PoGOLino is a scintillator-based neutron detector. Its main purpose is toprovide data on the neutron flux in the upper stratosphere at high latitudes atthermal and nonthermal energies for the PoGOLite instrument. PoGOLite is aballoon borne hard X-ray polarimeter for which the main source of backgroundstems from high energy neutrons. No measurements of the neutron environment forthe planned flight latitude and altitude exist. Furthermore this neutronenvironment changes with altitude, latitude and solar activity, three variablesthat will vary throughout the PoGOLite flight. PoGOLino was developed to studythe neutron environment and the influences from these three variables upon it.PoGOLino consists of two Europium doped Lithium Calcium Aluminium Fluoride(Eu:LiCAF) scintillators, each of which is sandwiched between 2 BismuthGermanium Oxide (BGO) scintillating crystals, which serve to veto signalsproduced by gamma-rays and charged particles. This allows the neutron flux tobe measured even in high radiation environments. Measurements of neutrons intwo separate energy bands are achieved by placing one LiCAF detector inside amoderating polyethylene shield while the second detector remains unshielded.The PoGOLino instrument was launched on March 20th 2013 from the Esrange SpaceCenter in Northern Sweden to an altitude of 30.9 km. A description of thedetector design and read-out system is presented. A detailed set of simulationsof the atmospheric neutron environment performed using both PLANETOCOSMICS andGeant4 will also be described. The comparison of the neutron flux measuredduring flight to predictions based on these simulations will be presented andthe consequences for the PoGOLite background will be discussed.
展开▼
