MuSiP

Next-generation Muon Spin Spectroscopy (μSR) with sub-millimeter spatial resolution using high-precision silicon pixel tracking.

Muon Spin Rotation/Relaxation/Resonance (μSR) is an exceptionally sensitive tool for probing local magnetic fields at an atomic scale inside matter. However, traditional μSR instruments lack fine spatial resolution, projecting a wide beam that averages data over macroscopic sample areas.

MuSiP breaks this barrier by pairing advanced Silicon Pixel (Si) detectors with high-throughput real-time digital electronics. By reconstructing individual decay positron tracks, MuSiP achieves unprecedented sub-millimeter lateral resolution, opening up the exploration of micro-structured materials, heterogeneous thin films, and localized variations in quantum matter.

🧬 System Architecture & Experimental Setup

The MuSiP framework relies on a multi-stage instrument configuration designed to operate seamlessly under high-intensity muon beams (such as those at PSI). The system is broadly divided into three main operational pillars:

  1. The Muon Tracker Subsystem: Multiple high-granularity silicon pixel layers that pinpoint the exact injection vector and decay vertex of the incoming muons.
  2. Real-Time Edge Electronics: Hardware pipelines utilizing ultra-low latency FPGA tracking triggers to filter nanosecond decay events out of dense beam background.
  3. The Micro-Focus Sample Environment: Tailored cryostats and spectrometers designed to position small, heterogeneous quantum samples directly in line with the high-resolution pixel focus.
(a) A photo of a quad hosting four Si-pixel chips. (b) The arrangement of four tracking layers using quads modules in the prototype spectrometer. (c) Comparison of the μSR signal measured by the Si-Pixel spectrometer vs. the GPS reference of a 6 mm diameter Al disc placed between two permanent magnets producing a transverse field of 6.3 mT at the centre.

⚡ Real-Time Tracking & Online Data Processing

Operating under high event rates requires extreme data reduction directly at the sensor boundary. Borrowing architecture paradigms from high-energy physics trigger complexes, MuSiP implements on-the-fly geometric track fitting.

Beam profile of the four layer Quad-Telescope in 3D. One chip in layer 3 was not working ;).

📚 Talks & Key Publications

The development, hardware verification, and material science capabilities of the MuSiP project have been detailed across several recent publications and international conference proceedings:

🔬 Journal Articles

  • High-resolution timing for vertex-reconstructed muon-spin spectroscopy using plastic scintillators and MuTRiG ScienceDirect / NIM A. [Link to Article]
  • New Frontiers in muon-spin spectroscopy using Si-pixel detectors ScienceDirect / NIM A. [Link to Article]
  • Advanced muon-spin spectroscopy with high lateral resolution using Si-pixel detectors Physical Review Research. [Link to Article]

📢 Selected Talks & Presentations

  • Advanced Muon Spectroscopy with Si-Pixel Detectors Overview of next-generation low-energy muon beam tracking setups and cryostat integration. Presented at the SμS Users Meeting, PSI. [Slides PDF]
  • Real-time DAQ System for Muon-Spin Spectroscop Focus on firmware logic implementations, processing latency constraints, and data stream. [Slides Slides]
  • New Frontiers in Muon-Spin Spectroscopy Using Si-Pixel Detectors Evaluation of front-end ASIC electronics operating inside high magnetic fields and low-temperature experimental conditions. Presented at the Vienna Conference on Instrumentation (VCI). [Slides PDF]

For inquiries regarding collaboration, hardware testing, or beamtime development schedules, please contact the project coordinators via the main repository handles.