# International Muon Ionization Cooling Experiment Edward McKigney Imperial College RAL March 25, 2002 Physics Motivation and Cooling Introduction.

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International Muon Ionization Cooling Experiment Edward McKigney Imperial College RAL March 25, 2002 Physics Motivation and Cooling Introduction

Physics Motivation Neutrino Factory Layout Feasibility Studies Overview of Muon Cooling Approaches to Cooling Cooling Experiment Issues Summary

Physics at a Neutrino Factory Complex I Long baseline - Neutrino oscillations: precision measurements of mixing parameters, matter effects, CP violation! Short baseline - High brilliance neutrino beams, nuclear effects, polarized structure functions, charm factory High intensity proton source - Unstable isotope beams and other synergies with nuclear physics High brilliance muon beams - Rare muon decays, muonic atoms,... R & D - First step towards a muon collider: s-channel Higgs and Susy Higgs production, high precision/resolution E cm for new particle studies

Physics at a Neutrino Factory Complex II Most fundamental particle physics discovery of the decade: Neutrinos have mass and mix! As in the quark sector, there are three mixing angles and a phase to measure, but the pattern of angles is very different, and the mass hierarchy needs to be resolved. CKM Matrix (almost diagonal)  12  12.8°  23  2.2°  13  0.4° MNS Matrix (LMA) (heavily mixed)  12  20-45°  23  35-45°  13 < 10° Natural Inverted

Physics at a Neutrino Factory Complex III L=baseline (km) E =energy (GeV) Gives best sensitivity to  13 of any technique: A neutrino factory gives the best precision for measuring all of the neutrino mixing parameters! A high energy e beam offers unique possibilities!

Physics at a Neutrino Factory Complex IV Comparing gives both sgn(  m 2 32 ) and CP phase:

Physics at a Neutrino Factory Complex V There is a rich program of non-oscillation physics at a Neutrino Factory Complex High rate neutrino DIS with both polarized and unpolarized targets Measurement of charm production and search for CP violation in the D 0 system (perhaps 1 million charm events per year in a small near detector) Measurement of D s branching ratios and more ideas being developed…

Neutrino Factory Layout There are several designs (CERN, US Study I and II, RAL) which all share common features. This is the only way to produce high energy intense e beams.

Neutrino Factory Layout at RAL Kamiokande You Are Here

US Neutrino Factory Feasibility Studies Two feasibility studies have been completed in the US, establishing: that a neutrino factory is technically feasible likely performance, cost, cost drivers and needed R&D Both studies include cooling

Need for Muon Cooling Need ~0.1  /p-on-target to reach Neutrino Factory flux goal  Must accept a large fraction of production phase space – therefore must cool the muon beam  In current studies, cooling  X ~10 in accelerated muon flux  Only ionization cooling is fast enough to cool muons before most decay  The Neutrino Factory cooling program is the first step toward beams cold enough to be used in a Muon Collider Ionization cooling has never been observed experimentally and studies show it is a delicate design and engineering problem Need an Ionization Cooling Experimental demonstration!

Ionization Cooling: Background RF dE/dx RF dE/dx RF dE/dx In principle ionization cooling should work, but in practice it is subtle and complicated Absorbers remove total momentum, RF restores longitudinal momentum Approximation of the cooling relation

Simplest Conceptual Scheme But, there is an important subtlety: One must alternate the direction of the focusing field in order to prevent a build-up of angular momentum

Tapered-SFOFO Cooling Lattice: (R. Palmer – BNL)

CERN Cooling Channel Design (A. Lombardi, CERN, Neutrino Factory Note NF-34)

Another Approach: Ring Cooler Simulations show cooling in both the transverse and longitudinal planes It is not known how to inject and extract the beam from this configuration A successful ring cooler design could give a Neutrino Factory higher performance at lower cost.

Tapered-SFOFO Cooling Performance

Cooling Experiment The aims of the muon ionization cooling experiment are : to show that it is possible to design, engineer and build a section of cooling channel capable of giving the desired performance for a Neutrino Factory to place it in a muon beam and measure its performance in a variety of modes of operation and beam conditions to validate the cooling simulations As stated in the 2001 review of Muon Collaboration activities by the U.S. Muon Technical Advisory Committee: The “cooling demonstration” is the key systems test for the Neutrino factory Much work over many years has established the components needed for muon cooling: SC solenoids, absorbers, RF cavities It is time to assemble a realistic cooling cell and carry out the test

Single Particle Emittance Measurement Multi-particle methods do not provide sufficient accuracy Single Particle methods rely on HEP style instrumentation Trajectory in solenoid and TOF measurement of single particles (x, y, z, x’, y’, z’, t) before and after cooling channel A collection of single particle events is used to reconstruct the beam phase space Emittance measurement comes from phase space Must understand trajectories and B-Fields very well (fringe fields!)

Emittance Measurement (P. Janot)

Emittance Measurement Quality of Measurements: Correctable bias from multiple scattering and measurement precision smaller than 1% Statistical precision in  /  better than 1% for 1000 muons From these results we expect an ultimate precision on  out/  in < 10 -3 Need particle ID for  /  separation ( TOF, upstream) and  /e separation (range or Cerenkov, downstream) with purity better than 1%

Important Detector Issues Detectors must operate in strong solenoidal fields & with intense RF-cavity backgrounds & contribute negligible emittance degradation Working out safe design and operating approaches is a crucial and challenging part of the MUCOOL R&D effort underway at Fermilab

Summary There is a strong case for doing Neutrino Physics Neutrino physics has been one of the most active areas of particle physics in the last decade and ties together HEP, Solar Physics, Astrophysics and Cosmology A Neutrino Factory offers unique opportunities for doing Neutrino Physics A Neutrino Factory yields the highest flux neutrino beams achievable, and the beam parameters are well controlled and understood A Neutrino Factory is the only way to produce beams of electron type neutrinos There is a diverse program of non-Neutrino physics to be done at a Neutrino Factory Complex A cooling experiment is the key milestone on the path to a Neutrino Factory and there is a strong international community determined to make it happen!

Double-Flip Cooling Channel

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