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Liquid Argon Neutrino Programme


Liquid argon TPC as a neutrino detector

Liquid argon (LAr) Time-Projection Chambers (TPCs) function as excellent neutrino detectors. The high density of the liquid argon provides a relatively high rate of neutrino interactions, and the high-granularity that a TPC allows leads to astounding images of the particles produced in a neutrino interaction (see below for one of the first neutrino interactions from MicroBooNE!)

The particle physics group at Manchester have a vibrant research group involved in the design, construction, and operation of these detectors in various settings, as well as the analysis of the data collected. This mainly falls under two projects, the DUNE long baseline neutrino oscillation experiment, and the SBN short baseline neutrino oscillation programme.

Short Baseline Neutrino Programme (SBN)

The SBN project plans to implement a suite of three LArTPC neutrino detectors in the same neutrino beam at Fermilab in the US. The detectors will be placed at distances up to 600m along the Booster Neutrino Beam (BNB), which has already been used to provide a high-purity muon neutrino beam for the MiniBooNE experiment from 2002 to 2012.

The MicroBooNE project was designed to investigate the low-energy excess seen in MiniBooNE and make detailed measurements of low energy neutrino cross sections on argon. The detector was installed in its 470 m location in the BNB in 2014 and will be taking its first data run in 2015. The SBN project will then add two more detectors. A near detector, SBND (Short-Baseline Neutrino Detector)—previously known as LAr1-ND—is currently being designed and will be installed in a new hall at 100 m in 2017. In addition, the refurbished ICARUS T600 detector will be installed at 600 m.

The SBN programme is intended to search for sterile neutrinos in the region of phase space where the LSND and MiniBooNE experiments observed low-significance signals. If these sterile neutrinos exist, they open up exciting new possibilities for physics beyond the standard model. The SBN programme, with three liquid argon detectors at varying baselines, coupled with the high-purity Booster Neutrino Beam, will provide unprecedented sensitivity to short-baseline oscillations due to sterile neutrinos.

The LArTPC technology has a large advantage over Cherenkov detectors, such as the one employed by the MiniBooNE experiment. In particular, it allows very good separation between showers from electrons and photons—a Cherenkov detector cannot tell the two apart. This will allow the MicroBooNE experiment to investigate the low-energy excess seen in MiniBooNE, to determine whether it is electron-like or photon-like.

As well as searching for sterile neutrinos, the three detectors serve as important R&D test-beds for a future 40 kton detector which is proposed to be used for the DUNE experiment. They will also be used to make very detailed studies of neutrino interactions on argon.

Deep Underground Neutrino Experiment (DUNE)

DUNE (Deep Underground Neutrino Experiment) is a long-baseline neutrino experiment which will be hosted by Fermilab.

DUNE will make measurements of three-neutrino oscillations with unprecedented precision, aiming to determine the neutrino mass hierarchy and search for leptonic CP violation. To achieve this, a neutrino beam will be constructed at Fermilab, and directed toward the Sanford Underground Research Facility (SURF) 1300 km away. At SURF, a 40 kton (34 kton fiducial volume) LAr neutrino detector will be built 4850 feet (1.5 km) underground. The LArTPC technology being used allows very high precision measurements of every neutrino detected, and the high statistics measurements that can be made with the planned beam power and detector size will shed light on the most mysterious known fundamental particles of nature.

In addition to accelerator neutrinos, DUNE will be able to make measurements of atmospheric neutrinos and will be on the lookout for neutrinos from supernova bursts. It will also search for baryon number violating processes, such as proton decay and neutron-antineutron oscillations.

People

Work At Manchester

The group at Manchester began working on the Fermilab SBN project in 2014, and will undertake an important task in the construction of the SBND detector. Manchester are also an official member of the MicroBooNE collaboration. We expect to make a major construction contribution to DUNE over the next few years.

The group have a diverse range of physics analyses, including

  • δCP and mass hierarchy sensitivity studies for DUNE.
  • Sterile neutrino oscillations at SBN.
  • Investigations of the MiniBooNE low-energy excess, including studying NC single-photon production with SBND and MicroBooNE.
  • Searches for nucleon decay, and neutron-antineutron oscillations.
  • Investigations of nuclear effects in quasi-elastic interactions.
  • Supernova neutrino detection.

Further Information & Links

Physics Plots

The predicted sensitivity of SBN to sterile neutrinos through νe appearance, compared with the LSND allowed regions and two separate global fit allowed regions. Using the three-detector configuration allows the entire LSND 99% confidence region to be observable at 5σ, under a two-neutrino oscillation hypothesis.
Expected signal in MicroBooNE for the global best-fit sterile neutrino. The coloured histograms show the expected backgrounds, assuming a 95% rejection efficiency for cosmogenic backgrounds. The white histogram shows the excess that would be observed after the combined MicroBooNE and SBN runs.


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