Sensitivity of the SciBar Cosmic Ray Telescope (SciCRT) to solar neutrons

Abstract

The SciBar Cosmic Ray Telescope (SciCRT) is aimed to help elucidate the acceleration mechanism of high-energy ions that may produce neutrons at the Sun. It is a fully active scintillator tracker which consists of 14,848 plastic scintillator bars, originally constructed for accelerator neutrino oscillation experiments. The SciCRT; it has a huge detector volume compared with conventional Solar Neutron Telescopes (SNTs), e.g. 15 times larger than Mexico SNT. Furthermore, the SciCRT can measure the energy deposition of each particle as neutron ADC data which have not been registered before. Neutron ADC data provide us with a precise measurement of energies deposited at the detector. The SciCRT was deployed at the summit of Mt. Sierra Negra (4,600 m) and began to acquire data in September 2013. Then we partially upgraded the DAQ system developed originally for an accelerator experiment, as the readout rate of the DAQ system was significantly limited for our experiment. This paper highlights sensitivity numerical studies of solar neutrons that the SciCRT is able to register. At first, we focus in the accuracy to determine the spectrum power-law index, assuming an instantaneous emission of solar neutrons. This is required to determine the power-law index within an error of ±1.0 in order to discuss the efficiency of the acceleration. Then in the case of the fixed power-law index, we discuss the capability of discriminating three different lengths of emission times: 0 min, 5 min, and 8 min. Finally we evaluate whether it is possible to discriminate a different combination of these two parameters simultaneously. Thus, we show that data from the SciCRT will unlock the degeneracy problem amid the emission time and the energy spectrum of solar neutrons.