Magnet vacuum vessel w/radiation shield and cold mass in place

Magnet leads (left) and the three cryocoolers on the top of the spectrometer solenoid service tower

Initial cool down of the completed spectrometer solenoid

Spectrometer solenoid cold mass coil ass’y

Leak check of the magnet cold mass assembly

PROGRESS ON THE FABRICATION AND TESTING OF THE MICE SPECTROMETER SOLENOIDS*

PROGRESS ON THE FABRICATION AND TESTING OF THE MICE SPECTROMETER SOLENOIDS*

* This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231.

S.P. Virostek, M. A. Green,

D. Li and M.S. Zisman

Lawrence Berkeley National Lab

Berkeley, CA 94720, USA

Abstract: The Muon Ionization Cooling Experiment (MICE) is an international collaboration that will demonstrate ionization cooling in a section of a realistic cooling channel

using a muon beam at Rutherford Appleton Laboratory (RAL) in the UK. At each end of the cooling channel a spectrometer solenoid magnet consisting of five superconducting

coils will provide a 4 tesla uniform field region. The scintillating fiber tracker within the magnet bore tubes will measure the emittance of the muon beam as it enters and exits

the cooling channel. The 400 mm diameter warm bore, 3 meter long magnets incorporate a cold mass consisting of two coil sections wound on a single aluminum mandrel: a

three-coil spectrometer magnet and a two-coil section that matches the solenoid uniform field into the MICE cooling channel. The fabrication of the first of two spectrometer

solenoids has been completed, and preliminary testing of the magnet is nearly complete. The key design features of the spectrometer solenoid magnets are presented along with

a summary of the progress on the training and testing of the first magnet.

B E R K E L E Y L A B

Paper ID 3192

Magnet cold mass and cryostat showing position of leads, cryocoolers helium pipes and supports

• Radiation shield is direct cooled by a separate LN reservoir

MICE consists of two spectrometer solenoid systems (the subject of this poster) and the MICE cooling channel which is made up of three absorber & focus-coil modules (AFC modules) and two RF & coupling-coil modules (RFCC modules). Muon ionization cooling occurs in liquid hydrogen absorbers located within the AFC modules. The muons are reaccelerated by four RF cavities contained in each of the two RFCC modules. The spectrometer solenoid modules couple the muon beam to the adjacent AFC modules and are used to measure the incoming and outgoing emittance of the muons. The tracker detectors within the solenoid bores are five planes of scintillating fibers that measure the position of the particles within the magnet bore.

INTRODUCTION

• Final vacuum leak check of the spectrometer solenoid cold mass assembly prior to installation into the magnet vacuum vessel

• Cold mass cooled indirectly with cryocoolers (LHe recondenser)

• Cooler condensers located in sleeves welded to top of cryostat

The tracker solenoid magnet consists of five superconducting coils wound on a common mandrel. All five of the coils are designed for a nominal current of 275 amps. During training of the magnet, all five coils are run in series using a single power supply. During training of the first magnet, all coils reached a current of 196 amps. However, a problem with the cold mass cooling circuit prevented the training from proceeding further. A series of design improvements were incorporated during assembly of the second magnet. The training of the second magnet is currently under way… Additional text TBD

MAGNET TRAINING & TESTING