Speaker
Description
Abstract for MULTIPAC draft for Users Meeting
MULTIPAC is a spectrometer that can perform γ-γ time-differential perturbed angular correlation (γ-γ TDPAC) experiments under controlled conditions such as an applied external magnetic field up to 8.5 T and temperatures ranging between 3 to 375 K. MULTIPAC differs from conventional γ-γ TDPAC spectrometers in the use of modern multi-pixel photon counters (MPPC), which offers advantage over the standard photomultiplier tubes, due to its compact size (allowing for the MPPC-detector combo to be fitted into bore of the superconducting solenoid magnet), resistance to magnetic fields, ease of maintenance, and requiring only low voltage. Additionally, the MPPC maintains a low quantum efficiency (< 25%) and the high gain ($≈10^{5-6}$) comparable to that of a photo multiplier tube.
MULTIPAC uses a cryogen-free helium-based system to cool down both the sample space environment and the superconducting magnet (separately), thus preserving helium gas as an expensive and scarce natural resource and is safer to operate (no massive amount of helium released in the event of a magnetic quench) as opposed to the more commonly used liquid helium as a coolant.
In addition, MULTIPAC also features a vibrating sample magnetometer (VSM) to leverage upon the field provided by its inbuilt superconducting magnet. In sum, MULTIPAC is an all-in-one package that allows users to explore the multiferroic properties of compatible materials by probing its microscopic hyperfine structure using suitable probes from the TDPAC spectroscopy, and its macroscopic properties using VSM, while allowing for external influences from the external magnetic and electric field.
