TG Neutron Monitor

SAMADHA - TESTA GRIGIA STATION

THE TESTA GRIGIA NEUTRON MONITOR

The modular neutron monitor installed in 2014 at the Testa Grigia laboratory was designed, realized and tested at the SVIRCO Observatory in Rome (INAF-IAPS).

The general design of the NM has a variable geometry to be adapted to counters of different lengths.
In the Testa Grigia configuration, it consists of a LND 3He proportional counter of length 190.8 cm and diameter 5 cm, surrounded by 23 modules, each composed by a polyethylene reflector, with a hole housing a lead ring (producer) and a polyethylene inner moderator.

Each component is reasonably light, since the weight of the heaviest element is lower than 23 kg, so only one operator is required for transporting and assembling the whole neutron monitor even in its biggest arrangement (about 800 kg).
The possibility to transport it easily makes the instrument suitable for measurements in high mountains sites or in remote locations that are difficult to access.

Its counting rate corresponds to about 31% of a single unit standard NM-64 neutron monitor.

Counting rates are corrected for pressure variation to the reference pressure of 642.6 hPa using a barometric coefficient of 0.72%/hPa.

The vertical rigidity cutoff at Testa Grigia is R = 4.71 GV (2015).

The figure shows the percent variations of the neutron monitor counting rate (pressure corrected) with respect to the mean value over 20 days in summer 2016, compared with the corresponding data of the 18-IGY Neutron Monitor at the Jungfraujoch Sphinx Observatory located in Switzerland at 3570 m a.s.l. (46.55° N, 7.98° E, vertical rigidity cutoff V = 4.54 GV in 2015).
In this time interval the average counting rate was 1730/min.