500 mA news : last update July 19, 2005

SPEAR3 2004 Closeout Report

SPEAR3 Commissioning Update

First SPEAR3 Beam into SSRL Beam Line Hutch

A major milestone for the SPEAR3 commissioning occurred at 17:56 on Monday, March 8, 2004, when the first SPEAR3 synchrotron light was observed on a monitor located inside BL9-3's monochromator housing
(Fig. 1). This was followed by threading the beam through the focusing optics to deliver beam inside the experimental hutch enclosure some 20 mins later. The in-hutch picture of the beam (Fig. 2) shows banding, which is consistent with the effect of the separated pole pairs in the wiggler viewed at the 5-mrad off-axis observation angle of BL9-3. This effect could not be seen with the old SPEAR2 ring as its source size was so big that the radiation from each pole pair could not be resolved. Thus even in this first photo the effect of the reduced source size on SPEAR3 is immediately seen.

Fig. 2

Fig. 1

A video which chronicles the installation activities is available at:

SPEAR3 Overview

Text Box: Table 2.  Relative increase in photon flux and brightness for 

SSRL entered a new era of synchrotron radiation experimentation with the completion of the SPEAR 3 upgrade project in 2008.  The SPEAR 3 storage ring, with parameters summarized in Table 1, produces beams having one to two orders of magnitude higher brightness and flux density than the old SPEAR 2 ring (Table 2), accommodates several new high performance insertion devices and beam lines, and is capable of top-off operation by virtue of its improved at-energy injection system. Brightness for new undulators exceeds 1018 at 5 keV. The 4-year, 58 M$ upgrade project is administered by the DOE, with ~50% joint funding from NIH.

The project completely replaced the SPEAR vacuum chamber, magnets, support rafts, RF, power supplies, cable plant and shielding tunnel floor in a 7-month shutdown period that began March 31, 2003. Text Box: Table 1.  Parameters for SPEAR 2 and SPEAR 3.0 480 tons of SPEAR 2 magnet girders, vacuum chambers, power supplies, and most cables and controls were removed from the SPEAR site.  Shielding, utilities and other ancillary systems were modified, a new cable plant was installed in trays outside the tunnel, new power supplies were installed in a refurbished building, a new concrete floor was poured and mounting plates for SPEAR 3 magnet and vacuum chamber support girders were installed and aligned. Pre-assembled girders were installed in the second week of August, followed by straight section vacuum chamber, mode-damped RF cavity, insertion device and beam line front end component installation in September and early October.  The vacuum system was pumped down, cable and utility connections completed, and the ring aligned in October.  System testing took place in November and beam commissioning is now in progress. Beam was returned to users in March of 2004.

SPEAR3 will operate at 100 mA until all beam line optical components are upgraded, radiation shielding is added, and approved is received for higher current operation. The accelerator physics and engineering groups will fully utilize AP time characterize and optimize ring lattice and beam parameters, develop the fast orbit feedback system (having a 4 kHz orbit acquisition rate), and to ascertain beam stability issues that might be encountered at higher currents.


SPEAR3 2004 Closeout Report



SPEAR 3 Design Report (CDR)


last updated: APR 05, 2005 15:35 a.mueller