Sector focused cyclotron

Richardson, J.R. Sector Focusing Cyclotrons, Progress in Nuclear Techniques and Instrumentation, North-Holland Publishing Co. Amsterdam, 1965. 

Figure 14.9 Top view of the sectors, or the hills and valleys, in a sector-focused cyclotrons. In (a) the concept of strong vertical focusing at the transition regions, edges, of the sectors is shown for straight sectors. A larger focusing effect is obtained hy spiraling the sectors as shown in (b). Note that the particles travel counterclockwise in this figure.

FIG. 13.8. A 150 MeV sector-focused cyclotron showing the magnet with its spiral-ridged pole pieces and U-wave D-design. 

A water-cooled copper foil (0.1 mm thick) is irradiated by the internal beam of a sector focused cyclotron with 1.2 mA H ions of 24 MeV for 90 min. The reaction Cu(p,pn) u occurs with a probability of 0.086 b. Copper consists to 69% of Cu. The proton beam has a cross-section of only 15 mm. (a) How many u atoms have been formed (b) What fraction of the projectiles have reacted to form Cu (c) What cooling effect is required (kW) at the target ... 

A simple mass spectrometer of low resolution (many quadrupoles, magnetic sectors, time-of-flight) cannot easily be used for accurate mass measurement and, usually, a double-focusing magnetic/electric-sector or Fourier-transform ion cyclotron resonance instrument is needed. 

Mass spectrometer configuration. Multianalyzer instruments should be named for the analyzers in the sequence in which they are traversed by the ion beam, where B is a magnetic analyzer, E is an electrostatic analyzer, Q is a quadrupole analyzer, TOP is a time-of-flight analyzer, and ICR is an ion cyclotron resonance analyzer. For example BE mass spectrometer (reversed-geometry double-focusing instrument), BQ mass spectrometer (hybrid sector and quadrupole instrument), EBQ (double-focusing instrument followed by a quadrupole). 

With few exceptions, magnetic sector instruments are comparatively large devices capable of high resolution and accurate mass determination, and suited for a wide variety of ionization methods. Double-focusing sector instruments are the choice of MS laboratories with a large chemical diversity of samples. In recent years, there is a tendency to substitute these machines by TOE or by Fourier transform ion cyclotron resonance (FT-ICR) instruments. 

Key Q = Quadmpole IT = ion trap DFMS = Double focusing magnetic sector TOP = Time of flight FTICR = Fourier transform ion cyclotron resonance. 

An overview of commercial ICP mass spectrometers from different companies (quadrupole based ICP-MS with and without collision/reaction cell, double-focusing sector field instrumentation with single and multiple ion collectors, time-of-flight (ToF), ICP-ion trap-MS and non-commercial ICP-Fourier transform ion cyclotron resonance (FTICR) mass spectrometers is given in Figure 5.2. By using ion traps and FTICR mass spectrometers in ICP-MS isobaric interferences of atomic ions... 

The precursor ion selection, fragmentation, and product ion analysis can be separated in space or in time, as shown in Figure 1.29. Separation in time requires trapped ions, as available in the quadrupole ion trap or the ion cyclotron resonance trap. Separation in space necessitates at least two physically distinct mass analyzing devices, one for precursor ion selection (MS-1) and one for product ion analysis (MS-2). The simplest in-space tandem instruments are the triple quadrupole mass spectrometer (QqQ), the double-focusing sector tandem mass spectrometer (EB or BE), and the reflectron time-of-flight mass spectrometer. In a triple quadrupole, the first and third quadrupoles (Q) are mass analyzers, while the center quadrupole iq) serves as the collision cell. In sector instruments, a collision cell is situated... 

A sample contains a mixture of three compounds, the molecular ions of which can be separated by a mass spectrometer at a resolution of 9500. Your laboratory is equipped with the following instruments (a) a double-focusing magnetic-sector spectrometer, (b) a single-quadmpole spectrometer, (c) a quadrupole ion-trap spectrometer, (d) a linear time-of-flight (TOP) spectrometer, (e) a refiectron-TOF spectrometer, and (f) a Fourier transform ion cyclotron mass spectrometer. Suggest aU possible choices among these instruments that you can employ for the analysis of this mixture. 

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