Design and construction of SMART

Presented by Seigo KatoNov. 12, 2005

http://www.quark.kj.yamagata-u.ac.jp/~kato

Characteristics of a fixed-angle spectrometer

Advantages cascade mode selectable resolution future extension (3-rd dipole) zero-degree measurement (beam stop at first stage) trace back to the target by double position detection no need of rotation mechanism and space heavy shield for detectors neutron TOF

Disadvantages need of beam swinger need of arbitrary-angle twister beam dump

to be discussed in this report

Layout of the experimental hallsThe concrete is not strong here.

Selectable resolution

41 % 20 msr 1/4000

4 % 10 msr 1/13000

Possible extension: a super-high-resolution mode

Ray-tracing

Beam swinger

For the angular dependence measurements, the incoming beam direction is changed instead of the outgoing particle direction.

pre-assembling at manufacturer’s factory

configuration: DQQD

bending: - 45 and +135 deg

designed by H. Shimizu

Arbitrary-angle beam twisterBecause the direction of the dispersion in the beam swinger has to be within the median plane, we need a beam image rotator for arbitrary angles.

)sin(

)sin(

)cos(

)cos(

sin

sin

cos

cos

cos0sin0

0cos0sin

sin0cos0

0sin0cos

'

')(

B

A

B

A

B

A

B

A

y

y

x

x

S

effect of rotator S()

1-000

01-00

0010

0001

)(

cos0sin0

0cos0sin

sin0cos0

0sin0cos

)(

ST

invert-rotator T()

before inversion

after inversion

Graphical understanding of the invert-rotator T()

is easy to obtain and is not inferior to as a rotator.

1*00

0100

001*

0001

3Q

Q-triplet is an incomplete inverter because we cannot specify *’s.

A Q-septet rotated by /2 can rotate the beam image by after vertical inversion.

)0(

1000

0100

0010

0001

TQ7

Q-septet is a complete inverter.

reference: S. Kato, Nucl. Instr. & Meth. A254(1987)487

How to make a vertical inverter

Asymmetric quadrupole magnets between horizontal and vertical directions

Bottom yokes of Q1 and Q2 are open for the beam dump.

Q1

Q2

Q3

left halves:

field line curves

right halves:

field strength contours

(convenient for Q-magnets)

Quadrupole magnets before installation

Q1 magnet being painted

Q3 (left) and Q2 (right)

Total system installed

reference: T. Ichihara et al, Nucl. Phys. A569(1994)287c

Performances

What was SMART for me from technical viewpoint?

A big challenge to overcome many problems

Hints to subsequent spectrometers QQD spectrometers such as BBS, HKS, HES fixed spectrometer proposed for GSI eA-collider

Farewell to SMART

I would like to express my thanks to the collaborators