FERMILAB ELECTRON COOLING PROJECT: FIELD MEASUREMENTS IN THE COOLING SECTION SOLENOID

To provide the maximum possible cooling rate for the Recycler Electron Cooling (REC) [1], the cooling section has to be immersed into a high-quality longitudinal magnetic field. Namely, the solenoidal field of 50- 150 G should have an integral of the transverse component below 1 G⋅cm over the whole 20-m cooling section [2]. The transverse field components are measured by a dedicated compass-based sensor [3], which has been designed and manufactured at Budker INP, Novosibirsk. The paper describes results of the field measurements performed on the cooling section solenoid prototypes as well as the design and the calibration procedure of the sensor. 1 SOLENOID DESIGN The cooling section solenoid proposed for the REC is made up from ten identical modules. Each module consists of the main solenoid, two solenoidal correctors on both ends, 10 pairs of dipole correctors, a cylindrical magnetic shield, and an instrumentation gap between neighbouring solenoids. Some parameters of a solenoid module are shown in Table 1. Two prototypes of the module had been manufactured and measured by a dedicated compass-based sensor [3]. The main goal of the measurements is to align mechanical position of solenoids and adjust currents of correctors to provide an integral of the transverse components below 1 G⋅cm over the module length. Table 1: The basic parameters of the cooling section solenoids. Solenoid length 192 c