Speaker
Description
A high-performing clinical proton computed tomography (pCT) system requires single-particle tracking detectors with good spatial resolution, high rate capability, and a minimal material budget to reduce coulomb scattering, particularly critical for the low-energy protons encountered in pCT. Large-area Floating Strip Micromegas with a two-dimensional strip readout are particularly well suited for this purpose, as they provide a very low material budget of 0.52% X/X0 while achieving the detector dimensions of up to 400 mm required for clinical imaging.
At the chair for medical physics at LMU Munich a large-area Floating Strip Micromegas with an active area of 400×400mm² is being developed, targeting future clinical pCT applications. The readout structure is formed by four 50µm double-sided flex PCB, jointed without insensitive gaps. The stitching procedure has been significantly simplified by relocating the support pillars, which define the size of the amplification region, from the readout structure onto the mesh using an inhouse manufacturing process. Design and manufacturing processes were validated in the production of prototype detectors with an active area of 200x200 mm².
To optimize the strip geometry with respect to charge sharing between orthogonal strip layers and amplitude, a dedicated multi-quadrant Floating Strip Micromegas with 200×200 mm² active area has been designed and constructed. The detector is segmented into 16 sectors, each implementing a different strip geometry, enabling direct and controlled comparison within a single detector environment while minimizing systematic uncertainties.
Floating Strip Micromegas exhibit inherently localized and fast-recovering discharges at higher rate capability and lower material budget than resistive Micromegas. Due to the particular signal form of floating strip detectors, such discharges can still damage readout channels. The discharge protection circuit integrated on the Scalable Readout System VMM3a hybrids was found to be insufficient in this case. Therefore, an external protection circuit with a small form factor was developed. Different circuit configurations are compared experimentally and in simulations in terms of protection efficiency and signal attenuation using detectors with active areas of 64×64 mm² and 200×200 mm², identifying an optimal configuration for Floating Strip Micromegas and paving the way for a robust and clinically deployable readout solution.
We will present design and construction procedures for detector, bulk-mesh and protection circuit and discuss signal formation and performance in electron beams, with radioactive sources and simulation.
| Name of the speaker | Max Meurer |
|---|---|
| Eligible for the Georges Charpak Young Scientist Award. | yes |