Stawell Underground Physics Laboratory

The Stawell Underground Physics Laboratory (SUPL) is a laboratory 1 km deep in the Stawell Gold Mine, located in Stawell, Shire of Northern Grampians, Victoria, Australia. Together with the planned Agua Negra Deep Experiment Site (ANDES) at the Agua Negra Pass, it is one of just two underground particle physics laboratories in the Southern Hemisphere and shall conduct research into dark matter.[1]

"SUPL" redirects here. For Secure User Plane Location, see Assisted GPS.
Stawell Underground Physics Laboratory
Established2022
Research typeResearch laboratory
Field of research
Physics, dark matter
LocationStawell, Victoria, Australia
37.07°S 142.81°E / -37.07; 142.81 (Stawell Gold Mine)
AffiliationsUniversity of Melbourne
the Centre of Excellence for Particle Physics
the Australian Nuclear Science and Technology Organisation
University of Adelaide
Italian National Institute of Nuclear and Particle Physics.
Websitehttps://www.supl.org.au/

The project is a collaboration between six international partners. It will be led by the University of Melbourne with the Swinburne University of Technology, the University of Adelaide, the Australian National University, the Australian Nuclear Science and Technology Organisation (ANSTO) and the Italian National Institute for Nuclear Physics.[2]

It is expected that the project will collaborate closely with the Gran Sasso Laboratory in Italy.[3]

Construction commenced in 2019,[4] and though it was expected to be complete by the end of 2021[5] due to delays from corporate mergers it opened in August 2022.[6]

General information

The project's Southern Hemisphere location has bearing on the possible differential detection of the putative WIMP-wind. Northern Hemisphere instruments are showing hints of a June "bump" of possible dark matter hits,[7] which is expected given the galaxy's rotation, but it is hard to be sure that it is not a false signal due to some subtle seasonal environmental effect. A Southern Hemisphere location, on the opposite side of the Earth with its converse seasons, could help to provide valuable confirmation one way or another.

Secondly, the sundry particles (apparently from the constellation Cygnus)[8][9] would have travelled through the Earth itself before reaching SUPL's instruments.[10]

Finally, its Southern Hemisphere location also makes it potentially very sensitive to daily variation effects which would be a smoking-gun for self-interacting dark matter or dark matter with a significant stopping rate.[11][12][13]

Inasmuch as neutrino experiments do not benefit in the same way from a Southern Hemisphere location, and IceCube is already extant, it is unlikely that any neutrino detectors will be housed at SUPL.

Funding

The first phase of the project received $1.75 million funding in the 2015 Australian federal budget. With matching funding from Victoria,[14] construction started 2016[15] and was expected to be complete in 2017.[16] However, a series of corporate mergers in 2015 and 2016 disrupted plans.[17] The project was stalled when the new owners dismissed most of the labour force[18] and shut down the Stawell gold mine to a "care and maintenance" state in December 2016. In December 2017, yet another new owner announced their intention to reopen the mine and were supportive of the underground laboratory,[17] allowing hope that construction would restart.[19]

In 2019, the project resumed. The 2019 Australian federal budget included $5 million for SUPL,[20] and in July 2019 a memorandum of understanding between Stawell Gold Mines Pty Ltd, the Northern Grampians Shire Council, and the University of Melbourne was signed[21] to build and operate the laboratory.

Construction

SUPL is planned to be located at a depth of 1,025 metres (3,363 ft), providing approximately 2900 metre water equivalent shielding against background cosmic rays.[22]: 3  As a decline (ramp) mine, cars and trucks can be driven to the laboratory site.[16] The laboratory will consist of a bespoke cavity of approximately 10 metres high and 10 metres wide (33×33 ft) excavated into the rock from an existing part of the mine.[2]

The laboratory will be divided into 25 metres (80 ft) of clean room space for experiments, and 15 metres (50 ft) of "dirty" loading area.[22]: 4–5  A side tunnel 5 m wide and 20 m long (15×65 ft) will house physical plant and personnel facilities.[16][22]: 4–5 

SABRE
Main article: DAMA/LIBRA § SABRE

The first experiment planned for SUPL is SABRE[22]: 4 [23] (Sodium-iodide with Active Background REjection), based on 50 kg of thallium-doped sodium iodide.[24][25] Two detectors will be built:[24] one at LNGS and one at SUPL. Improving on the DAMA/LIBRA experiment, the SUPL detector implements additional features for background rejection: a 12 kL liquid scintillator veto, and a muon veto (experiment member, M. Mews, remains the expert on said muon veto). [26][16] Consistent results between the two would be very strong evidence.

As of August 2022, the SABRE experiment is expected to be constructed underground in SUPL during the last months of 2022, with data collection beginning in 2023.[6]

References
  1. "Government Digs Deep With Plan For Stawell's Future" (Press release). Premier of Victoria. 13 February 2015.
  2. "Swinburne goes underground in search for dark matter". Swinburne University of Technology. 29 July 2019. Retrieved 12 September 2019.
  3. Coughlan, Matt (24 September 2014). "Stawell particle physics laboratory - scientists to speak on Tuesday". Wimmera Mail-Times.
  4. Staff (24 September 2019). "Progress on dark matter lab". www.ansto.gov.au. ANSTO. Retrieved 13 May 2020.
  5. "'Waiting for a ghost': the search for dark matter 1km under an Australian town". the Guardian. 9 October 2021.
  6. "Laboratory to study dark matter opens 1km under Australian town – with no bananas allowed". the Guardian. 18 August 2022. Retrieved 19 August 2022.
  7. Jamieson, Valerie (3 May 2011). "Second experiment hints at seasonal dark matter signal". New Scientist.
  8. Monroe, Jocelyn; Battat, James (2009). "Winds of Change in the Hunt for Dark Matter" (PDF). MIT Physics Annual.
  9. Billard, J.; Mayet, F.; Grignon, C.; Santos, D. (January 2011). "Directional detection of Dark Matter with MIMAC: WIMP identification and track reconstruction". Journal of Physics: Conference Series. 309 (1): 012015. arXiv:1101.2750. Bibcode:2011JPhCS.309a2015B. doi:10.1088/1742-6596/309/1/012015. S2CID 85554552.
  10. Slezak, Michael (18 July 2014). "Panning for dark matter in an Australian gold mine". New Scientist. Retrieved 20 May 2015.
  11. Kouvaris, C.; Shoemaker, I. (2014). "Daily modulation as a smoking gun of dark matter with significant stopping rate". Physical Review D. 90 (9): 095011. arXiv:1405.1729. Bibcode:2014PhRvD..90i5011K. doi:10.1103/PhysRevD.90.095011. S2CID 118374091.
  12. Foot, R.; Vagnozzi, S. (2015). "Diurnal modulation signal from dissipative hidden sector dark matter". Physics Letters B. 748: 61–66. arXiv:1412.0762. Bibcode:2015PhLB..748...61F. doi:10.1016/j.physletb.2015.06.063.
  13. Foot, Robert; Vagnozzi, Sunny (2015). "Dissipative hidden sector dark matter". Physical Review D. 91 (2): 023512. arXiv:1409.7174. Bibcode:2015PhRvD..91b3512F. doi:10.1103/PhysRevD.91.023512. S2CID 119288106.
  14. "Funding Go Ahead For Stawell Physics Lab" (Press release). Victoria Minister for Regional Development. 20 November 2015.
  15. "Work begins 1km underground at dark matter physics lab site" (Press release). Northern Grampians Shire Council. 5 May 2016. The drilling which commenced on 28 April will extract a 50 metre long core from the main cavern site.
  16. Froborg, Francis (20 July 2016). SABRE: WIMP Modulation Detection in the Northern and Southern Hemisphere. Identification of Dark Matter 2016. Sheffield. p. 11.
  17. Mannix, Liam (5 August 2018). "Stock market the biggest obstacle to finding dark matter down a mine". The Age.
  18. Martin, Stephen; Petrucci, Nabila; Judd, Bridget (14 December 2016). "Stawell gold mine in Victoria to close, up to 150 jobs on the line". Australian Broadcasting Corporation.
  19. Piovesan, Anthony (7 December 2017). "Future uncertain for Stawell's underground physics lab". Ararat Advertiser. Retrieved 7 March 2018.
  20. Williams, Lachlan (5 April 2019). "$5 million federal government funding allocated to Stawell Underground Physics Laboratory". Ararat Advertiser.
  21. "MoU signed for Stawell Underground Physics Lab" (Press release). Northern Grampians Shire Council. 19 July 2016.
  22. Urquijo, Phillip (15 September 2015). Searching for Dark Matter at the Stawell Underground Physics Laboratory (PDF). Heavy Ion Acceleration Symposium 2016. EPJ Web of Conferences. Vol. 123, no. 4002. Canberra. pp. 1–7. arXiv:1605.03299. doi:10.1051/epjconf/201612304002. Page 4 gives the latitude of the laboratory as 37°03′S = 37.05°S, but it is not clear if this is accurate for the laboratory proper, or is an approximation based on the latitude of the town of Stawell.
  23. Barberio, Elisabetta (2 November 2015). "Direct Dark Matter Detection in Australia (colloquium abstract)". University of Sydney School of Physics. Retrieved 17 January 2016.
  24. Froborg, Francis (9 September 2015). SABRE: WIMP Modulation Detection in the Northern and Southern Hemisphere (PDF). Topics in Astroparticle and Underground Physics.
  25. Barberio, Elisabetta (16 September 2015). "How we plan to bring dark matter to light". The Conversation.
  26. Roberts, Glenn Jr. (12 October 2015). "Australia's first dark matter experiment". Symmetry Magazine.

37.07°S 142.81°E / -37.07; 142.81 (Stawell Gold Mine)

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