We review the ongoing effort in the US, Japan, and Europe of the scientific community to study the location and the detector performance of the next-generation long-baseline neutrino facility. For many decades, research on the properties of neutrinos and the use of neutrinos to study the fundamental building blocks of matter has unveiled new, unexpected laws of nature. Results of neutrino experiments have triggered a tremendous amount of development in theory: theories beyond the standard model or at least extensions of it and development of the standard solar model and modeling of supernova explosions as well as the development of theories to explain the matter-antimatter asymmetry in the universe. Neutrino physics is one of the most dynamic and exciting fields of research in fundamental particle physics and astrophysics. The next-generation neutrino detector will address two aspects: fundamental properties of the neutrino like mass hierarchy, mixing angles, and the CP phase, and low-energy neutrino astronomy with solar, atmospheric, and supernova neutrinos. Such a new detector naturally allows for major improvements in the search for nucleon decay. A next-generation neutrino observatory needs a huge, megaton scale detector which in turn has to be installed in a new, international underground laboratory, capable of hosting such a huge detector.
For many decades, research on the properties of neutrinos and the use of neutrinos to study the fundamental building blocks of matter has unveiled new, unexpected laws of nature. In the basic version of the standard model of particle physics, neutrinos enter as massless, neutral, spin one-half particles. Left-handed neutrinos form an electroweak isospin doublet with their charged, massive partners, electrons, muons, and taus. The right-handed neutrinos form an electroweak isospin singlet. Today, we have strong experimental evidence that neutrinos have a nonvanishing mass and that they change flavor while propagating in space. This phenomenon is called neutrino oscillations. These experimental observations imply an extension of the standard model and point to a more general formalism. Up to now, no other experimentally proven indication for physics beyond the standard model has been found with accelerator-based experiments at LEP, the Tevatron, and LHC. The search for neutrino oscillations has been triggered by astrophysics experiments with neutrinos, namely, the observation of neutrinos from the Sun and, later on, neutrinos generated in the interaction of cosmic rays with the Earth’s atmosphere: atmospheric neutrinos. At the same time solar neutrino spectroscopy allows a much better understanding and theoretical description of our star. The detection of a handful of neutrinos from a supernova in 1987 by the Kamiokande and IMB experiments gave a fundamental input and verification of supernova models. Over the last few decades, the results of neutrino experiments have triggered a tremendous amount of development in theory: theories beyond the standard model or at least extensions of it, development of the standard solar model and modeling of supernova explosions as well as the development of theories to explain the matter-antimatter asymmetry in the universe.
Today, the common way of describing neutrino oscillations is the following.
The neutrinos
The coefficients
The MNSP matrix can be parametrized in three
Developing the above equation leads to the probability expressed as
We can write
This expression of the probability is exact for neutrino oscillations in vacuum.
It is important to remark that neutrino oscillation experiments have no access to the absolute neutrino mass. On the other hand, they are a powerful instrument to have information on the mass square differences:
According to the sign of
In this paper, we will use the definition of the observables from above to describe the physics case of the proposed new long-baseline experiments.
The above-mentioned examples make neutrinos physics one of the most dynamic and exciting fields of research in fundamental particle physics and astrophysics. The next-generation neutrino detector will address two aspects: fundamental properties of the neutrino like mass hierarchy, mixing angles and the CP phase, and low-energy neutrino astronomy with solar, atmospheric, and supernova neutrinos. Such a new detector naturally allows for major improvements in the search for nucleon decay. A next-generation neutrino observatory needs a huge, megaton scale detector which in turn has to be installed in a new, international underground laboratory, capable of hosting such a huge detector.
In the US, the strategy for a future long-baseline experiment has been under development over the last decade. The scientific goals of a future US-based long-baseline neutrino project have been discussed and reviewed extensively by the US National Research Council and the Particle Physics Advisory Panels. The National Research Council reports in 2003 and 2011 have endorsed a project with a large capability underground detector located at a distance of >1000 km from Fermilab.
In Europe, a roadmap has been established in 2008 and updated in 2011 by ASPERA (AStroParticle ERAnet). In the 2011 update one can read
In Japan, projects exploring the lepton sector CP symmetry both with a 100 kt detector based on a liquid Argon time projection chamber and a 560 kt water Cherenkov detector (Hyper-Kamiokande) are being planned [
As shown above, there is a worldwide consensus among physicists on the scientific priorities and the next-generation neutrino detector and infrastructure. One can also see the very strong competition between different countries to host such observatory for the next 30 to 50 years.
The US accelerator neutrino program at Fermilab consists of a diverse set of experiments with intense neutrinos beams. The Fermilab Main Injector with the NuMI neutrino beamline operates at 350 kW with a tunable neutrino beam covering from 0.5 GeV to 10 GeV, and the neutrino beamline from the 8 GeV Booster accelerator (BNB) operates with a low-energy neutrino beam covering from 0.2 GeV to 1 GeV. The current and near future program is listed as follows: the MINOS experiment is a 5 kt magnetized steel/scintillator detector operating in the NuMI beamline at a baseline of 735 km. The main goals of MINOS consist in the measurement of muon neutrino disappearance and the parameters that govern atmospheric neutrino oscillations [
The strategy for a future long-baseline experiment in the US has been under development over the last decade [
The long-baseline neutrino experiment (LBNE) is the next major planned neutrino program in the US. The experiment as currently envisioned comprises a new 700 kW beamline at Fermilab, whose spectrum is optimized for this physics and which is upgradable to handle more than 2 MW of beam power from the future high-intensity proton accelerator (named the Project-X upgrade [
The LBNE beam design is a conventional, horn-focused neutrino beamline. The components of the beamline will be designed to extract a proton beam from the Fermilab Main Injector (MI) and transport it to a target area where the collisions generate a beam of charged particles that decay in a decay pipe. The facility is designed for initial operation at proton-beam power of 700 kW, with the capability to support an upgrade to 2.3 MW. In the reference design, extraction of the proton beam occurs at MI-10, a new installation on the Main Injector accelerator. After extraction, this primary beam establishes a horizontally straight heading west-northwest toward the far detector, but will be bent upward to an apex before being bent downward at the appropriate angle, 101 milliradians (5.79°) as shown in Figure
Schematic view of the LBNE beam design located at Fermilab.
The target marks the transition from the intense, narrowly directed proton beam to the more diffuse, secondary beam of particles that in turn decay to produce the neutrino beam. After collection and focusing, the pions and kaons need a long, unobstructed volume in which to decay. This decay volume in the LBNE reference design is a pipe of circular cross-section with its diameter (4 meters) and length (200 meters) optimized such that decays of the pions and kaons result in neutrinos in the energy range useful for the experiment. The decay volume is followed immediately by the absorber, which removes the remaining beam hadrons.
The experience gained from the various neutrino projects at FNAL has been employed extensively in the LBNE beamline conceptual design. In particular, the NuMI beamline serves as the prototype design. Nevertheless, the LBNE beamline contains considerable innovation with regards to simplicity of construction and radiological protection.
The reference design for the primary beam and the neutrino beam is suitable for the initial beam power of ~700 kW in all respects. Some aspects of the reference design are also appropriate for a beam power of ≥2.3 MW. These include the radiological shielding and the size of the underground enclosures as well as systems such as the beam absorber and the remote handling, which cannot be upgraded after exposure to a high-intensity beam. Some aspects of the reference design are planned for a beam power upgrade to 2.3 MW. The underground enclosures will have the appropriate steel and concrete shielding required for future beam upgrades.
The LBNE beamline is expected to initially use ~700 kW of proton power from the Main injector at an energy of 120 GeV (
The muon charged current event rate in a 100 kt detector at 1300 km for neutrino (a) and antineutrino (b) running for the LBNE beam design with beam power of 700 kW and
The LBNE water Cherenkov detector design consists of a very large excavated cavity in a very strong and stable rock formation at the 4850 ft level in the Homestake facility. The cylindrical cavity will be lined with a smooth liner and filled with extremely pure water. The reference design calls for a total water mass of 266 kt and a fiducial mass of 200 kt. PMTs will surround the fiducial volume on the top, bottom, and around the perimeter. The wall PMTs will be suspended by cables about half a meter from the inner surface of the liner. The top and floor PMTs will be mounted to the structural framework. Each PMT will be connected via cable to readout electronics on the balcony above the water detector. The baseline design includes a top veto region, which will consist of an array of horizontally oriented PMTs optically separated from the rest of the detector. The veto will be used to tag cosmic ray muons that enter the detector from above that form a background for astrophysical neutrino measurements.
Provisions will be made to fill the detector with purified water and to recycle this water through the purification system and cool it. There will be provision to periodically calibrate the detector and monitor its status and performance. Finally, there will be provisions to prevent radon contamination of the detector water.
The optimum shape of the detector from excavation considerations at the Homestake site in the Yates rock formation (an amphibolite formation with some rhyolite intrusions) is a vertical circular cylinder. There are two limitations on the maximum diameter: the light attenuation length in water (~90 meters) and the maximum rock excavation diameter that does not require extraordinary rock support. The studies of both the Large Cavity Advisory Board (composed of world experts in underground construction) and Golder Associates concluded that an excavated cylindrical cavity with a diameter of 65 meters was completely feasible and cost efficient.
The major detector components are (1) the water containment system, (2) the photomultiplier mounting, housing and cable system, (3) the electronics readout and trigger system, (4) calibration procedures, (5) the water purification and cooling system, and (6) event reconstruction and data analysis. Table
A summary of the important water Cherenkov detector design parameters.
Detector design parameter | Value |
---|---|
Fiducial volume | 200 kt (200,000 m3) |
Location | Homestake 4850 ft level |
Shape | Right circular cylinder |
Cylinder excavation dimensions | 65.6 m diameter |
Dome height | 16 m |
Vessel liner dimensions | 65 m diameter |
Water volume dimensions | 65 m diameter |
Total water volume | 263,800 m3 |
Distance from Neat line to PMT equator | 0.85 m |
Dimensions of instrumented volume | 63.3 m diameter |
Instrumented volume | 241,000 m3 |
Fiducial volume cut | 2 m |
Fiducial volume dimensions | 59.3 m diameter |
Number of PMTs | 29,000 |
PMT diameter | 12 in (304 mm) |
Peak QE of PMTs (at 420 nm) | 30% |
PMT spectral response | 300–650 nm |
PMT transit time spread | 2.7 ns |
Light gain from light collectors | 41% |
Max water pressure on PMTs | 7.9 bar |
Number/type veto PMTs | 200 |
Water fill rate | 250 gal/min (0.95 m3/min) |
Detector fill time | 195 days |
Water circulation rate | 1200 gal/min (4.5 m3/min) |
Water volume exchange time | ~40 days |
Water temperature | 13°C |
Electronics burst capability |
|
Electronics time resolution |
|
Electronics dynamic range | 1–1000 PE |
Timing calibration |
|
PMT pulse height calibration |
|
Radon content | <1 mBq/m3 |
Schematic design of a 200 kt water Cherenkov detector in the Homestake underground facility.
The LBNE LArTPC consists of two massive cryostats in a single cavern, oriented end-to-end along the beam direction (roughly east to west), and located at the 4850 level (4850 L) of the Homestake underground facility. The fiducial mass of each, as defined for neutrino oscillation studies, is 17 kt and the active (instrumented) mass is 20 kt, resulting in a total active mass of 40 kt. Figure
Location of LAr-FD at the 4850 L. Primary access to the upper level of the LAr-FD cavern is through a horizontal tunnel that connects to the Ross shaft. A second horizontal tunnel near the midpoint of the cavern provides secondary egress to the existing 4850 L tunnels. A decline tunnel to the lower level is used to remove waste rock during construction and serves as a secondary egress from the cryostat septum area during operations. Cavern supply air enters the cavern from the Ross shaft and exits through a new ventilation shaft that connects to the Oro Hondo.
Detector configuration within the cavern. The TPC is located within a membrane cryostat, shown in orange. The interior dimensions of each cryostat are 24 m wide × 18 m high × 51 m long. The highbay is 150 m long and has a 32 m span. Cryogenic equipment is located in the septum area between the two cryostats. The right-hand side shows a cut view of the cryostat. The anode and cathode wire planes are hung from the ceiling of the cryostat. Each anode plane consists of
In an LArTPC, a uniform electric field is created within the TPC volume between cathode planes and anode wire planes. Charged particles passing through the TPC release ionization electrons that drift to the anode wire planes. The bias voltage is set on the anode plane wires so that ionization electrons drift between the first several (induction) planes and are collected on the last (collection) plane. Readout electronics amplify and continuously digitize the induced waveforms on the sensing wires at several MHz and transmit these data to the data acquisition (DAQ) system for processing. The wire planes are oriented at different angles allowing a 3D reconstruction of the particle trajectories. In addition to these basic components, a photon-detection system provides a trigger for proton decay and galactic supernova neutrino interactions.
The principal parameters of the LBNE liquid argon far detector are given in Table
LAr-FD principal parameters.
Parameter | Value |
---|---|
Active (fiducial) mass | 40 (33) kt |
Location | Homestake 4850 ft level |
Number of detector modules (cryostats) | 2 |
Shape | Rectangular |
Drift cell configuration within module | 3 wide |
Drift cell dimensions | 2 |
Detector module dimensions | 22.4 m wide |
Anode wire spacing | ~5 mm |
Wire planes (orientation from vertical) | Grid (0°), Induction 1 (45°), Induction 2 (−45°), and Collection (0°) |
Scintillation light detection | Yes |
Photon yield | >1 pe/10 MeV |
Drift electric field | 500 V/cm |
Maximum drift time | 2.3 ms |
Signal/noise for 1 MIP | ~9 |
The LBNE liquid argon detector design is an extension of the successful ICARUS design; nevertheless, it has several innovative elements: the cryostat construction uses commercial stainless steel membrane technology engineered and produced by industry. These vessels are widely deployed in liquefied natural gas (LNG) tanker ships and tanks and are typically manufactured in sizes much larger than that of the LAr-FD. This is an inherently clean technology with passive insulation. The time projection chamber (TPC) is the active detection element of the LAr-FD. The TPC is located inside the cryostat vessel and is completely submerged in LAr at 89 K. Its active volume is 14 m high, 22.4 m wide, and 45.6 m long in the beam direction. It has four rows of cathode plane assemblies (CPAs) planes interleaved with three rows of anode plane assemblies (APAs) planes that are oriented vertically, parallel to the beamline, with the electric field applied perpendicular to the planes. The maximum electron-drift distance between a cathode and an adjacent anode is 3.7 m. Both the cathode and anode plane assemblies are 2.5 m wide and 7 m high. Two 7 m modules (either APA or CPA) stack vertically to instrument the 14 m active depth. In each row, 18 such stacks are placed edge-to-edge along the beam direction, forming the 45.6 m active length of the detector. Each cryostat houses a total of 108 APAs and 144 CPAs. A “field cage” surrounds the top and ends of the detector to ensure uniformity of the electric field. The field cage is assembled from panels of FR-4 sheets with parallel copper strips connected to resistive divider networks.
Each APA has three wire planes that are connected to readout electronics: two induction planes and one collection plane (X). A fourth wire plane, grid plane (G), is held at a bias voltage but is not instrumented with readout electronics. The gird plane improves the signal-to-noise ratio on the U plane and provides electrostatic discharge protection for the readout electronics. A key innovative feature of the LBNE LAR detector is the use of cold electronics. Requirements for low noise and for extreme purity of the LAr motivate locating the front-end electronics in the LAr (hence “cold electronics”) close to the anode wires, which reduces the signal capacitance (thereby minimizing noise). The use of CMOS electronics in this application is particularly attractive since the series noise of this process has a noise minimum at 89 K. The large number of readout channels required to instrument the LAr-FD TPCs motivates the use of CMOS ASICs. Signal zero-suppression and multiplexing will be implemented in the ASIC, minimizing the number of cables and feedthroughs in the ullage gas, and therefore reducing contamination from cable outgassing.
Both detector designs for LBNE, the water Cherenkov and liquid argon, were reviewed extensively for cost, schedule, and scientific performance. The fiducial masses of both detectors were chosen to achieve similar performance for neutrino oscillation physics, in particular the sensitivity to CP violation. The reviews concluded that both detectors could achieve the performance goals for neutrino physics; nevertheless, there were some advantages to the liquid argon detector due to its fine granularity. Liquid argon is also a complementary technology in terms of searching for proton decay and its sensitivity to low-energy electron neutrinos (instead of electron antineutrinos) from supernova. Furthermore, it was clearly cost-prohibitive to design and build both types of detectors; therefore, through an extensive process of selection, the liquid argon option was selected as the reference design for LBNE.
In addition to the far detector, the LBNE design also includes near detectors to monitor the neutrino beam before it leaves the Fermilab site. The set of detector systems for the near detectors reference design consists of a beamline-measurements system (BLM) and a neutrino-detection system (ND for “neutrino detectors”). The near detectors will be located at the near site (Fermilab), downstream of the beamline. The BLM will be located in the region of the Absorber Complex at the downstream end of the decay region to measure the muon fluxes from hadron decay. The neutrino detector will be placed in the near detector hall, 450 m downstream of the target, and underground. The reference-design neutrino measurements system technology is a liquid-argon-filled time projection chamber tracker (LArTPCT), matching the interaction material in the LAr-FD (described in Volume 4 of this CDR). The LArTPCT will consist of a 1.8 m × 6 m × 1.8 m × 4 m TPC and a 2.7 m diameter
The LBNE project has a broad range of scientific objectives, listed below. Measurements of the parameters that govern Precision measurements of Search for proton decay, yielding measurement of the partial lifetime of the proton ( Detection and measurement of the neutrino flux from a core-collapse supernova within our galaxy or a nearby galaxy, should one occur during the lifetime of the detector. Other accelerator-based neutrino oscillation measurements. Measurements of neutrino oscillation phenomena using atmospheric neutrinos. Measurement of other astrophysical phenomena using medium-energy neutrinos.
The detector design was driven largely by objectives (1)–( 4).
Observation of
Figure
3
In addition, a liquid argon detector of this size can achieve <1% precision on measurements of
The scientific capability for detection of nucleon decay and supernova using a large liquid argon TPC has been discussed elsewhere in this paper. We will not cover it in detail here. The 34 kt liquid argon TPC can achieve sensitivity to proton lifetimes of ~
The cost of the LBNE project includes the design and constructions of the beamline, the far and near detectors, and the surface and underground civil constructions needed for the beamline and to house the detectors and shield them from cosmic rays. A preliminary cost and schedule estimate for the entire project was assembled and reviewed in March 2012. The costs include the engineering and scientific manpower that is needed for the design and construction activities. It also includes appropriate contingencies and overheads. The total cost for the project as described above is approximately US $1.5 B in FY2010 currency. The schedule for the project partly depends on the availability of funds; however a preliminary technical evaluation of the schedule suggests an experiment start in year ~2022.
The cost of the complete LBNE project is considered too high for the current budgetary climate in the US, and, therefore, the US, Department of Energy has asked for an approach to reach the scientific goals of LBNE in a phased manner. Furthermore, strategies and consultation are sought to enhance international participation in the project. In response to this request, various phasing strategies as well as alternatives have been examined. To address all of the fundamental science goals listed above, a reconfigured LBNE would need a very long baseline (>1,000 km from accelerator to detector) and a large detector deep underground. However, it is not possible to meet all of these requirements in a first phase of the experiment within the budget guideline of about half of the projected cost of the full project.
Therefore, options are being assessed that meet some of the requirements, and three viable options have been identified for a Phase 1 long-baseline experiment that have the potential to accomplish important science at realizable cost. There are listed below. Using the existing NuMI beamline in the low-energy configuration with a 30 kt liquid argon time projection chamber (LAr-TPC) surface detector 14 mrad off-axis at Ash River in Minnesota, 810 km from Fermilab. Using the existing NuMI beamline in the low-energy configuration with a 15 kt LAr-TPC underground (at the 2340 ft level) detector on-axis at the Soudan mine in Minnesota near the MINOS detector, 735 km from Fermilab. Constructing a new low-energy LBNE beamline with a 10 kt LAr-TPC surface detector on-axis at Homestake in South Dakota, 1,300 km from Fermilab.
The scientific capabilities of the above options have been discussed in [
This option is seen as a start of a long-term program that would achieve the full goals of LBNE in time and allow probing the standard model most incisively beyond its current state. Ultimately this option would exploit the full power provided by Project-X. At the present level of cost estimation, it appears that this preferred option may be 10% more expensive than the other two options, but cost evaluations are continuing. The major limitation of the preferred option is that the underground physics program including proton decay and supernova collapse cannot start until later phases of the project. Placing a 10 kt detector underground instead of the surface in the first phase would allow such a start and increase the cost by about $135 M. Negotiations to obtain such funding from US domestic funding sources or international participants are in progress.
Project-X is a multimegawatt proton facility being developed to support intensity frontier research in elementary particle physics, with possible applications to nuclear physics and nuclear energy research, at Fermilab. The centerpiece of this program is a superconducting
In Table
Beam conditions and power possible during the Project-X phase and further upgrades to the 8 GeV performance. An accumulator ring at 8 GeV could be used to improve the duty factor.
Accelerator stage | Energy | Current | Duty factor | Power available |
---|---|---|---|---|
Continuous wave linac | 3 GeV | 1 mA | Continuous wave | 3000 kW |
Pulsed linac | 8 GeV | 43 |
4.33 ms/0.1 sec | 350 kW |
8 GeV upgrade | 8 GeV | 500 |
6.67 ms/0.066 sec | 4000 kW |
Main injector | 60 GeV | 35 |
9.5 |
2100 kW |
Main injector | 120 GeV | 19 |
9.5 |
2300 kW |
Proton beam power as a function of proton energy from the Fermilab Main Injector. Shown are current capabilities labeled as NuMI. The recently funded upgrades (labeled as ANU) will increase the power to 550 kW at 60 GeV or 700 kW at 120 GeV. Project-X as currently conceived will allow beam power of 2 MW at 60 GeV and 2.3 MW at 120 GeV.
Precision on parameters
Based on the indication of
In Japan, two different approaches are considered for the study of lepton CP symmetry using the neutrino beam at J-PARC. One configuration is suitable for water Cherenkov technology, and the other is suitable for liquid argon TPC technology. Since water Cherenkov technology has an excellent performance for a sub-GeV low multiplicity final state environment, a relatively short baseline of 295 km with a low-energy narrowband neutrino beam is adopted to compare the difference between
In this section we describe the Japanese approach, including the accelerator-based neutrino source in Japan, the Okinoshima Giant Liquid Argon Observatory, and the Hyper-Kamiokande project.
J-PARC (Japan Proton Accelerator Research Complex) is a KEK-JAEA joint facility of a MW-class high-intensity proton accelerator research facility (Figure
J-PARC accelerator and experimental facility.
In the accelerator complex,
The proton beam from the main ring synchrotron (MR) travels the J-PARC neutrino beam facility and produces an intense beam of muon neutrinos pointing west. The J-PARC neutrino beam facility is composed of the following components (Figure Preparation section: matches the beam optics to the arc section. Arc section: bends the beam ~ Final focus section: matches the beam optics to the target both in position and in profile. The level of control at the mm level is necessary which corresponds to 1 mrad Graphite target and horn magnet: produce intense secondary Muon monitor: monitors the On-axis neutrino monitor: monitors the
J-PARC neutrino beam facility.
This facility is designed to be tolerate around ~1 MW beam power. This limitation is due to the temperature rise and thermal shock for the components such as the Al horn, graphite target, and Ti vacuum window. Since this region is a high-radiation environment, a careful treatment of the radioactive water and air is required. Moreover, a maintenance scenario of radioactive components has to be carefully planned.
Till June 2012 the J-PARC neutrino beam delivered up to 0.19 MW to T2K (Tokai-to-Kamioka long-baseline neutrino experiment) [
MR power improvement scenario.
Till June 2012 | Next step | Target | |
---|---|---|---|
Power (MW) | 0.19 | 0.30 |
|
Energy (GeV) | 30 | 30 |
|
Rep. cycle (sec.) | 2.56 | 2.40 |
|
No. of bunches | 8 | 8 |
|
Particles/bunch | 1.26 |
1.9 |
|
Particles/ring | 1.0 |
1.5 |
|
Linac (MeV) | 181 | 400 |
|
RCSa |
|
|
|
The items to be modified are listed as follows. For the linac, a 400 MeV operation is required to avoid severe space charge effects at RCS injection. The installation of necessary equipment is foreseen from the summer of 2013. The repetition cycle of the MR has to be improved from 2.56 seconds to 1.28 seconds. For this purpose, the RF and the magnet power supply improvements are necessary. The necessary R&D for these components has been started as of 2012. A system to localize the beam loss at the dedicated collimator system must be installed.
Assuming a successful R&D program on the higher repetition cycle and on the increase of the number of particles per bunch as well as sufficient resources the accelerator power will be upgraded to 0.75 MW within a time scale of five years.
The use of a giant liquid argon time projection chamber (TPC) with 100 kton size is an excellent opportunity to realize a broad range of scientific topics. It would be ideal for the next-generation accelerator-based neutrino research investigating the lepton sector CP symmetry and would extend the search for the proton decay via modes favored by the supersymmetric grand unified models (e.g.,
Specification of giant liquid argon time projection chamber.
Diameter for active argon (m) | 70 |
Drift length (m) | 20 |
Active mass (ton) | 107753 |
Signal readout area (m2) | 3848 |
Maximum drift time at 1 kV/cm (ms) | 10 |
Charge readout views | 3 mm pitch, two perpendicular strips |
Scintillation light readout | 1000 8′′ PMT |
The effects of lepton sector CP phase in the energy spectrum shape of the appearance oscillated as a difference between
It should be noted that if one precisely measures the
An optimal experimental setup including parameters such as the length of the baseline, the angle with respect to the neutrino beam axis and the detector technology affects the extraction of the CP phase [
In order to realize the project within a reasonable time scale, it makes sense to utilize the currently available facilities as much as possible. On the other hand, this may present boundary conditions for the project. In our case, J-PARC is a currently available and indispensable facility for our project. We have to consider the project taking into account its available intensity (750 kW) and energy (30 GeV). To obtain an experimental result within a reasonable time scale, it would be preferable if we could extract lepton CP symmetry information without relying on a time-consuming antineutrino beam setting. If the baseline of the experiment becomes longer, the neutrino energy has to increase in order to fit the neutrino spectrum within the neutrino oscillation maximum. Given the proton accelerator energy setting, which creates a limitation on the available neutrino energy, there is a limitation on the baseline of the experiment, accordingly.
Thus, the optimal choice for the investigation of lepton sector CP symmetry using a liquid argon TPC is the measurement of the energy spectrum shape of the appearance oscillated
The necessary conditions for the measurement are a long baseline (>600 km) to see the second oscillation maximum in a measurable energy region (>400 MeV), an on-axis beam for wide energy coverage, and a giant detector to overcome the finite beam flux and long baseline.
With the same configuration as T2K (
J-PARC to Okinoshima long-baseline neutrino experiment.
The analysis presented here is based on the assumption of a neutrino run only with an exposure of
Figure
Energy spectra at
Allowed regions in the perfect resolution case are shown in Figure
Allowed regions in the perfect resolution case. Twelve allowed regions are overlaid for twelve true values,
The site study of the Okinoshima Giant Liquid Argon Observatory has been initiated taking into account geological, geographical, and infrastructure considerations [
The main island of Okinoshima, Dogo, is almost circular with a diameter of about 16 km and the center is a mountainous zone with an altitude of 500 m and more than one candidate location for the giant liquid argon observatory can be found. The distance from the main island of Japan (Honshu) is about 80 km. The population is about 16,000 and the economy mainly depends on the fishery and tourist business.
Though the islands were born of volcanic activity around 5 to 6 million years ago, there is stable bedrock, called Oki-Gneiss, which is the oldest rock in Japan (more than 3 billion years old) and which is suitable for the construction of a big cavern. Typical specific gravity and axial strength of Oki-Gneiss is 27 kN/m3 and 79 MPa, respectively.
The cross-sectional drawing of the potential location of the cavern is shown in Figure
Potential cavern for Okinoshima Giant Liquid Argon Observatory.
A conceptual design of the cavern has been carried out and is also shown in Figure
There would not be a difficulty in transportation since there are regular daily commercial connecting flights and ferry services between Honshu and the main harbor of Dogo (Saigou port) which is close to the location of the candidate site. Moreover, there is a sufficient traffic access route between Saigou port and the candidate site to carry heavy equipment needed for the civil engineering work, the large amount of liquid argon, and the detector components.
The Chugoku Electric Power Company provides electricity for Okinoshima. The existing total electricity capacity is 32 MW and may be enough for the construction and operation of the observatory.
The procurement of 100 kton of liquid argon, which should be done within about 5 years with minimum cost, is another important issue to be considered. One possible solution is to purchase liquid Argon from several large-scale manufacturing plants which have large production capacities. The demand from the Giant Liquid Argon Observatory is estimated to be roughly 10 to 15% of their annual production capacity; hire 4 tanker trucks dedicated for the liquid Argon ground transportation. The cost of trucks for 5 years is not the major part of the total cost for the project.
So far there is no show stopper to realize the Okinoshima Giant Liquid Argon Observatory.
Hyper-Kamiokande (Hyper-K), being proposed by the Hyper-Kamiokande working group [
The schematic view of the Hyper-K is shown in Figure
Detector parameters of the baseline design.
Detector type | Ring-imaging water Cherenkov detector | |
---|---|---|
Address | Tochibora mine | |
Kamioka town, Gifu, Japan | ||
Lat. |
| |
Long. |
| |
Candidate site | Alt. | 508 m |
Overburden | 648 m rock (1,750 m water equivalent) | |
Cosmic ray muon flux | 1.0~2.3 |
|
Off-axis angle for the J-PARC |
| |
Distance from the J-PARC | 295 km (same as Super-Kamiokande) | |
| ||
Total volume | 0.99 megaton | |
Detector geometry | Inner volume (fiducial volume) | 0.74 (0.56) megaton |
Outer volume | 0.2 megaton | |
| ||
Inner detector | 99,000 20 inch |
|
Photomultiplier tubes | 20% photocoverage | |
Outer detector | 25,000 8 inch |
|
| ||
Water quality | Light attenuation length | >100 m at 400 nm |
Rn concentration | <1 mBq/m3 |
Schematic view of the Hyper-Kamiokande detector. The detector consists of two cylindrical water tanks lying side by side.
The Hyper-K detector candidate site, located 8 km south of the Super-K, is in the Tochibora mine of the Kamioka Mining and Smelting Company, near Kamioka town in Gifu prefecture, Japan. The experiment site is accessible via a drive-in, 2.6 km long, horizontal mine tunnel. The detector will lie under the peak of Nijuugo-yama, having 648 meters of rock or 1,750 meters-water-equivalent (m.w.e.) overburden. The cosmic ray muon rate at the candidate site is reduced to
The expected detector performance of Hyper-K, assuming 20% photocoverage, is summarized in Table
Expected detector performance of Hyper-Kamiokande.
Resolution or efficiency | |
---|---|
Vertex resolution | |
at 500 MeV/ |
28 cm (electron)/23 cm (muon) |
at 5 GeV/ |
27 cm (electron)/32 cm (muon) |
Particle ID | |
at 500 MeV/ |
|
at 5 GeV/ |
|
Momentum resolution | |
at 500 MeV/ |
5.6% (electron)/3.6% (muon) |
at 5 GeV/ |
2.0% (electron)/1.6% (muon) |
Electron tagging | |
from 500 MeV/ |
98% |
from 5 GeV/ |
58% |
| |
J-PARC |
64% (nominal)/50% (tight) |
J-PARC |
|
J-PARC |
95% (nominal)/97.6% (tight) |
| |
|
45% |
Atmospheric |
1.6 events/Mton/year |
|
7.1% |
atmospheric |
1.6 events/Mton/year |
|
6.7% |
atmospheric |
6.7 events/Mton/year |
| |
Vertex resolution for 10 MeV electrons | 90 cm |
Angular resolution for 10 MeV electrons | 30° |
Energy resolution for 10 MeV electrons | 20% |
Hyper-K provides rich neutrino physics programs as summarized in Table
Physics targets and expected sensitivities of the hyper-Kamiokande experiment updated from [
Physics target | Sensitivity | Conditions |
---|---|---|
Neutrino study w/J-PARC |
||
(i) CP phase precision | <20° | at |
mass hierarchy (MH) is known | ||
(ii) CPV |
74% | at |
MH known | ||
54% | at |
|
MH unknown | ||
69% | at |
|
MH known | ||
42% | at |
|
MH unknown | ||
| ||
Atmospheric neutrino study | 10-year observation | |
(i) MH determination | >3 |
at |
(ii) |
>90% CL | at |
| ||
Nucleon decay searches | 10 years data | |
(i) |
|
|
|
||
(ii) |
|
|
|
||
| ||
Solar neutrinos | ||
(i) |
200 |
7.0 MeV threshold (total energy) |
(ii) |
|
5 years, only stat. error |
| ||
Astrophysical objects | ||
(i) Supernova burst |
170,000–260,000 |
at Galactic center (10 kpc) |
30–50 |
at M31 (Andromeda galaxy) | |
(ii) Supernova relic |
300 |
>20 MeV |
(iii) WIMP annihilation at Sun | 5-year observation | |
|
at |
|
|
||
|
at |
|
|
Transition probability of muon neutrino to electron neutrino at the distance of 295 km for neutrino (left top panel) and antineutrino (right top). Each color shows the appearance probability for each
Natural, free, and atmospheric neutrinos also provide a good opportunity to study neutrino properties. In particular, thanks to the relatively large
Oscillated
The experimental search for nucleon decays by large detectors, which has been performed for more than three decades and gave stringent constraints on the grand unification picture of elementary particles, is also one of major goals of the Hyper-K project. Hyper-K extends the sensitivity to nucleon decays far beyond that of Super-K. The sensitivity to the partial lifetime of protons for the decay mode
Hyper-K also serves as an astrophysical neutrino observatory and explores the inside of stars by using neutrinos as a probe. Hyper-K will examine the possible flux variation of neutrinos from the Sun by detecting 200 solar neutrinos per day above 7 MeV total neutrino energy. If a Supernova explosion happens at the center of our galaxy, Hyper-K will accumulate
EUROnu is a design study within the European Commission Seventh Framework Program, Research Infrastructures. It is investigating the three possible options for a future, high-intensity neutrino oscillation facility in Europe. The aim is to undertake conceptual designs for the facilities, determine the performance of the corresponding baseline detectors, and compare the physics reach and cost of the facilities. The work is being undertaken by the EUROnu consortium, consisting of 15 partners and a further 15 associate partners [
The three facilities being studied are as follows. The CERN to Fréjus Super Beam, using the 4 MW version of the Superconducting Proton Linac (SPL) at CERN [ The Neutrino Factory, in which the neutrino beams are produced from the decay of muons in a storage ring. This work is being done in close collaboration with the International Design Study for a Neutrino Factory (IDS-NF) [ The Beta Beam, in which the neutrino beams are produced from the decay of beta emitting ions, again stored in a storage ring.
The project started on September 1, 2008 and will finish on August 30, 2012, and thus, is very advanced at the time of writing. The work done on the accelerator facilities, the detectors, and in determining the physics performance will be described in the following subsections.
A Super Beam creates neutrinos by impinging a high-power proton beam onto a target and focussing the pions produced towards a far detector using a magnetic horn. The neutrino beam comes from the pion decay (Figure
(a) Layout of the CERN to Fréjus Super Beam. (b) Conceptual engineering design of the 4 target and horn system for the Super Beam.
Given the difficulty in producing a single target and horn able to work in a 4 MW beam, the option taken in EUROnu is to use four of each instead. The beam will then be steered on to each target in turn, so that they all run at 12.5 rather than 50 Hz and receive 1 MW. For the targets and the horns, this results in a smaller extrapolation from technology already in use. An outline design for the 4 target and horn system is shown in Figure
The final area studied is the beam delivery from the SPL to the target. As shown in Figure
In a Neutrino Factory, the neutrinos are produced from the decay of muons in a storage ring. The muons are produced by impinging a 4 MW proton beam onto a heavy metal target and focussing the pions produced into a decay channel using a 20 T superconducting solenoid. In the original baseline, the muons from the pion decay are captured, bunched, phase rotated, and finally cooled in the muon front-end, before being accelerated using a linac, two recirculating linear accelerators (RLAs) and a nonscaling fixed-field alternating gradient accelerator (ns-FFAG) to 0.9 GeV, 3.6 GeV, 12.6 GeV, and 25 GeV, respectively (see Figure
(a) Original baseline layout of the neutrino factory. (b) Pion production as a function of atomic number, assuming a cylindrical target 20 cm long and 2 cm in diameter.
However, following the measurement of
The work in this project is being done in close collaboration with the International Design Study for a Neutrino Factory (IDS-NF) [
A related issue is the transmission of secondaries into the muon front-end. As well as the required large flux of muons, there are also still many protons, pions, and electrons. If nothing is done about these, they will be lost throughout the front-end, resulting in levels of activation about 100 times above the canonical level for hands-on maintenance. The front-end is being redesigned in EUROnu to include a chicane, to remove the higher momentum unwanted particles, and an absorber, to remove those at lower momentum. The efficiency for transmission of useful muons is about 90%, while the unwanted particles are reduced to a manageable level. This scheme has recently been incorporated in the neutrino factory baseline.
For the cooling channel, an engineering demonstration of the cooling technique, ionization cooling, is being constructed at the STFC Rutherford Appleton Laboratory. This project, called MICE [
The design of the acceleration system is well advanced, though full 6D tracking still needs to be done. Following the reduction to 10 GeV, two options now exist for this system. The first uses a linac and two RLAs, while the second replaces the higher-energy RLA with a ns-FFAG. Both options are under study to determine which would be best based on performance and cost. As ns-FFAGs are an entirely novel type of accelerator, a proof-of-principle machine called EMMA [
The EMMA proof-of-principle accelerator at the Daresbury Laboratory.
Production of (anti)neutrinos from beta decay of radioactive isotopes circulating in a race-track-shaped storage ring was proposed in 2002 [
(a) Layout of the CERN Beta Beam. (b) The prototype ion collection device constructed for Beta Beam studies.
One of the main issues studied by EUROnu is the production, acceleration, and storage of a sufficient flux of ions to meet the physics goals. The isotope pair that was first studied for neutrino production, in the EURISOL FP6 Design Study [
As a result, research on a novel
Research and development of a 60 GHz pulsed ECR source to bunch the ions produced are continuing within EUROnu. A prototype device has been constructed and successful magnetic tests have been done. These will be followed by tests with the gyrotron and with beam. Compatibility and possible integration of Beta Beams in the upgrade program for the LHC is essential and is being actively studied. Requirements to have very short and intense bunches in the decay ring (due to signal/noise in the detector) favors beam instabilities for which solutions will be found by reoptimizing the bunch structure over the accelerator cycle.
The baseline isotopes could use the MEMPHYS detector [
The focus of EUROnu is on the accelerator facilities. Nevertheless, to make a genuine comparison between physics performance and cost, it is also important to include the neutrino detectors in the study. Thus, the project includes the baseline detectors for each facility, with the aim of determining their performance in detecting neutrinos and the cost of construction.
The baseline for the Neutrino Factory is a magnetized iron neutrino detector (MIND). This is an iron-scintillator calorimeter, with alternating planes of 3 cm thick iron and 2 cm thick solid scintillator. One detector is now planned, of 100 kT mass at around 2000 km. This is based on the MINOS detector [
The physics group in EUROnu is determining the physics reach of each facility and combination of facilities using the parameters provided for the accelerators and detectors. They also assess and include the corresponding systematic errors in a uniform way and optimize performance based on information from other experiments. Following the recent indications of large LENF: the low-energy neutrino Factory, with a 10 GeV muon energy, BB100: a SPL-1st: a 4 MW SPL Super Beam with 500 kt water Cherenkov detector at Fréjus, corresponding approximately to the first oscillation maximum. SPL-2nd: as above, but with the detector at Canfranc, corresponding to approximately the second oscillation maximum. SPL+BB: the combination of BB100 and SPL-1st.
Summary of the physics performance of the facilities described in the text. (a) The 1
For the low-energy Neutrino Factory, the signal systematic error used is 2.4%, while it is 5% for the other facilities. The systematic error used for the background in all cases is 10% and 10-year running time is assumed.
The EUROnu comparative costing is based on the three facilities being located at CERN, to put the costing on the same basis. Similar assumptions are being made and common costs are being used wherever possible. It is being overseen by a costing panel. To complement this, the major safety aspects and technical risks of the facilities are being assessed. As only limited resources are available, the emphasis in costing is to achieve the best relative precision between the facilities. The same principle is being applied for the safety assessment. It will use existing experience, where that exists. The technical risks will be assessed by the facilities at the end of the design study.
Neutrinos are messengers from astrophysical objects as well as from the early universe and can give us information on processes, which cannot be studied otherwise. Underground experiments, like Super-Kamiokande (SK) [
The FP7 Design Study LAGUNA (2008–2011) was a Pan-European effort of 21 beneficiaries, composed of academic institutions from Denmark, Finland, France, Germany, Poland, Spain, Switzerland, and UK, as well as industrial partners specialized in civil and mechanical engineering and rock mechanics. The goal of the study was to assess the feasibility of this research infrastructure in Europe and the related costs.
The LAGUNA consortium has evaluated possible extensions of the existing deep underground laboratories in Europe: Boulby (UK), Canfranc (Spain), and Modane (France) and considered the creation of new laboratories in the following sites:
(a) Map of the seven possible underground sites in Europe. (b) Exemplary layouts studied in LAGUNA DS for each site.
The LAGUNA collaboration decided to go ahead with a new study, LAGUNA-LBNO (2011–2014) to investigate two sites in detail: the shortest baseline from CERN, Fréjus at 130 km with no matter effect and therefore providing a clean measurement of CP violation and the longest baseline at Pyhäsalmi (2300 km) with matter effects and therefore able to determine the mass hierarchy. A third site, Umbria in Italy at 730 km from CERN, is investigated with lower priority. Umbria is a green field location in the existing CERN-CNGS beam.
LAGUNA-LBNO is a collaboration of about 300 physicists and engineers from 13 countries including 39 research institutions and industrial partners. Two non-European countries, Japan and Russia, are partners of the project. LAGUNA-LBNO will provide a realistic scheme for the tank construction and the costing of the detector itself. The costs involved with liquid procurement and long-term running of the new underground laboratory will be evaluated. New beam options based on the existing CERN accelerator complex are investigated and the physics potential of each detector option at the two locations will be studied.
At the Pyhäsalmi site, two options are studied: a 50 kt liquid scintillator detector (LENA) and the GLACIER detector with 20 kt and 50 kt liquid argon for a staged instrumentation. Both detectors are located at a depth of roughly 4000 m.w.e. For the Fréjus site, the MEMPHYS project in combination with a
The
Effective extrapolation to the required scale needs concrete R&D. A ton-scale LAr LEM-TPC detector has been successfully operated at CERN in Blg 182 within the CERN RE18 experiment (ArDM). The detector has been moved to the Canfranc underground laboratory in Spain to search for direct WIMP signals. In order to prove the performance for neutrino physics, additional dedicated test beam campaigns are being considered, to test and optimize the readout methods and to assess the calorimetric performance of such detectors. A 1 kt detector can be built assuming the GLACIER design with a 12 m diameter and 10 m vertical drift. The layout of the GLACIER tank and its implementation in the Pyhäsalmi mine is shown in Figure
Schematic view of the Pyhäsalmi mine and the GLACIER and LENA detector with their access shafts.
Thanks to the very good imaging capabilities of the GLACIER detector in combination with a neutrino beam from CERN the experiment has outstanding physics potential. The high resolution of the detector allows the precise measurement of the first and second oscillation maximum and therefore the precise determination of
As stated above, the GLACIER experiment is scalable and therefore a staged approach is actively developed. The first phase is a 20 kt double phase LAr LEM-TPC (GLACIER) combined with a magnetized muon detector (MIND). The beam is based on a conventional neutrino beam line with a baseline of 2300 km towards Pyähsalmi, Finland (CN2PY) with protons from an upgraded CERN SPS (700 kW). An Expression of Interest has been submitted to the CERN SPSC for this project [
The experiment allows the precise determination of oscillation parameters by measuring all transition probabilities
(a) The 68% and 90% CL contours in the
Thanks to the deep underground location, this initial phase can reach a number of outstanding physics goals. The new underground neutrino observatory addresses the unification of elementary forces by searching for nucleon decay. The limit on the proton lifetime will be improved to
In a second phase (≥2025), the detector can be upgraded to reach the full seize of 100 kt and the beam power will be increased with a HP-PS (2 MW) or a neutrino factory, for example, which allows 75% coverage of the CP violation parameter space at
The
(a) The PMT support structure is optically shielded from the tank walls; (b) each optical module contains a fully enclosed PMT equipped with a Winston cone. Nonscintillating mineral oil is added to prevent gammas emerging from the PMTs from reaching the scintillator [
The optical modules will contain
The detector tank has to be placed in an underground cavern to provide shielding from cosmic radiation. The design foresees a volume around the detector tank to be filled with pure water acting as a Cherenkov veto for cosmic muons as well as a shielding for fast neutrons. The preferred locations are either in the Pyhäsalmi mine in central Finland, at a depth of 1400 m (4000 m.w.e.), or in the Laboratoire Souterrain de Modane adjacent to the Fréjus tunnel in the French-Italian Alps with a rock overburden corresponding to 4800 m.w.e. A detailed description of the LENA project can be found in [
The concept of neutrino spectroscopy has been successfully demonstrated by both KamLAND and Borexino. The low-energy threshold of LSc offers a wide range of physics based on neutrinos from terrestrial and astrophysical sources. The core research program will be the detection of neutrinos with energies reaching from sub-MeV to tens of MeV, but LENA can also contribute to several aspects of neutrino and particle physics associated to GeV energies.
The huge target mass of LENA gives the opportunity of a high statistics spectral measurement of the solar neutrino flux. Approx.
LENA offers excellent capabilities for the observation of a galactic core-collapse Supernova [
While the predicted rate of galactic Supernovae is about one to three per century, the isotropic neutrino background from Supernovae on cosmic scales is expected to provide a flux of approx.
The inverse beta decay offers an excellent detection channel for
Furthermore, LENA allows for an indirect search for dark matter (DM) by observing neutrinos produced in the annihilation or decay of DM particles. LENA is especially sensitive in the region of 10 to 100 MeV which is not easily accessed by other experiments.
Within LAGUNA-LBNO, the use of LENA as a target for a possible future neutrino beam is currently under investigation [
Sensitivity of LENA to the neutrino mass hierarchy for the 2288 km long-baseline CERN to Pyhäsalmi and for different detector and beam performances at
To reconstruct the complex vertices created by the interactions of GeV neutrinos, a reliable tracking and identification of all final state particles is needed. The possibility of particle tracking in unsegmented LSc detectors is currently investigated in a great effort, returning promising results on the neutrino energy reconstruction and NC background identification.
The NC/CC discrimination applied in this analysis relies on pulse shape analysis/tagging of muon decay electrons to suppress NC background events featuring charged pions and on a multivariate analysis (again relying mostly on pulse shape parameters) to distinguish
When a high-energy charged particle passes through the LSc, it creates a superposition of spherical light waves, forming a spherical backward running light front and a v-shaped forward light front resembling a Cherenkov cone, thus creating distinct arrival time patterns at the PMTs. Analyzing these patterns allows for a track reconstruction, as it has been shown for cosmic muons by KamLAND and Borexino. Recent studies investigate the capability of this method for
Visualization of the tracking for electron (a) and muon (b) events in LENA. The pictures show density profiles for the light emission inside the scintillator. Due to the broader and shorter profile of the emerging electromagnetic shower,
Neutrino mixing parameters can also be determined in LENA using much shorter baselines. Based on high-intensity synchrotrons producing GeV protons,
Last but not least, neutrino physics is not the only field where LENA can improve our current knowledge of elementary physics. Due to its high target mass and the excellent background discrimination, LENA is capable of increasing the limit of the proton lifetime to
The LENA detector and its implementation in the Pyhäsalmi mine is shown in Figure
The
The project aims at a fiducial mass around half a megaton obtained with 2 cylindrical detector modules of 65 meters in diameter and 103 meters in height. A schematic view is shown in Figure
Possible layout for the future neutrino observatory at the Fréjus tunnel. The MEMPHYS detector is made of two independent tanks 60 m apart from each other. Each tank is 65 m in diameter and 103 m in height.
For a MEMPHYS detector at the Fréjus site, situated at 130 km from CERN, the first peak of the neutrino oscillation probability occurs at a beam energy between 0.2 and 0.4 GeV. The sensitivity of the MEMPHYS experiment to CP violation is shown in Figure
Sensitivity to leptonic CP violation of the MEMPHYS experiment at 3
The deep underground position of the MEMPHYS neutrino observatory (4800 m.w.e.) allows a very rich nonaccelerator physics program. We summarize in Table
Summary of nonaccelerator physics in MEMPHYS.
Topic | MEMPHYS ( |
(~ |
---|---|---|
Proton decay: | In |
In |
|
< |
~ |
|
< |
~ |
| ||
SN |
||
CC |
|
~ |
ES |
|
~ |
| ||
DSN |
|
|
| ||
Solar |
||
|
|
~ |
| ||
Atm. |
|
~ |
Geo |
Needs |
Needs |
Reactor |
|
~ |
The (
The coverage of large area with PMTs at a “low” cost implies a readout integrated electronics circuit (called ASIC) for groups of PMT (matrix of
(a) Schematic view of the MEMPHYNO prototype. (b) Photograph of the PMm2 matrix of
The development on grouped electronics and photosensors is of very high interest for all the three detector options of the LAGUNA project. In particular the strong synergy with the LENA detector leads to a joint study within a collaborative effort between German and French groups [
In parallel to the development on photosensors and electronics, a large effort on the simulation of the detector performance is ongoing.
The neutrino event generator is based on GENIE [
Neutrinos physics is one of the most dynamic and exciting fields of research in fundamental particle physics and astrophysics. The next-generation neutrino detector will address fundamental properties of the neutrino like mass hierarchy, the mixing angle
The authors are grateful to the European Commission for the financial support of the project through the FP7 Design Studies LAGUNA (Project no. 212343), LAGUNA-LBNO (Project no. 284518), and EUROnu (Project no. 212372). The EC is not liable for any use that may be made of the information herein. They thank the French Centre National de Recherche Scientifique for the support of the project in form of the PICS. They are also grateful to the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (Grant no. 23244058). This work was partially supported by the US Department of Energy.