1. Floor Movement Measurement at ATF Ring
ATF2 meeting at KEK December 19, 2006
Floor Movement Measurement
at ATF Ring
R. Sugahara, M. Masuzawa, H. Yamaoka
Measured on October 31, 2006 P1

2. Floor movement was measured at the ATF ring on October 31, 2006
using two STS-2 seismometers of Streckeisen.
- Spec. of STS-2
Range in frequency – 50 Hz
Sensitivity 15 V/kine
(* kine = cm/sec) P2

3. Measurement Area
(Max. L w/o exp. joint ~ 27m) X Y P3

4. at ATF Ring
October 31, 2006 X Y P4

5. Power Spectral Density for L=0

6. Integrated Spectrum for L=0

7. <Coherency in X>
(a) Huddling test
<Coherency in X>
(e) L = 12m
(b) L = 2m
(f) L = 17m
(c) L = 4m
(g) L = 22m
(h) L = 27m
(d) L = 7m P7

8. <Coherency in V>
(a) Huddling test
(e) L = 12m
(b) L = 2m
(f) L = 17m
(c) L = 4m
(g) L = 22m
(h) L = 27m
(d) L = 7m P8

9. <X-direction> <V-direction> Coherency when stamping
(c) L=27m, quite
(a) L=27m, quite
(b) L=27m, stamping at L=22m
(d) L=27m, stamping at L=22m P9

10. === Expansion joint ===
Coherency
with Exp. Joint
(a) Huddling test
(e) Huddling test
<X-direction>
<V-direction>
(b) L = 1m
(f) L = 1m
=== Expansion joint ===
(c) L = 3m
(g) L = 3m
(h) L = 5m
(d) L = 5m
P10

11. Estimated Frequency Area of Good Coherency
versus Distance, L
P11

12. Estimated Wave Velocity of Floor Motion
Assuming: wave length ~ 2*L
Velocity = 2*L*f
P12

13. Summary
- Floor movement was measured at ATF ring with two STS-2 seismometers.
- Measurement was made at two points with various distances and coherency
between two points was analyzed.
- Coherent area in frequency was roughly estimated and plotted as a function of
distance.
- Assuming a distance (L) is a half of wave length, the velocity of the
propagating wave was estimated. The velocity looks independent of L
in X and vertical direction, and looks proportional to L in Y direction.
What does this mean?
- Coherency was also measured crossing an expansion joint of the floor.
Plot of coherent area in frequency versus distance looks almost the same
to that for measurement without crossing expansion joint. So the main source
of the floor movement is speculated to be a motion of the earth, not the surface
wave propagating the floor.
P13

14. <<< --- >>>

15. L=3m across an expansion joint

16. L=3m across an expansion joint

17. <Y-direction> (a) Huddling test (e) L = 12m (b) L = 2m
(b) L = 2m
(f) L = 17m
(c) L = 4m
(g) L = 22m
(h) L = 27m
(d) L = 7m