Beam-intensity measurements

Most of the diagnostics concept for monitoring the Super-FRS beam intensity and transmission are FAIR accelerator based: particle detection combination (PDC), with three types of particle detectors (SEM, IC, plastic scintillator or diamond detector) at the entrance of the Pre-Separator (target) and the Main Separator to measure the beam current and counting. Special care is needed at the target region for the signal transportation and the front-end electronics location due to the high radiation level.

 

As an example, a two-gap IC with 50 mm diameter active area used to measure 12C ion-beam intensity is shown, see figure below. The detector was fit in a gas sensitive housing with stainless steel foils (0.1 mm) separating it from the vacuum. The IC analogue signal was fed into a current to frequency converter.

[1] S. Schlemme et al., GSI Scientific Report (2015) p. 369

 

Two-gap IC with active area of 50 mm diameter.
Intensity curve measured for 12C at 62 MeV/nucleon [1].

At the highest particle rates it is foreseen to operate a SEM transmission monitor equipped with thin metallic foils (SEETRAM) in current mode. The IC/SEETRAM current is calibrated by using a fast-counting diamond detector.

[2] F. Schirru et al., Diam. Relat.  Mater. 49 (2014) 96

scCVD diamond detector (2x2 mm2) [2].

The signal properties (amplitude, slope and charge) of a pcCVD diamond detector exposed to 60 h of irradiation corresponding to an integrated flux of 6.2⋅ 1013  12C/cm2 were studied as a function of the accumulated flux [3].

Amplitude and slope of the pcCVD-DD signals as a function of the irradiation time at two different beam attenuation factors f1 and f2.

[3] S. Schlemme et al., Diam. Relat. Mater. 99 (2019) 107536

The counting efficiency of a a large 20.0× 20.0× 0.3 mm3 pcCVD diamond detector was studied as a function of the beam rate and for different values of absorbed ions [4].

[4] F. Schirru et al, 2020 JINST 15 C04040

Irradiations carried with high intensity 1 GeV/nucleon Pb and U beams at GSI validates the combination of:

  • 7 ×7 mm2 single crystal diamond
  • 25 ×25 mm2 polycrystalline diamond

as counting detectors up to few MHz at the FPF0 target chamber of the Super-FRS [5].

[5] M. Alfonsi et al., 2024 JINST 19 C05009

 

 

3D model of slots for the beam diagnostic devices at FPF0
3D model of slots for the beam diagnostic devices at FPF0 (beam direction from right to left).

The final detectors prepared at the GSI detector laboratory in 2024 are under test.

Partner: GSI


Loading...