Bismuth Organic Liquid Detector with Cherenkov Light and Charge Readout for Positron Emission Tomography

• Applicants: Professor Dr. Klaus Schäfers; Professor Dr. Christian Weinheimer
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields ; Medical Physics, Biomedical Technology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 406703021

• Final Report Year: 2024

Final Report Abstract

TriMethyl Bismuth (TMBi) has been proposed as a novel organic detector material for positron emission tomography (PET) due to its high efficiency for gamma absorption through photoeffect, its high density and the possibility for fast timing measurements using Cherenkov light emission. In this project, TMBi was characterized regarding relative permittivity and free ion yield following Onsagers theory. The free ion yield was measured as G0fi = (0.110 ± 0.001stat )/100 eV) which is far below expectation for a PET detector, but in agreement of a recent measurement of our French colleagues. As purity of TMBi turned out to be crucial, purification strategies were developed and tested to achieve ultrapure TMBi required for charge measurements. Both distillation and electrostatic filtering were shown to be effective in purifying TMBi, although not solving all impurity problems. On the other side this holds promise for similar organic liquids. Towards safe operation, it was shown experimentally that TMBi is prone to degradation under high electric fields due to breakdown discharges and impurities. We could demonstrate that stable conditions can be achieved under argon atmosphere at 1 bar pressure for field strengths up to 20 kV/cm. As the free ion yield is very low, TMBi cannot be further proposed as PET detector material although it does provide Cherenkov light emission for fast timing. But we found some good arguments to consider TMPb as a PET detector medium.

Publications

• Ionization parameters of Trimethylbismuth for high-energy photon detection. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 958, 162646.
  Farradèche, M.; Tauzin, G.; Mols, J.-Ph.; Bard, J.-P.; Dognon, J.-P.; Weinheimer, C.; Schäfers, K.P.; Sharyy, V. & Yvon, D.
  
• Electro-purification studies and first measurement of relative permittivity of TMBi. Journal of Instrumentation, 17(12), P12021.
  Peters, S.; Gerke, B.; Hannen, V.; Huhmann, C.; Marquardt, N.; Schäfers, K.; Yvon, D.; Sharyy, V. & Weinheimer, C.
  
• High resolution MCP-PMT readout using transmission lines. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1027, 166092.
  Follin, M.; Chyzh, R.; Sung, C.-H.; Breton, D.; Maalmi, J.; Chaminade, T.; Delagnes, E.; Schäfers, K.; Weinheimer, C.; Yvon, D. & Sharyy, V.
  
• Suppression of electrical breakdown phenomena in liquid TriMethyl Bismuth based ionization detectors. Journal of Instrumentation, 17(09), P09029.
  Gerke, Björn; Peters, Simon-Nis; Marquardt, Nils; Huhmann, Christian; Hannen, Volker Michael; Holtkamp, Michael; Karst, Uwe; Yvon, Dominique; Sharyy, Viatcheslav; Weinheimer, Christian & Schäfers, Klaus
  
• Characterization of the BOLDPET optical prototype, an innovative Cherenkov detector for 511 keV γ radiation. Journal of Instrumentation, 19(07), P07018.
  Chyzh, R.; Tauzin, G.; Yvon, D.; Sung, C.-H.; Breton, D.; Maalmi, J.; Schäfers, K.; Weinheimer, C. & Sharyy, V.