The cryogenic storage ring CSR

Area of Science:

• Atomic and Molecular Physics
• Accelerator Physics
• Physical Chemistry

Background:

• Long-term ion beam storage is crucial for advanced experiments.
• Previous storage rings faced limitations in storage time and beam quality.
• Cryogenic environments offer potential for enhanced ion beam stability.

Purpose of the Study:

• To design, construct, and operate an electrostatic cryogenic storage ring (CSR).
• To investigate the storage capabilities and beam properties of the CSR for various ion species.
• To establish a platform for future experiments on ion fragmentation processes.

Main Methods:

• Construction of a 35m circumference cryogenic storage ring with liquid helium cooling.
• Operation at temperatures as low as 5.5 K.
• Utilizing capacitive pickups for beam diagnostics (intensity, dispersion, focusing).
• Employing Schottky noise analysis for momentum distribution.
• Photodetachment and residual gas collision studies for lifetime measurements.

Main Results:

• Achieved storage time constants of several minutes to nearly an hour for anion and cation beams at 60 keV.
• Demonstrated extremely low anion detachment rates due to residual gas collisions.
• Derived a residual gas density below 140 cm⁻³, corresponding to pressures < 10⁻¹⁴ mbar.
• Observed momentum distribution broadening on a 1000 s timescale.

Conclusions:

• The electrostatic cryogenic storage ring (CSR) successfully provides ultra-high vacuum and long storage times for ion beams.
• The achieved cryogenic conditions significantly enhance ion beam lifetime and stability.
• The CSR is a promising facility for future research into ion fragmentation dynamics.