The paper is devoted to the results of the EAS neutron component investigations by means of the PRISMA-32 array. The array consists of 32 en-detectors and enables to record delayed thermal neutrons accompanying showers. For registration of thermal neutrons, the scintillator based on $^{6}Li$ isotope as a target is used in the detectors. Some results of the processing of data accumulated over a long period of time are presented: the lateral distribution function of neutrons in EAS and preliminary results on EAS neutron multiplicity spectrum and distribution of showers in e/n ratio.
The Experimental complex NEVOD includes several different setups for studying various components of extensive air showers (EAS) in the energy range from 10^10 to 10^18 eV. The NEVOD-EAS array for detection of the EAS electron-photon component began its data taking in 2018. It is a distributed system of scintillation detectors installed over an area of about 10^4 m^2. A distinctive feature of this array is its cluster organization with different-altitude layout of the detecting elements. The main goal of the NEVOD-EAS array is to obtain an estimation of the primary particle energy for events measured by various detectors of the Experimental complex NEVOD. This paper describes the design, operation principles and data processing of the NEVOD-EAS array. The criteria for the event selection and the accuracy of the EAS parameters reconstruction obtained on the simulated events are discussed. The results of the preliminary analysis of experimental data obtained during a half-year operation are presented.
A novel type of EAS array (PRISMA-32) has been constructed on the base of NEVOD-DECOR experiment (MEPhI,Moscow) and is now taking data. It consists of 32 specially designed scintillator en-detectors able to measure two main EAS components: hadrons (n) and electrons (e). First results on thermal neutron lateral as well as temporal distributions are presented. Obtained exponential neutron lateral distributions are consistent with that expected for normal hadron production with exponential transverse momentum distribution. As there are no other experimental data on thermal neutron distributions and so, to compare results with other measurements, we additionally obtained electron lateral distribution function (using the same detectors) and compared it with NKG - function. Recorded neutron temporal distributions are very close to that obtained with data of our previous prototypes.
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.
Low energy ground-based cosmic ray air shower experiments generally have energy threshold in the range of a few tens to a few hundreds of TeV. The shower observables are measured indirectly with an array of detectors. The atmospheric absorption of low energy secondaries limits their detection frequencies at the Earths surface. However, due to selection effects, a tiny fraction of low energy showers, which are produced in the lower atmosphere can reach the observational level. But, due to less information of shower observables, the reconstruction of these showers are arduous. Hence, it is believed that direct measurements by experiments aboard on satellites and balloon flights are more reliable at low energies. Despite having very small efficiency ($sim$0.1%) at low energies, the large acceptance ($sim$5 m$^2$sr) of GRAPES-3 experiment allows observing primary cosmic rays down below to $sim$1 TeV and opens up the possibility to measure primary energy spectrum spanning from a few TeV to beyond cosmic ray knee (up to 10$^{16}$ eV), covering five orders of magnitude. The GRAPES-3 energy threshold for primary protons through Monte Carlo simulations are calculated, which gives reasonably good agreement with data. Furthermore, the total efficiencies and acceptance are also calculated for protons primaries. The ability of GRAPES-3 experiment to cover such a broader energy range may provide a unique handle to bridge the energy spectrum between direct measurements at low energies and indirect measurements at ultra-high energies.
We are developing a kilo-pixels Ti/Au TES array as a backup option for Athena X-IFU. Here we report on single-pixel performance of a 32$times$32 array operated in a Frequency Division Multiplexing (FDM) readout system, with bias frequencies in the range 1-5 MHz. We have tested the pixels response at several photon energies, by means of a $^{55}$Fe radioactive source (emitting Mn-K$alpha$ at 5.9 keV) and a Modulated X-ray Source (MXS, providing Cr-K$alpha$ at 5.4 keV and Cu-K$alpha$ at 8.0 keV). First, we report the procedure used to perform the detector energy scale calibration, usually achieving a calibration accuracy better than $sim$ 0.5 eV in the 5.4 - 8.9 keV energy range. Then, we present the measured energy resolution at the different energies (best single pixel performance: $Delta$E$_{FWHM}$ = 2.40 $pm$ 0.09 eV @ 5.4 keV; 2.53 $pm$ 0.10 eV @ 5.9 keV; 2.78 $pm$ 0.16 eV @ 8.0 keV), investigating also the performance dependency from the pixel bias frequency and the count rate. Thanks to long background measurements ($sim$ 1 day), we finally detected also the Al-K$alpha$ line at 1.5 keV, generated by fluorescence inside the experimental setup. We analyzed this line to obtain a first assessment of the single-pixel performance also at low energy ($Delta$E$_{FWHM}$ = 1.91 eV $pm$ 0.21 eV @ 1.5 keV), and to evaluate the linearity of the detector response in a large energy band (1.5 - 8.9 keV).