Algorithms of data processing and controlling experimental equipment

1. Algorithms of data processing and controlling experimental equipment Magnetic Resonance Spectroscopy Popov Timophey Komolkin Andrey, Sukharjevskiy Stanislav

2. Principles of Magnetic Field Resonances Radio Frequency Pulse Method Continuous Wave Method Real-time Operating Systems Review Why QNX? Current ESR-project Content:

3. Magnetic Resonance Researches Resonances Nuclear Magnetic Resonance Electron Spin Resonance Methods Continuous Wave Method Radio Frequency Pulse Method

4. Nuclear Magnetic Resonance Before and after energy absorption S high energy low energy B B hn N M M • Relaxation • Spin-spin relaxation • Spin-lattice relaxation p p / 2 M M M M – magnetization vector

5. Nuclear Magnetic Resonance NMR condition • Field-frequency correlation for 1H-nucleus • Magnetic field: ~ 10 000 oersted • Resonance frequency: ~ 42.5 MHz

6. Electron Spin Resonance Electron Spin: Magnetic potential energy of electron spin in magnetic field: Sz Splitting Energy RF-induced transition H0 Increasing magnetic field B

7. Electron Spin Resonance Integral intensity – proportional to quantity of unpaired electrons in a sample. Width of spectral line – characteristic of RF-energy absorption conditions. G-factor – using to initialize optional particles, participating in reactions with free radicals. • X-band spectrometers (wavelength 3 cm) • Magnetic field: ~ 3 400 oersted • Resonance frequency: ~ 9,5 GHz • Q-band spectrometers (wavelength 8 mm) • Magnetic field: ~ 15 500 oersted • Resonance frequency: ~ 35 GHz

8. Continuous Wave Method Sweep Coils The oscillation of sweeping magnetic field must be far less then increasing of external field CW-specrometer Sweep Generator S N Altering Magnetic Field We have to solve magnetic field scan linearization problem Receiver & Amplifier RF Generator

9. Magnetic Field Scan Linearization H H I I t t Sweep Magnetic Field Scan Signal dA t H dH1 t Continuous Wave Method 1. First scan cycle: linearization 2. Second cycle: Slow H-field scan with sweeping H1-field and continuous transmission data to computer. Major condition: First derivative

10. w w0 2w0 3w0 4w0 Continuous Wave Method Double Integrating Trend line Evening-out Fourier Transform Noise reduction Fast Fourier Transform If we have 2k measurements: Method is usually used for wide spectral lines and in ESR-spectrometry

11. RF-pulse Method Interhardware communication We need guaranteed fast communication between all nodes in this experiment RF-Pulse specrometer Smart Pulse Generator S N • Features: • Constant strong external magnetic field • Free induction decay (FID) time ~ 10 ms – 1 s • Short RF-pulses (10-100 ms) Receiver & Amplifier

12. RF-pulse Method Realization t Data processing Data processing Controlling Smart Pulse Generator Receiver Amplifier ADC Time to data processing and updating visual information Generating pulse sequence FID-waiting & Data buffering !!! Other processes are sleeping !!!

13. w w0 2w0 3w0 4w0 RF-pulse Method features Fourier Transform of nuclear echoes (FID) FT • Data Collecting • Data Collecting • Signal-to-noise ratio reduction • Evening-out • Real time visualization • Characteristic decay time 10ms – 1s

14. Real Time Review Real Time Real Philosophy

15. Real-time Review Criteria & Requirements: • Interrupt latency (less than 1 ms) • Context-switch time • System Size • Rebooting time • Development andexecution division Hard Real Time Systems– any delays and interrupts are not allowed on any conditions (e.g. aircraft navigation system) Soft Real Time Systems– some delays are allowed, but it results in increase production cost and decrease of system efficiency as a whole (e.g. computer network)

16. RT mechanisms: Priority system Scheduling algorithms Interprocess communication (IPC) Operating with timers and interrupts RT-System classes: Embedded systems (VXWorks, RTEMS) Real-time kernels (QNX, OS9) Real-time UNIXes (RTLinux, LynxOS) Real-time Windows (Windows Embedded) Real-time Review

17. Why Fundamental Principles System & Users’ Processes • microkernel architecture • message-based interprocess communication • Process manager • Filesystem manager • Device Manager • Network Manager Kernel Architecture Device drivers • message passing – the Kernel handles the routing of all messages among all processes throughout the entire system • scheduling – the scheduler is a part of Kernel and is invoked whenever a process change state as the result of a message or interrupt • choose to disappear at standard processes, simply becoming extensions to the system process they’re associated with • retain their individual identity as standard process

18. Why microkernel Device manager File system manager Process manager Network manager Interprocess communication (IPC) Single-computer model • QNX is message-based OS • Message – a packet of bytes passed from one process to another • All messages contains information about its state and priority, runtime information, synchronizing the execution and so on. • Entire process and message space among all incorporated QNX-computers • Sensible distribution network resources amount executing real-time processes

19. My Current ESR Project Wave conductor Klystron (high radio frequency generator) S Detector Strong magnetic field scan Receiver Amplifier Resonator with sample ADC

20. Credits & References: • Komolkin Andrey V. • Sukharjevskiy Stanislav M. • Quantum Magnetic Phenomena Department of Physical Faculty SPbSU • SWD Software • http://hyperphysics.phy-astr.gsu.edu/hbase/molecule/esr.html • http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/nmr/nmr1.htm