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101-448: Neutrino oscillation is parameterized by the PMNS matrix and the mass squared differences between the neutrino mass eigenstates . Assuming that three flavors of neutrinos participate in neutrino mixing, there are six variables that affect neutrino oscillation: the three angles θ 12 , θ 23 , and θ 13 , a CP-violating phase δ , and any two of the three mass squared differences. There

202-518: A "shower containment region" which observe the trailing portion of particle showers which began in the fiducial region. Finally, a 1.7 meter long "muon catcher" region is constructed of steel plates interleaved with 10 active planes of liquid scintillator. The NOνA experiment includes scientists from a large number of institutions. Different institutions take on different tasks. The collaboration, and subgroups thereof, meets regularly via phone for weekly meetings, and in person several times

303-555: A cathode plane in the centre and readout MicroMegas modules at both sides parallel to the cathode. TPCs are filled with argon -based drift gas under atmospheric pressure. Charged particles crossing TPC ionise the gas along their track. The ionisation electrons drift from the cathode to the sides of the TPC, where they are detected by the MicroMegas providing a 3D image of a path of the traversing charged particle. Y and Z coordinates are based on

404-482: A charged lepton production, a nucleon is usually realised from the nucleus . Because of charge conservation , for neutrinos it is mostly a proton and for antineutrinos – a neutron: Cherenkov energy threshold (minimal total energy of a charged particle to produce Cherenkov light ) is proportional to the particle mass, and in water it equals 0.8 MeV for electrons, 160 MeV for muons and 1400 MeV for protons. Thus, protons released in neutrino interactions often fall below

505-523: A high degree of precision. Its measurements in this area will complement other similar upcoming experiments, such as MINERνA , which also uses the NuMI beam. Since it is capable of detecting neutrinos from galactic supernovas , NOνA will form part of the Supernova Early Warning System . Supernova data from NOνA can be correlated with that from Super-Kamiokande to study the matter effects on

606-427: A list of world-class results: δ CP takes values from - π to π (i.e. from −180° to 180°) and can be measured by comparing oscillations of neutrinos to those of antineutrinos. The CP symmetry would be conserved, and thus the oscillation probabilities would be the same for neutrinos and antineutrinos, for δ CP equal to 0 or ± π . T2K provided the first and the strongest yet constraint on δ CP , rejecting at

707-497: A measurement of the oscillation parameters θ 23 and Δ m 23 with a precision of 1.7° and 1%, respectively, as well as a confirmation at the level of 3 σ or more of the matter-antimatter asymmetry in the neutrino sector in a wide range of possible true values of δ CP – the parameter responsible for the CP (matter-antimatter) asymmetry. Achievement of these goals requires the reduction of statistical and systematic errors. Thus

808-434: A muon neutrino beam, while negative pions and kaons decay mainly into μ and ν μ , forming a muon antineutrino beam. All remaining hadrons and charged leptons are stopped by a 75-ton block of graphite (so-called beam dump) and in the ground, while neutrinos travel underground towards the far detector. T2K is the first experiment in which the concept of off-axis neutrino beam

909-497: A number of limitations, like low reconstruction efficiency of particles produced almost perpendicular and backward with respect to the direction of the interacting neutrino , as well as too high momentum threshold to reconstruct a large part of produced pions and knocked-out nucleons (protons and neutrons). In Charged Current Quasi-Elastic (CCQE) interactions, the dominating interaction in the ND280 near detector, kinematics of produced lepton

1010-696: A physics analysis in January 2010, initially with an incomplete ND280 detector, and starting from November 2010 with the full setup. The data taking was interrupted for one year by the Great Tohoku Earthquake in March 2011. The proton beam power, and thus the neutrino beam intensity, was constantly growing, reaching by February 2020 the power of 515 kW and a total number of accumulated protons on target of 3.6×10 protons with 55% of data in neutrino-mode and 45% in antineutrino-mode. The T2K experiment operated in

1111-403: A plastic scintillator. An additional 4 veto layers of the scintillator surround the module on the sides to distinguish particles entering from the outside from those produced by interactions inside the module. The total mass of iron in one module is 7.1 tons and constitutes 96% of the module weight. On the neutrino beam axis, in the middle of the cross between the vertical and horizontal arm, there

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1212-571: A quasi-3D readout. This readout configuration increases the detection of short tracks almost uniformly in all directions. Due to its geometry and coupled with the TOF and the HATPCs, the SuperFGD has the capability to detect fast-neutrons, which could be useful in the reconstruction of the antineutrino energy. The High Angle Time Projection Chambers (HATPCs) will surround the SuperFGD in the plane perpendicular to

1313-483: A significant upgrade of the beamline and the ND280 detector, doping of SK water with gadolinium to allow ν / discrimination in the far detector, as well as improvements in the software and analysis methods will be done. The beam upgrade plan requires one year long shut down of the J-PARC Main Ring accelerator in 2021, followed by a constant gradual increase of the proton beam power until

1414-812: A single phase angle called δ C P {\displaystyle \delta _{\mathrm {CP} }} related to charge-parity violations (i.e. differences in the rates of oscillation between two states with opposite starting points which makes the order in time in which events take place necessary to predict their oscillation rates), in which case the matrix can be written as: where s i j {\displaystyle s_{ij}} and c i j {\displaystyle c_{ij}} are used to denote sin ⁡ θ i j {\displaystyle \sin \theta _{ij}} and cos ⁡ θ i j {\displaystyle \cos \theta _{ij}} respectively. In

1515-621: A subscript showing the charged lepton that it partners with in the charged-current weak interaction . These three eigenstates of the weak interaction form a complete, orthonormal basis for the Standard Model neutrino. Similarly, one can construct an eigenbasis out of three neutrino states of definite mass, ν 1 {\displaystyle \nu _{1}} , ν 2 {\displaystyle \nu _{2}} , and ν 3 {\displaystyle \nu _{3}} , which diagonalize

1616-512: A timing resolution of the order of 140 ps. The capability to determine track direction sense has been proven in the actual ND280 to be critical to reduce background generated outside the active inner detectors. The impact the ND280 Upgrade will have on the analyses at T2K is two-fold. Firstly, an increase in statistics thanks to the 2 ton SuperFGD target will allow to nearly double the amount of data in certain samples. Secondly and more relevant,

1717-457: A variety of experiments (see neutrino mixing for a description). The CP-violating phase δ C P {\displaystyle \delta _{\mathrm {CP} }} has not been measured directly, but estimates can be obtained by fits using the other measurements. As of November 2022, the current best-fit values from Nu-FIT.org, from direct and indirect measurements, using normal ordering, are: As of November 2022,

1818-463: A well-defined beam energy to reduce spurious background counts. It is situated 810 km from the origin of the NuMI beam and 14  milliradians (12 km) west of the beam's central axis. In this position, it samples a beam that has a much narrower energy distribution than if it were centrally located, further reducing the effect of backgrounds. The detector is designed as a pair of finely grained liquid scintillator detectors. The near detector

1919-535: A well-defined cone of Cherenkov light observed by PMTs as a clear, sharp ring. In contrast, electrons, because of smaller mass, are more susceptible to scattering and almost always produce electromagnetic showers , observed by PMTs as a ring with fuzzy edges. Neutrino energy is calculated based on the direction and energy of a charged lepton produced in the CCQE interaction. In this way, ν μ and ν e spectra are determined, leading to

2020-573: A year. Participating institutions as of May 2024 are: In late 2007, NOνA passed a Department of Energy "Critical Decision 2" review, meaning roughly that its design, cost, schedule, and scientific goals had been approved. This also allowed the project to be included in the Department of Energy congressional budget request. (NOνA still required a "Critical Decision 3" review to begin construction.) On 21 December 2007, President Bush signed an omnibus spending bill , H.R. 2764, which cut

2121-516: Is a particle physics experiment studying the oscillations of the accelerator neutrinos . The experiment is conducted in Japan by the international cooperation of about 500 physicists and engineers with over 60 research institutions from several countries from Europe, Asia and North America and it is a recognized CERN experiment (RE13). T2K collected data within its first phase of operation from 2010 till 2021. The second phase of data taking ( T2K-II )

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2222-442: Is a 2 by 2 by 0.5 metres (6 ft 7 in × 6 ft 7 in × 1 ft 8 in) detector consisting of approximately 2 million 1 cm scintillating polystyrene cubes . The cubes are woven with a series of optical fibres designed to detect the light emitted by the particles produced during the interactions in the target. Unlike the current FGDs, the SuperFGD has a three-fold projective 2D readouts providing

2323-566: Is a measurement of neutral pions production in neutral current neutrino interactions on water: This reaction can mimic electron neutrino interactions because photons from π decay can be mis-reconstructed as an electron in the Super-Kamiokande detector, thus this reaction can mimic electron neutrino interactions and constitute an important background in electron neutrino appearance measurement. Three Time Projection Chambers (TPCs) are gas-tight rectangular boxes, with

2424-451: Is a naturally occurring element with the highest cross-section on the capture of neutrons at thermal energy. For 25 meV neutrons, the cross-section for gadolinium is about 10 times higher than for hydrogen . The fraction of neutrons that will be captured in SK is 50% for 0.01% Gd concentration and 90% for 0.1% concentration – the planned final Gd concentration in SK. The signal from neutron capture

2525-506: Is a new detector located next to the INGRID and ND280 detectors, devoted to neutrino interaction studies. It provided the first neutrino beam data using a full detector setup during the 2019/2020 winter run. The WAGASCI-BabyMIND consists of several sub-detectors: Thanks to such a structure, a high water to scintillator mass ratio was obtained (80% H 2 O + 20% CH) and the acceptance is high and approximately constant in all directions. All

2626-507: Is an additional module built only from layers of the plastic scintillator (Proton Module) with a mass of 0.55 tons. Its purpose is to register quasielastic interactions and compare the obtained results with the simulations. The ND280 detector is used to measure the flux, energy spectrum and electron neutrino beam pollution for the same off-axis angle as for the far detector. ND280 also investigates various types of muon and electron neutrino and antineutrino interactions. All this allows estimating

2727-419: Is at Fermilab and samples the unoscillated beam. The far detector is in northern Minnesota, and consists of about 500,000 cells, each 4 cm × 6 cm × 16 m, filled with liquid scintillator . Each cell contains a loop of bare fiber optic cable to collect the scintillation light, both ends of which lead to an avalanche photodiode for readout. The near detector has the same general design, but

2828-513: Is currently no compelling theoretical reason to expect any particular value of, or relationship between, these parameters. θ 23 and θ 12 have been measured to be non-zero by several experiments but the most sensitive search for non-zero θ 13 by the Chooz collaboration yielded only an upper limit. In 2012, θ 13 was measured at Daya Bay to be non-zero to a statistical significance of 5.2  σ . The following year, T2K discovered

2929-417: Is delayed by a fraction of a millisecond (the time the neutron travels across the water before the capture plus the time when Gd remains in the excited state) with respect to the charged lepton signal and usually appears within a distance of 50 cm (the distance travelled by the neutron before the capture) from the neutrino interaction point. Such a double flash event (the first flash from the charged lepton,

3030-476: Is enough in the reconstruction of the incoming neutrino energy. However, other types of neutrino interactions in which additional particles ( pions , kaons , nucleons ) were lost, may be mis-reconstructed as CCQE and introduce a bias in the reconstructed neutrino energy spectrum. Thus, it is essential to optimize the detector to be sensitive to additional particles and nuclear effects . Three main measures need to be taken to address these issues: The Upgrade of

3131-486: Is expected to start in 2023 and last until commencement of the successor of T2K – the Hyper-Kamiokande experiment in 2027. T2K was the first experiment which observed the appearance of electron neutrinos in a muon neutrino beam . It also provided the world best measurement of oscillation parameter θ 23 and a hint of a significant matter-antimatter asymmetry in neutrino oscillations. The measurement of

NOvA - Misplaced Pages Continue

3232-496: Is identical to the matrix for neutrinos under CPT symmetry . Due to the difficulties of detecting neutrinos , it is much more difficult to determine the individual coefficients than in the equivalent matrix for the quarks (the CKM matrix ). In the Standard Model, the PMNS matrix is unitary . This implies that the sum of the squares of the values in each row and in each column, which represent

3333-600: Is in slight tension with the T2K result. The T2K best-fit point lies in the region disfavoured by NOvA at the confidence level of 90%. There are ongoing works to obtain a joint fit to data from both experiments to quantify consistency between them. Future upgrades of T2K is expected to provide more precise measurements of Δ m 23 and θ 23 parameters, cross-section measurements which will extend our understanding of neutrino interactions and thus improve theoretical models used in neutrino generators, as well as further constrain on

3434-419: Is intended to measure θ 13 and δ . It will have a 295 km baseline and will use lower energy neutrinos than NOνA, about 0.6 GeV. Since matter effects are less pronounced both at lower energies and shorter baselines, it is unable to resolve the mass ordering for the majority of possible values of δ . The interpretation of Neutrinoless double beta decay experiments will also benefit from knowing

3535-413: Is maximal for around 600 MeV neutrinos. In this neutrino energy range, the dominant type of neutrino interactions are charged current quasielastic interactions, for which it is possible to reconstruct the energy of the interacting neutrino only on the basis of the momentum and direction of the produced charged lepton. The higher neutrino energies are suppressed by the off-axis configuration, decreasing

3636-520: Is only about 1 ⁄ 200 as massive. This 222 ton detector is constructed of 186 planes of scintillator-filled cells (6 blocks of 31 planes) followed by a muon catcher. Although all the planes are identical, the first 6 are used as a veto region; particle showers which begin in them are assumed to not be neutrinos and ignored. The next 108 planes serve as the fiducial region; particle showers beginning in them are neutrino interactions of interest. The final 72 planes are

3737-519: Is resolvable by NOνA, it will be possible to obtain measurements of δ and the mass ordering by also observing ν ¯ μ → ν ¯ e . {\displaystyle {\bar {\nu }}_{\mu }\rightarrow {\bar {\nu }}_{e}.} The parameter δ can be measured because it modifies the probabilities of oscillation differently for neutrinos and anti-neutrinos. The mass ordering, similarly, can be determined because

3838-662: Is surrounded by the electromagnetic calorimeter and a magnet recycled from the UA1 experiment producing 0.2 T uniform horizontal magnetic field and instrumented with scintillator planes constituting the Side Muon Range Detector. The Pi-Zero ( π ) Detector (P0D) contains 40 plastic scintillator module planes, which in the central part are interleaved with 2.8 cm thick bags fillable of water and thick brass sheets, and in two peripheral regions scintillator modules are sandwiched with lead sheets. By comparison of

3939-451: The NuMI beam on 15 December 2010. As a prototype, NDOS served the collaboration well in establishing a use case and suggesting improvements in the design of detector components that were later installed as a near detector at Fermilab, and a far detector at Ash River, MN ( 48°22′45″N 92°49′54″W  /  48.37912°N 92.83164°W  / 48.37912; -92.83164  ( NOνA far detector ) ). Once construction of

4040-474: The Pontecorvo–Maki–Nakagawa–Sakata matrix ( PMNS matrix ), Maki–Nakagawa–Sakata matrix ( MNS matrix ), lepton mixing matrix , or neutrino mixing matrix is a unitary mixing matrix which contains information on the mismatch of quantum states of neutrinos when they propagate freely and when they take part in weak interactions . It is a model of neutrino oscillation . This matrix

4141-604: The δ CP phase and confirmation if the CP symmetry is conserved or violated in the neutrino oscillation at the 3σ significance level in the T2K-II and 5σ in the Hyper-Kamiokande experiment. T2K uses a muon neutrino or muon antineutrino beam produced at the J-PARC facility using a proton beam gradually accelerated to 30 GeV by a system of three accelerators : first to 400 MeV energy by

NOvA - Misplaced Pages Continue

4242-594: The 2008 fiscal year to build its detector, pay its staff, or to continue in the pursuit of scientific results. However, in July ;2008, Congress passed, and the President signed, a supplemental budget bill, which included funding for NOνA, allowing the collaboration to resume its work. The NOνA prototype near detector (Near Detector on Surface, or NDOS) began running at Fermilab in November and registered its first neutrinos from

4343-2169: The 3  σ ranges (99.7% confidence) for the magnitudes of the elements of the matrix were: | U | = [   | U e 1 |   | U e 2 |   | U e 3 |   | U μ 1 |   | U μ 2 |   | U μ 3 |   | U τ 1 |   | U τ 2 |   | U τ 3 |   ] = [   0.803 ∼ 0.845     0.514 ∼ 0.578     0.142 ∼ 0.155     0.233 ∼ 0.505     0.460 ∼ 0.693     0.630 ∼ 0.779     0.262 ∼ 0.525     0.473 ∼ 0.702     0.610 ∼ 0.762   ] {\displaystyle |U|={\begin{bmatrix}~|U_{\mathrm {e} 1}|~&|U_{\mathrm {e} 2}|~&|U_{\mathrm {e} 3}|\\~|U_{\mu 1}|~&|U_{\mu 2}|~&|U_{\mu 3}|\\~|U_{\tau 1}|~&|U_{\tau 2}|~&|U_{\tau 3}|~\end{bmatrix}}=\left[{\begin{array}{rrr}~0.803\sim 0.845~~&0.514\sim 0.578~~&0.142\sim 0.155~\\~0.233\sim 0.505~~&0.460\sim 0.693~~&0.630\sim 0.779~\\~0.262\sim 0.525~~&0.473\sim 0.702~~&0.610\sim 0.762~\end{array}}\right]} Gonzalez-Garcia, M.C.; Maltoni, Michele; Salvado, Jordi; Schwetz, Thomas (21 December 2012). "Global fit to three neutrino mixing: Critical look at present precision". Journal of High Energy Physics . 2012 (12): 123. arXiv : 1209.3023 . Bibcode : 2012JHEP...12..123G . CiteSeerX   10.1.1.762.7366 . doi : 10.1007/JHEP12(2012)123 . S2CID   118566415 . T2K T2K (" Tokai to Kamioka ")

4444-543: The 3σ (99.7%) significance level almost half of the possible values, ruling out the both CP conserving points at the significance level of 95% and giving a strong hint that CP violation may be large in the neutrino sector. The CP violation is one of the conditions proposed by the Russian physicist Andrei Sakharov , necessary to produce the excess of matter with respect to antimatter at the early universe , which forms now our matter-built Universe . CP violation in quark section

4545-728: The Linac linear accelerator, then up to 3 GeV by the RCS (Rapid Cycle Synchrotron), and finally up to 30 GeV by the MR synchrotron (Main Ring). Protons collide with a graphite target, producing mesons , mainly pions and kaons , which are then focused by a set of three magnetic horns and directed into a tunnel called the decay volume. Depending on the horns polarity, either positive or negative particles are focused. Positive pions and kaons decay mainly into μ and ν μ , forming

4646-405: The MicroMegas modules. This reduces the number of readout channels and allows for a spatial resolution which is as good as the one in the current TPCs. The six Time-of-Flight (TOF) detectors surrounding the HATPCs and SuperFGD are a series of plastic scintillator layers designed to identify the particle direction sense through the measurement of the time of flight for each crossing track with

4747-752: The Mozumi Mine, under Mount Ikeno in the Kamioka area of Hida city. It is a stainless steel cylindrical tank of about 40 m height and diameter, filled with 50,000 tons of water and instrumented with around 13,000 photomultiplier tubes (PMT). It detects a cone of Cherenkov light emitted by charged particles moving in water faster than light in this medium. Its goal is to measure muons and electrons produced in charged current quasielastic interactions (CCQE) of ν μ and ν e , respectively. Due to relatively large mass, muons usually do not change their direction and thus produce

4848-474: The ND280 detector (ND280 Upgrade) addresses these requirements by replacing a part of the P0D sub-detector with three types of new sub-detectors. The existing downstream part, consisting of two Fine-Grained scintillation Detectors (FGDs) and three Time Projection Chambers (TPCs), will maintain their sandwiched structure and continue to detect forward going leptons and high momentum hadrons. The upstream part which now hosts

4949-415: The ND280 detector (without barrel part of the electromagnetic calorimeter) was completed in 2009. The missing part of the calorimeter was installed in the fall of 2010. T2K far detector is the large Super-Kamiokande detector, which has been running since 1996 and studying proton lifetime and oscillations of atmospheric , solar and accelerator neutrinos. T2K experiment started to take neutrino data for

5050-577: The NOvA building was complete, construction of the detector modules began. On 26 July 2012 the first module was laid in place. Placement and gluing of the modules continued over a year until the detector hall was filled. The first detection occurred on 11 February 2014 and construction completed in September that year. Full operation began in October ;2014. PMNS matrix In particle physics ,

5151-428: The P0D sub-detector will be replaced by three novel sub-detectors: a scintillating 3D target (Super Fine-Grained Detector or SuperFGD), two new TPCs on top and below the SuperFGD (High-Angle TPCs or HATPCs), and six Time-of-Flight (TOF) detectors surrounding the new structure. Each of these sub-detectors is briefly described below. The installation of the new sub-detectors into ND280 will be done in 2022. The SuperFGD

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5252-635: The Super-Kamiokande detector is water-based. Cross sections on carbon and on the water can be determined from a comparison of neutrino interactions in the two FGDs. The Electromagnetic Calorimeter (ECal) surrounds the inner detectors (P0D, TPCs, FGDs) and consists of scintillator layers sandwiched with lead absorber sheets. Its role is to detect neutral particles, especially photons, and measure their energy and direction, as well as to detect charged particles providing additional information relevant for their identification. The Side Muon Range Detector (SMRD) consists of scintillator modules which are inserted into

5353-459: The active material in the detectors is made up of plastic scintillator and is read as explained in section Signal readout . The main goal of the WAGASCI-BabyMIND detector is a reduction of the systematic error in the T2K oscillation analysis, which will be achieved thanks to its complementarity with respect to the ND280 detector: Super-Kamiokande detector is located 1000 m underground in

5454-476: The amount of interaction between modes with and without water in the bags, it is possible to extract the number of neutrino interactions occurring on the water – the target material inside the far detector Super-Kamiokande. The size of the entire active P0D volume is around 2.1 m × 2.2 m × 2.4 m (X×Y×Z) and its mass with and without water is 15.8 and 12.9 tons respectively. The main goal of the Pi-Zero Detector

5555-478: The amount of wrong-sign neutrinos (anti-neutrinos in the neutrino-mode beam and neutrinos in the anti-neutrino mode beam) by around 5 - 10%. Reduction of the repetition cycle will require a series of hardware upgrades, including a major upgrade of the Main Ring power supplies and a minor upgrade of the focusing horn power supplies, all of which will be installed during the long shutdown in 2021. Increasing

5656-411: The amplitude of mass eigenstate i = 1 , 2 , 3 {\displaystyle \,i=1,2,3\;} in terms of flavor   α = {\displaystyle ~\alpha =\;} " e ", " μ ", " τ "; parameterizes the unitary transformation between the two bases: The vector on the left represents a generic neutrino expressed in the flavor-eigenstate basis, and on

5757-480: The broadest scope for making this measurement unambiguously with least dependence on the value of δ . Many future experiments that seek to make precision measurements of neutrino properties will rely on NOνA's measurement to know how to configure their apparatus for greatest accuracy, and how to interpret their results. An experiment similar to NOνA is T2K , a neutrino beam experiment in Japan similar to NOνA. Like NOνA, it

5858-476: The case of Majorana neutrinos, two extra complex phases are needed, as the phase of Majorana fields cannot be freely redefined due to the condition ν = ν c   {\displaystyle \nu =\nu ^{c}~} . An infinite number of possible parameterizations exist; one other common example being the Wolfenstein parameterization . The mixing angles have been measured by

5959-455: The city of Hida , Gifu prefecture . The properties and composition of the neutrino flux are first measured by a system of near detectors located 280 metres (920 ft) from the beam production place at the J-PARC site, and then again in the Super-Kamiokande detector. Comparison of the content of different neutrino flavours in these two locations allows measurement of the oscillations probability on

6060-597: The comparison between ν μ → ν e and ν μ → ν e oscillation channels. NOvA is conducted in the United States and measures accelerator neutrino oscillation at the distance of 810 km on the way between beam production place in Fermilab and far detector in Ash River , Minnesota . NOvA provided a less precise measurement of δ CP , which

6161-401: The confidence level of 99.9985% (4.3 σ ) the disappearance of the muon neutrinos and were consistent with the previous measurements of oscillation parameters measured by the Super-Kamiokande detector for atmospheric neutrinos . The construction of the neutrino beamline started in 2004 and it was successfully commissioned in 2009. Construction of the entire INGRID detector and majority of

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6262-447: The current form until 2020. In 2021 the first data run with gadolinium loaded into the Super-Kamiokande far detector was taken. In 2021–2022 a major upgrade of the neutrino beamline and the ND280 near detector will be performed. From 2023 till 2026 neutrino data will be taken within the second phase of the T2K experiment (T2K-II). In 2027, the successor of the T2K experiment – the Hyper-Kamiokande (HK) experiment – will be launched with

6363-502: The entire active material (enabling particle tracking) of the near detectors is plastic scintillator . The light produced by traversing charged particles in the plastic scintillator bars and planes is collected by wavelength-shifting fibres and detected by Hamamatsu Multi-pixel photon counters located at one or both ends of the fibres. Scintillator bars are organised into layers, where bars in two neighbouring layers are perpendicular to each other providing together 3D information about

6464-412: The expected number and type of interactions in the far detector, reducing the systematic error in the neutrino oscillations analysis associated with models of neutrino interactions and flux. ND280 is composed of the set of inner sub-detectors: Pi-Zero detector and a tracker with 2 Fine-Grained Detectors interleaved with 3 Time Projection Chambers, placed inside of a metal frame called a basket. The basket

6565-400: The experimental neutrino oscillation data to an extended PMNS matrix with a fourth, light "sterile" neutrino and four mass eigenvalues, although the current experimental data tends to disfavor that possibility. In general, there are nine degrees of freedom in any unitary three by three matrix. However, in the case of the PMNS matrix, five of those real parameters can be absorbed as phases of

6666-451: The first θ 13 -controlled oscillation maximum. In addition to its primary physics goals, NOνA will be able to improve upon the measurements of the already measured oscillation parameters. NOνA, like MINOS , is well suited to detecting muon neutrinos and so will be able to refine our knowledge of θ 23 . The NOνA near detector will be used to conduct measurements of neutrino interaction cross sections which are currently not known to

6767-450: The first and second TPCs. Together the FGDs and TPCs make up the tracker of ND280. The FGDs provide the active target mass for the neutrino interactions and are able to measure the short tracks of proton recoil. The first FGD is composed of scintillator layers only, while the second FGD is composed of alternating layers of scintillator and water. The second FGD is partially composed of water because

6868-595: The funding for high energy physics by 88 million dollars from the expected value of 782 million dollars. The budget of Fermilab was cut by 52 million dollars. This bill explicitly stated that "Within funding for Proton Accelerator-Based Physics, no funds are provided for the NOνA activity in Tevatron Complex Improvements." So although the NOνA project retained its approval from both the Department of Energy and Fermilab, Congress left NOνA with no funds for

6969-406: The gaps in the magnet. The SMRD records muons escaping the inner parts of the detector at large angles with respect to the beam direction. The remaining types of particles (except for neutrinos) are mostly stopped in the calorimeter. SMRD can also act as a trigger for cosmic rays . Finally, it can help identify beam interactions in the surrounding walls and in the magnet itself. WAGASCI-BabyMIND

7070-501: The horn current will require using an additional (third) horn power supply. Meanwhile, the higher proton beam power demands enhancement of the cooling capacity of the secondary beamline components such as the graphite target, the magnetic horns and the beam dump, as well as disposal of a larger amount of irradiated cooling water. The current design of the ND280 detector is optimized for the detection and reconstruction of forward-going leptons ( muons and electrons ), but it also has

7171-451: The incoming neutrino beam. Their design is similar to that of the existing TPCs, as they both use the MicroMegas modules technology for track reconstruction. The main novel feature of the HATPCs, aside from their high angle coverage, is the use of the resistive MicroMegas technology. The latter consists of applying a layer of resistive material to increase the charge-sharing capabilities of

7272-411: The lepton fields and thus the PMNS matrix can be fully described by four free parameters. The PMNS matrix is most commonly parameterized by three mixing angles ( θ 12 {\displaystyle \theta _{12}} , θ 23 {\displaystyle \theta _{23}} , and θ 13 {\displaystyle \theta _{13}} ) and

7373-691: The mass ordering, since the mass hierarchy affects the theoretical lifetimes of this process. Reactor experiments also have the ability to measure θ 13 . While they cannot measure δ or the mass ordering, their measurement of the mixing angle is not dependent on knowledge of these parameters. The three experiments that have measured a value for θ 13 , in deceasing order of sensitivity are Daya Bay in China, RENO in South Korea and Double Chooz in France, which use 1-2 km baselines, optimized for observation of

7474-469: The masses has not been determined. NOνA is an order of magnitude more sensitive to θ 13 than the previous generation of experiments, such as MINOS . It will measure it by searching for the transition ν μ → ν e {\displaystyle \nu _{\mu }\rightarrow \nu _{e}} in the Fermilab NuMI beam. If a non-zero value of θ 13

7575-651: The measurement of the oscillation parameters relevant for muon neutrino disappearance and electron neutrino appearance. T2K is a successor of the KEK to Kamioka ( K2K ) experiment, which ran from 1999 till 2004. In the K2K experiment , an accelerator beam of muon neutrinos was produced at KEK facility in Tsukuba ( Japan ) and sent towards the Super-Kamiokande detector, located 250 km away. The K2K experiment results confirmed at

7676-451: The most reactive in SK but were yet indistinguishable from neutrinos from other sources. It will also improve the detector performance for supernova explosions in our galaxy and study better matter-antimatter differences in accelerator neutrino oscillations. The successor of the T2K experiment, the Hyper-Kamiokande (HK) experiment, will use the upgraded system of the currently used accelerator and neutrino beamline and upgraded set of

7777-497: The neutrino's free-particle Hamiltonian . Observations of neutrino oscillation established experimentally that for neutrinos, as for quarks , these two eigenbases are different – they are 'rotated' relative to each other. Consequently, each flavor eigenstate can be written as a combination of mass eigenstates, called a " superposition ", and vice versa. The PMNS matrix, with components U α i {\displaystyle U_{\alpha \,i}} corresponding to

7878-454: The neutrino-antineutrino oscillation asymmetry may bring us closer to the explanation of the existence of our matter-dominated Universe. The intense beam of muon neutrinos is produced in the J-PARC facility (Japan Proton Accelerator Research Complex) in Tokai on the east coast of Japan. The beam is directed towards the Super-Kamiokande far detector located 295 kilometres (183 mi) away in

7979-519: The neutrinos pass through the Earth, which, through the MSW effect , modifies the probabilities of oscillation differently for neutrinos and anti-neutrinos. The neutrino masses and mixing angles are, to the best of our knowledge, fundamental constants of the universe. Measuring them is a basic requirement for our understanding of physics. Knowing the value of the CP violating parameter δ will help us understand why

8080-453: The new configuration will allow for better detection of additional final state particles: high angle particles thanks to the increased angular acceptance, and less energetic particles because of lower detection thresholds. This detector acceptance improvement is important to cover almost the same phase space available at the far detector (SK). In addition, final state particles will allow probing nuclear effects which are essential for constraining

8181-481: The new, 250,000-ton water Cherenkov far detector – the Hyper-Kamiokande detector. The building of an additional Intermediate Water Cherenkov detector at a distance of around 2 kilometres (1.2 mi) is also considered for the HK experiment. Phase II of the T2K experiment is expected to start at the beginning of 2023 and last until 2026, following by the commencement of the HK experiment. The physics goals of T2K-II are

8282-496: The number of interactions with meson production, which are background in the oscillation analysis in the T2K experiment. The near detector complex is located at a distance of 280 metres (920 ft) from the graphite target. Its purpose is to measure the neutrino flux before oscillations and to study neutrino interactions. The system consists of three main detectors: Except for the Time Projection Chambers in ND280,

8383-436: The number of protons per pulse has to increase to 3.2x10 . In addition to increasing the primary proton beam power, the current in the horns focusing secondary particles ( pions , kaons , etc.) with a chosen electric charge will also be increased from 250 kA to 320 kA. This will increase the amount of right-sign neutrinos (neutrinos in the neutrino mode beam and anti-neutrinos in the anti-neutrino mode beam) by 10%, and reduce

8484-453: The oscillation of these neutrinos. To accomplish its physics goals, NOνA needs to be efficient at detecting electron neutrinos, which are expected to appear in the NuMI beam (originally made only of muon neutrinos) as the result of neutrino oscillation. Previous neutrino experiments, such as MINOS , have reduced backgrounds from cosmic rays by being underground. However, NOνA is on the surface and relies on precise timing information and

8585-477: The position of the detected ionisation electrons on the MicroMegas modules, and X coordinate is based on the electrons drift time. In the magnetic field, the curvature of this path allows to determine charge and momentum of the particle, and the amount of the ionisation electrons per unit distance is used to identify particles based on the Bethe-Bloch formula . Two Fine-Grained Detectors (FGDs) are placed after

8686-552: The probabilities of different possible events given the same starting point, add up to 100%. In the simplest case, the Standard Model posits three generations of neutrinos with Dirac mass that oscillate between three neutrino mass eigenvalues, an assumption that is made when best fit values for its parameters are calculated. In other models the PMNS matrix is not necessarily unitary, and additional parameters are necessary to describe all possible neutrino mixing parameters in other models of neutrino oscillation and mass generation, such as

8787-591: The right is the PMNS matrix multiplied by a vector representing that same neutrino in the mass-eigenstate basis. A neutrino of a given flavor α {\displaystyle \alpha } is thus a "mixed" state of neutrinos with distinct mass: If one could measure directly that neutrino's mass, it would be found to have mass m i {\displaystyle m_{i}} with probability | U α i | 2 {\displaystyle \left|U_{\alpha \,i}\right|^{2}} . The PMNS matrix for antineutrinos

8888-638: The second flash from the Gd deexcitation photons) is a signature of an antineutrino interaction. The first loading of 13 tons of Gd 2 (SO 4 ) 3 ·8 H 2 O ( gadolinium(III) sulfate octahydrate ) into SK water was done in July–August 2020 and lead to a 0.011% concentration of Gd. T2K collected its first data with Gd in SK in March–April 2021. Usage of gadolinium-doped water will allow studying remote supernova neutrinos , for which ν e 's are

8989-413: The see-saw model, and in general, in the case of neutrinos that have Majorana mass rather than Dirac mass . There are also additional mass parameters and mixing angles in a simple extension of the PMNS matrix in which there are more than three flavors of neutrinos, regardless of the character of neutrino mass. As of July 2014, scientists studying neutrino oscillation are actively considering fits of

9090-454: The start of the HK experiment. The beam power should reach 750 kW in 2022 and then grow to 1.3 MW by 2029. In February 2020, the proton beam power reached 515 kW with 2.7x10 protons per pulse and with 2.48 seconds between pulses (so-called repetition cycle). To reach 750 kW, the repetition cycle will be reduced to 1.32 s with 2.0x10 protons per pulse, while for 1.3 MW the repetition cycle has to be further decreased to 1.16 s and

9191-413: The systematic effects of the oscillation analysis. It is an important step as well in the transition to using semi-inclusive or exclusive models in neutrino oscillation physics, as opposed to current inclusive models which use only the final state lepton in their predictions. The third element to be improved within T2K – phase II is the introduction of gadolinium into the Super-Kamiokande , which so far

9292-422: The three neutrino mixing angles, only θ 12 has been resolved as being neither maximal or minimal. If the measurements of NOνA and other future experiments continue to show θ 23 as maximal and θ 13 as minimal, it may suggest some as yet unknown symmetry of nature. NOνA can potentially resolve the mass hierarchy because it operates at a relatively high energy. Of the experiments currently running it has

9393-427: The threshold and remain undetected. Neutron, as a neutral particle, does not produce Cherenkov light. However, it can be absorbed by another nucleus, which goes into an excited state and during deexcitation produced gamma rays . High energy photons (for gadolinium their total energy is about 8 MeV) scatter electrons from an atom and/or produce electron-positron pairs , which then produce Cherenkov light. Gadolinium

9494-404: The transition ν μ → ν e {\displaystyle \nu _{\mu }\rightarrow \nu _{e}} excluding the non-appearance hypothesis with a significance of 7.3  σ . No measurement of δ has been made. The absolute values of two mass squared differences are known, but because one is very small compared to the other, the ordering of

9595-476: The traversing particles. The main purpose of the INGRID detector is the monitoring of the direction and intensity of the beam on a daily basis by direct detection of neutrino interactions. The INGRID detector consists of 16 identical modules arranged in the shape of a cross, 7 in a vertical and 7 in a horizontal arm, plus 2 modules outside the cross. The height and width of the arms are 10 metres (33 ft). A single module consists of alternating layers of iron and

9696-518: The universe has a matter-antimatter asymmetry . Also, according to the Seesaw mechanism theory, the very small masses of neutrinos may be related to very large masses of particles that we do not yet have the technology to study directly. Neutrino measurements are then an indirect way of studying physics at extremely high energies. In our current theory of physics, there is no reason why the neutrino mixing angles should have any particular values. And yet, of

9797-400: The way between near and far detectors. Super-Kamiokande is able to detect interactions of both, muon and electron neutrinos, and thus measure the disappearance of muon neutrino flux, as well as electron neutrino appearance in the beam. T2K experiment was proposed in 2003 with the following measurement goals: Since the start of the data taking in 2010, the T2K experiment succeeded to provide

9898-486: Was confirmed already in 1964, but it is too small to explain the observed matter-antimatter imbalance. The strong CP violation in the neutrino sector could lead to matter excess production through the process called leptogenesis and thus such measurement would be important step to understand how the Universe were formed. The NOvA experiment is the other neutrino oscillation experiment capable to measure δ CP through

9999-416: Was filled with ultra-pure water. SK is not able to measure the charge of the registered particle. That means it is not possible to distinguish neutrino from antineutrino interaction based on a charge of produced lepton (e.g. μ is produced by ν μ while μ by ν μ ). In (anti)neutrino-nucleus interactions, apart from

10100-534: Was introduced in 1962 by Ziro Maki , Masami Nakagawa , and Shoichi Sakata , to explain the neutrino oscillations predicted by Bruno Pontecorvo . The Standard Model of particle physics contains three generations or " flavors " of neutrinos, ν e {\displaystyle \nu _{\mathrm {e} }} , ν μ {\displaystyle \nu _{\mu }} , and ν τ {\displaystyle \nu _{\tau }} , each labeled with

10201-431: Was realized. The neutrino beam at J-PARC is designed so that it can be directed 2 to 3 degrees away from the Super-Kamiokande far detector and one of the near detectors, ND280. The average energy of neutrinos decreases with the deviation from the beam axis. The off-axis angle was chosen to 2.5° to maximize the probability of oscillation at a distance corresponding to the far detector, which for 295 kilometres (183 mi)

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