Fermilab electron cooling project: field measurements in the cooling section solenoid

Abstract

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 compassbased 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.

Accelerator Physics at the Tevatron Collider

“…Because the cooling section has good magnetic shielding, external magnetic fields are decreased by a factor of >1,000 inside [83] and do not create any measurable perturbations. On the other hand, dipole magnetic fields created by imperfections in the cooling section magnetic field are significant and typically the main component of the total angle.…”

“…83 Evolution of δp (blue line) and of the transverse emittances (95 %, normalized) during a cooling rate measurement. The brown line indicates when the electron beam was turned on and set to 100 mA.…”