Lattice Design for PRISM-FFAG A. Sato Osaka University for the - - PowerPoint PPT Presentation

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Sep 11, 2022 582 likes •765 views

Lattice Design for PRISM-FFAG A. Sato Osaka University for the PRISM working group contents PRISM overview PRISM-FFAG dynamics study & its method PRISM Phase Rotated Intense Slow Muon source Anticipated PRISM beam design

SLIDE 1

Lattice Design for PRISM-FFAG

A. Sato

Osaka University for the PRISM working group

SLIDE 2

PRISM overview
PRISM-FFAG dynamics study
& its method

SLIDE 3

PRISM

Phase Rotated Intense Slow Muon source

muon intensity 1011-1012μ/sec kinetic energy 20MeV energy spread +-(0.5-1.0)MeV beam repetition 100-1000Hz pion contamination < 10^-18

Anticipated PRISM beam design characteristics

high intensity muon beam narrow energy-spread high purity dedicated for the stopped muon experiments LFV : mu-e conversion sensitivity of 10-18

SLIDE 4

PRISM Layout

Pion capture section

The highest beam intensity in the world could be achieved by large-solid angle capture of pions at their production.

Decay section

π − μ decay section consisting of a 10-m long superconducting solenoid magnet.

Phase rotator

to make the beam energy spread narrower. To achieve phase rotation, a fixed-field alternating gradient synchrotron (FFAG) is considered to be used.

FFAG advantages:

synchrotron oscillation

need to do phase rotation

large momentum acceptance

necessary to accept large momentum distribution at the beginning to do phase rotation

large transverse acceptance

muon beam is broad in space

SLIDE 5

Phase rotation simulation

1 2 3 4 5 1 2 3 4 5

 RF : 5MHz, 128kV/m

ΔE/E = 20MeV+12%-10%

 RF : 5MHz, 250kV/m

ΔE/E = 20MeV+4%-5%

SLIDE 6

Construction of the PRISM-FFAG

Among the all PRISM components, the phase rotator section can be constructed from japanese fiscal year (JFY) of 2003 for five years. FY2003 Lattice design, Magnet design RF R&D FY2004 RFx1gap construction & test Magnetx1 construction & field meas. FY2005 RF tuning Magnetx9 construction FFAG-ring construction FY2006 Commissioning Phase rotation FY2007 Muon acceleration (Ionization cooling)

RF PS RF AMP RF Cavity FFAG-Magnet Kicker Magnet for Injection

SLIDE 7

Optics Design for PRISM-FFAG

Large Transverse Acceptance horizontal > 20000 pi mm mrad vertical > 3000 pi mm mrad Long Straight section to install RF cavities

requirements

magnets : large aperture and small opening angle. non-linear effect and magnetic fringing fields are important to study the beam dynamics of FFAGs.

SLIDE 8

conventional method

Dr. thesis of M.Yoshimoto

PoP-FFAG(KEK)

SLIDE 9

new method to study dynamics

to study : acceptance (H,V) tune tune shift beam size etc parameters : number of cell FD,DFD,FDF k value F/D ratio gap size

quasi-realistic magnetic field 3D tracking by geant3.21

can model realistic fringing field

SLIDE 10

How to make quasi-realistic 3D magnetic fields

step 1 : calculate magnetic field (Bx(~Bθ),Bz) of each z-θcross sections (r1-r5). x-axis is considered as θ-axis (approximation). step 2 : convert the field (Bθ,Bz) to (Bz,Bθ,Br) by using Maxwell eq.

Bz(zi) = By(zi) B

θ (zi) = Bx(zi)

Br(zi) = dBz dr      

(Z i )

(Zi − Zi−1) + Br(Zi−1)

step 3 : to make a fine mesh field map, apply a 2D spline interpolation to the above field map.

r1 r2 r3 r4 r5 r x(θ) z

F magnet D magnet D magnet field clump field clump

MAGNET CYCLE = 3420

F D D

z x(θ) r

SLIDE 11