W-PIE

The W-PIE neutron spectrometer is a unique device designed for on-line neutron spectrometry measurements. The system features an extremely high counting efficiency, making it suitable to perform neutron spectrometry and absolute flux measurement for applications such as:

• homeland security
• cargo inspections
• calibration laboratories
• background suppression in high-energy physics experiments
• cosmic ray neutron sensing (CRNS) in agriculture
• snow water equivalent (SWE) measurements in hydrology

W-PIE employs ⁶Li as neutron converter, ⁴He as scintillating medium, and 24 independent low-voltage SiPMs as photosensitive components. The detector is surrounded by increasingly thick moderating assemblies, defining 4 detection sub-volumes each optimised for a specific spectral region. Signals are acquired and analysed by the built-in electronics and unfolding algorithm, or they can be saved as raw data for off-line analysis.

The response function of W-PIE, calculated via Monte Carlo simulations, is available for either on-line and off-line analysis. The response function and unfolding algorithm have been validated after thoroughly testing with reference radioactive sources, with quasi-monoenergetic neutron fields, and in the high-energy reference neutron field facility CERF at CERN.

The device is available in two configurations:

• W-PIE – standard, high-energy version, with Cd and Pb inserts, designed to be sensitive to neutrons up to 10 GeV
• HERMES W-PIE – lightweight and standalone low energy version, without high-Z inserts, designed to be sensitive to neutrons up to about 100 MeV

The W-PIE version is powered over Ethernet and communicates with a PC through Ethernet connection.

The HERMES W-PIE version is a standalone unit featuring a single board computer, a 4G router, a GPS and a dual-SIM system allowing remote control.