Neutrino Interaction Cross Sections Research Articles

Search for eV sterile neutrinos at a nuclear reactor — the Stereo project

The re-analyses of the reference spectra of reactor antineutrinos together with a revised neutrino interaction cross section enlarged the absolute normalization of the predicted neutrino flux. The tension between previous reactor measurements and the new prediction is significant at 2.7 σ and is known as “reactor antineutrino anomaly”. In combination with other anomalies encountered in neutrino oscillation measurements, this observation revived speculations about the existence of a sterile neutrino in the eV mass range. Mixing of this light sterile neutrino with the active flavours would lead to a modification of the detected antineutrino flux. An oscillation pattern in energy and space could be resolved by a detector at a distance of few meters from a reactor core: the neutrino detector of the Stereo project will be located at about 10 m distance from the ILL research reactor in Grenoble, France. Lengthwise separated in six target cells filled with 2 m3 Gd-loaded liquid scintillator in total, the experiment will search for a position-dependent distortion in the energy spectrum.

Neutrino-nucleus interactions in the few-GeV region

Knowledge of neutrino interaction cross sections is an important and necessary ingredient in any neutrino measurement and it is crucial to achieve the precision goals of the neutrino oscillation program, making possible new discoveries like the CP violation in the leptonic sector. We briefly review the major features of the neutrino cross sections in the few-GeV region, paying special attention to nuclear effects.

Decisive disappearance search at highΔm2with monoenergetic muon neutrinos

"KPipe" is a proposed experiment which will study muon neutrino disappearance for a sensitive test of the $\Delta m^2\sim1 \mathrm{eV}^2$ anomalies, possibly indicative of one or more sterile neutrinos. The experiment is to be located at the J-PARC Materials and Life Science Facility's spallation neutron source, which represents the world's most intense source of charged kaon decay-at-rest monoenergetic (236 MeV) muon neutrinos. The detector vessel, designed to measure the charged current interactions of these neutrinos, will be 3 m in diameter and 120 m long, extending radially at a distance of 32 m to 152 m from the source. This design allows a sensitive search for $\nu_\mu$ disappearance associated with currently favored light sterile neutrino models and features the ability to reconstruct the neutrino oscillation wave within a single, extended detector. The required detector design, technology, and costs are modest. The KPipe measurements will be robust since they depend on a known energy neutrino source with low expected backgrounds. Further, since the measurements rely only on the measured rate of detected events as a function of distance, with no required knowledge of the initial flux and neutrino interaction cross section, the results will be largely free of systematic errors. The experimental sensitivity to oscillations, based on a shape-only analysis of the $L/E$ distribution, will extend an order of magnitude beyond present experimental limits in the relevant high-$\Delta m^2$ parameter space.

The LAr1-ND Experiment

LAr1-ND is a Liquid Argon Time Projection Chamber (LArTPC) based experiment which will operate in the Booster Neutrino Beam (BNB) at Fermilab, at a distance of 110m from the target. The 112t active volume detector will make precision measurements of the neutrino interaction cross section in argon, as well as forming the near detector for the short-baseline neutrino (SBN) programme at Fermilab. The 4m × 4m × 5m TPC consists of 2 anode planes, each composed of 3 wire planes, with a central cathode. In combination with the MicroBooNE and ICARUS-T600 detectors, this experiment provides a powerful opportunity to understand observed neutrino anomalies, and has the potential to make precision measurements of oscillations to sterile states.In addition to the physics goals, the detector technology developed and used in this experiment will form an important step towards the future detectors for long-baseline neutrino experiments. The detector design will be discussed in the context of its physics potential, and contribution to future technologies.

Results from ND280 near detector

Since the beginning of operation of the Tokai to Kamioka experiment (T2K) the Near Detector system (ND280) has been collecting neutrino interactions. It was able to collect large statistics of data within a few years of operation of the T2K experiment because of high beam intensity and its close location to the production point, a distance of the 280 m from the production target. This paper presents results of a measurement of charged current interactions in ND280 which are used to suppress systematic errors in the oscillation analysis. Systematic effects due to uncertainty in the beam profile and cross sections of neutrino interactions are also discussed.

Reaction mechanisms atMINERνA

The MINER$\nu$A experiment investigates neutrino interactions with nucleons needed for an understanding of electroweak interactions of hadrons. Since nuclear targets are being used many-body effects may affect the extracted cross sections and the energy reconstruction. The latter is essential for the extraction of neutrino oscillation properties. We investigate the influence of nuclear effects on neutrino interaction cross sections and make predictions for charged current quasielastic (QE) scattering, nucleon-knock-out and pion- and kaon-production on a CH target. The Giessen Boltzmann--Uehling--Uhlenbeck (GiBUU) model is used for the description of neutrino-nucleus reactions. Integrated and differential cross sections for inclusive neutrino scattering, QE processes and particle production for the MINER$\nu$A neutrino flux are calculated. The influence of final state interactions on the identification of these processes is discussed. In particular, energy and $Q^2$ reconstruction for the MINER$\nu$A flux are critically examined. The $Q^2$ dependence of the inclusive cross sections is found to be sensitive to the energy reconstruction. Cut-offs in flux distributions have a large effect. Final state interactions affect the pion kinetic energy spectra significantly and increase the kaon cross sections by cross feeding from other channels.

Fibre laser hydrophones for cosmic ray particle detection

The detection of ultra high energetic cosmic neutrinos provides a unique means to search for extragalactic sources that accelerate particles to extreme energies. It allows to study the neutrino component of the GZK cut-off in the cosmic ray energy spectrum and the search for neutrinos beyond this limit. Due to low expected flux and small interaction cross-section of neutrinos with matter large experimental set-ups are needed to conduct this type of research. Acoustic detection of cosmic rays may provide a means for the detection of ultra-high energetic neutrinos. Using relative low absorption of sound in water, large experimental set-ups in the deep sea are possible that are able to detect these most rare events, but it requires highly sensitive hydrophones as the thermo-acoustic pulse originating from a particle shower in water has a typical amplitude as low as a mPa. It has been shown in characterisation measurements that the fibre optic hydrophone technology as designed and realised at TNO provides the required sensitivity. Noise measurements and pulse reconstruction have been conducted that show that the hydrophone is suited as a particle detector.

Highlights from T2K

T2K is a long baseline neutrino oscillation experiment. A high intensity proton beam at J-PARC produces a narrow-band muon-neutrino beam with a peak energy of 0.6 GeV at the far detector, Super-Kamiokande, 295km from the production point. The T2K experiment has observed electron neutrino appearance in a muon neutrino beam and measured sin22θ13 = 0.140−0.032+0.038 (0.170−0.037+0.045) assuming the normal (inverted) hierarchy. In addition the latest measurements of θ23 and ∆m322 are reported, along with the latest T2K neutrino interaction cross section measurements of the inclusive CC, CCQE and NCE channels.

T2K cross section measurements

We describe how the T2K near detector will be used to measure the neutrino interaction cross sections necessary for T2K to reach the final precision for its νe-appearance and νμ-disappearance results. We then present the first near detector cross section result, for charged current inclusive scattering of muon neutrinos, based on data taken during 2010 and 2011 and corresponding to 1.08×1020 protons on target.

Supernova Neutrino Detection

Detecting neutrinos is the key to understanding core-collapse supernovae, but this is notoriously difficult due to the small interaction cross section of neutrinos and the low frequency of supernovae in galaxies. The revolutionary implications of the detection of about 20 neutrinos from SN 1987A tell us that this quest is worthy. However, there is the sobering fact that there have been no other detections, before or since. Now, after decades of effort and patience, we have good reasons to anticipate that detecting supernova neutrinos again is within reach, in particular for the Diffuse Supernova Neutrino Background (DSNB). A first detection of the DSNB in a short time is possible if Super-Kamiokande is upgraded with the proposed modification of dissolved gadolinium to allow neutron tagging. Longer-term, a comprehensive understanding of core-collapse supernovae will require something like the possible Hyper-Kamiokande detector, eventually also with dissolved gadolinium. This systematic path towards increasing sensitivity will surely lead to further revolutionary discoveries in astrophysics.

From eV to EeV: Neutrino cross sections across energy scales

Since its original postulation by Wolfgang Pauli in 1930, the neutrino has played a prominent role in our understanding of nuclear and particle physics. In the intervening 80 years, scientists have detected and measured neutrinos from a variety of sources, both man made and natural. Underlying all of these observations, and any inferences we may have made from them, is an understanding of how neutrinos interact with matter. Knowledge of neutrino interaction cross sections is an important and necessary ingredient in any neutrino measurement. With the advent of new precision experiments, the demands on our understanding of neutrino interactions is becoming even greater. The purpose of this article is to survey our current knowledge of neutrino cross sections across all known energy scales: from the very lowest energies to the highest that we hope to observe. The article covers a wide range of neutrino interactions including coherent scattering, neutrino capture, inverse beta decay, low-energy nuclear interactions, quasielastic scattering, resonant pion production, kaon production, deep inelastic scattering, and ultrahigh energy interactions. Strong emphasis is placed on experimental data whenever such measurements are available.

Exploring nuclear effects in neutrino interactions with MINERvA

With the new era of neutrino-oscillation experiments, it becomes crucially important to know the neutrino interaction cross-sections with a high precision. This is the primary scientific aim of MINERvA experiment located in Fermilab. Another task is to examine the nuclear medium effects in neutrino-induced interactions such as final state modifications in the nucleus. The MINERvA collaboration has all the necessary tools in hand to achieve the above-stated goals: high-intensity neutrino beam, fine-granulated detector with EM and hadron calorimetry regions, various integrated nuclear targets and high-statistics event sample.

Hunt for θ13 with LENA

In a hunt for by far missing neutrino mixing angle θ13 the accelerator experiments have recently indicated non-zero value and the dedicated reactor neutrino experiments are moving towards the data-taking phase to confirm that. The small effect of θ13 to the neutrino oscillation probabilities can be also complementarily probed using artificially made source of mono-chromatic neutrinos with low energies originated from electron capture processes. Due to the small energy of neutrino and tiny interaction cross section, and the expected scale of θ13 support the use of large liquid scintillation detector. In this work, the estimated sensitivities for measurement of mixing angle θ13 is presented in context of proposed LENA detector. Instead of the existing and earlier investigated neutrino source 51Cr, more feasible source candidate 75Se is used. The search for possible sterile neutrino flavors is also discussed.

The T2K ND280 off-axis pi–zero detector

The pi–zero detector (PØD) is one of the subdetectors that makes up the off-axis near detector for the Tokai-to-Kamioka (T2K) long baseline neutrino experiment. The primary goal for the PØD is to measure the relevant cross-sections for neutrino interactions that generate π0's, especially the cross-section for neutral current π0 interactions, which are one of the dominant sources of background to the νμ→νe appearance signal in T2K. The PØD is composed of layers of plastic scintillator alternating with water bags and brass sheets or lead sheets and is one of the first detectors to use Multi-Pixel Photon Counters (MPPCs) on a large scale.

EFFECTS OF NEUTRINO ELECTROMAGNETIC FORM FACTORS ON NEUTRINO INTERACTION WITH FINITE TEMPERATURE ELECTRON MATTERS

The differential cross-section of neutrino interaction with dense and warm electron gasses has been calculated by taking into account the neutrino electromagnetic form factors. The significant effect of electromagnetic properties of neutrino can be found if the neutrino dipole moment, μ ν , is ≥ 5.10-9 μB and neutrino charge radius, Rv, is ≥ 5.10-6 MeV-1. The importance of the retarded correction, detailed balance and Pauli blocking factors is shown and analyzed. Many-body effects on the target matter which are included via random phase approximation (RPA) correlation as well as photon effective mass are also investigated.

Electroweak stars: how nature may capitalize on the standard model's ultimate fuel

We study the possible existence of an electroweak star — a compact stellar-mass object whose central core temperature is higher than the electroweak symmetry restoration temperature. We found a solution to the Tolman-Oppenheimer-Volkoff equations describing such an object. The parameters of such a star are not substantially different from a neutron star — its mass is around 1.3 Solar masses while its radius is around 8km. What is different is the existence of a small electroweak core. The source of energy in the core that can at least temporarily balance gravity are standard-model non-perturbative baryon number (B) and lepton number (L) violating processes that allow the chemical potential of B+L to relax to zero. The energy released at the core is enormous, but gravitational redshift and the enhanced neutrino interaction cross section at these energies make the energy release rate moderate at the surface of the star. The lifetime of this new quasi-equilibrium can be more than ten million years. This is long enough to represent a new stage in the evolution of a star if stellar evolution can take it there.

Status of the JEM EUSO telescope on International Space Station

JEM-EUSO is a large telescope looking at the earth from the ISS. It uses a huge volume of the earth's night sky atmosphere in which an extremely energetic cosmic ray particle ( E > 10 19 eV ) generates a straight-line N2 fluorescence signal on the path of the cascade shower moving at the speed of light for a length of 10–100 km depending on the incident angle. The space–time resolved calorimetry of showers is achieved with a large-aperture Fresnel lens optics and a large-area focal surface of detectors. Such a system in space is capable of detecting thousands of events with energy above 10 20 eV ( > 1000 super-LHC) in a few years of operation on orbit, allowing a particle channel of astronomy and for research of fundamental physics in the universe. Neutrino interaction cross-sections at such high energies are expected to increase in the Standard Model, and EUSO expects a reasonable chance of observing the cosmogenic neutrino events among those detectable showers, because the atmospheric target mass of the EUSO TPC exceeds 1 trillion tons. This experiment JEM-EUSO is currently considered by the Japan Aerospace Exploration Agency (JAXA) for a possible payload on the Japan Experiment Module (JEM) of the International Space Station (ISS).

Scintillator counters with WLS fiber/MPPC readout for the side muon range detector (SMRD) of the T2K experiment

The T2K neutrino experiment at J-PARC uses a set of near detectors to measure the properties of an unoscillated neutrino beam and neutrino interaction cross-sections. One of the sub-detectors of the near-detector complex, the side muon range detector (SMRD), is described in the paper. The detector is designed to help measure the neutrino energy spectrum, to identify background and to calibrate the other detectors. The active elements of the SMRD consist of 0.7cm thick extruded scintillator slabs inserted into air gaps of the UA1 magnet yokes. The readout of each scintillator slab is provided through a single WLS fiber embedded into a serpentine-shaped groove. Two Hamamatsu multi–pixel avalanche photodiodes (MPPC's) are coupled to both ends of the WLS fiber. This design allows us to achieve a high MIP detection efficiency of greater than 99%. A light yield of 25–50p.e./MIP, a time resolution of about 1ns and a spatial resolution along the slab better than 10cm were obtained for the SMRD counters.

High-energy astrophysics with neutrino telescopes

Neutrino astrophysics offers new perspectives on the Universe investigation: high-energy neutrinos, produced by the most energetic phenomena in our Galaxy and in the Universe, carry complementary (if not exclusive) information about the cosmos with respect to photons. While the small interaction cross section of neutrinos allows them to come from the core of astrophysical objects, it is also a drawback, as their detection requires a large target mass. This is why it is convenient to put huge cosmic neutrino detectors in natural locations, like deep underwater or under-ice sites. In order to supply for such extremely hostile environmental conditions, new frontier technologies are under development. The aim of this work is to review the motivations for high-energy neutrino astrophysics, the present status of experimental results and the technologies used in underwater/ice Cherenkov experiments, with a special focus on the efforts for the construction of a km3-scale detector in the Mediterranean Sea.

First results of the ANTARES neutrino telescope

The ANTARES Collaboration successfully completed in May 2008 the deployment of an underwater neutrino detector in the Mediterranean Sea, offshore the France coast, at 2475 m b.s.l. The main purpose of this experiment is the detection of high energy neutrinos produced in astrophysical sources. Neutrinos being neutral, stable and weakly interacting particles can travel undeflected trough the Universe reaching the Earth even from the inner core of very distant objects. They are therefore very powerful messengers which can provide us invaluable information about processes which are hardly accessible with other messengers like photons. The detection of astrophysical neutrinos is very challenging due to the very small neutrino interaction cross-section and the huge background produced by other cosmic rays. Very large instrumented volumes and a very efficient shielding are therefore needed to detect astrophysical neutrinos. Moreover a very good angular resolution is mandatory to trace detected neutrinos back to their origin. ANTARES with 0.04 km2 muon effective area at Ev > 10 TeV shielded by more than 2000 m of water and an angular resolution of 0.3° at Ev > 10 TeV, perfectly fits these requirements. The ANTARES deployment started in 2006 and many data have been already collected with a partial detector. The detector in its final configuration is described and preliminary results of data analysis, especially about calibration issues, are shown. The completion of the ANTARES detector paved the way towards an even larger submarine neutrino telescope in the Mediterranean Sea like the one planned by the KM3NeT project.