Its fairly low redshift makes it a promising candidate for high-energy neutrino detection. However, a neutrino search for this GRB reported by the IceCube collaboration yielded a null result. In this paper, we utilize the upper limit from the IceCube observation to test different GRB prompt emission models. We find that, at least for this specific burst, the dissipative photosphere model could be ruled out in a large parameter space. The internal-shock model can survive only with a large bulk motion Lorentz factor Γ, where the most stringent and conservative constraints are Γ > ∼ 450 and Γ > ∼ 200, respectively. Also, the ratio of the total dissipated energy that goes into the protons and electrons (ϵ p /ϵ e ) can be constrained with a given Γ. For Γ < 400, ϵ p /ϵ e < 10 is required. For the Internal-collision-induced Magnetic Reconnection and Turbulence (ICMART) model, the constraint from GRB 221009A is modest. Under the ICMART model, only for extreme situations when most dissipated energy deposit into protons and all accelerated protons are suitable for producing neutrinos, a slightly large bulk motion (Γ > ∼ 250) is required.

The Long Journey of ICARUS: From the LAr-TPC Concept to the First Full-Scale Detector

The Liquid Argon Time Projection Chamber (LAr-TPC) technology was conceived at the end of the 1970s as a way to combine the excellent spatial and calorimetric performance of the traditional bubble chambers with the electronic read-out of the TPCs, obtaining the so-called “electronic bubble chambers”. This technology was intended to be applied in particular to neutrino physics as an alternative to Ring Water Cherenkov detectors. The main technological issues of such an innovative technique were investigated from the very beginning within the ICARUS program, with staged R&amp;D starting from prototypes of increasing mass to arrive, at the end of 1990s, at the largest LAr-TPC detector ever built at that time: ICARUS-T600, with almost 500 tons of active LAr. The successful operations of the ICARUS-T600 LAr-TPC in its more than twenty years of life, from the first run at surface in Pavia (Italy) in 2001 to the LNGS (Italy) underground run being exposed to the CNGS beam from CERN to Gran Sasso (2010–2013) and finally to the ongoing run at Fermilab (USA) for sterile neutrino searches (2020–), have demonstrated the huge potential of the LAr-TPC technique, paving the way to future larger LAr-TPCs detectors as DUNE.

The TRISTAN 166-pixel detector: Preliminary results with a planar setup

We present the first experimental results achieved with a monolithic array of 166 Silicon Drift Detectors (SDD). This detector was developed for the TRISTAN experiment, targeting the search for a sterile neutrino in the keV mass range by means of accurate Beta spectroscopy of the Tritium decay. We briefly report on the design and characterization with X-rays of the full signal chain: from the SDD array, operated in a planar configuration with all the components of the final system, to the acquisition platform simultaneously acquiring all 166 channels. The average energy resolution is better than 250eV FWHM at 5.9keV at a temperature of 0 °C, a 6 μs shaping time, and an average count rate of 1kcps per channel, 100 times smaller than the final experiment one.

State-of-the-art collapsar jet simulations imply undetectable subphotospheric neutrinos

Mounting evidence suggests that the launching of collapsar jets is magnetically driven. Recent general relativistic magneto-hydrodynamic simulations of collapsars reveal that the jet is continuously loaded with baryons, owing to strong mixing with the cocoon. This results in a high photosphere at $\gtrsim 10^{12}$ cm. Consequently, collisionless internal shocks below the photosphere are disfavored, and the neutrino production in the deepest jet regions is prevented, in contrast to what has been assumed in the literature. We find that subphotospheric neutrino production could only take place in the presence of collisionless sub-shocks or magnetic reconnection. Efficient particle acceleration is not possible in the cocoon, at the cocoon-counter cocoon shock interface, or at the shock driven by the cocoon in the event of a jet halted in an extended envelope. These subphotospheric neutrinos have energy $E_\nu \lesssim 10^5$ GeV for initial jet magnetizations $\sigma_0=15$-$2000$. More than one neutrino and antineutrino event is expected to be observed in Hyper-Kamiokande and IceCube DeepCore for sources located at $z \lesssim \mathcal{O}(0.1)$. Because of their energy, these neutrinos do not contribute to the diffuse flux detected by the IceCube Neutrino Observatory. Our findings have implications on neutrino searches ranging from gamma-ray bursts to luminous fast blue optical transients.

Searching for neutral particles at the highest energies at the Pierre Auger Observatory

The Pierre Auger Observatory, being the largest air-shower experiment in the world, offers an unprecedented exposure to neutral particles at the highest energies. Since the beginning of data collection more than 18 years ago, several searches for ultra-high-energy (UHE,E&gt; 1017eV) photons and neutrinos have been performed. The upper limits on the diffuse flux of UHE photons and neutrinos derived from Auger data are among the most stringent in the world, severely constraining models for the origin of UHE cosmic rays. In addition, the Pierre Auger Observatory contributes to current efforts in multimessenger astronomy through follow-up searches for UHE photons and neutrinos in association with transient events, such as gravitational wave events. The various activities concerning searches for UHE photons and neutrinos in the data from the Pierre Auger Observatory are presented and the current results are summarized. In addition, future perspectives will be discussed.

Neutrino mass measurement and sterile neutrinos search with the KATRIN experiment

In this proceeding, we report on the latest results of the KATRIN experiment on the effective electron anti-neutrino mass and the search for sterile neutrinos. KATRIN performed a high resolution and high statistics spectroscopy measurement of the tritium β-decay spectrum around its endpoint energy. The analysis of ~ 1265 h of data acquired during the first two measurement campaigns of 2019 led to the most stringent limit on the neutrino mass with mν &lt; 0.8 eV- (90% CL). We also report on the improved KATRIN exclusion limits for the eV- and keV-scale sterile neutrinos search. Finally, the future of KATRIN with the TRISTAN detector aiming at further improve the laboratory-based sensitivity to keV-scale sterile neutrino is discussed.

Creation of the second neutrino laboratory at the SM-3 reactor in order to increase the accuracy of the &amp;quot;Neutrino-4&amp;quot; experiment

In the experiment &amp;quot;Neutrino-4&amp;quot; on the search for a sterile neutrino, the effect of oscillations was found at a confidence level of 3 standard deviations. In order to significantly increase the accuracy of the experiment, a second neutrino laboratory is created at the SM-3 reactor (Dimitrovgrad, Russia) and a new neutrino detector is developed. The scintillation-type detector consists of 4 modules having a multi-sectional structure with a horizontal arrangement of 100 sections with PMTs located on both sides of the section. The possibility of increasing the accuracy of the experiment by a factor of 2.7 is shown, which will make it possible to achieve a confidence level of more than 5 standard deviations and answer the question of the existence of a sterile neutrino. Keywords: sterile neutrino, reactor antineutrino.

Создание второй нейтринной лаборатории на реакторе СМ-3 с целью увеличения точности эксперимента "Нейтрино-4"

In the experiment "Neutrino-4" on the search for a sterile neutrino, the effect of oscillations was found at a confidence level of 3 standard deviations. In order to significantly increase the accuracy of the experiment, a second neutrino laboratory is created at the SM-3 reactor (Dimitrovgrad, Russia) and a new neutrino detector is developed. The scintillation-type detector consists of 4 modules having a multi-sectional structure with a horizontal arrangement of 100 sections with PMTs located on both sides of the section. The possibility of increasing the accuracy of the experiment by a factor of 2.7 is shown, which will make it possible to achieve a confidence level of more than 5 standard deviations and answer the question of the existence of a sterile neutrino.

Multi-messenger studies with the Pierre Auger Observatory

The combination of data from observatories measuring ultra-high energy cosmic rays, photons, neutrinos and gravitational waves has provided new insights into the most extreme phenomena in the Universe. Sharing information within a broad community is the foundation of the multi-messenger approach. The Pierre Auger Observatory, the world’s largest cosmic ray detector, provides sensitivity to photons and neutrinos above 1017eV, thus contributing significantly to this joint effort. The latest results from diffuse and targeted searches will be reviewed here, along with results from follow-up analyses and future perspectives. In particular, preliminary limits on photon fluence from a selection of gravitational wave sources detected by LIGO/Virgo and results of the search for ultra-high energy neutrinos from binary black hole mergers will be presented.

Searching for high-energy neutrinos from the most luminous supernovae with the IceCube Neutrino Observatory

The sources of the astrophysical neutrino flux discovered by IceCube remain for the most part unresolved. Extragalactic core-collapse supernovae (CCSNe) have been suggested as potentially able to produce high-energy neutrinos. In recent years, the Zwicky Transient Facility has discovered a population of exceptionally luminous supernovae, whose powering mechanisms have not yet been fully established. A fraction of these objects fall in the broader category of type IIn CCSNe, showing signs of interaction with a dense circumstellar medium. Theoretical models connect the supernova photometric properties to the dynamics of a shock-powered emission, predicting particle acceleration. In this contribution, we outline the plan for a search of high-energy neutrinos targeting the population of superluminous and type IIn supernovae with the IceCube Neutrino Observatory.

Neutrinos from the Brightest Gamma-Ray Burst?

We discuss implications that can be obtained by searches for neutrinos from the brightest gamma-ray burst (GRB), GRB 221009A. We derive constraints on GRB model parameters such as the cosmic-ray loading factor and dissipation radius, taking into account both neutrino spectra and effective areas. The results are strong enough to constrain proton acceleration near the photosphere, and we find that the single burst limits are comparable to those from stacking analysis. Quasi-thermal neutrinos from subphotospheres and ultra-high-energy neutrinos from external shocks are not yet constrained. We show that GeV–TeV neutrinos originating from neutron collisions are detectable, and urge dedicated analysis on these neutrinos with DeepCore and IceCube as well as ORCA and KM3NeT.

Light sterile neutrino and leptogenesis

We studied models of leptogenesis where three right-handed Majorana neutrinos are involved and the minimal-extended seesaw mechanism including an additional singlet field produces four light neutrinos. This study shows that the type of mass ordering and heavy Majorana scales can be determined by inputting the simplest orthogonal matrix into the Casas-Ibarra(CI) representation of seesaw. The CP asymmetry produced from the decays of heavy neutrinos and the dilution mass are predicted in terms of the mass and mixing elements of the fourth neutrino. Upon the choice of CI matrix, the existence of a light sterile neutrino is required to explain the high-energy lepton asymmetry in light of phenomenological measurements. Although there are several free parameters attributable to an additional neutrino, the model can be in part constrained by low-energy experiments such as sterile neutrino searches and neutrinoless double-beta decays, as well as the observed baryon asymmetry in the universe.

ARIEL experiments and theory

I present an overview of experiments at TRIUMF ARIEL and ISAC facilities covering both the current and the future envisioned programs. I also briefly review theory program at TRIUMF that relates to the ARIEL experimental program. I highlight several recent experimental results from the nuclear astrophysics, nuclear structure, fundamental symmetries, and the sterile neutrino search. Finally, I mention ongoing theoretical ab initio calculations of the proton capture on 7Li related to the X17 boson observation.

Safe liquid scintillators for large scale detectors

Many experiments in particle physics, in particular in the field of neutrino searches, rely on organic liquid scintillators as target and detection material. The size of these detectors was continously growing in the last decades, up to the kiloton scale. In several cases these detectors are located at sites with enhanced safety requirements such as underground laboratories or in the vicinity of nuclear reactors. Therefore, there is strong demand in liquids which are safe with respect to aspects such as fire protection, human health or environmental pollution. The flash point, the vapor pressure or the toxicity need to be significantly improved as compared to classical solvents such as xylene or pseudocumene. We present and compare the performance and optical properties of scintillators based on high flash point solvents. In particular, polysiloxane based scintillators are characterized by outstanding properties in terms of safety.

EUSO-SPB2 Fluorescence Telescope trigger test within the EUSO@TurLab Project

The second generation Extreme Universe Space Observatory on a Super-Pressure Balloon (EUSO-SPB2) mission is on track to be approved by NASA for a long duration flight (up to 100 days) in 2023 from Wanaka, New Zealand. EUSO-SPB2 will monitor the night atmosphere of the Southern hemisphere from 33 km altitude to detect Ultra-High Energy Cosmic Rays (UHECRs) and search for astrophysical and cosmogenic neutrinos. EUSO-SPB2 features two telescopes, a Cherenkov (CT) and a Fluorescence (FT) Telescope. The hardware implementation and performance of the FT trigger logic were tested at the TurLab facility, hosted at the University of Turin. The tests proved the correct hardware implementation of the trigger logic and its ability to detect μs timescale transient signals.