Tapered channel for six-dimensional muon cooling towards micron-scale emittances

2015

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A muon collider requires a reduction of the six-dimensional emittance of the captured muon beam by several orders of magnitude. In this study, we describe a novel rectilinear cooling scheme that should meet this requirement. First, we present the conceptual design of our proposed scheme wherein we detail its basic features. Then, we establish the theoretical framework to predict and evaluate the performance of ionization cooling channels and discuss its application to our specific case. Finally, we present the first end-to-end simulation of 6D cooling for a muon collider and show a notable reduction of the 6D emittance by 5 orders of magnitude. We find good agreement between simulation and theory.

Section: A Cooling Before Bunch Recombinationmentioning

confidence: 99%

Rectilinear six-dimensional ionization cooling channel for a muon collider: A theoretical and numerical study

Stratakis

2015

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“…In a given lattice Q 6D starts of small due to losses from initial matching, then rises to a large value (Q 6D ¼ 10 is typical for the channels discussed here) and finally falls as the emittance of the beam approaches its equilibrium value. We found [23] that good cooling efficiency requires that the channel is tapered. In that case when Q 6D starts to fall off, the lattice is modified to reduce the beta function.…”

Section: Ionization Cooling Theorymentioning

confidence: 95%

Influence of space-charge fields on the cooling process of muon beams

Stratakis

Grote

2015

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Obtaining muon beams with high density in 6D phase space is essential for realization of muon colliders, neutrino factories based on accelerated muons beams and other experiments involving muons. While several schemes to compress the beam phase space by means of muon cooling have been proposed, very little is known about the impact of particle-particle interactions in the whole design. In this paper, we examine the influence of space-charge fields on the cooling process of muon beams. We show that the cooling efficiency decreases with the degree of intensity, leading to emittance growth and particle loss for beams with large intensities. We further show that the emittance growth is only longitudinal and present a space-charge compensation solution by means of increasing the rf gradient. With the aid of numerical simulations, we obtain a quantitative relationship between the required compensation gradient and bunch charge and compare our results to earlier theoretical findings.

“…Several 6D ionization cooling channel designs have been proposed [10][11][12][13]. Simultaneous transverse and longitudinal cooling is achieved by using wedge-shaped absorber materials or a differential path length in an absorber region with nonvanishing dispersion.…”

Section: Introductionmentioning

confidence: 99%

“…These 6D ionization cooling channels operate with muon beams of central momentum ≈220 MeV=c and cannot provide cooling beyond ϵ T ≈ 280 μm-rad and ϵ L ≈ 1.5 mm [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

High field – low energy muon ionization cooling channel

Sayed

Neuffer

2015

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Muon beams are generated with large transverse and longitudinal emittances. In order to achieve the low emittances required by a muon collider, within the short lifetime of the muons, ionization cooling is required. Cooling schemes have been developed to reduce the muon beam 6D emittances to ≈300 μm-rad in transverse and ≈1-1.5 mm in longitudinal dimensions. The transverse emittance has to be further reduced to ≈50-25 μm-rad with an upper limit on the longitudinal emittance of ≈76 mm in order to meet the high-energy muon collider luminosity requirements. Earlier studies of the transverse cooling of low energy muon beams in high field magnets showed a promising performance, but did not include transverse or longitudinal matching between the stages. In this study we present the first complete design of the high field-low energy ionization cooling channel with transverse and longitudinal matching. The channel design was based on strong focusing solenoids with fields of 25-30 T and low momentum muon beam starting at 135 MeV=c and gradually decreasing. The cooling channel design presented here is the first to reach ≈50 micron scale emittance beam. We present the channel's optimized design parameters including the focusing solenoid fields, absorber parameters and the transverse and longitudinal matching.