Calibration and validation of the lunar exploration neutron detector (LEND) observations for the study of the moon volatiles

TL;DR

This paper presents an improved calibration method for the Lunar Exploration Neutron Detector (LEND), enabling accurate predictions of neutron observations and insights into lunar volatiles through detailed modeling and cross-calibration with historical data.

Contribution

The paper introduces a comprehensive calibration approach for LEND using neutron transport modeling and cross-calibration with multiple datasets, enhancing the accuracy of lunar neutron flux measurements.

Findings

Enhanced calibration accuracy for all LEND detectors.

Successful prediction of neutron and charged particle count rates over ten years.

Illustration of high spatial resolution in lunar neutron mapping.

Abstract

This paper reviews improved calibration methods for the Lunar Reconnaissance Orbiter Lunar Exploration Neutron Detector. We cross calibrated the set of LEND observations and models of its detectors physical geometry and composition against the McKinney Apollo 17 era measured neutron flux, Lunar Prospector Neutron Spectrometer epithermal neutron observations, Earth based Galactic Cosmic Ray observations and altitude dependent models of the Moon neutron emission flux. Our neutron transport modeling of the LEND system with the Geant4 software package allows us to fully decompose the varying contributions of lunar, spacecraft and instrument dependent sources of neutrons and charged particles during the LEND mission. With this improved calibration, we can now fully predict every observation from the eight helium 3 detectors and the expected total and partial count rates of neutrons and charged particles for the entirety of LEND now ten plus year observation campaign at the Moon. The study has resulted in an improved calibration for all detectors. The high spatial resolution of LEND collimated and uncollimated sensors are illustrated using the neutron suppression region associated with the south polar Cabeus permanent shadowed region.