Frictional Cooling. Columbia University & the Max-Planck-Institute. R. Galea, A. Caldwell, S.Schlenstedt, H. Abramowicz. What is Frictional Cooling (FC)? Simulation of the frontend of a Muon Collider based on FC Targetry & Capture Magnet Drift Region Phase Rotation Cooling section
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Frictional Cooling
Columbia University & the Max-Planck-Institute
R. Galea, A. Caldwell, S.Schlenstedt, H. Abramowicz
2004 Workshop on Muon Collider Simulation
What is Frictional Cooling?
Nuclear scattering, atomic excitation, charge exchange…
muon too slow to ionize
1/2 from ionization
At high energy end change is only logarithmic whereas it is roughly proportional to speed at low energies
Bring muons into a kinetic energy range where the dT/ds increases with kinetic energy (T)
A constant accelerating force (an Electric field (E)) can be applied to the muons resulting in an equilibrium kinetic energy
Same as freefall and reaching terminal velocity
Gravity opposing friction
A strong solenoidal field (B) is needed to guide the muons until they are cooled, so apply EB to get below the dT/ds peak
Oscillations around equilibrium limits final emittance
s(Mm) dominates over e-strippingin all gases except He
s small above electron binding energy, but not known. Keep T as high as possible
Simulation of Muon Collider based on FC:
Full MARS target simulation, optimized for low energy muon yield: 2 GeV protons on Cu with proton beam transverse to solenoids (capture low energy pion cloud).
GeV
0.4m
28m
p’s in red
m’s in green
GEANT3.21 simulation
View into beam
Phase Rotation:
Emax=5MV/m
t1=100ns t2=439ns
Simulation of the cooling cell:
Simulation of the cooling cell:
E
Muonium Formation
Simulate the effect of muonium formation in the tracking, an effective charge as given by sI/(sF+sI) was used
For m- the capture cross sections were parameterized and included in the simulation
Although earlier studies showed promising results for m- this scheme has not been fully investigated for this flavor.
using calculations of Cohen (Phys. Rev. A. Vol 62 022512-1)
Out of the Cooling Cell:
At z=11m
Beam Characterization
Muon Acceleration:
RMS 1ms to 3ns
RMS 1.2MeV/c to 5MeV/c
Results:
1.7x10-10 (pm)3
Nevis Experiment already reported at NuFact03
R.Galea, A.Caldwell, L.Newburgh, Nucl.Instrum.Meth.A524, 27-38 (2004)
arXiv: physics/0311059
RAdiological Research Accelerator Facility
Results of RARAF experiment
Experiment showed that MC could reproduce data under various conditions. Simulations of Frictional Cooling is promising.
Exp. Confirmation still desired.
Low acceptance but thicker windows was the culprit
Frictional Cooling Demonstration at MPI Munich
Cryostat housing 5T solenoid.
Status of Experiment
FWHM=250eV
Frictional Cooling is an exciting potential alternative for the phase space reduction of muon beams intended for a Muon Collider