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Machine Information

STORAGE-RING PARAMETERS: General technical information, horizontal and vertical lattice functions, and arc lattice functions (normal and superbends).

PHOTON-SOURCE PARAMETERS: Brightness curves for bend magnets, superbends, and insertion devices. Insertion-device information includes energy ranges, number of periods, period length and operating-gap ranges for ALS undulators and wigglers.

Storage-Ring Parameters

 

General Parameters

Parameter Value
Beam particle electron
Beam energy 1.9 GeV
Injection energy 1.9 GeV
Beam current (all operation is in top-off with ΔI/I ≤ 0.3%) 500 mA in multibunch mode
Filling pattern 256–320 bunches; possibility of one 5- to 6-mA “camshaft” bunch in the filling gap
Bunch spacing: multibunch mode 2 ns
Circumference 196.8 m
Number of straight sections 12
Number of insertion devices 12
Radio frequency 499.642 MHz (±6 kHz)
Beam size in straight sections, rms (1.9 GeV multibunch mode) 251 µm x 8 µm (horizontal x vertical)
Top-off injection rate 0.5–1.0 mA/shot every 13–40 seconds
 Horizontal emittance  2.0 nm·rad
 Vertical emittance  0.04 nm·rad
 Energy spread (ΔE/E, rms)  0.95 x 10-3
 Pulse Length (FWHM)  60 ps*
*The bunch length is deliberately increased using harmonic cavities to improve the beam lifetime.

 

arc_sector
The ALS has 12 straight sections and 12 arc-shaped sections, like the one shown above, containing bend magnets (B) with a defocusing gradient, quadrupoles (QFA, QDA, QF, and QD), and sextupoles (SF, SD,SHF, and SHD). Three of the arc sections contain superconducting bend magnets (superbends) and therefore have a modified lattice as shown in the lower image.

 

Horizontal and Vertical Lattice Functions (α, β, γ), Horizontal Dispersion Functions (ηx and ηx′),
and 1-σ Beam Sizes (σ) and Divergences (σ′) at Photon Source Points*

BEAM
PORT		 ANGLE** [DEGREES] DEVICE AXIS α
 β
[m]		 γ
[m-1]		 ηx
[m]		 ηx′ σ [µm] σ′ [µrad]
BL x.0 0.0 Insertion device x 0.000 21.27 0.047  0.15  0.000  251  9.7
BL x.0 0.0 Insertion device y 0.000 1.72 0.581 8.3 4.8
BL x.0.1 0.0 Upstream insertion device x 0.061 21.34 0.047 0.15 0.000 251 9.7
BL x.0.1 0.0 Upstream insertion device y 0.756 2.7 0.581 10.4 4.8
BL x.0.2 0.0 Downstream insertion device x -0.06 21.35 0.047 0.15 0.000 251 9.7
BL x.0.2 0.0 Downstream insertion device y -0.76 2.7 0.581 10.4 4.8
BL x.1 6.3 Bending magnet x -0.34 0.23 0.047 0.026 0.043 32.7 106.4
BL x.1 6.3 Bending magnet y 9.177 26.55 3.209 32.6 11.3
BL x.2 12.6 Bending magnet x 0.685 0.48 3.085 0.027 -0.05 40.3 89.7
BL x.2 12.6 Bending magnet y -0.05 1.28 0.786 7.1 5.6
SB BL x.2 12.6 Superbend magnet x 0.226 0.28 3.811 0.012 -0.04 26.2 95.8
SB BL x.2 12.6 Superbend magnet y 0.027 2.28 0.439 9.5 4.2
BL x.3 17.4 Bending magnet x -0.69 0.48 3.085 0.027 0.046 40.3 89.7
BL x.3 17.4 Bending magnet y 0.045 1.28 0.786 7.1 5.6
SB BL x.3 17.4 Superbend magnet x -0.23 0.28 3.811 0.012 0.042 26.2 95.8
SB BL x.3 17.4 Superbend magnet y -0.03 2.28 0.439 9.5 4.2
BL x.4 22.6 Bending Magnet x 0.827 0.34 4.923 0.031 -0.06 39.4 116.2
BL x.4 22.6 Bending Magnet y -10.7 24.26 4.685 31.4 13.7
angles*These are generic lattice functions. There are small sector-to-sector variations in the parameters for a given source angle because of the distortion in the lattice functions of the superbends and the insertion devices. For more precise information, contact Christoph Steier.
**Angle refers to the direction of the radiation from the source point, as shown at right.

 

Normal-Arc Lattice-Function Plot2013_arc_lattice

Superbend-Arc Lattice Function Plot2013_superbend_lattice

Photon-Source Parameters

 

Summary Graph of Brightness Curves for All Insertion Devices2013_als_brightess

Insertion-Device and Bend-Magnet Parameters

The ALS has six elliptically polarizing undulators, two in straight 4, two in straight 11, and one each in straights 6 and 7. All are arranged with chicanes so that two such devices can be installed to feed two independent beamlines. They can be used in a variety of polarization modes, including circular, elliptical, horizontal, and vertical. These modes can be chosen by appropriate phasing of the magnet rows. The brightness and flux curves below are shown for horizontal and circular polarization. Curves for elliptical and vertical polarization are similar to the horizontal polarization curve, but the minimum photon energy is higher.

Note: Brightness and flux were calculated at a machine energy of 1.9 GeV, 500 mA current, vertical emittance of 40 x 10-12m·rad, horizontal emittance of 2.0 x 10-9 m·rad, and lattice parameters as listed in the Storage Ring Parameters.

 

Insertion-Device Parameters

DEVICE BEAMLINE ENERGY RANGE
(AT 1.9 GeV)		 PERIOD
LENGTH		 NO. OF
PERIODS		 OPERATING GAP
RANGE		 EFFECTIVE FIELD
RANGE
U30 Undulator 6.0.1 120–5000 eV
4000–11000 eVd		 30 mm 50 5.5–2.7 mm 1.5–0.13 T
U50 Undulator 8.0.1 80–3000 eV 50 mm 89 14–45 mm 0.85–0.10 T
U80 Undulator 12.0.1  20–1900 eV 80 mm 55 24.7–83 mm 0.80–0.07 T
U100 Undulator 9.0.1 8–1500 eV 100 mm 43 22.7–116 mm 0.98–0.05 T
U100 Undulator 10.0.1 12–1500 eV 100 mm 43 23.1–116 mm 0.80–0.05 T
EPU35 Elliptical Polarization Undulator 6.0.2

265–4000 eVa

 35 mm 52.5 12–40 mm 0.71–0.06 T
EPU50 Elliptical Polarization Undulator 4.0.2 73–3000 eVa 50 mm 37 14–55 mm 0.80–0.10 Tb
0.58–0.10 Tc
EPU50 Elliptical Polarization Undulator 11.0.1 75–3000 eVa 50 mm 36.5 14.3–55 mm 0.85–0.10 Tb
0.57–0.10 Tc
EPU50 Elliptical Polarization Undulator 11.0.2 71–3000 eVa 50 mm 37 13.8–55 mm 0.86–0.10 Tb
0.58–0.01 Tc
EPU70 Elliptical Polarization Undulator 7.0.2 16–2000 eVa 70 mm 26.5 12.5–75 mm 1.18–0.07 T
W114 Wiggler 5.0.1
5.0.2
5.0.3		  6–21,000 eVd 114 mm 29 12.5–180 mm 1.94–0.03 T
QEPU90  4.0.3  8–1600 eVa 90 mm 20.5 14.5–99 mm  1.18–0.06 Tb
0.78–0.06 Tc
a Elliptical polarization mode.         b Vertical field.         c Horizontal field.         d Wiggler mode.