Open AccessJournal Article10.1088/0957-0233/12/9/314

Microcontroller based double beam modulation system for atomic scattering experiments

- 02 Aug 2001

- Vol. 12, Iss: 9, pp 1480-1485

TL;DR: A flexible modulation and counting system based on a low cost PIC microcontroller is described, and it is shown that typical savings in data acquisition time of approximately 30% can be achieved.

Abstract: Double beam modulation is widely used in atomic collision experiments in the case where the noise arising from each of the beams exceeds the measured signal. A method for minimizing the statistical uncertainty in a measured signal in a given time period is discussed, and a flexible modulation and counting system based on a low cost PIC microcontroller is described. This device is capable of modifying the acquisition parameters in real time during the course of an experimental run. It is shown that typical savings in data acquisition time of approximately 30% can be achieved using this optimized modulation scheme.

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In this paper, a method for minimizing the statistical uncertainty in a measured signal in a given time period is discussed, and a flexible modulation and counting system based on a low cost PIC microcontroller is described.

Table 1. S represents signal counts, NA and NB are noise background counts due to beam A and beam B respectively (interacting with background gas/surfaces) and β is the background noise when neither beam is present.

Figure 1. Standard double beam modulation pulse sequence, employing equal counting times in all four channels.

Figure 2. Time optimized modulation sequence based on sample count rates: R1 = 55 000 s−1, R2 = 50 000 s−1, R3 = 500 s−1, R4 = 5500 s−1. Then for a 1 ms modulation cycle t1 = 423 µs, t2 = 403 µs, t3 = 40 µs and t4 = 134 µs.

Figure 3. Schematic of microcontroller based modulation and counting unit. The entire unit is housed in a single width NIM unit. Operational parameters and data are transferred via a standard RS232 serial link to a PC workstation which carries out calculation of optimization parameters.

Figure 4. Simplified flow diagram of the modulation and counting control sequence.

Figure 5. Synchronized modulation and counter gating sequence. The sample channel widths shown are t1 = 350 µs, t2 = 300 µs, t3 = 150 µs and t4 = 200 µs. There is a non-counting period (typically 20 µs) around each beam transition to allow for transients and settling.

Citations

Journal Article•10.1080/00207210903170849

A PIC microcontroller-based system for real-life interfacing of external peripherals with a mobile robot

N. Nirmal Singh, +2 more

- 01 Feb 2010

- International Journal of Electronics

TL;DR: The present article describes the development of a peripheral interface controller (PIC) microcontroller-based system for interfacing external add-on peripherals with a real mobile robot, for real life applications.

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Book Chapter•10.1007/978-3-642-33965-3_2

Interfacing External Peripherals with a Mobile Robot

Amitava Chatterjee, +2 more

- 01 Jan 2013

TL;DR: This chapter discusses how real-life interfacing of external peripherals with a ready-made mobile robot can be successfully achieved for the KOALA robot using serial communication in interrupt driven mode.

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References

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TL;DR: In this paper, the cross section for the production of He + (2 S ) by electrons incident upon He + 1 S in the energy range from threshold to 750 eV was measured in arbitrary units with an accuracy of ± 5 % and at higher energies its energy dependence is in close agreement with that calculated by means of the plane-wave Born approximation.

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Journal Article•10.1088/0508-3443/17/3/309

The determination of atomic collision cross sections using crossed electron and ion beams (and some sources of error in such experiments)

M F A Harrison

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TL;DR: In this article, the application of the method of crossed beams to the study of collisions between electrons and ions is discussed and basic principles of the design of a collision region are given and an expression is derived for the collision cross section in terms of the measured electron and ion collision rate.

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Journal Article•10.1103/PHYSREVA.49.4585

Merged-beams energy-loss technique for electron-ion excitation: Absolute total cross sections for O5+(2s-->2p).

E W. Bell, +15 more

- 01 Jun 1994

- Physical Review A

TL;DR: A merged-beams electron-energy-loss technique is described, by which absolute cross sections can be measured for near-threshold electron-impact excitation of multipy charged ions, and evidence is observed for high-lying metastable autoionizing states which are made to ionize by electron impact.

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Journal Article•10.1088/0022-3735/4/2/025

A control unit for experiments with colliding charged-particle beams

L Molyneux, +2 more

- 01 Jan 1971

- Journal of Physics E: Scientific Instrum...

TL;DR: In this paper, a control unit, constructed from integrated circuit logic units, is described which will generate waveforms necessary to control experiments with colliding charged-particle beams, and it can be modified to produce the simpler waveforms which suffice for a number of experiments.

...read moreread less

Microcontroller based double beam modulation system for atomic scattering experiments

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Citations

A PIC microcontroller-based system for real-life interfacing of external peripherals with a mobile robot

Interfacing External Peripherals with a Mobile Robot

References

Case Studies in Atomic Collision Physics I

A measurement of the cross section for production of He+(2S) ions by electron impact excitation of ground state helium ions

The determination of atomic collision cross sections using crossed electron and ion beams (and some sources of error in such experiments)

Merged-beams energy-loss technique for electron-ion excitation: Absolute total cross sections for O5+(2s-->2p).

A control unit for experiments with colliding charged-particle beams

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