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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
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)
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