Australia Telescope National Facility

Australian Cosmic Ray Modulation Research
M. L. Duldig
, PASA, 18 (1), in press.

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Subsections

Recent Instrumentation

Hobart Surface Multi-directional Telescope

In a collaboration between the Universities of Nagoya, Shinshu and Tasmania and the Australian Antarctic Division, a surface multi-directional scintillator telescope system was installed on the Sandy Bay campus of the University of Tasmania in December 1991. The telescope comprises two trays of 9 m² area (3 x 3, 1 m² scintillators) and generates 13 directions of view through appropriate coincidence circuitry (Fujii et al. 1994; Sakakibara et al. 1993). This experiment is located at approximately the co-latitude of the Nagoya surface telescope system and results in almost complete latitude coverage of both hemispheres. The bi-hemisphere collaboration was established to study solar and sidereal anisotropies and Forbush decreases. These decreases are associated with geomagnetic storms and the telescope system has been used to identify precursor cosmic ray signatures (see Section 8 below).

Liapootah Underground Multi-directional Telescope

The same collaboration that established the Hobart surface telescope system also installed an underground multi-directional telescope in an access tunnel at the Liapootah power station in central Tasmania (Mori et al. 1991, 1992; Humble et al. 1992). The major thrust of research for this telescope system is the study of sidereal anisotropies and it has played a key role in deducing the structure of these anisotropies (see Section 7 below).

Transportable Neutron Monitor

The University of Tasmania and the Australian Antarctic Division jointly developed a transportable neutron monitor to undertake a cosmic ray latitude survey in early 1991, around the time of the last solar maximum (Humble et al. 1991a). The equipment is housed in an insulated 20 foot shipping container and consists of a slightly modified 3 NM-64 monitor. The container was carried aboard the Australian research and supply icebreaker Aurora Australis from Hobart to Mawson in January 1991 where it was offloaded for two months before returning in March. A second survey from Hobart to Mawson and return was conducted over the summer of 1992-93 (Humble et al. 1991a). A new collaborative program with the Bartol Research Institute of the University of Delaware began in 1994 when the monitor was loaded onto the US Coast Guard icebreaker Polar Star in Hobart. The monitor then surveyed from Hobart to McMurdo and on to Seattle (Bieber et al. 1995). Once in the USA the Bartol group added inclinometers so that the response of the monitor could be more accurately determined (Bieber et al. 1997). The monitor has since undertaken annual latitude surveys between Seattle and McMurdo and will do so for at least a full solar cycle. During the 1998-99 survey a new He³ counter was employed in place of one of the BF₃ counters (Pyle et al. 1999). The aim of this exercise was to demonstrate that new and cheaper counters could be used as replacements for the ageing IQSY counters whilst maintaining almost identical response characteristics.

Kingston Neutron Monitor

The Brisbane neutron monitor was decommissioned at the end of January 2000 and transported back to Hobart. The monitor was then installed in a new observatory at the Kingston headquarters site of the Australian Antarctic Division. In October 2000 the Darwin monitor will be similarly moved to the Kingston observatory resulting in an 18 NM-64 monitor with high counting rate. This monitor and a similar one at Mawson will continue observations for the foreseeable future.

Next Section: Cosmic Ray Modulation
Title/Abstract Page: Australian Cosmic Ray Modulation
Previous Section: Establishing the Australian Network
Contents Page: Volume 18, Number 1

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