Muon Front End for PRISM

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23 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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J. Pasternak

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),



-

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
!



J. Pasternak

Pion/Muon Transport

Kickers

Vertical Septum


Vertical dispersion

matching

Negative

v
ertical

deflection corrector

Vertical
dispersion

suppressor


Solenoidal

matching cell

Bend solenoidal

channel in „Pi/2

Pi/2”

configuration

(to compensate

the drift)

FFAG line

for betatron matching

(J
-
B. Lagrange)


Dispersion

Creator

(
Orbit matching
)

The goal
-

70% muon transport

efficiency!

This design is under studies within the
PRISM

Task Force
.

Quad matching


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
solenoidal

muon

transport and
matching

From the target to adiabatic matching

Betatron

function [m]

z[m]

z[m]

B in T

Target

Matching

point

Solenoidal

field

Central momentum

“+20%”


-
20%”



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.


J. Pasternak

Optics

and B field in
solenoidal

muon

transport and
matching (II)

Matching

point

B in T

Solenoidal

field

z[m]

Betatron

function [m]

z[m]

Central momentum

“+20%”


-
20%”

Solenoidal

matching section


Betatron

functions needs to be


matched to AG channel (~ 1
-
4 m).


Solenoidal

field needs to be


smoothly switched off.


J. Pasternak

the vertical layout of the AG part of the front end

Beam direction



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).

Quad

matching

Dispersion

Creator

Injection Septum

Achromatic Dispersion deflector

Straight FFAG matching section

Horizontal Layout of the
Muon

Front End for PRISM

PRISM

FFAG

FFAG ARC (Part of the Dispersion Creator)


Ring and the solenoid are well

s
eparated in space.



The main challenge is the room

a
round the injection septum

Solenoidal

c
hannel

Straight FFAG matching section

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
MuSIC

at RCNP



in Osaka.