ILC CDC group KEK subgroup weekly Monday meeting
16:00- 25 July 2007

Attended by Fujii, Kuroiwa, Matsuda and Yonamine.

I. Work at the cryogenic center (16:00-17:00 together with Sugimoto san):

Since Sugimoto san has finished his measurement on CCD, we re-installed
the MP-TPC into the magnet and has started the data taking with cosmic
rays at 1T for Ar/CF4/Isobutene (96:3:3).

II. Discussions (17:00-18:00):

(A) The basic characteristics of the Ar/CF4/Isobutene gas mixtures by the
Garfield simulation(Yonamine):

So far the calculations were made to find:
(a) Drift velocity (see Fig. 1)
(b) Transverse diffusion (Fig 2)
(c) Longitudinal diffusion (Fig. 3)
(d) Attachment (so far only a test calculation at 1T and 2kV)

Please see the figures (in the attached File-1) for details. He
plans to calculate these parameters for the magnetic fields of 0T, 1T, 3T
and 4T with the Isobutene concentration of 0% (to check the results by
comparing to the calculation by a Saclay student)、1% and 3%. We fix the CF4
concentration to be 3% tentatively.

(B) The manual of the analysis program (Yonamine):
In progress.

(C) Resister box (Kuroiwa):

After a short discussion on the operation condition of LC TPC, we
agreed to take the cosmic data for the Ar/CF4/isobutene gas mixtures with
the drift field of around "100V" and 200V. We need to prepare a new resistor
box for 200V.

(D) MFC:

TM is to consult with the company for the easiest way of the MFC
calibration to improve the accuracy of the gas concentration beyond 1% of
the full scale.

(F) Plan of data taking:

We plan to continue the data taking at 1T with the isobutene
concentration of 3% for a week to accumulate about 60k events. Then, we move
to 3%. We keep the CF4 concentration of 3% unless we find a good reason to
change it.

(G) Next meeting:

On July 5, 2007 at 16:00 (R222). After this meeting we will have
the TV meeting with Takeshita san on the MPPC.