Patent Number: 047572094
Section: claims

1. A neutron chopper comprising: a chopper rotor,  bearings at each end of the chopper rotor supporting the rotor for rotation about an axis transverse to the neutron beam to be chopped, and  a motor for driving the chopper rotor, the motor including:  a hollow cylindrical steel rotor coaxially arranged with respect to the chopper rotor, the motor rotor surrounding the bearing at one end of the chopper rotor but the motor rotor being radially spaced from the bearing which it surrounds, so that the motor rotor is not directly supported by said bearing, and  a ring of non-magnetic material fixed to, and coaxial with, said one end of the chopper rotor, the motor rotor being fixed to the ring, whereby the ring serves to interconnect the chopper and motor rotors. 2. A neutron chopper as defined in claim 1 wherein one end of the motor rotor is fixed to the ring, the other end of the motor rotor being free of attachment to any other part of the neutron chopper. 3. A neutron chopper as defined in claim 1 including a stator concentrically surrounding the motor rotor. 4. A neutron chopper as defined in claim 3 wherein the stator is embedded in an electrically insulating material which is resistant to neutron radiation. 5. A neutron chopper as defined in claim 1 wherein the motor rotor is press fit on to the ring. 6. A neutron chopper as defined in claim 1 wherein the motor is a hysteresis type motor.