Minutes of 36th FFIR meeting on 3/28/2002

The meeting was held in a room of 3-425 at KEK, 13:30-15:00, 3/28/2002. We discussed on the present status of support tube R&D and preparation of magnet configurations at final focus system and dump line.

(1) Support tube R&D (H.Yamaoka)

(transparencies, 5 pages, pdf ,600kB ) Vibration-properties of a cantilever arm have been measured at multiple(18) positions along the arm of 20t x 100w x 695L in mm. The arm was oscillated with about 0.2G acceleration and frequencies swept in f=3 and 1000Hz. One measurement took about several seconds, then 50 measurements were averaged for a result. Five resonant frequencies were measured at 30, 188, 419, 584 and 992Hz with vibration-patterns, which should be compared with ANSYS calculations (31, 192, 457, 534, 1022Hz). These frequencies agree within 10%. For further comparison, MAC( Modal Assurance Criteria) test was done by using FFT-elements on the resonances, where MAC=1 and 0 corresponds to perfect and no agreement, respectively. All MAC-values are expected to be 1 for perfect models in calculations. However, the third resonance has significantly low MAC-value. Since the third resonance has large twisted component, the oscillation pattern can be affected by "small differences" of accelerometer-sensitivities to be well calibrated.

Damping coefficients were also measured at each resonant frequency, whose results are consistent with expectations.

Vibration-properties of two "identical" arms, which have been constructed with same structure and support-mechanism, were measured with two "identical" oscillators. The two FFT results were different especially at high frequencies. Very careful assemble ( bolting etc. ) must be required.

(2) Magnet configurations for background estimations by GEANT

Although K.Kubo showed a list of magnet properties (location, length, field strength) at the dump line as follows, the apertures must be provided for designs of magnets. Also, beam profiles at the magnets are needed for the designs. He will prepare the distributions at all magnets. The dump line design should be based on superconducting final focus magnets for the most severe backgrounds expected. The magnet configuration of final focus system will be provided by N. Yamamoto.
Magnet parameters in present (tentative) dump line design. 
(K.Kubo, 2002.03.28)
Name	 S(m)	     Length(m)	   B'(T/m)
QF1   0.1285D+02   0.3000D+01   0.1317D+02
QD1   0.1625D+02   0.3000D+01   0.1207D+02
QD2   0.6145D+02   0.3000D+01   0.4907D+02
QF2   0.6485D+02   0.3000D+01  -0.6700D+02
Name	 S(m)	      Length(m)	    B(T)
BH1   0.2125D+02   0.5000D+01   0.1039D+01
BH2   0.5625D+02   0.2000D+01  -0.1660D+01
BV1   0.6805D+02   0.3000D+01   0.8970D+00
BV2   0.7425D+02   0.3000D+01  -0.8969D+00
BV3   0.8875D+02   0.5000D+01   0.1001D+01
BH3   0.1038D+03   0.5000D+02  -0.8342D+00
S(m): Distance from IP to the entrance of each magnet. 

The next meeting will be on 11 April (Thu.), 2001 13:30 - 15:00 at 3 gokan, 425.