Analysis of Multiple Coulomb Scattering of muons in the MICE liquid H 2 absorber Selection criteria ➢ There is a single reconstructed track in the upstream tracker that ● is of sufcient quality (χ 2 /NDF < 4) ● has passed clear from the difuser structure ● <90mm projected distance from experimental axis at the point of the difuser ● is expected to be reconstructed in the DS tracker ● <100mm projected distance from the experimental axis at the DS tracker ➢ Velocity selection through the Time Of Flight (TOF) trackers ● This also ensures sufcient muon beam purity References [1] - MICE Collaboration, “Demonstration of cooling by the Muon Ionization Cooling Experiment”, Nature}, vol. 578, pp. 53–59, 2020. doi:10.1038/s41586-020-1958-9 [2] - S. Agostinelli et al., “Geant4—a simulation toolkit”, Nucl. Instrum. Methods Phys. Res. A, vol. 506, no. 3, pp. 250–303, 2003. doi:10.1016/S0168-9002(03)01368-8 [3] - H. A. Bethe, “Molière’s theory of multiple scattering”, Phys. Rev. E, vol. 89, pp. 1256–1266, 1953. doi:10.1103/PhysRev.89.1256 The muon is 207 times more massive than the electron, reduced bremsstrahlung losses makes it an attractive candidate for two future particle physics experiments: ● Neutrino factory ● Muon Collider The primary challenge is the muons short life- time (2.2 µs at rest) and the relatively long cooling periods required by the current techniques to obtain high-brightness beams. MICE – The Muon Ionization Cooling Experiment Has experimentally demonstrated Ionization Cooling (IC) [1] ; a novel, fast cooling method. The cooling rate is expressed as: Gavriil Chatzitheodoridis, University of Strathclyde, Department of Physics, Glasgow, UK. gavriil.t.chatzitheodoridis@strath.ac.uk The method exploits the frictional forces on a muon beam when passing through a low-Z material. ● The cooling term describes transverse emittance reduction due to ionizing collisions, and the ● heating term emittance increase due to Multiple Coulomb Scattering (MCS). Evaluating accuracy of MCS models are key in enabling design of IC cooling channels. Method Straight particle tracks for 3 momenta settings (~170, 200 & 240MeV/c) are analysed upstream (US) and downstream (DS) of the absorber vessel using the scintillating fbre trackers in two confgurations: ● With the vessel empty and ● full of liquid hydrogen, providing 33cm through the material The empty and full confguration data-sets are subject to identical selection criteria that aim at reducing systematic uncertainties and providing an unbiased sample to measure MCS. Results & Future work The scattering distributions are expressed as the angles between the upstream and downstream momentum vectors when projected into two orthogonal planes: Early results for the two absorber confgurations and the three beam momenta are illustrated in Figure [2]. The decrease in width can be observed as the beam momenta increases, whilst the width increases at all settings when liquid Hydrogen is added in the beam path. The future aim of the analysis is to compare these distributions with predictive models such as GEANT4 [2] simulations and Moliere’s [3] mathematical model by convoluting the empty confguration with the model, and comparing with the experimental full distribution. Acknowledgements The work described here was made possible by grants from the Department of Energy and National Science Foundation (USA), the Istituto Nazionale di Fisica Nucleare (Italy), the Science and Technology Facilities Council (UK), the European Community under the European Commission Framework Programme 7, the Japan Society for the Promotion of Science and the Swiss National Science Foundation, in the framework of the SCOPES programme. We gratefully acknowledge all sources of support. We acknowledge the use of Grid computing resources deployed and operated by GridPP in the UK. We are also grateful to the staf of ISIS for the reliable operation of ISIS. Introduction [Figure 2] Distribution of θ y (left) and θ x (right) for the three momenta settings. For vessel full of liquid H 2 (top) and empty (bottom) confgurations. These are pending systematic error corrections associated to remnant beam misalignments and residual magnetic felds in the channel. [Figure 1] The MICE cooling channel confguration comprising of the LH 2 absorber vessel situated between two scintillating fbre trackers (Sci-Fi), 3 TOF detectors, the difuser, 2 Cherenkov (Ckov) detectors, Kloe light calorimeter (KL) and and the Electron Muon Ranger (EMR). TOF0 TOF1 US Sci-Fi tracker DS Sci-Fi tracker LH 2 TOF2 EMR Difuser Ckov A,B KL