Transcript The Normal Conducting RF Cavity for + MICE # Summers D. Li, A. DeMello, S.

The Normal Conducting RF Cavity for
+
MICE
#
Summers
D. Li, A. DeMello, S. Virostek, M. Zisman; D.
Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A
#University of Mississippi, Oxford, MS 38677, U.S.A.
Abstract
The international Muon Ionization Cooling Experiment (MICE) is a demonstration experiment of muon ionization cooling. MICE cooling
channel requires normal conducting and low frequency RF cavities to compensate for muon beams’ longitudinal energy lost in the MICE
cooling channel. The MICE cooling channel has eight 201-MHz normal conducting RF cavities with the conventional beam irises terminate
by large and thin beryllium windows. The cavity design is based on a successful prototype cavity for the US MuCool program. The first
five MICE RF cavities are complete. Low power measurements of the first five cavities have been conducted. The measurements agree
well with theoretical predictions.
42-cm
RF Cavity and Coupling
Coil (RFCC) Module
International MICE
Spectrometer
Solenoid 1
Liquid Hydrogen Absorber and Focusing
Coil (AFC) Module
Spectrometer
Solenoid 2
Layout of the International Muon Ionization Cooling Experiment at Rutherford Appleton Laboratory, UK
measure ~ 10% of transverse emittance reduction of muon beams
The RFCC Module
Curved thin
Be window
Cavity design parameters
SC coupling Coil
Frequency: 201.25 MHz
2
Shunt impedance (VT /P): ~ 22 MΩ/m
Quality factor (Q0): ~ 53,500
Be window diameter and thickness:
42-cm and 0.38-mm
Peak RF power dissipation:
4.6 MW for ~ 16+ MV/m
Eight 201-MHz cavities for the MICE
cooling channel, two pairs of 4-cavity in
each RFCC module, cavity gradient will be
operated at 8 MV/m, limited by available
RF power.
Cavity fabrication
Four 201-MHz NC cavities
+ This
• Spinning of half cavity shells using
6-mm copper sheets
• E-beam welding to join the cavity
• Port extruding
• Brazing of water cooling lines
• Cleaning and electro-polishing (EP)
work was supported by the Office of Science, U.S. Department
of Energy (DOE) under DOE Contract No. DE-AC02-05CH11231
Cavity measurements
The first five cavities (one spare) have been
measured, the cavity body frequency
(equivalent to cavity with flat windows on
irises) variations are within ±400 kHz as
predicted (based on fabrication techniques
and theoretical studies). The measured
frequencies are:
Cavity #1
Cavity #2
Cavity #3
Cavity #4
Cavity #5
Frequency (MHz)
201.084
Q
44,400
201.247
200.740
201.707
44,600
44,600
44,200
Summary
MICE RF cavity fabrication has been
progressing well, next five cavities will be
ready soon. Preliminary cavity
measurements agree well with designs.
Other auxiliary cavity components are
either in final design phase or production.