Sunlab

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The Sydney University Underground Neutrino Laboratory

SUNLAB, the Sydney Underground Neutrino LABoratory, was set up in Broken Hill, 1200 km west of Sydney in the state of New South Wales (Australia), to serve as a unique underground facility in Australia for a variety of experiments. The main aim was to set up a water Cerenkov solar neutrino detector which would also be able to detect neutrinos from stellar collapse, but the site was also studied from the point of view of setting up a double beta decay experiment in collaboration with Dr. L Mitchell from Flinders University.

The unique characteristic of this facility was that it was inside a silver, zinc and lead mine (the North Mine, owned by the Pasminco Mining Company). Two sites inside this mine had been explored, one at a depth of 1230 m and the other at a depth of 1335 m. At this depth the cosmic ray background, which is so prevalent at sea level and can make these type of experiments impossible to carry out, is very small. For example, at the depth of 1230 m, which corresponds to an equivalent depth of 3300 m of water, the cosmic ray flux is attenuated by a factor of 1 million. Only the highest energy muons (and neutrinos, of course) can penetrate at this depth.

Initial investigations in this laboratory commenced around 1982 to determine the background radiation environment in the site and to determine the feasibility of building a water Cerenkov solar neutrino detector. A 10 ton water Cerenkov prototype was built in 1989 and this detector operated until the closure of the mine at the beginning of 1993. This closure was unexpected and unfortunate because the site had proved to be excellent for a solar neutrino experiment.

During the 11 years that our group was using the facilities at Broken Hill we carried out many investigations into the feasibility of building a water Cerenkov detector for solar neutrinos. The main measurements include:

  • The underground cosmic ray flux from the 10 ton water Cerenkov detector;
  • A determination of the gamma ray background;
  • A determination of thermal and epithermal neutrons from the underground environment;
  • Measurements of the concentration of radioactive radon underground;
  • Studies into the use of lead as a shielding material for underground experiments.

Even though the final aim of building a solar neutrino detector was not carried out, the thorough investigations into radioactivity at these depths serve as valuable information on the issues facing underground detectors and the background which can mimic the rare signals that are sought inside laboratories like this all around the world.

Publications

  • L.S. Peak, The Lost Neutrinos from the Sun, Aust. J. Phys. 33, (1980), 821.
  • A.M. Bakich, L.S. Peak, N.T. Wearne, An Absolute Measurement of Cherenkov Emission by Relativistic Muons in Pure Water, Aust. J. Phys. 37, (1984), 567.
  • A.M. Bakich, M. Omori, L.S. Peak, N.T. Wearne, Assessment of Underground Gamma Ray Fluxes at a Depth of 1230 m., Nucl. Instr. and Meth. A 226, (1984), 383.
  • A.M. Bakich, L.S. Peak, The Efficiency of Lead Shielding for Background Reduction in Underground Neutrino Experiments, Nucl. Instr. and Meth. A 240, (1985), 429.
  • A.M. Bakich, L.S. Peak, The Response of Wavelength Shifting Panels in Large Water Cerenkov Systems., Nucl. Instr. and Meth. A 247, (1986), 334.
  • L.S. Peak, The Search for Solar Neutrinos, The Australian Physicist 24, (1987), 32.
  • M. Omori, Photon Intensity Control Without Filters, Nucl. Instr. and Meth. A 263, (1988), 463.
  • A.M. Bakich et al., The Sydney Underground Solar Neutrino Detector, Nucl. Instr. and Meth. A 273, (1988), 853.
  • M. Omori, A Simple Method to Estimate Small Photoelectron Numbers for a Photomultiplier using the Log-Normal Function, Nucl. Instr. and Meth. A 276, (1989), 602.
  • A.M. Bakich, Aspects of Neutrino Astronomy, Space Science Reviews, 49, (1989), 259.
  • A.M. Bakich, R.C. Cederblad, P.R. Gerhardy, M. Omori, L.S. Peak, Measurement of Underground Gamma Ray Spectra for Solar Neutrino Studies, Nucl. Instr. and Meth. A 278, (1989), 565.
  • L.S. Peak, P. Soler, Assessment of the Photoelectron Number for Photomultipliers under Conditions of Low Light Intensities, Nucl. Instr. and Meth. A 301, (1991), 341-349.
  • S.R. Hashemi-Nezhad, L.S. Peak, Temperature Related Effects in Radon Dosimetry Using Plastic Track Detectors, Nucl. Tracks and Radiat. Meas. 20, (1992), 575-581.
  • P. Soler, Z.H. Wang, Optical Properties of Wavelength Shifting Panels, Nucl. Instr. and Meth. A 324, (1993), 482-490.
  • M. Omori, G. Braoudakis, L.S. Peak, U-238 Spontaneous Fission-induced Background in NaI Scintillators, Nucl. Instr. and Meth. A 329, (1993), 183-187.
  • G. Braoudakis, L.S. Peak, Investigation of the Background Gamma Spectrum in an Underground Environment, Nucl. Instr. and Meth. A 332, (1993), 292-299.
  • S.R. Hashemi-Nezhad, L.S. Peak, Measurement of Plate-out rate of Rn-222 Daughters in Laboratory Conditions: Implications for Radon Dosimetry., Nucl. Tracks and Radiat. Meas. 21, (1993), 225-234.
  • M. Omori, Pulse Shape Discriminator Application to Low Level Counting Experiments, Nucl. Instr. and Meth. A 335, (1993), 553-560.
  • S.R. Hashemi-Nezhad, Determination of the Energy Limits and Efficiency of Track Detectors for the Formation of Etched-through Tracks, Nucl. Instr. and Meth. B86, (1993), 303-310.
  • S.R. Hashemi-Nezhad, L.S. Peak, Radon Dosimetry in an Underground Working Environment using Plastic Track Detectors, Radiation Protection in Australia, Vol. 12 No. 4 (1994), 139-144.
  • S.R. Hashemi-Nezhad, L.S. Peak, Background Neutron Flux Determination at a Depth of 3200 mwe Underground, Nucl. Instr. and Meth. A 357, (1995), 524-534.
  • F.J.P. Soler, Multiple Reflections in an Approximately Parallel Plate, Optics Comm. 139, (1997), 165-169.
  • G. Braoudakis, L.S. Peak, F.J.P. Soler, Use of Lead for the Reduction of Background Gamma Rays in Underground Experiments, Nucl. Instr. and Meth. A 403 (1998), 499.
  • S.R. Hashemi-Nezhad, L.S. Peak, Limitation on the Response of He-3 Counters due to Intrinsic Alpha Emission, Nucl. Instr. and Meth. A 416 (1998), 100-108.

Conferences

  • A.M. Bakich, L.S. Peak, The Sydney University Solar Neutrino Program, AIP Conference Proceedings on Solar Neutrinos and Neutrino Astronomy 126, Homestake, (1984), 238.
  • A.M. Bakich et al., Design and Construction of SUNLAB: the Sydney Underground Neutrino Program, Proceedings of the 20th International Cosmic Ray Conference, Moscow, Vol. 6, (1987), 318.
  • A.M. Bakich, R.C. Cederblad, P.R. Gerhardy, J. Malos, M. Omori, L.S. Peak, C.J. Sheerman, P. Soler, The Sydney Underground Solar Neutrino Detector, 1987 London Conference on Position Sensitive Detectors, Nucl. Instr. and Meth. A 273, (1988), 853.
  • A.M. Bakich, G. Braoudakis, L.S. Peak, The Significance of Accidental Triggering for a Modular Cherenkov Detector System, Proceedings of the 21st International Cosmic Ray Conference, Vol. 7, Adelaide, (1990), 183-186.
  • A.M. Bakich, R.C. Cederblad, M. Omori, L.S. Peak, R.L. Walsh, Measurement of Underground Gamma Ray Spectra for Solar Neutrino Studies., Proceedings of the 21st International Cosmic Ray Conference, Vol. 7, Adelaide, (1990), 187-190.
  • A.M. Bakich, R.C. Cederblad, M. Omori, L.S. Peak, R.L. Walsh, Measurement of Underground Neutron Fluxes for Solar Neutrino Studies., Proceedings of the 21st International Cosmic Ray Conference, Vol. 7, Adelaide, (1990), 191.
  • A.M. Bakich et al., Progress Report of the Sydney Underground Laboratory SUNLAB, Proceedings of the 21st International Cosmic Ray Conference, Vol. 7, Adelaide, (1990), 192-195.
  • P.Soler, Assessment of Photoelectron Number at Very Low Light Intensities, Proceedings of the 21st International Cosmic Ray Conference, Vol. 10, Adelaide, (1990), 175-178.
  • L.S. Peak, Rapporteur Paper on Muons, Proceedings of the 21st International Cosmic Ray Conference, Vol. 11, Adelaide, (1990), 332-341.
  • A.M. Bakich, Rapporteur Paper on Solar Neutrinos, Proceedings of the 21st International Cosmic Ray Conference, Vol. 11, Adelaide, (1990), 347-352.
  • S.R. Hashemi-Nezhad, L.S. Peak, Radon Dosimetry in an Underground Working Environment using Plastic Track Detectors, 18th Annual Conference of the Australian Radiation Protection Society (Sydney, October 1993), Radiation Protection in Australia, Vol. 12 No. 4 (1994), 139.
Retrieved from "http://www.physics.usyd.edu.au/hienergy/index.php/Sunlab"
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