- Email: [email protected]
A versatile next generation nucleon decay & neutrino detector
Nuclear Instruments and Methods in Physics Research A 461 (2001) 322–323
A versatile next generation nucleon decay & neutrino detector Michael D. Marx Department of Physics & Astronomy, SUNY, Stony Brook, NY 11794, USA
Abstract We present a concept for an underwater third generation nucleon decay and neutrino detector, with remarkable versatility and reduced costs. # 2001 Elsevier Science B.V. All rights reserved. PACS: 29.40.Ka
The second generation of underground water Cherenkov detectors, as realized by the SuperKamiokande experiment, has established with remarkable success the continued viability of this technique. This experiment has demonstrated the existence of neutrino oscillations [1], improved the limits of proton decay, and explored the spectrum of solar neutrino’s to very low energies. Based on these successes, many have now begun to discuss the possibilities for a third generation detector with a fiducial mass 20 times that of Super-Kamiokande (i.e. about 106 tons total). It is likely that the case for this detector will be made jointly on the basis of extending the ep0 mode of proton decay (which should be proportional to the increase in volume), and on the utility of such a large detector as a target for a neutrino beam to explore the mixing matrix for neutrino’s. Possible configurations of such detectors have been explored but the costs of excavation, the tank structure, and the photo-detectors almost equally dominate the half-billion dollar costs of such detectors [2]. E-mail address: [email protected] (M.D. Marx).
This motivates a proposal for a versatile next generation nucleon decay and neutrino detector that eliminates the cost of excavation and reduces the cost of the structure. It provides the possibility of optimizing use for both physics programs. We propose to construct the detector as two large (e.g. 50 ! 75 m diameter) concentric spheres constructed of steel and concrete. The inner sphere would be watertight, lined, and then filled with pure water. The annulus between the spheres would be open to the seawater. Many small pressure vessels would be built as an integral part of the structure of the inner sphere, with windows to allow photodetectors within each pressure vessel to view the inner fiducial volume and the annulus veto volume (see Fig. 1). The detector would be constructed at a drydock, filled with pure water, commissioned, and towed to any desired ocean (or deep lake) location, at which point it would be submerged to any desired depth (typically 1–2 km). The detector would be connected to a towing/tender vessel by an umbilical containing power, signal and water lines. A water purification system at the surface allows the pressure to be adjusted in the inner sphere to balance the hydrostatic pressure on the
0168-9002/01/$ - see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 9 0 0 2 ( 0 0 ) 0 1 2 3 3 - X
M.D. Marx / Nuclear Instruments and Methods in Physics Research A 461 (2001) 322–323
323
Fig. 1.
sphere. Maintenance of the detector, can be accomplished on the surface where the photodetectors and electronics can be accessed by opening any of the pressure vessels. There are several attractive features of this detector configuration. The detector size can be optimized for the program, and a single tender vessel could service multiple detectors, for example, with differing photocathode coverages. The portability of the scheme provides the possibility of moving the system to another location, if a new neutrino source became operational, or to provide measurements at several distances from the neutrino source. This kind of detector configuration should also be considered for a central, highly instrumented core of a large underwater array, such as those being proposed for neutrino astronomy [2,3]. The photodetector array contained in individual pressure vessels can be optimized. Each vessel could contain multiple phototubes or hybrid detectors. The windows could be incorporated into a light collection system, utilizing many of the extant suggestions for improvements, including mirrors, wavelength shifters, or light-cones [4].
This configuration would naturally accommodate the kind of detector being proposed for AQUARICH [5]. Using the detector scheme proposed here could dramatically reduce the costs relative to a similarsize system built underground. This reduction could provide the key to early approval as does the portability of the detector which minimizes geo-political issues.
References [1] Y. Fukuda et al., Phys. Rev. Lett. 81 (1998) 1562. [2] C.-K. Jung, in: M. Diwan, C.-K. (Eds.), the Proceedings of the First International Workshop on Next Generation Nucleon Decay and Neutrino Detectors, Stony Brook, NY September 23–25, 1999, Jung, AIP Conf. Proc., Vol. 533, Melville, NY, 2000, to be published. [3] S. Navas-Concha (ANTARES) and G. Riccobene (NEMO). [4] NNN Nucleon Decay Workshop, February 25–26, 2000, University of California, Irvine at http://www.ps.uci.edu/ nnn/agenda-files.html. [5] P. Antonioli et al., Nucl. Instr. and Meth. A 433 (1999) 104–120.
SECTION V.
A versatile next generation nucleon decay & neutrino detector Michael D. Marx Department of Physics & Astronomy, SUNY, Stony Brook, NY 11794, USA
Abstract We present a concept for an underwater third generation nucleon decay and neutrino detector, with remarkable versatility and reduced costs. # 2001 Elsevier Science B.V. All rights reserved. PACS: 29.40.Ka
The second generation of underground water Cherenkov detectors, as realized by the SuperKamiokande experiment, has established with remarkable success the continued viability of this technique. This experiment has demonstrated the existence of neutrino oscillations [1], improved the limits of proton decay, and explored the spectrum of solar neutrino’s to very low energies. Based on these successes, many have now begun to discuss the possibilities for a third generation detector with a fiducial mass 20 times that of Super-Kamiokande (i.e. about 106 tons total). It is likely that the case for this detector will be made jointly on the basis of extending the ep0 mode of proton decay (which should be proportional to the increase in volume), and on the utility of such a large detector as a target for a neutrino beam to explore the mixing matrix for neutrino’s. Possible configurations of such detectors have been explored but the costs of excavation, the tank structure, and the photo-detectors almost equally dominate the half-billion dollar costs of such detectors [2]. E-mail address: [email protected] (M.D. Marx).
This motivates a proposal for a versatile next generation nucleon decay and neutrino detector that eliminates the cost of excavation and reduces the cost of the structure. It provides the possibility of optimizing use for both physics programs. We propose to construct the detector as two large (e.g. 50 ! 75 m diameter) concentric spheres constructed of steel and concrete. The inner sphere would be watertight, lined, and then filled with pure water. The annulus between the spheres would be open to the seawater. Many small pressure vessels would be built as an integral part of the structure of the inner sphere, with windows to allow photodetectors within each pressure vessel to view the inner fiducial volume and the annulus veto volume (see Fig. 1). The detector would be constructed at a drydock, filled with pure water, commissioned, and towed to any desired ocean (or deep lake) location, at which point it would be submerged to any desired depth (typically 1–2 km). The detector would be connected to a towing/tender vessel by an umbilical containing power, signal and water lines. A water purification system at the surface allows the pressure to be adjusted in the inner sphere to balance the hydrostatic pressure on the
0168-9002/01/$ - see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 9 0 0 2 ( 0 0 ) 0 1 2 3 3 - X
M.D. Marx / Nuclear Instruments and Methods in Physics Research A 461 (2001) 322–323
323
Fig. 1.
sphere. Maintenance of the detector, can be accomplished on the surface where the photodetectors and electronics can be accessed by opening any of the pressure vessels. There are several attractive features of this detector configuration. The detector size can be optimized for the program, and a single tender vessel could service multiple detectors, for example, with differing photocathode coverages. The portability of the scheme provides the possibility of moving the system to another location, if a new neutrino source became operational, or to provide measurements at several distances from the neutrino source. This kind of detector configuration should also be considered for a central, highly instrumented core of a large underwater array, such as those being proposed for neutrino astronomy [2,3]. The photodetector array contained in individual pressure vessels can be optimized. Each vessel could contain multiple phototubes or hybrid detectors. The windows could be incorporated into a light collection system, utilizing many of the extant suggestions for improvements, including mirrors, wavelength shifters, or light-cones [4].
This configuration would naturally accommodate the kind of detector being proposed for AQUARICH [5]. Using the detector scheme proposed here could dramatically reduce the costs relative to a similarsize system built underground. This reduction could provide the key to early approval as does the portability of the detector which minimizes geo-political issues.
References [1] Y. Fukuda et al., Phys. Rev. Lett. 81 (1998) 1562. [2] C.-K. Jung, in: M. Diwan, C.-K. (Eds.), the Proceedings of the First International Workshop on Next Generation Nucleon Decay and Neutrino Detectors, Stony Brook, NY September 23–25, 1999, Jung, AIP Conf. Proc., Vol. 533, Melville, NY, 2000, to be published. [3] S. Navas-Concha (ANTARES) and G. Riccobene (NEMO). [4] NNN Nucleon Decay Workshop, February 25–26, 2000, University of California, Irvine at http://www.ps.uci.edu/ nnn/agenda-files.html. [5] P. Antonioli et al., Nucl. Instr. and Meth. A 433 (1999) 104–120.
SECTION V.