Minutes of 21th FFIR meeting on 1/24/2001

The meeting was held in a room of 3-425 at KEK, 13:30-14:30, 1/24/2001. We have (1) present status of support tube prototype R&D by H.Yamaoka and (2) discussed on the 0th draft of the ACFA report.

(1) Present status of support tube prototype R&D (transparencies, 5 pages, pdf ,1.14MB ) Yamaoka first reviewed the previous problem which has been speculated as a gain-calibration issue. However, it was resolved by a proper definition for outputs of the power spectrum(FFT) in a unit of dB. Assuming a sine-wave like oscillation with a peak voltage of V, the (logarithmic) power, dBV is defined by dBV = 10 log(V_rms)^2 = 20 log(V) -3 because of V_rms = V/sqrt(2). At the previous meeting, we thought dBV=10 log V^2, then we incorrectly compared V'=10^{dBV/20} and V. We should compare V'=10{(dBV+3)/20} and V. With this correction, two independent measurements are consistent. The ANSYS predicts the first and second resonance frequencies (eigen modes) at 33 and 207 Hz, respectively. The first resonance was observed as expected. However, several resonant oscillations were also observed at other frequencies. Analyzing oscillations along the prototype tube, the major reason was speculated to be due to a rigidity of the support tube, that is, the present support is not rigid enough for the direct comparison with the ANSYS calculations assuming a perfect rigidity.

(2) Discussion: ACFA report The first version( pdf,20 pages, 1.27MB or report.0.tar.gz(all tex files), 2.77MB or enter a directory of report.0 ) was shown at this meeting. There were many comments to update the draft. (1) A section of "JLC parameters" should be moved to "Project overview" and K.Yokoya will rewrite the section. (2)While background and mask designs are based on a JLC model of B=2Tesla and L*=2m, the report must include new and updated estimation/design based on the JLC model of B=3Tesla and L*=4.3m which have been studied by Y.Sugimoto. (3) "Neutron background" will be re-written by A.Miyamoto, which is based on a Fluka Monte Carlo simulation. (4) Hawaii group (H.Yamamoto and A.Giauluca) will write a section of "Pair monitor". (5) Taiwan group can update a section of "Luminosity monitor and active mask". (6) H.Yamaoka will rewrite a section of "support system" which is expected to include some results from R&D of the prototype. (7) K.Kubo will re-write a section of "Dump line". (8) H.Yamaoka also prepare a chapter of " Detector Magnet". We also discussed on possibilities of new sections of "Superconducting final quadrupole magnets" and "new FF optics" since they are closely related to the new IR design as mentioned above in (2). The deadline of these updates is 2/7/2001,the next meeting. Submissions should be e-mail to Tauchi (toshiaki.tauchi@kek.jp ), whose format is free at least text-file, however tex files are prefered.

The next meeting will be on 7 February (Wed.), 2001 13:30 - 15:30 at 3 gokan, 425.