Study of individual pulses at the Antarctic high-altitude neutron monitor DOMC

A pair of neutron monitors (NMs) is installed on the high Central Antarctic plateau, at the Concordia station (3200 m altitude) and measures the nucleonic component of nucleonic-muon-electromagnetic cascades in- duced by high-energy cosmic rays in the atmosphere. The installation includes two NMs: DOMC, a standard mini-NM, and a bare (lead-free) DOMB NM. The newly installed data acquisition (DAQ) system records in- dividual pulses corresponding to mostly neutrons in the detector’s counting tube. Here we analyze different types of pulses and study the distribution of the waiting times between individual pulses as well as the pulse height, recorded by the DOMC NM during a quiet period of January 2020. The distribution appears double- peaked with peaks corresponding to the frequency of individual atmospheric cascades and the intra-cascade variability, respectively. We discuss also the nature of different components contributing to the pulses and se - paration of the signal from noise. It is shown that the waiting-time distribution has distinguished timescales, >30 ms defined by the cosmic-ray induced atmospheric cascades, and < 10 ms reflecting the intra-cascade variability. The new DAQ system allows one to study the development of the atmospheric cascade.

Pretoria Radiocarbon Dates I

In 1969 radiocarbon dating facilities were established at the National Physical Research Laboratory of the C.S.I.R. in Pretoria (25° 43′ S Lat, 28° 21′ E Long; alt 1500 m). The counters are situated in an underground room built of selected concrete and covered by ca. 12 m earth. In this room, the nucleonic component of cosmic radiation is practically absent and the meson flux is reduced by a factor of 3.5 as compared to the surface at sea level in Groningen, Netherlands. A neutron monitor which registers 30 cpm on the surface, counts ca. 0.1 cpm in the underground room.

Critique of successive differencing method of regression analysis

Various regression techniques have been proposed to calculate barometric coefficients from time-varying cosmic rays recorded by neutron monitors. One of these, the successive differencing method, was carefully examined by applying the technique to simulated time-dependent and time-independent cosmic-ray data and also by investigating the mathematical foundations of the technique. When applying the successive differencing method to time-independent data, the slope and slope error values were found to be dependent on the order in which the data appeared. By ordering the data from highest to lowest pressure, the slope error increased markedly. This falsification of the slope can be shown to be due to improper weighting of the differenced data. Calculations have also been performed to show that the successive differencing method, when applied to intensities containing a linear time dependence, produces a regression slope which retains a time dependence proportional to the difference between the first and last pressure values. The falsification of the slope due to improper weighting of the differenced data can be very much larger than the maximum effect of any reasonable time variation of the nucleonic component.