First demonstration of ionization cooling by the Muon Ionization Cooling Experiment


Published in:
RAL Preprint: RAL-P-2019-003


High-brightness muon beams of energy comparable to those produced by state-of-the-art electron, proton and ion accelerators have yet to be realised. Such beams have the potential to carry the search for new phenomena in lepton-antilepton collisions to extremely high energy and also to provide uniquely well-characterised neutrino beams. A muon beam may be created through the decay of pions producedin the interaction of a proton beam with a target. To produce a high-brightness beam from such a source requires that the phase space volume occupied by the muons be reduced (cooled). Ionization cooling is the novel technique by which it is proposed to cool the beam. The Muon Ionization Cooling Experiment collaboration has constructed a section of an ionization cooling cell and used it to provide the first demonstration of ionization cooling. We present these ground-breaking measurements.


MICE note: Note xxx
Citation: BibTeX
References: inSPIRE


Figure 1a (top panel) 1b (bottom panel). The MICE apparatus along with the calculated magnetic field, Bz [T], and nominal horizontal width of the beam, sigma(x) [mm]. The modelled field is shown on the beam axis and 160 mm from the axis in the horizontal plane. The readings of Hall probes, situated 160 mm from the beam axis, are also shown. Dashed lines indicate the position of the tracker stations and absorber. The nominal RMS beam width is calculated assuming a nominal input beam using linear beam transport equations. Acronyms used in the schematic are described in the text. (1a: PDF, jpg ; 1b: PDF, jpg)

Figure 2. Distribution of the beam in phase space for the 6-140 Full LH2 setting: (above the diagonal) measured in the upstream tracker and (below the diagonal) measured in the downstream tracker. Measured particles’ positions are shown, coloured according to the amplitude of the particle. (PNG, jpg)

Figure 3. The distributions of measured muon amplitudes. The upstream distributions are shown by orange circles while the downstream distributions are shown by green triangles. Both upstream and downstream distributions are normalised to the bin in the upstream distribution with the most entries (see text). Coloured bands show the uncertainty, which is dominated by systematic uncertainties. Vertical lines indicate the approximate channel acceptance above which scraping occurs. (PDF, jpg)

Figure 4. Downstream to upstream ratio of number of events. A ratio greater than unity in the beam core is evidence for ionization cooling and is evident for 6-140 and 10-140 beams with both the full LH2 absorber and the LiH absorber. The effect predicted from simulation is shown in red, while that measured is shown in black. Uncertainty is shown by a blue fill for data and a pink fill for simulation and is dominated by systematic uncertainty. Vertical lines indicate the channel acceptance above which scraping occurs. (PDF, jpg)

Figure 5. The upstream and downstream normalised beam density quantiles, indicated by orange and green lines respectively, as a function of the fraction of the upstream sample. For each configuration, the density is normalised to the highest density region in the upstream sample. Uncertainty is indicated by the thickness of the coloured bands and is dominated by systematic uncertainty. (PDF, jpg)

Methods, figure 1. Distribution of amplitudes with corrected and uncorrected distribution shown for the 10-140 LH2 full configuration. The uncorrected data is shown by open points while the corrected data is shown by filled points. The upstream distribution is shown by orange circles while the downstream distribution is shown by green triangles. Systematic uncertainty is shown by coloured bands. Statistical error is shown by bars and is just visible for a few points. (PDF, jpg)

Updated by Long, Kenneth almost 3 years ago · 14 revisions