Prévessin, 6 November 2014
APERTURE STUDY ON THE PSB
EXTRACTION AND RECOMBINATION LINES
J.L. Abelleira, W. Bartmann. J. Bourburgh
Thanks to: g
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Aperture study of present septa
Comparison with future septa
Study including extraction
Study possibilities to increase aperture (more kicker strength…)
Could we install the lengthened septa in the present machine?
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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From PS BOOSTER
SMV20
SMV10
The BT transfer line
3 septa
1.4 GeV 2.0 GeV
B x1.3  Bdlx1.3
995
1225
1064
1300
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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B
B
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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Beam size definition
Beam size definition
(Half) beam sizes computed as
𝐴𝑥,𝑦 = 𝑛𝑠𝑖𝑔 ∙ 𝑘𝛽 ∙ 𝛽𝑥,𝑦 ∙
𝜖𝑁;𝑥,𝑦
γ𝑟 β𝑟
+ |𝐷𝑥,𝑦 σ | + 𝐶𝑂 ∙
𝛽𝑥,𝑦
𝛽𝑀𝐴𝑋;𝑥,𝑦
CO = 1.5 mm
Ek = 1.4 GeV
𝑘𝛽 = 1.2
𝜖𝑁,𝑥 [m] 𝜖𝑁,𝑦 [𝑚]
𝜎
LHC
2
2
1.07x10-3
Fixed target
10
5
1.35 x10-3
ISOLDE
15
9
1.35 x10-3
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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Orbit comparison
dbt1bvt10
dbt1smv10
dbt4bvt10
dbt4smv10
dbtbvt20
dbtsmv20
Element
Bending magnet
Septum
Bending magnet
Septum
Bending magnet
Septum
Present [mrad]
76.80
73.56
76.80
73.56
74.17
71.31
Upgraded [mrad]
75.27
72.03
75.27
72.03
72.82
69.96
future
septum
Present
septum
In order to
to keep same orbit at
SMV exit, trajectories are
rematched
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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Present
Upgraded
Gap height
(horizontal plane) [mm]
60.4
60.4/62.0
Gap width
(vertical plane) [mm]
102
102
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
blade thickness
[mm]
5
5
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Wider septa apertures do not allow more beam
nnsig
=1.5
=1.0
sig
=2.0
=2.3
sig
sig=2.5
Limitation in
septum blade,
coming from
distance
between beam
centers
No Limitation
here
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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1. BT1.SMV10
PRESENT
FUTURE
Blade: 5 mm
Vertical
Horizontal
Present
Upgraded
Present
Upgraded 62.0 mm
Upgraded 60.4 mm
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
ISOLDE
2.6
2.5
2.5
2.6
2.5
Fixed target
3.5
3.4
3.1
3.1
3.1
LHC
5.6
5.4
7.1
7.2
7.0
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1. BT4.SMV10
PRESENT
FUTURE
Vertical
Horizontal
Present
Upgraded
Present
Upgraded 62.0 mm
Upgraded 60.4 mm
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
ISOLDE
2.6
2.5
2.5
2.6
2.5
Fixed target
3.5
3.4
3.1
3.1
3.1
LHC
5.6
5.5
7.1
7.2
7.0
10
BT.SMV20
PRESENT
FUTURE
Vertical
Horizontal
Present
Upgraded
Present
Upgraded 62.0 mm
Upgraded 60.4 mm
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
ISOLDE
2.0
1.9
3.0
3.1
3.0
Fixed target
2.7
2.6
3.9
3.9
3.8
LHC
4.2
4.2
8.7
8.8
8.6
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Extraction septum
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No additional limitation found in PSB extraction septum BE.SMH (3.0 σx, 5.5σy for ISOLDE beam)
No additional limitation found in extraction kicker
Circulating beam
Extracted beam
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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Recombination orbits
As the limitation comes from the
distance at the exit of the septa, more
beam will fit if the distance is increased
Recombination
quadrupole of
integrated strength kl
1
f=𝑘
𝑙
But this fights against the kickers, as more kicker strength is needed!
LIU-ABT systems : PS. Beam parameters
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Recombination orbits
Another solution would be to move the quadrupole, but not enough space between
septa and quad
For these reasons, the present recombination geometry is kept.
LIU-ABT systems : PS. Beam parameters
14
Situation with present beams
Richard Catherall
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For the moment (and for the last 10 years) there are no specific requests for a primary
proton beam energy at 1.0 GeV for any experiments at ISOLDE.
The 1 GeV beam is therefore not essential to the ISOLDE physics program and to the best
of my knowledge, there are no plans to request this primary beam energy in the future.
The possibility to switch between 1.4GeV and 2 GeV is of great importance as the
different energies are required for an optimal production of specific isotopes.
Could we install the magnets during this RUN 2?
worst-case energy case would be the same: 1.4 GeV
I expect a very small difference in beam losses from the present situation.
I will give the exact number.
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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Conclusions
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With the present recombination geometry, the limiting factor in aperture is the distance between
the center of deflected and undeflected beams at the exit flange of the septum.
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For the reason explained above, an increase on the gap width is not justified.
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With the new septa there is a small reduction in the vertical aperture that comes from the increase
in length, but this value is very small (in the order of 1/10 sigma)
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An increase of the gap height (horizontal aperture) gives a very small gain (1/10 sigma in the best
case) so in principle is better to keep the same dimension.
APERTURE SPECIFICATION OF PSB-PS RECOMBINATION SEPTA
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