A Cosmic Ray Research Tunnel

In 1997, half of a classic-looking tunnel entrance was listed on the Tasmanian Heritage Register. Today, the listing has been revised to protect the length of the tunnel and to mark its link to internationally-recognized cosmic ray research.

Located in Cambridge underneath Tunnel Hill, the 164m long tunnel was officially opened in May 1892, despite a number of people critical of the decision to establish a Bellerive to Sorell railway line.  The naysayers labelled the line the 'Idiotic Railway', while the Mercury's reporting was more cautiously optimistic that the line would assist in 'opening up outlying agricultural and pastoral lands by means of railway communication'.

The life of the railway line was short-lived.  By the 1920s the line and rolling stock needed substantial upgrades, and the advent of motor vehicles overtook rail in terms of speed and cost effectiveness. Despite protests from Sorell residents and farmers, the last official journey ran in July 1926. The Mercury recorded somewhat dramatically that 'the guard waved a green flag, the driver jumped into his cab, and with a hiss of steam, the train of two good trucks and five tiny carriages was off for Sorell – and oblivion'.

During World War II the tunnel was used by the Electrolytic Zinc Company and the Defence Department for storing records. However, it was after the war that the University of Tasmania would use it as a base for research that would become internationally recognised.

The University of Tasmania's Physics Department was founded immediately after World War II by Dr Geoff Fenton, under the guidance of Professor AL McAulay. As part of its research into cosmic radiation, the University set up detectors and recording equipment in a small hut, located about 30 metres from the northern entrance of the tunnel. From this station, observations monitored cosmic rays as they hit the earth. In an obituary to Dr Fenton, Martin George explains that the idea of using the tunnel was 'to filter out lower-energy secondary radiation'.

The tunnel was one of many sites from which the University conducted its cosmic ray research, alongside Macquarie Island, Sandy Bay and Poatina. Collectively, the research contributed greatly to the astronomical community. In recognition of this large body of work the twelfth International Cosmic Ray Conference was held in Hobart in 1971.

In the 1960s, the University's hut was extended further towards the centre of the tunnel, and today the tunnel remains as two parts separated. Both parts are now in private ownership.

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