Discover the fascinating world of particle physics through our detailed document on scattering experiments. Learn how targets are hit by incident particles, leading to scattered particles and fragments that are studied using advanced particle detectors. Explore the roles of Photomultiplier Tubes (PMTs) and solid-state detectors in converting detected particles into electrical pulses, and understand how the Multi-Channel Analyzer (MCA) and RazorMax CompuScope perform Pulse Height Analysis (PHA) for more complex measurements.

In a scattering experiment in nuclear or particle physics, a target is hit by incident particles, which are scattered – possible along with fragments of the target and even with newly-created particles. These products of scattering experiments are directed into an array of particle detectors for study.

Photomultiplier Tubes (PMTs) convert detected light photons into electrical pulses. By following scintillator materials that absorb nuclear particles and produce photon pulses, PMTs may also detect non-photon nuclear particles. Alternately, solid state detectors use semiconductor structures to detect nuclear particles directly.

When a photon or particle impinges upon them, both detector types produce a short electrical pulse whose amplitude is proportional to its energy. The workhorse instrument of particle physics is the Multi-Channel Analyzer (MCA). This instrument performs Pulse Height Analysis (PHA) upon pulses produced by particle pulses and presents a histogram of the number of such pulses detected against their energy.

Housed within a PC, a 4-channel Gage RazorMax CompuScope can detect pulses from up to four particle detectors. Such a system can emulate an MCA by performing PHA on the host PC. Furthermore, since the particle pulses are individually digitized and acquired, more complex measurements are possible.

In most experiments, CompuScopes are triggered by an External Trigger pulse that is simultaneous with some sort of excitation. However, particles are often emitted randomly so that CompuScopes must trigger internally on these pulses, rather than on a non-existent external ex citation pulse.

Triggers from the four RazorMax CompuScope channels may be Boolean ORed together to create the trigger event. This way, RazorMax acquisition on all four input channels will be triggered by the arrival of a particle pulse on any combination of the connected detectors. In coincidence experiments, the signature of various nuclear transitions is the simultaneous creation of two or more particles with trajectories at specific relative angles. Particle pulses acquired by the RazorMax can be analyzed to detect coincidence.

In CompuScope Multiple Record Mode, successive records – typically of under microsecond duration for particle pulses – may each be acquired after a lightning-fast sub-microsecond re-arm time, which allows count rates of up to 500 Kilohertz. Each record is tagged with a Trigger TimeStamp, which is the output of a high-speed on-board counter that is latched by the trigger event. Accordingly, the TimeStamp provides the arrival time of each particle pulse, which may be used to determine pulse count rates and inter-pulse delays.

Records may be stacked in on-board RazorMax memory or continuously streamed to RAM in the host PC. The streaming target may also be a Graphical Processing Unit (GPU) card that performs Digital Signal Processing (DSP) on the records, which could involve PHA. Users can develop their own software applications in several programming languages using Gage’s powerful SDK sample programs.