Annual reports

Key points

The ILL Annual Reports from 1970 to 1990 only mention cryomagnets relatively late on, no doubt because the low temperatures/sample environment group was not directly in charge of the previous coils. The text in blue is additional commentary to the annual report information.

A first (5 Tesla) cryomagnet is purchased and a 10 Tesla cryomagnet is ordered for D7. A technician (Peter Suttling) is assigned to this equipment on a full-time basis.

Delivery problems with the 10 Tesla cryomagnet for D7: The manufacturer (THOR UK) is already two years behind schedule and is still experiencing difficulties. Another 10 Tesla cryomagnet is therefore ordered from another company (IGC USA  [1]).

10 Tesla cryomagnet for D7: the cryomagnet manufactured by the company IGC is delivered and tested.
6 Tesla cryomagnet for the 3-axis spectrometers: has also met with problems during manufacture.
5 Tesla horizontal field magnet for D2: after being tested and then sent back to Oxford Instruments for modifications and repair, it is now operational.
10 Tesla cryomagnet from THOR Cryogenics Ltd (UK): This was rejected during acceptance tests at the ILL. THOR suggests transforming it into a 7 Tesla system. As the ILL instruments were not non-magnetic at the time, it was necessary to try to counterbalance the very large forces (4x104 N) produced by the leakage field.
It is proving impossible for a single technician to take charge of all these cyromagnets.

7 Tesla cryomagnet from THOR (previously 10 Tesla): repaired and in operation.
6 Tesla cryomagnet for the 3-axis instruments: still not delivered due to severe "training" problems (the coils are "trained" in the factory to withstand high magnetic fields).
D3 magnet: the cryostat is experiencing problems in the vicinity of the cold valve.

7.4 Tesla cyromagnet from THOR: due to the presence of ferromagnetic parts on the instruments, the cold centring system has had to be rebuilt so that it can withstand forces up to 300 daN.
6 Tesla cryomagnet from Oxford Instruments: still not delivered.

ILL now has 5 cryomagnets.
6 Tesla cyromagnet from Oxford Instruments: has finally been delivered but does not exceed 4.35 Tesla.
7.4 Tesla cyromagnet from THOR: implosion!

6 Tesla cryomagnet for the 3-axis instruments: coils replaced by Oxford Instruments. After a 6-year wait, it finally reaches the 6 Tesla everyone has been hoping for!

1987 to 1990
The cryomagnets work well despite a few problems with cryogenics. They are not even mentioned in the 1989 and 1990 reports. So it has taken almost 10 years for both the manufacturers and ILL to master this technology.
In 2015, ILL is equipped with cryomagnets which can generate up to 15 Tesla (vertical field) and 17 Tesla (horizontal field). On the initiative of Louis-Pierre Regnault, an entirely different technology, known as pulsed fields, now makes it possible to achieve 40 Tesla for neutron experiments.


  1. IGC Polycold Systems Inc. of Petaluma, Calif. Bought up in 2005 by Helix Technology Corp. of Mansfield, Mass. which has now closed down.