Photo of Jeff Hartnell

Jeff Hartnell
Professor of Physics (Physics and Astronomy)
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T: +44 (0)1273 873214


Research

My research is centred on understanding the elusive neutrino and answering some of the big questions about the universe such as why there is so much more matter than antimatter.

Research in particle physics is as exciting today as it has ever been, exploring the heart of Nature. The fundamental particles of matter come in two categories: the quarks and the leptons. Of the six leptons, three are charged and three are neutral. Much has been learnt over the past century about the charged leptons: the electron, muon and tau. In comparison, the 3 neutral leptons known as neutrinos are regarded as poorly understood "ghosts": they rarely interact with matter, passing through solid steel as light does through glass. Neutrinos were first discovered nearly 60 years ago but much is still unknown: their masses, whether they are their own anti-particle, the fundamental constants that determine their quantum mechanical superposition and so on.

 

The NOvA Experiment

I am PI of the Sussex long-baseline neutrino oscillations group, funded by a 1.5 million Euro ERC grant and STFC. We work primarily on NOvA and DUNE. With NOvA we do the extraordinary thing of firing a beam of neutrinos 810km through the Earth (seriously!). The three neutrinos have slightly different masses and so for a given energy the heaviest neutrino travels slightly slower than the lightest. This difference in speed gives rise to a quantum mechanical effect called neutrino oscillations and it is very hard to detect, which is why we need to fire the neutrinos over such a long distance.

The recent discovery in 2012 of the last neutrino mixing angle (θ13) has opened a door to discovering the pattern of the neutrino masses and whether neutrinos violate CP symmetry: two of the very last missing pieces of the standard model of particle physics extended to include neutrino masses. Neutrinos may provide the answer to the big question of why the universe is dominated by matter and not antimatter. With the NOvA experiment we will compare data taken with a beam of neutrinos to those from a beam of antineutrinos, looking for differences. The physics reach of NOvA is unique due to its long 810 km baseline combined with the high power and well understood beam of (anti)neutrinos. We have a facebook page and feel free to like us! For DUNE at Sussex we are working on the prototype detectors and DAQ to develop the exciting liquid argon time-projection chamber technology for the next generation experiment that will be a sensitive probe of leptonic CP violation.

I am an elected member of the NOvA Executive Committee and a convenor of the muon (anti)neutrino disappearance analysis group.

SNO+

I am a member of the SNO+ collaboration. The systems I lead the development of have to decide which data to keep and then transfer it around the globe, process it and deliver it to the teams involved in each analysis.

SNO+ will explore a fascinating and remarkably diverse range of physics. We will study (1) neutrinoless double beta decay (2) solar neutrino oscillations and astrophysics (3) geo-neutrinos, coming from radioactive decays in the Earth (4) reactor neutrino oscillations, using nuclear power reactors 100s of km away (5) supernova neutrinos (6) proton and neutron decay.

MINOS

I worked on the MINOS long-baseline neutrino oscillation experiment for a decade, right through construction and test beam calibration to first data and the final results. I was a member of the Executive Committee and Authors and Publication Committee from 2009-2012. In 2006 I co-founded the muon antineutrino physics analysis group that I was a convenor of all the way through to the first results and papers (see below) in 2011.

Publications

I have 18 papers in Physical Review Letters (PRL), the leading international peer-reviewed journal used for particle physics results. In total I am an author of 47 papers published in peer-reviewed journals (5675 citations). The full and up to date list can be found from SPIRES here. Of the 47, 3 are renowned (500+ citations on inspire); 2 are famous (250-499 citations), 10 are very well-known (100-249 citations) and a further 10 are well-known (599-50 citations); my h-index is 31. Particular highlights are listed below.

My first two papers from NOvA are:

  • P. Adamson et al., “First measurement of electron neutrino appearance in NOvA”, Phys.Rev.Lett. 116 (2016) no.15, 151806.
  • P. Adamson et al., “First measurement of muon-neutrino disappearance in NOvA”, Phys.Rev. D93 (2016) no.5, 051104.

My invited review paper, "Long-baseline Neutrino Oscillation Experiments", that I wrote for a special issue on neutrino physics for Advances in High Energy Physics with Gary Feldman at Harvard in the USA and Takashi Kobayashi at KEK in Japan. Volume 2013 (2013), Article ID 475749, 30 pages.

The MINOS antineutrino results:

  • P. Adamson et al., "First direct observation of muon antineutrino disappearance", Phys.Rev.Lett. 107:021801, 2011.
  • P. Adamson et al., "Search for the disappearance of muon antineutrinos in the NuMI neutrino beam", Phys.Rev.D 84:071103, 2011.

My most highly cited papers are those making the world's best measurement of the neutrino oscillation frequency for a source of muon neutrinos, specifically the neutrino mass squared splitting (Δm2).

  • D. Michael et al., "Observation of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam", Phys.Rev.Lett. 97:191801, 2006.
  • P. Adamson et al., "A Study of Muon Neutrino Disappearance Using the Fermilab Main Injector Neutrino Beam", Phys.Rev.D 77:072002, 2008.
  • P. Adamson et al., "Measurement of Neutrino Oscillations with the MINOS Detectors in the NuMI Beam", Phys.Rev.Lett. 101:131802, 2008.
  • P. Adamson et al., "Measurement of the neutrino mass splitting and flavor mixing by MINOS", Phys.Rev.Lett. 106:181801, 2011.

Measurement of the third neutrino mixing angle, theta13, is one of the most important research topics in particle physics at present and the data we obtained with MINOS was the world's most sensitive at the time of publication.

  • P. Adamson et al., "Improved search for muon-neutrino to electron-neutrino oscillations in MINOS", Phys.Rev.Lett. 107:181802, 2011.
  • Y. Abe et al., "Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment", Phys.Rev.Lett. 108:131801, 2012

Talks at International Conferences

  • NOW, Italy, Sep/16, plenary NOvA results talk
  • PASCOS, Vietnam, July/16, review of long-baseline experiments
  • Moriond EW, Italy, Mar/16, plenary talk on NOvA
  • FLASY conf at Sussex, UK, Jun/14, plenary review of double-beta experiments
  • NExT meeting at QMUL, UK, Apr/14, plenary talk on long-baseline expts.
  • IoP HEPP conf. at RHUL, UK, Apr/14, plenary on neutrino mass
  • Baryon and Lepton Number Violation, Germany, Apr/13: parallel talk on NOvA
  • IoP Meeting on Future Long-Basline Neutrino Oscillation Experiments, UK, Nov/12: opening plenary talk reviewing the current state of the field
  • Topics in Astroparticle and Underground Physics, Germany, Sep/11: parallel talk on SNO+
  • International Workshop on Neutrino Factories, Super beams and Beta beams, Switzerland, Aug/11: plenary review "MINOS, MINOS+ and NOvA"
  • Neutrino Oscillations Workshop, Italy, Sep/10: plenary review "Neutrino Physics @ NuMI beam"
  • Particle Physics and Cosmology Conference, Italy, Jul/10: plenary review of neutrino oscillations
  • Lomonosov Conference, Russia, Aug/09: plenary review of MINOS results
  • La Thuile Conference, Italy, Feb/09: plenary review of MINOS results
  • KEK Topical Conference, Japan, Feb/07: plenary review of MINOS results
  • Institute of Physics Meeting, UK, Jun/05: plenary review of neutrino oscillations
  • American Physical Society Annual Conference, USA, May/04: parallel MINOS talk
  • Institute of Physics Annual Conference, UK, Mar/04 and Mar/03: parallel MINOS talk