Title: Floor Tilt and Vibration Measurements for the ATF2
1Floor Tilt and Vibration Measurements for the
ATF2
- Mika Masuzawa ,KEK
- IWAA06
- 29 September, 2006
2Contents
- Introduction
- ATF
- ATF2
- Measurements
- Comparison between ATF and ATF2
- Tilt measurements
- ATF
- ATF2
- Vibration measurements
- Comparison
- Variation at ATF2 (day to day)
- Summary
31. 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.
41. 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
51. 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.
61. 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.
71. Introduction ATF2
Assembly building
ATF measurements (tilt vibration)
ATF2 measurements (tilt vibration)
82a. 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.
92a. 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
102a. Measurements Floor tilt at ATF
50mrad
Big spikes in both x/y at 1040 am
An earthquake occurred.
No clear daily motion is seen.
11The 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
122a. 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.
132a. Measurements Floor tilt at ATF2
Not as flat as ATF Outside air temp.
dependence in x/y. X (north-south)
drifts Atmospheric pressure??
50mrad
142a. 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.
152b. Measurements Floor vibration
Chiller pump
Green floor
Concrete shield
2 m
Yellow floor
Floor paint removed For tilt measurements
162b. 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
172b. Measurements Floor vibration comparison
between ATF and ATF2
vertical
ATF2
ATF
Both measrured by acceleration sensors _at_1400
April 1, 2004.
18Amplitude of ground motion
M.Masuzawa
Presented at LCPAC at KEK,March 2006 by Andrei
Seryi
192b. 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.
20Vibration 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!
21What 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)
222b. Measurement ATF2 floor vibration (5
days)day to day variation
December 2004 S M T W Th F Sa
Weekend effect? Quieter
Sunday
Date
232b. 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
24It was a very windy weekend
Wave height and wave period at Port of Onahama
Sunday
25ATF2 floor (yellow)
2nd peak appears when the wave height was big.
ATF2 floor (Green)
26ATF2 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.
27Summary
- 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.
28Summary
- 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(?))