Detection of thermal neutrons with the PRISMA-YBJ array in extensive air showers selected by the ARGO-YBJ experiment

Abstract

We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and 6 LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector.2

Measurements of the low-energy neutron and gamma ray accompaniment of extensive air showers in the knee region of primary cosmic ray spectrum

“…with essentially different lifetime values: τ 1 ≈ 400 − 500 µs and τ 2 ≈ 5000 − 6000 µs. Similar results concerning the neutron accompaniment of the EAS were reported in [32,33]; it was stated there that the exponential component with smaller τ corresponds to evaporation neutrons born by interaction of the EAS hadronic particles in the nearest vicinity to detector site, while the slowest exponent with a millisecond order lifetime indicates the arrival of neutrons from distant interactions at the periphery of the shower. Pointwise dividing of average intensity curves from two plots of Figure 5 permits to trace the mutual ratio between momentary signal intensities of the bare and moderator covered neutron counters R(t) = I b (t)/I m (t), as both were detected in the course 9 of an EAS caused event development.…”

“…Such kind of neutron detectors is very convenient for mass application in the large scale shower installations because of its cheapness, production simplicity, and possibility of simultaneous registration both of the neutron and electron components of EAS in a single detector, with their further effective separation by the amplitude and time profiles of scintillation flash. Up to the present time, a prototype of suggested detector has been tested in a number of EAS experiments, and spatial and temporal characteristics of the thermal neutron flux which accompany the EAS passage were obtained both underground [28], at sea level [29,30,31,32], and in the mountains [33]. Currently, a systematic use of such neutron detectors is anticipated at the modern large size EAS array LHAASO [34].…”

EAS thermal neutron detection with the PRISMA-LHAASO-16 experiment

“…The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector. [12]. Moreover, during long stable running, results on the natural thermal neutron flux are obtained.…”

Loopy constraints on leptophilic dark matter and internal bremsstrahlung

“…Additional motivation could be provided by various cosmic ray anomalies. For instance, attempts to explain the cosmic ray positron excess observed by PAMELA [19,20], Fermi-LAT [21] and AMS-02 [22] in terms of DM annihilation typically require a leptophilic DM model [23][24][25][26][27][28][29][30][31][32] in order not to exceed the measured antiproton flux [33,34]. Finally, it is intriguing that the possible anomalies in the gamma ray signal from the Galactic Center [35][36][37], in the gamma ray emission from the Fermi Bubbles [38][39][40][41], and in radio signals from filamentary structures in the inner galaxy [42] could be explained in leptophilic DM models.…”