Sponsored by Vitrek, LLCReviewed by Maria OsipovaSep 18 2025
This article explores the intriguing realm of particle physics with Vitrek’s comprehensive document on scattering experiments. Learn how incident particles strike targets, resulting in scattered particles and fragments that can be analyzed using modern particle detectors.
The article examines the functions of Photomultiplier Tubes (PMTs) and solid-state detectors in converting observed particles into electrical pulses, as well as how the Multi-Channel Analyzer (MCA) and RazorMax CompuScope perform Pulse Height Analysis (PHA) for more complex measurements.
Particle Physics Experiments
In a scattering experiment in nuclear or particle physics, impacting particles strike a target and disperse it, possibly together with fragments of the target or freshly produced particles. These scattering experiment results are directed into an array of particle detectors for analysis.
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Photomultiplier Tubes (PMTs) turn detected light photons into electrical pulses. PMTs may detect non-photon nuclear particles by observing scintillator materials that absorb nuclear particles and generate photon pulses. Solid-state detectors use semiconductor devices to directly detect nuclear particles.
When a photon or particle collides with them, both detector types generate a brief electrical pulse with an amplitude proportionate to particle energy. The Multi-Channel Analyzer (MCA) is particle physics' workhorse equipment.
This apparatus performs Pulse Height Analysis (PHA) on particle pulses and displays a histogram of the number of pulses recorded versus their energy. A 4-channel Gage RazorMax CompuScope, housed within a PC, can detect pulses from up to four particle detectors simultaneously.
Such a system can simulate an MCA by conducting PHA on the host PC. In addition, because the particle pulses are independently digitized and collected, more sophisticated experiments may be performed.
Multiple Recording of Particle Pulses
In most experiments, CompuScopes are activated by an External Trigger pulse that coincides with some form of excitation. However, particles are frequently emitted at random. Therefore, CompuScopes must activate internally on these pulses, rather than on a non-existent external excitation pulse.
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Triggers from the four RazorMax CompuScope channels can be Boolean ORed together to generate the trigger event. A particle pulse on any connected detectors will initiate RazorMax acquisition on all four input channels.
In coincidence experiments, the signature of many nuclear transitions is the simultaneous formation of two or more particles with paths at specific relative angles. Particle pulses collected by the RazorMax can be analyzed to detect coincidence.
In CompuScope Multiple Record Mode, multiple records - typically of less than a microsecond duration for particle pulses - can be acquired following a lightning-fast sub-microsecond re-arm time, allowing count rates of up to 500 kHz.
Each record is assigned a Trigger Time Stamp, which is the result of a high-speed onboard timer that is locked by the trigger event.
As a result, the TimeStamp provides the arrival time of each particle pulse, which may be used to calculate pulse count rates and inter-pulse delays. Records can be piled in onboard RazorMax memory or streamed constantly to RAM in the host PC.
The streaming target could alternatively be a Graphics Processing Unit (GPU) card that performs Digital Signal Processing (DSP) on the recordings, potentially involving PHA. Users can create their own software applications in various programming languages, utilizing Gage's sophisticated SDK sample programs.
This information has been sourced, reviewed and adapted from materials provided by Vitrek, LLC.
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