A new imaging method for understanding chemical dynamics: efficient slice imaging using an in-vacuum pixel detector.

Area of Science:

• Atomic and Molecular Physics
• Experimental Physics
• Detector Technology

Background:

• Velocity map imaging (VMI) is a powerful technique for studying atomic and molecular dynamics.
• Traditional VMI setups often require gating the imaging detector, which can complicate data acquisition and analysis.
• There is a need for advanced detector systems that offer high performance and simplify experimental procedures.

Purpose of the Study:

• To present the implementation of the Timepix complementary metal oxide semiconductor (CMOS) pixel detector in VMI.
• To demonstrate the advantages of this new detector approach, including the elimination of detector gating.
• To evaluate the performance of the Timepix detector in terms of time-of-flight and spatial resolution.

Main Methods:

• The Timepix detector was integrated into a VMI setup.
• The detector was operated in time-of-flight mode, measuring particle impact position and time-of-flight.
• High spatial resolution was achieved using center-of-mass centroiding in conjunction with a microchannel plate.
• The photodissociation of NO(2) at 452 nm was studied as a test case.

Main Results:

• The Timepix detector successfully eliminated the need for gating the imaging detector.
• Time-of-flight measurements achieved a resolution of 12.5 ns and a dynamic range of approximately 100 μs.
• High spatial resolution was obtained, enabling detailed imaging.
• The energy resolution of the experimental setup was determined to be ΔE/E=0.05, limited by the setup, not the detector.

Conclusions:

• The Timepix detector is a compact and effective assembly for VMI.
• This detector technology offers significant advantages, including simplified experimental design and high-quality data acquisition.
• The Timepix detector is a promising tool for future imaging studies in atomic and molecular physics research.