Multidetector Experiment on Aragats
Analyzing the condition leading to winter flux enhancements authors of
[8] absolutely correct mention that “The relatively small amplitude
of the disturbance of the surface electric field during the event
2019-01-09 (2 kV/m as compared to 10–30 kV/m at summer TGE) indirectly
indicates that the charge of cloud layers during the considered event
was significantly less than the characteristic charge of the cloud layer
during summer thunderstorms.” However, afterward they formulate the
wrong conclusion: “Thus, similar to the summer events of surface
thunderstorm increases, the increase in the flux of energetic electrons
and photons in the cold season occurs as a result of the acceleration
and multiplication of electrons in the upward-directed electric field
created by the cloud “.
The main cause of the mistake was using data from a few Aragats
detectors only. Incorporating information from particle detectors
measuring energy spectra of charged and neutral particles give
comprehensive information and allow understanding physical mechanisms
responsible for such a complicated phenomenon as TGE. To investigate the
hour-to-hour variations of radon progeny radiation and for measuring
spectral lines, we perform monitoring of the natural gamma radiation on
Aragats with NaI(Tl), type 905-4 ORTEC spectrometer. Spectrometer uses
3” × 3” diameter and length crystal, has 1024 channels, and provide
relative energy resolution (FWHM ∼7%) [9]. Network of large NaI
crystal scintillators, overviewed by a large photocathode of PM-49
(15-cm diameter) also monitored particle flux on Aragats. The sensitive
area of each NaI crystal is ≈0.032m2; the efficiency to detect a gamma
ray is ≈60%. The energy threshold of two spectrometers is 300 KeV, of 3
other - 4 MeV. Numerous 1 and 3 cm thick molded plastic scintillators
arranged in stacks (a network of STAND1 detectors and STAND3 detector)
and in cubical structures (CUBE detector) monitor particle fluxes. Light
from the scintillators is re-radiated by wavelength shifting optical
fibers at larger wavelengths and propagates to photomultipliers of the
type PM-115M. The DAQ electronics stores all configurations of the
signals in the detector channels, see detector charts with all details
in [10]. All particle detectors and spectrometers operate 7/24 and
time series are available for comparisons and statistical analysis from
databases of cosmic ray division (CRD) of Yerevan physics institute
(YerPhI).
In Fig. 1 we show a very long flux enhancement of ≈10 hours duration,
that corresponds to the disturbed values of the near-surface electric
field. By 1-hour periods we show the episodes of spectral analyses shown
in Fig. 2 (4 from 5) and in Table 1.