Storage Ring Parameters

Sirius’ Storage Ring uses a 20-cell 5BA (Five Bend Acromat) magnetic lattice to achieve a very low beam emittance of 0.25 nm.rad,  making Sirius one of the brightest synchrotron light sources in the world.

An innovation in the Sirius lattice is the introduction of high field permanent magnets of 3.3 T in the middle of the central 0.58 T dipole of the 5BA cell. Besides contributing to the reduction of emittance, these high field dipoles will also produce hard X-rays with critical photon energy of about 20 keV, producing usable photon flux up to about 120 keV.

The main elements of the magnetic lattice of the Sirius Storage Ring are 120 low-field dipoles (0.58 T), 20 high field thin dipoles (3.3 T), 260 quadrupole, 280 sextupoles, 160 slow horizontal orbit corrector magnets, 80 quick horizontal orbit corrector magnets, slow vertical 120 orbit corrector magnets and 80 quick vertical orbit corrector magnets.


Parameters Value Unit
Energy 3.0 GeV
Gamma Factor 5870.854
Beta Factor 0.999999985
Velocity $ 2.9979 \times 10^{8}$ m/s
Magnetic Rigidity 10.0069 T.m
Nominal Current 350.0 mA


Parameters Value Unit
Type 5BA
Circunference 518.396 m
Revolution period 1.729 µs
Revolution frequency 0.5783 MHz
Long Straight Sections 5 x 7.5 m
Short Straight Sections 15 x 6.5 m


Parameters Value Unit
Linear Momentum Compaction $\rm 1.630 \times 10^{-4}$
Transverse coupling 1.0 %
Betatron Tunes 49.110 (h) x 14.165 (v)
Natural Chromaticities -119.2 (h) x -79.1 (v)
Beam size at center of SS-A 64.9 (h) x 3.4 (v) µm
Beam size at center of SS-B 19.1 (h) x 2.0 (v) µm
Beam size at center of BC 9.5 (h) x 3.5 (v) µm
Beam divergence at center of SS-A 3.8 (h) x 0.7 (v) µrad
Beam divergence at center of SS-B 13.0 (h) x 1.3 (v) µrad
Beam divergence at center of BC 26.9 (h) x 0.7 (v) µrad

Equilibrium Parameters

Parameters Value Unit
Natural Emittance 0.251 nm.rad
Natural Energy Spread 0.085 %
Natural bunch length 2.5 (8.2) mm (ps)
Energy loss from Dipoles per turn 475.3 keV
Energy loss from IDs per turn 400.0 keV
Radiation power from Dipoles 237.6 kW
Radiation power from IDs 200.0 kW
Damping partition number 1.30 (h) x 1.00 (v) x 1.70 (L)
Damping time (dipoles only) 16.78 (h) x 21.83 (v) x 12.83 (L) ms

RF Parameters

Parameters Value Unit
Frequency 499.658 MHz
Harmonic Number 864
Cavity Peak Voltage 3.0 MV
Synchronous phase 163.0 °
Synchronous tune $\rm 4.6 \times 10^{-3}$
Synchronous frequency 2.68 kHz
Energy Acceptance 5.1 %

Low Field Dipoles

Parameters Value Unit
Magnetic Field 0.5812 T
Bending Radius 17.218 m
Critical Energy 3.48 keV
Number of Dipoles 40 (B1) / 40 (B2) / 40 (BC_LF)
Hard-edge length of dipoles 0.8280 (B1) / 1.2310 (B2) / 0.4250 (BC_LF) m
Deflection angle 2.76 (B1) / 4.10 (B2) / 1.58 (BC_LF) °

High Field Dipoles

Parameters Value Unit
Magnetic peak field 3.2 T
Bending Radius at peak 3.127 m
Critical energy at peak 19.15 keV
Number of dipoles 20 (BC_HF)
Deflection angle 1.14 °