Floor Tilt and Vibration Measurements for the ATF2

1
Floor Tilt and Vibration Measurements for the
ATF2

• Mika Masuzawa ,KEK
• IWAA06
• 29 September, 2006

2
Contents

• Introduction
• ATF
• ATF2
• Measurements
• Comparison between ATF and ATF2
• Tilt measurements
• ATF
• ATF2
• Vibration measurements
• Comparison
• Variation at ATF2 (day to day)
• Summary

3
1. Introduction ATF

• ATF (The Accelerator Test Facility)
• ?Built for RD work for a future
  electron-positron linear collider.
• ?Produce, measure and control a very low
  emittance beam.
• Construction
• ?started in 1993
• by adding the damping ring to the pre-existing
  injection linac in the assembly building.
• Reinforcement of the floor was needed.
• A special foundation with more than 200 piles, 1
  m in diameter and 14 m in length, was used.
• Many expansion joints were introduced to prevent
  the floor from cracking due to thermal expansion
  and contraction. The expansion joints also play
  an important role in damping the floor motion and
  vibration.

4
1. Introduction ATF
Lowest among the same type accelerators
Beam energy 1.28 GeV
ex 1.0x10-9rad.m
ex 1.0x10-11 rad.m
sx 70 mm
sy 7 mm
Multi bunch 0.7x1010 /bunch x 20
Circumfrence 138m
5
1. Introduction ATF2

• The ATF2 project will extend the existing ATF
  extraction line with
• an ILC-type final focus system.
• Although the ATF2 beam energy is two orders of
  magnitude smaller than the ILC beam energy, many
  features of the ATF2 are common to the ILC final
  focus system.
• The ATF2 optics design is identical to that for
  the ILC, and the natural chromaticity and the
  relative beam energy spread are similar.
• The beam will be focused down to about 40 nm in
  the vertical direction at the IP, which is only a
  factor of 5 larger than at the ILC.
• Most of the tolerances, such as the tolerances on
  magnetic field, jitter vibration and power supply
  stability, are common between the ATF2 and the
  ILC.
• The beam center has to be controlled to within a
  few nanometers at the IP.

6
1. Introduction ATF2

• With all the similarities between the ATF2 and
  the ILC ,
• ?ATF2 will be a very good model for the ILC final
  focus system and a successful commissioning of
  the ATF2 project will assist in the design of the
  ILC.

Do we need to re-do the floor outside of the ATF
area? How large is the floor motion
(tilt/vibrataion) there ?? ?Lets measure them.
7
1. Introduction ATF2
Assembly building
ATF measurements (tilt vibration)
ATF2 measurements (tilt vibration)
8
2a. Measurements

• Tilt measurements
• Leica Nivel 20 digital tiltmeter
• Vibration measurements
• Servo type velocity sensor VSE355G2
• (Tokyo Sokushin Co. ,LTD.)
• For sensor resolution and huddle test results,
• ?http//acfahep.kek.jp/subg/ir/nanoBPM/
• Servo acceleration sensor MG-102S
• (Tokkyo-kiki Co., LTD.)
• For sensor resolution and huddle test results,
• ? R.Sugahara et.al., Performance of an active
  vibration system for GLC, IWAA2004.

9
2a. Measurements Floor tilt at ATF
At ATF beam line 10/25(Mon)-11/1(Mon) Access
time to the beam area was limited.
October 2004 S M T W Th F Sa
X perpendicular to the beam line (NS) Y
parallel to the beam line (EW)
X
Y
Sensors on the floor
10
2a. Measurements Floor tilt at ATF
50mrad
Big spikes in both x/y at 1040 am
An earthquake occurred.
No clear daily motion is seen.
11
The earthquake turned out to be one of the
large aftershocks of the 2004 Mid-Niigata
earthquake. The aftershock was reported as being
magnitude6.1 (and an intensity level 6- on the
7-grade Japanese intensity scale at its origin
in Niigata prefecture). The intensity level at
the KEK area was 23.
The 1st one (M 6.8) occurred on 24th.
KEK
12
2a. Measurements Floor tilt at ATF

• No clear diurnal motion was seen.
• No clear dependence on outside air temperature.
• The floor tilt recovered smoothly after the
  earthquake.

13
2a. Measurements Floor tilt at ATF2
Not as flat as ATF Outside air temp.
dependence in x/y. X (north-south)
drifts Atmospheric pressure??
50mrad
14
2a. Measurements Floor tilt at ATF2

• A clear day and night effect, about 10 mrad
  peak-to-peak, is seen in both x- and y-
  directions.
• There seems to be a drift in the x-direction,
  which shows a weak correlation with the
  atmospheric pressure.

15
2b. Measurements Floor vibration
Chiller pump
Green floor
Concrete shield
2 m
Yellow floor
Floor paint removed For tilt measurements
16
2b. Measurements Floor vibration amplitude
comparison between ATF and ATF2
X
V
Y
ATF2 (red) vibrates more than ATF(blue), especiall
y in vertical. ?could be a problem
17
2b. Measurements Floor vibration comparison
between ATF and ATF2
vertical
ATF2
ATF
Both measrured by acceleration sensors _at_1400
April 1, 2004.
18
Amplitude of ground motion
M.Masuzawa
Presented at LCPAC at KEK,March 2006 by Andrei
Seryi
19
2b. Measurements Floor vibration comparison
between ATF and ATF2

• We should try to damp the ATF2 floor vibration,
  to the level of the ATF area, by reinforcing the
  structure.
• Especially since the amplitude of a girder is
  larger than that of a floor.?see the next slide
  for an example.
• We recommended that the ATF2 floor should be
  reinforced.

20
Vibration amplitude
10
The amplitude ratio of the vibration of the
girder at the ATF beam line to the floor nearby.
The present ATF girder vibrates more, by an order
of magnitude than the floor!
21
What we will do

• The position of the final doublet quadrupoles
  (FD) must be stabilized to a few nm vertically
  and 50 nm horizontally.
• Motion of FD with respect to the IP is most
  critical.
• FD and IP will be installed on a common rigid
  support at ATF2 to reduce their relative motion.
• IF FD were to be mounted independently from the
  IP (ILC), an active stabilization system will be
  needed.
• High speed (gt 10 Hz) and high resolution (
  sub-nano level).
• Such system might be tested at ATF2 (yesterdays
  talk by
• Morita)

22
2b. Measurement ATF2 floor vibration (5
days)day to day variation
December 2004 S M T W Th F Sa
Weekend effect? Quieter
Sunday
Date
23
2b. Measurement ATF2 floor vibration ,day to
day variation
Anti-weekend effectfor low-frequency ( f gt
0.3Hz) floor vibration
Anti-weekend effect is significant (several
times larger) in X and Y. Not much effect in
V. Why?
Sunday
Exceeds 1 mm
24
It was a very windy weekend
Wave height and wave period at Port of Onahama
Sunday
25
ATF2 floor (yellow)
2nd peak appears when the wave height was big.
ATF2 floor (Green)
26
ATF2 floor vibration, wind speed and wave height
0.1Hz component follows wave height??
0.3Hz component follows wind speed??
Floor vibrates on windy days. Unfortunately no
data taken over this weekend at the current ATF
beam line.
27
Summary

• The diurnal effect in the floor tilt is a few
  times larger in the ATF2 beam extraction area
  than in the ATF beam line area.
• The peak-to-peak daily tilt was measured to be 10
  mrad in the ATF2 area when the outside air
  temperature varied by 15 degrees. There was no
  such daily tilt in the ATF area.
• An earthquake occurred during the measurement at
  the ATF area, but the floor tilt recovered
  smoothly.

28
Summary

• The floor vibration is also larger in the ATF2,
  especially in the vertical direction. The
  vibration amplitude at 10 Hz is 50-60 nm in
  vertical, which is larger than the vertical beam
  spot size expected by the ATF2.
• The ATF2 floor motion is significantly affected
  by strong wind and/or waves. This could be a
  result of the beam line being on the surface of
  the ground.

• Reinforcement is needed in the ATF2 area.

• Will be done as part of the ATF2 construction.

• Stay tuned and see how well we can stabilize the
  beam at the ATF2.
• (with reinforced floor, good girder/mover,
  active stabilization system(?))