Time of Flight beamline
Beamlines

Personnel Responsible: Aurelio Climent-Font

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Tipical ERDA-TOF spectra


By the end of 2009, the Time of Flight (ToF) beamline at CMAM was completely assembled and the first tests were performed.

ToF beamline is at the 10 degree port of the first switching magnet at the exit of the accelerator, allowing for high mass, low charge state ion beams to be delivered. In the beam line, two sets of four independent slits are located in order to define the beam spot on the sample, which is positioned by means of a 3-axis goniometer inside the scattering chamber. The incident beam current is measured continuously during the experiment by means of a Transmission Faraday Cup situated at the entrance of the chamber. A Time of Flight telescope, placed at 40º from the beam, collects the particles, measuring in coincidence both energy and time of flight for each particle. In this way it is possible to distinguish the mass of the detected particle.

To measure the time of flight, two time stations are placed inside the telescope. The length of flight between them can be adjusted, being 42cm the nominal value. When a particle crosses a time station, a fast signal is generated. This signal is used to fed Fast Preamplifiers and Constant Fraction Discriminators that determine when a particle is passing through. A time to amplitude converter is used to obtain a pulse with a height proportional to the time of flight between the two detectors. At the end of the telescope, a solid state detector measures the particle energy. Both time and energy signals are recorded in a list mode, marking every event with a timestamp. Further software treatment allows determining which events occurred in coincidence, making possible mass determination for each detected particle. For heavy particles, energy spectra obtained form time spectra are with much higher resolution than the ones obtained directly from energy detector. Beamline is fully controlled by a PC based system running a homemade acquisition software.

Although the beamline was originally planned for Elastic Recoil Detection and Analysis experiments, it is possible to carry out any experiment on which simultaneous detection of mass and energy of particles is needed.


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Top-view of the ERDA-TOF beamline

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Time of Flight stations

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BPM monitor, slits and faraday Cups

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Full-view of ERDA-TOF beamline