| MAX IV | |
| Type: | Synchrotron light source |
| Beam: | Electrons |
| Target: | Light source |
| Energy: | Large ring: 3.0 GeV,[1] Small ring: 1.5 GeV[2] |
| Current: | Large ring: 500 mA, normal current 400 mA,[3] Small ring: 500 mA |
| Length: | Linac: ~300 metres (1,000 ft)[4] |
| Radius: | Linac: 40mm, Storage rings: 15mm |
| Circumference: | Large ring: 528m (1,732feet), Small ring: 96m (315feet) |
| Location: | Brunnshög, Lund, Sweden |
| Coordinates: | 55.727°N 13.233°W |
| Institution: | Lund University |
| Dates: | 2016 - present[5] |
| Preceded: | MAX III |
MAX IV is the world's first 4th generation[6] [7] synchrotron light source facility in Lund, Sweden.[8] Its design[9] [10] and planning was carried out within the Swedish national laboratory, MAX-lab, which up until 2015 operated three storage rings for synchrotron radiation research: MAX I (550 MeV, opened 1986), MAX II (1.5 GeV, opened 1997) and MAX III (700 MeV, opened 2008). MAX-lab supported about 1000 users from over 30 countries annually. The facility operated 14 beamlines with a total of 19 independent experimental stations, supporting a wide range of experimental techniques such as macromolecular crystallography, electron spectroscopy, nanolithography and production of tagged photons for photo-nuclear experiments. The facility closed on 13 December (Saint Lucy's Day) 2015 in preparation for MAX IV.
On 27 April 2009 the Swedish Ministry of Education and Research, Swedish Research Council, Lund University, Region Skåne and Vinnova, a Swedish government funding agency, decided to fund the research center.[11]
The new laboratories, including two storage rings and a full-energy linac is situated in the northeastern quarter Brunnshög in Lund. The inauguration of MAX IV took place on the 21th of June, the day of summer solstice, 2016. The larger of the two storage rings has a circumference of 528 meters, operates at 3 GeV energy, and has been optimized for high-brightness x-rays. The smaller storage ring (circumference 96 meters) is operated at 1.5 GeV energy and has been optimized for UV.[12] There are also plans for a future expansion of the facility that would add a free-electron laser (FEL) to the facility, but is yet to be funded.
There are currently 16 beamlines at the facility with 10 of them located around the 3 GeV ring, 5 around the 1.5 GeV ring and one at the linac.[13]
MAX IV has two electron guns below ground level, one thermionic gun with a hot cathode, and one photogun with a photocathode, both with the RF-range frequency 3 GHz. The thermionic gun sends electrons via the linac into both storage rings[14] for a few seconds once every 10 minutes continuously in order to maintain the total amount of electrons in the storage rings at a constant level.[15] That is called a top-up injector. After half the linac, ~150 metres (500 ft), a diagonal transfer line sends about one quarter of the electrons up to ground level for the small storage ring. After the whole linac, a second diagonal transfer line sends the rest of the electrons up to ground level for the large storage ring. The photogun sends electrons the rest of the time via the linac to the short-pulse facility (SPF) at MAX IV.[16]
The small 1.5 GeV storage ring is called R1 and has a circumference of 96 metres (315 ft). It consists of 12 4.5 metres (15 ft) long rounded corners, called achromats, each followed by a 3.5 metres (~11 ft) long straight section. The achromats are double-bend achromats, meaning that they each contain two pairs of bending magnets.[17] The magnetic field is pointing downwards with a strength in the order of 1 T,[18] pulling the incoming electrons to the right and thus makes the electrons to go clockwise in the ring.[19]