1. Mass Spectrometry Brief introduction (part1) I. Sivacekflerovlab.jinr.ru 2012 Student Practice in JINR Fields of Research 1.oct.2012

2. Mass spectrometer Ion source – analyzing magnet – detector (basic setup) – Isotope identification – Molecule identification – Chromatography – Microscopes – AMS – RIBs and many more…

3. Charged particles and ions Neutral atoms (p = e) Charged atoms = ions (p ≠ e) Neutral particles (f.e. neutron) Charged particles (f.e. proton, electron…) Charged = with electric charge

4. How to create ion ? If energy is given to neutral atom – Excitation, de-excitation (a) – Ionization (b) Thermal ionization Chemical ionization ECR (uniform magnetic field; plasma; 2,45 GHz microwave power) E=hν Incident radiation - (a) (b) (Or other kind of energy)

5. Ions with kinetic energy Interactions of charged particles and ions: – ionization – excitation – elastic scattering – bremmstrahlung

6. Ion ionization Bethe formula for ion energy loss α ~ 1 MeV/cm (1 atm = 101 kPa = 760 Torr) Bragg curve – stopping power => Vacuum is needed ! Electron density of target Ion chargeIon velocity

7. Electric and magnetic field Electric field: (accelerates) Magnetic field E = |U 2 – U 1 | Lorentz Law (1)

8. Mass separation in magnetic field Mass-over-charge ratio r Generally at E-M field mag. field: E=0; |F m | = qvB.sinα radius =1 => r = (m/q)(v/B) (2)

9. Cyclotron Lorentz force in magnetic field keeps orbits Electrical field between duants accelerates ions Cyclotron frequency (particle velocity does not depend on time of flight thru magnetic field)* Duants (electrodes with HF oscillating electric field) Magnetic field Beamline * (2) => r = const. v

10. Detection of particles Generally, all types of detector can be used – Spectroscopic detectors Semiconductor Scintillators Gas detectors Time-of-flight (and many more) – Counters (quantitative analysis) Gas detectors Pick-ups Faraday cups (and many many more…) Warning: Since high ionization ability of charged ions, proper choice of detector strongly depends on application and characteristics of detected beam !!

11. Mass resolution Ability of device to resolve between two masses m and m+Δm Defined as (by FWHM) Strip strip number Dispersion on ion source Resolution on ion source-magnet-detector array Radius of ion in magnetic field Dispersion after magnetic sector D [mm/% p ] D = Δx/ΔBρ = Δx/Δp Translation on focal plane Ion impulse

12. NOW YOU ARE FREE FOR A WHILE End of part 1