Minute of the CDC Group Meeting held on 24-May-01 (10:25-12:45 at Fuji-F2). [0] We now have a new member of the JLC CDC group: Kuboshima Rie-san from Tsukuba University (M1). (She likes to play basketball and to watch stars.) [I] Reports on the present status 1) Kuroiwa-kun a) He looked closely at the events which provide densely populated small signals in the region close to the sense wires in the plot of pulse height vs. drift distance shown in the previous meeting. He found two types of problematic events: i) events with only very small electric noises somehow synchronized to the triggers; ii) events with a track poorly reconstructed using hit points associated with minor (secondary, tertiary....) peaks in the sense wire signals. The peak hunting part of the analysis program is sophisticated enough to deal with double or multi-track events while the track finding part is not yet refined enough correspondingly. A "single shot discriminator" algorithm may work better for cosmic ray tracks. Therefore the excess of small signals can be removed simply by ignoring hit points with small assigned charge, without any loss of efficiency. b) He is now accumulating cosmic ray tracks using the baby chamber with 20 ppm of oxygen. The spatial resolution seems better than that obtained with 50 ppm of oxygen. But he needs more statistics for 20 ppm data in order to draw a conclusion. *) The reason why the events with only electric noises are contained in the data is not understood. *) An improved algorithm for track finding (pattern recognition) has to be applied in a real multi-particle environment in which hit points associated with "minor" peaks can not be ignored. *) Gas flow rate has to be increased to reduce the oxygen content to a 20 ppm level because of limited gas tightness of the baby chamber. Where has the flammable gas detector once we had gone? *) He should estimate the life time of drift electrons as a function of oxygen concentration from the charge attenuation measured. *) Is the paper now in preparation going to include the beam data results and/or the influence of oxygen contamination? Both should be included (Kobayashi's personal opinion). 2) Hoshina-san For her talk on the development of the simulator program using Geant4 please take a look at http://www-jlc.kek.jp/~hoshina/cdc/meeting/CDC_Meeting/ CDCMeet20010524.ps.gz . 3) Hashiguchi-kun He is now preparing a DAQ software using ROOT. The performance of the software and the VME-based electronics is going to be tested as soon as a prototype FADC module and a VME CPU Board become available. The new DAQ system including the VME FADCs will be ready for the experiment at the KEK PS scheduled in this fall. *) He and his colleagues have decided to use a VME CPU board instead of a "VME crate controller" assuming a large amount of data per event to be handled at a high trigger rate since i) data transfer is much faster between a PC and a CPU board than in the case of a PC and a "crate controller ii) data selection and compression can be carried out within a fast VME system. 4) Kobayashi a) A brief summary of the activities of the JLC CDC Group so far. Now only the Japanese version is available. ==>> activities.ps b) He calculated the most probable energy loss as a function of p/mc using the empirical formula given by R.M.Sternheimer and R.F.Peierls. Agreement with our data seems satisfactory in the 1/beta**2 region and poorer on the Fermi plateau ( ==>> fig1.ps). The calculated values may be too large in the relativistic rise region as in the case of Argon based gases. However as for carbon dioxide the Monte-Carlo calculation by J.H.Cobb and W.W.M.Allison is in good agreement with that given by the formula used ( ==>> fig2.ps). It should be noted that our data points were obtained by applying a truncated mean method, which should be replaced with those given by Landau-distribution fitting. Hayasaka-kun is expected to do this job. II] What to do in this fiscal year a) Tension measurements of the wires of the 4.6 m chamber, which is now six years old, and realistic calculations of the expected wire sags due to electrostatic force especially for the sense wires. Kato-kun will be in charge of this. b) Study of the wire material to be used for the field wires (by Kato-kun?). Aluminum or copper beryllium? Another possible candidate is a gold plated carbon fiber. c) Beam experiment place: KEK PS (T1 beam line) time: This fall (November?) subject: A study of the influence of positive ions on the performance of a jet-type chamber filled with a cool gas (TENTATIVE). *) The proposal for the experiment will be prepared at TUAT. *) A short text describing the motive of the experiment and the basic idea will be written by Kobayashi. # The Japanese version has already been prepared. ==>> proposal.ps !) Any other proposals, ideas, suggestions are welcome in order to make the beam time productive. III] Others *) Themes of master theses of the students from Tsukuba University. Kumano-kun: Study of the isochrones using the baby chamber and the simulation by GARFIELD. Ichizaki-kun: Analysis of the beam data taken with the Baby chamber. Kuboshima-san: Development of the simulator using Geant4? # Their progress will be reported at the next meeting. *) The next CDC meeting will be held on June 21st (Thu) from 10:00 at the Room 425 in the Building No.3. ====================================