SuperNEMO demonstrator module construction.

Lead Research Organisation: University College London
Department Name: Physics and Astronomy

Abstract

Experiments over the last decade have confirmed that the elusive neutrino is not a strictly massless particle, like the photon, but does in fact possess a tiny non-zero mass. These measurements do not, however, tell us what that mass is. Physicists are therefore busy devising novel ways of pinning down the absolute mass of the neutrino. In a fascinating theoretical twist, it may be the case that the very small neutrino mass is naturally explained in terms of physics at a much higher energy scale known as the Grand Unification scale, which is far beyond the energies that can be directly accessed by experiments. Such a mechanism would require the neutrinos to have another bizarre property : they are their own anti-particles. In ordinary beta decay, an electron and a neutrino are emitted when a neutron in the nucleus converts into a proton. Very rarely and only in certain isotopes, two such decays can happen simultaneously, resulting in the emission of two electrons and two neutrinos. This process has been confirmed in a number of previous experiments. However, if neutrinos are their own anti-particles, it may be possible for the same decay to occur but with no neutrinos emitted - a process called neutrinoless double-beta decay. The SuperNEMO experiment is designed to search for neutrinoless double-beta decay with unprecedented sensitivity. SuperNEMO is, in essence, a giant Geiger counter. However, rather than a single 'click' indicating the presence of a radioactive decay, the detector will accurately reconstruct the trajectories of the emitted electrons and precisely measure their energies. This way, real double-beta decay events can be distinguished from 'background' or fake events. The precise measurement of the electron energies is crucial for the identification of neutrinoless double-beta decay, since in these events all the energy of the decay is carried by the two electrons. By contrast, double beta-decay in which part of the energy is carried away by the undetected neutrinos is characterised by a wide range of measured energies. At the centre of each SuperNEMO module sits a thin film containing the double beta-decay isotope, which to begin with will be Selenium-82. Surrounding the source is a Geiger tracking detector that is being developed and built in the UK. Electrons are then absorbed in blocks of plastic scintillator and the resulting light is recorded in photomultiplier tubes, giving an estimate of their energy. UK physicists have recently demonstrated a better measurement accuracy using this technique than has ever been achieved before. The UK will also be involved in developing the simulations that will be required to optimise the final detector design. The goal of this project is to build a demonstrator module, which is essentially a prototype of a final SuperNEMO module. This will enable us to prove all the steps involved in the construction of the final detector, and will enable us to demonstrate that the detector we have designed does have the required sensitivity. Approximately 90 physicists from several countries will be involved, but the largest contributions will come from France and the UK. The demonstrator module will initially be assembled and commissioned in the 'Nu-Lab', a new laboratory recently built at UCL's Mullard Space Science Laboratory. From there, it will be taken to the Laboratoire Souterrain de Modane, deep underneath the mountains on the French-Italian border, where we will be able to assess the performance of the detector under very low background conditions. The outcome of this project will be a working demonstrator module of the future SuperNEMO detector. We will be able to do exciting and competitive physics measurements using just this module, but more importantly we will know exactly how to build the much larger detector that we will need in order to discover neutrinoless double-beta decay.

Publications

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Argyriades J (2011) Spectral modeling of scintillator for the NEMO-3 and SuperNEMO detectors in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Argyriades J (2010) Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Argyriades J (2009) Measurement of the background in the NEMO 3 double beta decay experiment in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

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Arnold R (2010) Probing new physics models of neutrinoless double beta decay with SuperNEMO in The European Physical Journal C

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Saakyan Ruben (2013) Two-Neutrino Double-Beta Decay in ANNUAL REVIEW OF NUCLEAR AND PARTICLE SCIENCE, VOL 63

 
Description In the UK, we have built an ultra-low radioactivity tracking detector for SuperNEMO, obtaining world-leading low levels of radon and other impurities. This is a step toward proving the viability of this detection technique for the next generation of neutrinoless double-beta decay experiments.
Exploitation Route Many of the techniques developed in this project will have applications in low-background physics, such as the search for neutrinoless double-beta decay and dark matter. There may be applications to other fields of physics as well as beyond.
Sectors Education

 
Description The progress of the SuperNEMO project featured in an article appearing in The Guardian newspaper in October 2015, following the successful transport of the first tracker module from the UK to France. The calorimeter optical module technology developed for SuperNEMO has subsequently been used to develop instrumentation for proton beam therapy, leading to successful grant applications in this area of medical research.
First Year Of Impact 2015
Sector Education,Healthcare
Impact Types Cultural,Societal

 
Description Light Detector Development 
Organisation ENVINET
Country Germany 
Sector Private 
PI Contribution We continue to work with Hamamatsu, for example testing some of their new products such as Quartz Photon Intensifying Detectors (QUPIDs). Providing feedback to the manufacturers of such products yields benefits across the physics community and beyond. We also maintain close contact with another PMT supplier, ET Enterprises (Uxbridge, UK) and work closely on material characterisation with ELJEN (Texas, USA) and ENVINET (Czech Rep.) who supply the plastic scintillators for SuperNEMO. Such high light-output plastic scintillators have a wide range of medical and security applications.
Collaborator Contribution Delivery of prototype devices for characterisation by us.
Impact New devices for use in particle physics instrumentation, and which have a wide range of medical and security applications.
Start Year 2009
 
Description Light Detector Development 
Organisation ET Enterprises
Country United Kingdom 
Sector Private 
PI Contribution We continue to work with Hamamatsu, for example testing some of their new products such as Quartz Photon Intensifying Detectors (QUPIDs). Providing feedback to the manufacturers of such products yields benefits across the physics community and beyond. We also maintain close contact with another PMT supplier, ET Enterprises (Uxbridge, UK) and work closely on material characterisation with ELJEN (Texas, USA) and ENVINET (Czech Rep.) who supply the plastic scintillators for SuperNEMO. Such high light-output plastic scintillators have a wide range of medical and security applications.
Collaborator Contribution Delivery of prototype devices for characterisation by us.
Impact New devices for use in particle physics instrumentation, and which have a wide range of medical and security applications.
Start Year 2009
 
Description Light Detector Development 
Organisation Eljen Corporation
Country United States 
Sector Private 
PI Contribution We continue to work with Hamamatsu, for example testing some of their new products such as Quartz Photon Intensifying Detectors (QUPIDs). Providing feedback to the manufacturers of such products yields benefits across the physics community and beyond. We also maintain close contact with another PMT supplier, ET Enterprises (Uxbridge, UK) and work closely on material characterisation with ELJEN (Texas, USA) and ENVINET (Czech Rep.) who supply the plastic scintillators for SuperNEMO. Such high light-output plastic scintillators have a wide range of medical and security applications.
Collaborator Contribution Delivery of prototype devices for characterisation by us.
Impact New devices for use in particle physics instrumentation, and which have a wide range of medical and security applications.
Start Year 2009
 
Description Light Detector Development 
Organisation PMT Hamamatsu Photonics K.K.
Country Japan 
Sector Private 
PI Contribution We continue to work with Hamamatsu, for example testing some of their new products such as Quartz Photon Intensifying Detectors (QUPIDs). Providing feedback to the manufacturers of such products yields benefits across the physics community and beyond. We also maintain close contact with another PMT supplier, ET Enterprises (Uxbridge, UK) and work closely on material characterisation with ELJEN (Texas, USA) and ENVINET (Czech Rep.) who supply the plastic scintillators for SuperNEMO. Such high light-output plastic scintillators have a wide range of medical and security applications.
Collaborator Contribution Delivery of prototype devices for characterisation by us.
Impact New devices for use in particle physics instrumentation, and which have a wide range of medical and security applications.
Start Year 2009