Birmingham Gaseous Laboratory group

Dark Matter searches at Birmingham

Ioannis Katsioulas, Patrick Knights, Ioannis Manthos, Jack Matthews, Lex Millins, Tom Neep, Kostas Nikolopoulos, Giovanni Rogers, Robert Ward
Recent leavers: Ioannis Katsioulas, Rhys Owen

The New Experiments With Spheres-Gas (NEWS-G) network are a number of experiments working with the novel technology of a spherical proportional counter (SPC). The benefits of such a technology are;

  • Cheap and simple technology low threshold
  • single or few channel read-out
  • flexible gas, gain and pressure
  • good energy resolution
  • efficient fiducial cuts
University of Birmingham main campus at Edgbaston

For the ideal case of a small spherical sensor located at the centre of a spherical shell, the electric field goes as 1/r2 and the capacitance is proportional to the size of the inner sensor so is of order 1 pF. Charges produced in the volume will drift until ~1 mm from the sensor, where an avalanche occurs. This high amplification close the ball minimises the diffusion of the secondary charges and reduces the rise-time of a pulse. This allows single electron detection. The rise-time of pulses may be used to select the fiducial region of the detector.

The applications of such a versatile detector are many, including gamma ray and neutron spectroscopy, coherent nuclear neutrino scattering, double beta-decay searches and Dark Matter (DM) detection. SeDiNe (Spherical Detector of Neutrons) is one such sphere, 60 cm in diameter and made from low activity copper and installed at the Laboratoire Souterrain de Modane (LSM). Initially implemented to investigate the low thermal and fast neutron fluxes in the lab, SeDiNe has also been used to look for low mass dark matter particle candidates, and published NEWS-G's first result setting a word-leading limit for a 0.5 GeV/c2 DM candidate, at that time. In 2021 a 1.4 m diameter copper sphere "SNOGLOBE" installed in SNOLAB in Canada and currently taking data. As the second deepest and the cleanest underground laboratory in the world, SNOLAB offers a shelter from cosmic rays and secondary particles. The main physics aims to search for:

The Particle Physics group at the University of Birmingham offers major contribution to NEWS-G, holding critical positions of responsibility, and to SPC development. More specifically, it is leading the SPC instrumentation R&D, advancing the multi-anode "ACHINOS" sensor that permit the high gain - high pressure operation of the detector, and developing a comprehensive simulation framework that fully describes the response of the SPC. Moreover, the group has a leading role in research and development for the next stages of NEWS-G, including novel pure copper electroforming techniques and background mitigation, and physics potential studies. Additionally, the group is spearheading wider application of the detector for neutron spectroscopy. As well as having far reaching applicability beyond fundamental Physics, e.g. in medical environments, this technique can provide an invaluable tool for characterising the crucial neutron background at underground DM experiments.

The Particle Physics group has installed a 30 cm SPC at the Boulby underground Laboratory, in North Yorkshire (UK) for R&D purposes in the low cosmic muon background environment. Also, the group is capitalising the expertise developed by collaborating with Pacific Northwest National Laboratory (PNLL) on electroformed copper (EFCu), by currently commissioning such a facility in Boulby, that will permit the production of radiopure materials for detectors.

The NEWS-G activities of the Particle Physics group have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreements no 841261 (DarkSphere), no 845168 (neutronSphere) and No 101026519 (GaGARin).

University of Birmingham main campus at Edgbaston
University of Birmingham main campus at Edgbaston

Collaborations with colleagues in CEA-Saclay (France) are supported by the Internation Exchanges scheme of The Royal Society.

Interactions with the phenomenology community have been supported in part by the IPPP Associateship programme.

University of Birmingham main campus at Edgbaston


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