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Muon Front End for PRISM. J. Pasternak, Imperial College London/RAL STFC. Outline. Introduction General principle Layout Betatron functions Summary. Introduction. Injection/extraction for FFAG is challenging because of: - compact cell structure ( for Pamela, IDS-FFAG, PRISM),
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Muon Front End for PRISM J. Pasternak, Imperial College London/RAL STFC J. Pasternak
Outline • Introduction • General principle • Layout • Betatron functions • Summary
Introduction • Injection/extraction for FFAG is challenging because of: - compact cell structure ( for Pamela, IDS-FFAG, PRISM), - large emittance (for IDS-FFAG, PRISM), - large momentum range (PAMELA for extraction, but one at a time, for PRISM all momenta), - large magnetic rigidity (PAMELA -carbon, IDS-FFAG), - large repetition rate (PAMELA, PRISM). • The core of the challenge is the need to match the beam with a very large emittance into the injection conditions of the FFAG ring simultaneously for all momenta!
Pion/Muon Transport Negativevertical deflection corrector Vertical dispersionsuppressor Vertical Septum Vertical dispersion matching Quad matching Kickers Bend solenoidal channel in „Pi/2–Pi/2” configuration (to compensate the drift) DispersionCreator (Orbit matching) Solenoidal matching cell FFAG line for betatron matching (J-B. Lagrange) The goal - 70% muon transport efficiency! This design is under studies within the PRISM Task Force. J. Pasternak
Status of matching section • Optics in solenoidal matching section has been designed. • The preliminary quad channel setting was found. • Preliminary design for the dispersion creator based on 2 spectrometer magnets followed by the • π horizontal bend FFAG sections (2 cells)has been achieved, • The vertical dispersion creation and suppression is based on the “immediate method”. • Optics has been design (the mismatch at extreme momentum is ~1 cm – acceptable). • The design of betatron matching (including the FFAG section) was obtained. • The optics design will be followed by the tracking studies to evaluate the performance. • The final optimisation is the study on itself (could be based on the genetic algorithms). J. Pasternak
Optics and B field in solenoidalmuon transport and matching From the target to adiabatic matching B in T Matching point “+20%” “-20%” Solenoidal field Central momentum z[m] Target • Capture and decay channel will • use the solenoidal transport system. • The matching of the solenoidal • system with the FFAG is an • interesting, but challenging problem. Betatron function [m] z[m] J. Pasternak
Optics and B field in solenoidalmuon transport and matching (II) Matching point Solenoidal matching section B in T “-20%” z[m] Solenoidal field Central momentum “+20%” Betatron function [m] • Betatron functions needs to be • matched to AG channel (~ 1-4 m). • Solenoidal field needs to be • smoothly switched off. z[m] J. Pasternak
the vertical layout of the AG part of the front end • As the injection will be vertical, • the incoming beam and the circulating beam will be on two different levels. • Bending angle needs to be cancelled • and dispersion matched to zero in the • FFAG ring (for +- 20% momentum • deviation). • Mismatch of vertical orbits is of the • order of 1 cm at extreme momentum • (acceptable). Injection Septum Straight FFAG matching section Dispersion Creator Quad matching Achromatic Dispersion deflector Beam direction J. Pasternak
Horizontal Layout of the Muon Front End for PRISM • Ring and the solenoid are well • separated in space. • The main challenge is the room • around the injection septum PRISM FFAG Straight FFAG matching section FFAG ARC (Part of the Dispersion Creator) Solenoidal channel
Betatron Functions in the AG part of the Muon Front End for PRISM V H • Betatron functions are matched exactly between the solenoid and the FFAG (ON MOMENTUM). • The large horizontal beta is not yet fully satisfactory. It is due to a tricky matching conditions using • Straight FFAG sections. • The off-momentum behaviour will be addressed in the tracking studies.
Summary • Layout and optics of the muon front end for the PRISM • has been designed. • Still a lot of work is needed for the optimisation. • The muon transport efficiency will be established • in the tracking studies. • The dedicated tests of the modules (dispersion creator, • adiabatic matching etc.) could be realised at MuSICat RCNP • in Osaka.