This paper analyses neutron multiplicity spectra from massive targets at
depths of 3, 40, 210, 583, 1166, E 4000 m.w.e. The measurements, conducted
between 2001 E 2024, utilised three experimental setups with either 14 O 60
He-3 neutron detectors and lead (Pb) targets weighing 306, 565, O 1134 kg. The
total acquisition time exceeded six years. When available, the acquired spectra
were compared with Monte Carlo simulations. Our data challenges the practice of
approximating the muon-induced neutron multiplicity spectra with one power-law
function $k \times m^{-p}$, where m is the multiplicity, k is the depth-related
parameter decreasing with overburden, and p is the slope parameter that remains
unchanged with depth. Instead, we see the emergence of a second component. It
is evident already in the muon-suppressed spectrum collected on the surface and
dominates the spectra at 1166 E 4000 m.w.e. Inoltre, we see indications
of a possible structure in the second component that resembles emissions of
circa 74, 106, 143, E 214 neutrons from the target. Since the anomaly
varies only slightly with depth, it is not directly correlated with the muon
flux. We propose new underground measurements employing low-cost, large-area,
position-sensitive neutron counters to verify and investigate the observed
anomalies and ascertain their origin.

Questo articolo esplora i giri e le loro implicazioni.

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